X-43A Hits Mach 7

quiggy writes "As previously reported, NASA tested the X-43A yesterday. The results are in, and the scramjet hit Mach 7, setting a new speed record. CNN is also reporting the story, with a note that a similar jet could be tested by the end of the year, hopefully reaching Mach 10."

Comments

But at that speed...

[Alt_Cognito]

They will need to go back and save the whales etc...

Re:But at that speed...

[xs650]

The artilce that you linked to said

"Paul said although signs so far are positive, it still is too early to say the scramjet experiment succeeded. The scramjet experiment took place during the final few seconds of the flight, which lasted almost 10 minutes."

A quick search with google also did not turn up any reports of confirmed success. Do you have any?

Re:But at that speed...

[shthd]

I don't know if there is an independant peer review of their data but from their web site University of Queensland Hyshot Program Nasa's own press release doesn't say that they broke any records.... Either way Kudos to NASA....maybe now we'll get cheaper access to space

sublight speed ;)

[Janek Kozicki]

1 mach = 334 m/s ,
10 mach = 3340 m/s = 3.3 km/s ,
speed of light c = 300 000 km/s ,
(3 km/s)/(300 000 km/s) = 1/100 000 of c

this engine travelled at aprox 0.00001c !

good work scientists :)

Re:sublight speed ;)

[RadRafe]

That's nothing. You should see how fast they get those "electron" hot rods going.

Re:sublight speed ;)

[tomstdenis]

The true question is what is the comparison to the speed of lint? ;-)

Re:sublight speed ;)

[ewithrow]

Of course, rockets launched into space have to travel at least 11.18 km/s to reach escape velocity, which is a lot faster than mach 7. This isnt a speed record, really more of a design change in that the engine doesn't need to carry its own oxygen.

Congrats to NASA though.

Re:sublight speed ;)

[Fisher99]

So officially they can now call them sublight engines.

Re:sublight speed ;)

[Anonymous Coward]

I've always been under the impression that escape velocity is if a projectile was fired at ground level, and has no boosting at any later point. Space rockets are continiously accelerated upwards, and thus dont need to reach such speeds.

Re:sublight speed ;)

[Anonymous Coward]

Google calculator: 7.94559682*10^-06 c.

Re:sublight speed ;)

[Anonymous Coward]

Umm isn'c c == 300 000 m/s??

Re:sublight speed ;)

[Anonymous Coward]

Right, but once it is in space the game is different entirely. Speed is the name of the game if you want to get anywhere before your dead. I think that it is the speed in space that he is referencing.

Re:sublight speed ;)

[Anonymous Coward]

No.

Re:sublight speed ;)

[the_2nd_coming]

it is a speed record for air breathing engines.

Re:sublight speed ;)

[fredrikj]

Indeed. You need to account for friction, though. Wikipedia article on escape velocity.

Re:sublight speed ;)

[Kiryat Malachi]

Uhm.... no. You are correct in your definition of escape velocity, but orbiting spacecraft reach speeds just about as fast.

Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface. Thus, when Shuttle is orbiting at 300km altitude, it is traveling at 7.73 km/sec. In order to achieve that orbit, it has to achieve that speed, tangential to the direction of gravity. It can do this (neglecting friction) in one burst at ground level, or over time, but it has to hit that speed to hit orbit.

Re:sublight speed ;)

[Uber Banker]

Speed is a number and velocity is a vector. So an escape velocity can vary in speed as the angle of escape changes.

If space rockets are perpendicular (well, they're not really) to the tangent of the atmosphere on exit, their speed still has to be enough to let them escape, but this speed can be really low - I take it implicitly you mean the firing of the rocket is necessary to overcome gravity rather than to reach a certain speed. Conversly, planes in the outer atmosphere can go really fast (speed) but as their velocity does not have a vector pointing upwards they won't exit.

Acceleration has little to do with it other than making the escape more efficient (of course the rocket changing vector is also acceleration).

Re:sublight speed ;)

[SillyNickName4me]

It is a speed record for a vehicle driven by an air breathing engine (ie, it gets its oxygen from the atmosphere)

Rockets have gone faster, but they carry their own oxygen.

Re:sublight speed ;)

[TheF00]

Actually the record that was broke was the fastest air breathing vehicle. Rockets launched into space have to carry two propellents to achive those speeds. A ramjet scoops in oxygen from the atmosphere as the second propellent rather than carrying its own supply.

Re:sublight speed ;)

[AndroidCat]

Rockets still have to reach escape velocity, regardless of how long they boost. However you're right about ground level--the further away, the lower the escape velocity required.

If I jumped in a '57 Space Coupe (2457) and gunned it for the stars at a constant 120 MPH, after a very long time, I'd be far enough away that escape velocity would have come down to 120 MPH and it would be safe to switch off the ignition.

Re:sublight speed ;)

[Maimun]

So an escape velocity can vary in speed as the angle of escape changes.

Wrong! It absolutely does not matter which direction the velocity vector points to. All that matters is the kinetik energy of the body. The kinetic energy is 1/2 * m * (v^2), where v is scalar, the speed in your terminology.

See this page , it is really neat, you can compute escape velocities for different planets.

Re:sublight speed ;)

[Maimun]

Escape velocity is necessary only when you want to, well, escape the Earth :)). If you want to go into Earth's orbit, the velocity is 7.8km/s. In fact, this is the minimum velocity you need, given that the direction of the movement is perpendicular to the line that connects you with the center of the Earth, never to fall down. AFAIR, 7.8km/s is that velocity at the Earth's surface. Since there is air friction at the surface, it makes sense to consider that velocity at, say, 250km or more above the surface -- it is surely smaller there, of course, and grows smaller as you go up, because the Earth's gravitational pull grows weaker.

When I studied these things in secondary school, we called 7.8km/s, "first space velocity", and 11.2km/s, "second space velocity". I think the terms are Russian (pervaya kosmicheskaya skorosty, vtoraya kosmicheskaya skorosty).

Re:sublight speed ;)

[slim-t]

Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface.

I don't have a physics book handy, but I'm pretty sure mass has nothing to do with the velocity.

Re:sublight speed ;)

[shthd]

That's right.....mass always cancels out of the equations. It's Radius and valocity that determine orbit.

Re:sublight speed ;)

[wisdom_brewing]

speed record for air aspirated flight...

Re:sublight speed ;)

[Andy_R]

Actually, you don't need escape velocity to escape the earth. Any velocity will do if you carry on for long enough. Escape velocity is a measure of how fast you need to be moving to leave *if no additional thrust is applied*, which, given the fact that you are probably strapped to a huge big rocket if these things are relevant to you, is rarely the case.

Re:sublight speed ;)

[slim-t]

Then how did that original post get modded informative? I thought physics was pre-requisite for reading slashdot.

Seriously, there's a need for a "wrong" modifier, so people can mod such posts down without fear of recourse from meta-moderators who think the post is correct.

Re:sublight speed ;)

[MurphyZero]

The vector does come into play, because if you are travelling at twice the escape velocity, but directly at the center of the planet, you're not escaping anything. But beyond that, escape velocity is that needed for a parabolic trajectory, which, like you stated, is dependent solely on the KE. As long as the orbit will not intersect the planet, escape is possible. Also, since the parabolic is the minimum for escape, if kinetic energy dissipates (friction) before escape, then it won't escape. ALl this assumes the two-body problem and ignores any other bodies.

Re:sublight speed ;)

[shthd]

Somewhat cool story.....was way back in the early days when the Russians were putting Sputnik in orbit. The US officials asked the rocket scientists if they could tell how much mass the Soviets could launch in orbit. Alas, Werner had to dissappoint the senators.

Re:sublight speed ;)

[shthd]

Doh.....I'm gonna get flamed. I read more closely. Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface. The mass of the Earth determines the Acceleration due to Gravity; and thus the orbit for a given velocity. He's correct and i am a dumbass!

Re:sublight speed ;)

[atomicdragon]

I think the poster means the velocity's direction does not matter if you are ignoring friction. If you were to travel with escape velocity towards the center of the Earth, without hitting something, you would come out of the other side of the gravity well with the same velocity at the same altitude and would be ready to go. However, in the real world the Earth is kind of the way and hitting it at escape velocity would be one heck of demonstration of friction. In that case your velocity direction determines how your kinetic energy is divided between liquefying your craft and spreading the remaining parts across the planet.

Re:sublight speed ;)

[Maimun]

Yes, that is what I meant, thank you. Obviously, hitting something (the Earth, the Moon, a stray asteroid, GPS satellite, etc.) would be the end of the journey, but that is not the point.

Re:sublight speed ;)

[wass]

Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface.

Not exactly true. When solving the two-body system, a number of coordinate transformations change the equations of motion into a simple one-body equation that can be solved exactly. The mass in the transformed one-body system is called the reduced mass, which is defined as mu=(A*B)/(A+B), where A and B are the masses of the two bodies in question.

Assuming A>>B (ie, Earth is much greater than the mass of a satellite), this can be rewritten exactly as mu=B/(1+B/A), or w/ a first-order taylor expansion as mu=B-B^2/A. For a standard communications satellite, the second term is approximately 10^-18 times smaller, and can realistically be dropped, and the mass of the satellite is to within measurable uncertainties B.

But you're wrong in general when you say it's independent of the mass of the object it's orbiting. In the system of the moon orbitting Earth, there's about 1% error by replacing the reduced mass by moon's mass. For a more dramatic example look at a binary star system where one star has 3x the mass of another.

Re:sublight speed ;)

[Rallion]

Important to note...even in Star Wars, atmospheric ships (even the one with scramjets) can't even touch this. Actually, neither can the space-based ships, barring hyperdrive, of course.

What's up with that, Star Wars? It was already behind the game when it was new!

Re:sublight speed ;)

[rossdee]

"Orbital mechanics tells us that the velocity of an orbiting object is dependent on the mass of the object you're orbiting, and the distance you are from the surface."

Its the distance from the center of the object you are orbiting, not the surface.

Re:sublight speed ;)

[Anonymous Coward]

There is a free (beer) space shuttle simulator called Orbiter. I would recommend everyone to try it, in a few hours of experimenting you will learn so much information about space flight you will for example never post nonsense like that again *grin*.

Orbiter features more then just the shuttle, there is a slightly more powerful Delta Glider which you can in fact use to fly to Mars. And don't think it is easy, just getting to the orbit with the space shuttle will require a lot of training and reading the manual.

After two hours of so (of accelerated time of course) when I got near Mars, I was actually unable to land because of lack of fuel :(. It's a really strange feeling you get when flying on a hyperbolic curve, with no fuel, getting further and further from Mars and knowing that nothing can save you from dying in this damn spacecraft except from it being a simulation :). And yet another strange feeling is when you are descending to the Earth atmosphere with a wrong angle of attack and suddenly you just bounce of the atmosphere and Earth, there you go, hyperbolic curve again and our planet getting smaller and smaller... is that small thing Africa?

Just try it, it's a great game!

Re:sublight speed ;)

[WaKall]

Escape velocity only applies when you don't have a constant or prolonged thrust. This is the difference between rockets and bullets. A rocket need only produce force > mass* 9.8m/s*s for long enough to reach orbit, which is really only a fraction of the force it would need over a brief instant to reach escape velocity.

Force = Mass * Accelration : you've got to overcome 9.8m/s*s to beat gravity, and keep doing it to reach orbit.

Velocity = Acceleration * Time : to hit escape velocity (as in a projectile) you need to apply a crazy amount of force over a short amount of time.

Until we can produce that much force instantaneously, we're stuck with self-propelleds like rockets.

Re:sublight speed ;)

[Anonymous Coward]

Obviously, hitting something... would be the end of the journey, but that is not the point.

A theoretical physicist speaks!

Re:sublight speed ;)

[LJD65536]

The mass referred to is the mass of the Earth. While the mass of the vehicle can be neglected, orbital velocity is very much a function of the mass of the body that is being orbited. The mean angular motion of an Earth orbitting satellite is sqrt(G*m/a**3) where is the G is universal gravitational constant, a is the semimajor axis, and m is the mass of the Earth. In a circular orbit, the speed is mean motion * radius.

Re:sublight speed ;)

[mOdQuArK!]

By that standard, the two-stroke in my self-propelled lawnmower is a "sublight" engine.

Re:sublight speed ;)

[Anonymous Coward]

Well, if it points down, I think it ain't gonna escape too far... ;)

Re:sublight speed ;)

[SnowZero]

Well, it did happen a long time ago...

Re:sublight speed ;)

[rnelsonee]

No, the parent post is correct - the mass of the body you're trying to escape has everything to do with escape velocity. You might be thinking of the mass of the escaping object -- in which case you are correct - that doesn't matter.

But the original poster says the "mass of the object you're orbiting", which obvioiusly matters. The escape velocity for a small asteroid is obviously going to be different than the escape velocity of the Earth.

Re:sublight speed ;)

[Anonymous Coward]

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Re:sublight speed ;)

[Anonymous Coward]

slashdot is getting more popular everyday and the moderator pool is also less "pure geek concentrated"...

Re:sublight speed ;)

[NegativeK]

Seriously, there's a need for a "wrong" modifier, so people can mod such posts down without fear of recourse from meta-moderators who think the post is correct.

Mod it overrated. If it isn't really informative and it's modded so, take the points away - it's just as effective.

Re:sublight speed ;)

[slim-t]

You're right. I assumed the discussion was limited to escape velocities from Earth - and I took "the object you're orbiting" to mean the object you're putting into orbit.

Now I'm curious if orbiting was the correct word, because once it passes escape velocity, it will leave the orbit.

I still say we need a "wrong" modifier. Or "misinformed".

Or "drunk".

Re:sublight speed ;)

[slim-t]

Mod it overrated. If it isn't really informative and it's modded so, take the points away - it's just as effective. Overrated is a copout. How is a meta-moderator supposed to know why you moderated it down? With "wrong", meta-mods can figure out if it was indeed wrong.

Re:sublight speed ;)

[NegativeK]

With a 'wrong' mod, you end up with people disagreeing with each other over pure opinion. For instance, if someone says that MS is cool, and gives some non-flamish and non-trollish reasons why, someone can just negatively mod them to be 'wrong.'

Also, when I meta-moderate, I research things - facts, links, etc. When reviewing an informative rating, people should do as much. Maybe I'm too optimistic, though. =T

Re:sublight speed ;)

[Easy2RememberNick]

c = 299 792 458 m / s ...so it's even closer ;)

Re:sublight speed ;)

[airider]

I'm sorry, how can you say rewritten exactly when you use too assumptions A>>B and a Taylor expansion to approximate the answer. This is contradictory. The two methods you described simplify the system and make it less "exact" since it uses approximations. However, reduced mass is a decent way to solve this analytically, but to get better answers computers solve the non-simplified equations numerically.

Re:sublight speed ;)

[wass]

You must have missed the entire point of my post. I was showing how mu exactly is B/(1+B/A). This will always be true for the 2-body system. There is only one assumption I made, which was for the satellite that A>>B. This assumption doesn't do anything until it's realized with a 1st-order Taylor expansion.

The whole point of the Taylor expansion was to give an estimate of the difference between B and mu, and in this case it's -B^2/A (to 1st order). If you don't like the expansion then keep the exact form, or take the taylor expansion to higher orders.

Anyway, since you missed the mathematics of my post, here's a recap of simple Taylor expansions.

Binomial expansion : for 1>>|x| (and n not insanely large), (1+x)^n ~= 1+(x*n)

So 1/(1+x) ~= 1-x

Recall mu=B/(1+B/A) exactly. To within some specified precision, mu~=B-(B^2/A). You can compare exact to approximate answers to see what the error terms will be.

Re:sublight speed ;)

[MrScience]

What if it points straight down?

Re:sublight speed ;)

[Anonymous Coward]

So imagine that you have a rocket travelling a constant speed going straight up--let's say, 1 m/s. Furthermore, let's imagine that this rocket travels at this speed for 20 years. Then cut off the engine necessary to maintain this speed. Will it fall straight to earth?

Now, on to the orbital mechanics part.

Orbiting objects, believe it or not, are falling towards the earth. It's true! If the object weren't falling, it would go in a straight line.

Now, Galileo had something to say about falling objects... something like, if two bricks that weigh exactly the same fall at exactly the same rate when dropped side by side, why shouldn't the 2 bricks still fall at that same exact rate if they happen to be cemented together?

So, if two bricks follow the same exact orbit at the same exact speeds if they launched into the orbit side by side, why shouldn't the two bricks follow that same exact orbit if they are cemented together?

Re:sublight speed ;)

[Anonymous Coward]

perhaps this will clarrify the fact the Australia got there first.
'Successful' Scramjet needs $25m
AUSTRALIAN researchers have officially claimed the world's first supersonic combustion flight test, but they need $25 million to continue research.

International HyShot program leader Dr Allan Paull said today data analyzed from the recent test of the air-breathing supersonic ramjet engine, known as a scramjet, in Woomera showed the experiment worked.
"As far as we're aware, to the best of our knowledge, we've achieved supersonic combustion in flight for the very first time and we have measured it," Dr Paull said.
On a budget of a mere $2 million, Dr Paul's team won the honor of being first from multi-million-dollar funded projects from Japan, the United States and France.
Their history-making launch of a scramjet payload on a rocket launched from Woomera, in the South Australian desert, on July 30 will help revolutionize air transport.
The experiment saw the scramjet reach speeds of Mach 7.6, or more than seven times the speed of sound over seven crucial seconds.
When applied, the technology would substantially reduce the costs of launching satellites and could reduce flights between London and Sydney to two hours.
Dr Paull, who works out of the University of Queensland's Center for Hypersonic, said he planned to conduct 10 further test flights over the next five years.
But those plans were on hold because of a lack of funds.
The project needs $25 million from Australian investors to keep it in the country.
"Investment from overseas is welcome ... but we need investment in Australia to match that so we can keep the intellectual property in this country," Dr Paull said.
"We've asked for investment from Australia in the order of $25 million."
University of Queensland vice-chancellor Professor John Hay said Dr Paull's team's success could one day rank with Australia's most important innovations.
"Australia has proved we can develop this technology at a fraction of the cost of overseas programs," Prof Hay said.
"We must now build on success and secure the program in Australia so the intellectual property is not lost to the country.
"One would hope the federal government that's put money into Backing Australia's Ability program would see the extraordinary significance beyond Australia, as well in Australia, of this development.
"One would also expect that it forms a natural part of Queensland's Smart State development."
Search continues for scramjet engine
Monday, 5 May 2003
The team behind last year's world first successful launch of a revolutionary air-breathing scramjet engine has vowed to continue the search for its remains at Woomera in South Australia.
The University of Queensland's Dr Allan Paull says his team has narrowed the search area to five square kilometers of land on the Woomera Prohibited Area.
He says his team wants to find the engine so that it can see how well the payload held up under the strain of an 8,000 kilometer per hour journey.
"We expected it to melt - the front end of it to melt, and it seems that it has melted, it took a little bit longer to melt than we thought, which was good," he said.
"We're just interested though - the leading edges of it on certain parts of it get very, very hot and basically glow red hot when it was coming down and we're really curious to see how that material stood up to the re-entry."
as it re-entered the heavy atmosphere and subsequent air friction.
Note: that the speed was tested and recorded only during the horizontal axis and only when the scramjet engine had ignited and was running under scramjet power. (its own power)

Re:sublight speed ;)

[Anonymous Coward]

I think he was talking about the mass of the planet, not the mass of the satellite. You do need to know the mass of the planet to get the velocity.

Re:sublight speed ;)

[Wanker]

Since you're ignoring friction, this won't matter. ;-)

Re:sublight speed ;)

[Anonymous Coward]

Actually, it doesn't depend on the kinetic energy, but the total energy of the body. Depending on where you start in the gravity well, the necessary amount of kinetic energy to escape the gravity well will be different. If you're trying to escape the Earth's gravity from the moon, it's a much different problem than trying to escape the Earth's gravity from Cape Canaveral.

Re:sublight speed ;)

[Kiryat Malachi]

It's okay. I forgive you. :)

(I couldn't come up with a better sentence structure, I knew someone was gonna misread it...)

Re:sublight speed ;)

[Kiryat Malachi]

Hmm. Been a while since I did orbital mechanics, but yes, I believe it would fall to Earth (ignoring shit like relativistic frame dragging, which sounds like it might make a difference, but I know nothing about).

Orbit requires tangential velocity. If you assumed Earth is fixed in space and non-rotating, then yes, it should fall straight back down.

Re:sublight speed ;)

[srvivn21]

Mod it overrated. If it isn't really informative and it's modded so, take the points away - it's just as effective. Overrated is a copout. How is a meta-moderator supposed to know why you moderated it down? With "wrong", meta-mods can figure out if it was indeed wrong.

Do you meta-mod often?

I do (and I have for well over a year), and I have NEVER seen an overrated or underrated moderation in the meta-mod queue.

Overrated is a cop out, it seems to be immune to meta moderation, and I agree with the assesment that a "Wrong" moderation would be usefull.

Re:sublight speed ;)

[slim-t]

Do you meta-mod often?

I do (and I have for well over a year), and I have NEVER seen an overrated or underrated moderation in the meta-mod queue.

I go in spurts of meta-modding every day to not doing it for weeks. I suspected over/underrated were immune to meta-modding, but it's true I don't do it enough to be sure.

I wonder how my sarcastic "offtopic" moderation of Hemos will be taken by the meta-mods.

Re:sublight speed ;)

[Jim Starx]

It absolutely does not matter which direction the velocity vector points to.

And if it points down?? ;)

Re:sublight speed ;)

[Jim Starx]

Binomial expansion : for 1>>|x| (and n not insanely large), (1+x)^n ~= 1+(x*n)

I'm sorry, but isn't the point of a Taylor expansion that as n approaches infinity the series approaches an exact approximation within the bounds?? Wouldn't that mean that an insanely large n would be more accurate then a smaller sized n?

Re:sublight speed ;)

[Anonymous Coward]

But the earth isn't fixed and non-rotating... in this scenario, I was looking for a line of thought involving which direction the rocket was initially launched wrt the earth's orbit.

However, IF you assumed earth was fixed in space and non-rotating, then you are correct--the rocket should fall straight back down (though there is still a time period where the 1 m/s maintained velocity is sufficient to escape Earth's gravity after shutting off the engine, that time period is a lot longer than 20 years).

But we can go that way. The rocket that travelled 1 m/s for 20 years travelled a distance of 86400 secs/day * 365.24 days/year * 20 years * 1 meter/sec * 1 km/1000 meters = 631134.72 km. The radius of the earth is 6378 km, so this is about 637512 km above the earth's center of gravity, which as you can see is approximately 100 times the radius of the earth.

The orbital velocity at this distance works out to be 790 m/s. So even here, the rocket need not ever exceed 1 km/sec to orbit.

Re:sublight speed ;)

[Jim Starx]

The space shuttle doesn't constantly burn fuel for the entirety of the time that it is in orbit. They have to shut off the engines. No additional thrust is being applied so they do in fact have to hit escape velocity, that velocity just happens to be considerably less because of the altitude they hit it at.

Re:sublight speed ;)

[Jim Starx]

Escape velocity doesn't just apply to objects on the surface. It also applies to objects in the atmosphere. Escape velocity is reduced as your distance from the point of mass increases. At some point the escape velocity will lower itself below the speed of the rocket, at which time you can turn the rocket off and not Wiley E Coyote back to Earth. For escape velocity to truely not apply you would have to burn constantly the entirety of the time you are in orbit, when a space mission lasts more then a couple minutes this just isn't possible.

Re:sublight speed ;)

[Kiryat Malachi]

Actually, in the fixed/non-rotating case, there is no time period wherein 1 m/s maintained velocity is sufficient to escape Earth's gravity. Assuming no acceleration, the Earth's gravity will provide a constant (though very small) acceleration in the direction of Earth. Over infinite time, even a small acceleration can overcome that initial velocity, leading our hypothetical spacecraft to slowly, slowly slow down and then begin to fall back to Earth faster and faster. In the non-fixed/rotating frame, this is of course a lot more complex, but even there it should eventually decay (assuming there is no Sun/other planets/etc.).

Re:sublight speed ;)

[Kiryat Malachi]

Bleh. Too tired, too long since I've done real math (that doesn't relate to control systems). The integral of a decreasing quantity over an infinite period of time is not necessarily infinite, of course, and I'm too lazy to check whether the form of the force equation for gravity is one of the integrals that would converge to a finite quantity for infinite time.

So, if it is, ignore all my jibba-jabba about there being no such period of time.

Re:sublight speed ;)

[rnelsonee]

> Or "drunk"

Agreed. And you've got a point - 'orbiting' could be taken a different way. Let's blame the English language... And you're right that if it's orbiting, it hasn't really 'escaped'.

You should be able to self-modify as well... like if you know you're unsure... or drunk (like I am now :))

Re:sublight speed ;)

[wass]

Sorry, it's like 2 days later and I just see your reply now.

No, you can easily see that insanely large n makes the 1st-order Taylor expansion worthless in this case. If x approaches zero, the error approaches zero, but as n->infinity you get big problems.

Suppose you want to calculate (0.98)^3. This is 0.941192. Using the 1st-order Taylor expansion, one gets 1-3*0.2, or 0.94. Close, but obvious errors. In this case, n was 3 and x was 0.02.

Now suppose you want (0.98)^200. This is about 0.017588 or so. But using only 1st-order Taylor expansion one gets 1-200*0.02, or -3. Obviously there's a major problem there.

One simple way to remedy this for large n (used in statistical mechanics, for example, where n can be 10^23 or larger) is to Taylor expand the natural log of the function. So expanding ln((1-x)^n)=n*ln(1-x)~=-nx. Taking the antilog, one gets (1-x)^n for large n ~= exp(-nx).

Plug in the numbers for the bad example previously, n=200, x=0.2, and the answer (using python) is 0.01831. not great, but at least within order of magnitude.

Re:sublight speed ;)

[Jim Starx]

Oh I see, your just talking about 1st order expansions. I was thinking that n is the order of the taylor expansion. My mistake.

Mach 7?

[RadRafe]

Isn't that a shaver? You know, the one with seven blades?

Re:Mach 7?

[Anonymous Coward]

Nar its a band man...

Artist: Mach 7
Song: Alacazam

Oh hey oh hey oh
Hey oh hey oh
Oh hey oh hey oh
Hey oh hey oh

Let me into your world
I wanna feel the magic
Let me into your world
I wanna get the static
Oh-uh-oh let's dance the night away
Oh-uh-oh in a silent masquerade

Alacazam, Alacazam
I know that you want it
And I know that I can
Alacazam, Alacazam
Just give me the magic
Wanna do it again
Do it again, do it again with me

Let me into your mind
I wanna see the vision
Let me into your soul
I wanna feel the religion
Oh-uh-oh let's dance the night away
Oh-uh-oh in a silent masquerade

Alacazam... Alacazam...
Fascination... fascination...
.... come inside

Let me into your world
Let's dance the night away
Let me into your mind
Inside a masquerade

Re:Mach 7?

[ziggamon]

Yes, and not only will you get 7 cuts if you cut yourself - with this new ScramJet engine it will just blast your head off!

Re:Mach 7?

[smithmc]

Isn't that a shaver? You know, the one with seven blades?

Yeah, but nobody's ever seen one, because Gilette requires stores that carry it to have an underground bombproof vault with 24/7 armed security, and would-be buyers have to undergo background checks and put up a $10,000 deposit. Oh, that, and the cartridges cost $100 apiece...

Re:Mach 7?

[hesiod]

> Nar its a band man...

Wow, I hope the music is done well, because the lyrics are not.

Mach 10? Mach 10?

[burgburgburg]

The engines canna take it, Cap'n.

Re:Mach 10? Mach 10?

[Anonymous Coward]

I was watching Discovery Wings on Friday and they reported that the x-15 A2 flew a test scram jet and reached Mach 6.8, less than one full Mach number less than what was achieved yesterday. Problems were that the scram jet tore itself apart and broke away. Also, the air friction was so hight that it cut at the rear underside of the aircraft like a blow torch. The pilot landed safely, but the X-15 A2 never flew again. This was in the late 50's, early 60's.

4 posts...

[chimpo13]

and not a single Speed Racer joke. I'll reload in 30 seconds.

Re:4 posts...

[danratherfan]

Here he comes, here comes X-43a
He's a demon with a scramjet
He's a demon and he gets his own oxygen from the atmosphere

He's gainin' on you so you better look alive
He's busy traveling at a powerful Mach5! (or seven, or ten)

And when the odds are against him because they cuuuuuut his funding
You bet your life X-43a, will end up dead in a hanger some where.

Go X-43a, go X-43a, go X-43a, goooooooo.

Re:4 posts...

[chimpo13]

Kenneth, what is the frequency?

Mach10?!

[DigiShaman]

And just how do you keep something going that fast from burning up in the atmosphere?

Re:Mach10?!

[Phosphor3k]

As a previous poster stated, any vehicles that we launch into orbit need to attain a speed of 11.18 km/s, which is about mach 36, for escape velocity. I imagine they've got more than a few ways to protect this vehicle traveling at a paltry mach 7.

Re:Mach10?!

[ziggamon]

And just how do you keep something going that fast from burning up in the atmosphere?

Water cooling, dude, water cooling!

Re:Mach10?!

[benwb]

Probably because the NASA scientists launching these rockets are smart enough to not attempt Mach 10 at sea level.

Re:Mach10?!

[It's the tripnaut!]

And just how do you keep something going that fast from burning up in the atmosphere?


...by travelling in the exosphere.

Re:Mach10?!

[costas]

Mach 10 is a record for powered flight; it is not even close to the record of a man-maned craft; IIRC that goes to the Apollo reentry capsules that routinely hit Mach 27 on re-entry. So the heat problem has been solved for quite a while.

The real problem here is that a scramjet engine is very sensitive to its input (the air coming in) as it only spends literally milliseconds in the combustion chamber. So you have to wonder what aerodynamic tricks the X-43A designers are pulling to smooth that flow before it goes into the intake. Notice the side-view of the aircraft; the belly is smooth and curvy in order to produce many small shocks ahead of the intake and slow down the air as much as possible. A terrific aerodynamic feat, I just have to wonder if it will be reproducible (i.e. stable enought and robust to any aerodynamic event) for a manned aircraft. [Yes, I am an aerodynamicist].

Re:Mach10?!

[Phosphor3k]

Mod me down, I'm an idiot. That speed of 11.18 km/s assumes there will be no further boost during flight, and is the speed of the vehicle right when it leaves the ground. So, the vehicle can go much slower, as long as there is acceleration throughout the flight.

Re:Mach10?!

[j3110]

Have you not seen the commercials? Don't you know it comes with the Indicator(TM) lubricating strip? It has less irritation... even against the grain!

Seriously though, someone else said that Mach isn't 757 mph higher in the atmosphere. Considering that, and the known fact that air is thinner at higher altitudes, I don't think you would have as many problems as you think you might... I would be more worried about what happens when the thing hits a pair of migrating European swallows carrying a coconut.

Re:Mach10?!

[mindstrm]

If it reached escape velocity it wouldn't be orbiting.. it would be escaping, never to return.

Re:Mach10?!

[teridon]

where's my mod points?

"Escape velocity is defined to be the minimum velocity an object must have in order to escape the gravitational field of the earth, that is, escape the earth without ever falling back. [...] So, an object which has this velocity at the surface of the earth, will totally escape the earth's gravitational field (ignoring the losses due to the atmosphere.)"

For the small of brain, the 11 km/s value applies only to unpowered shots (e.g. a cannon) launched from the surface of the earth. Rockets and other powered vehicles don't need to obtain escape velocity to obtain orbit.

Re:Mach10?!

[j3110]

>> IIRC that goes to the Apollo reentry capsules that routinely hit Mach 27 on re-entry. So the heat problem has been solved for quite a while.

Yeah, it's been solved as long as you can affix ceramics to the side of your jet. :)

The payload of something rocket powered is going to be much greater than a puny jet. I bet if you dropped down closer to sea level after getting spead up, just like any other plane, you would find your terminal velocity in a very unfullfilling way. :) I learned that lesson from MS Flight Sim. It's not a heat problem so much as a these-wings-weren't-built-for-this problem.

Re:Mach10?!

[DigiShaman]

From what I understand about jets, is that the faster they go, the exponential amount of fuel they will burn. So let's just say jets of the future can go Mach 7. Will those jets be able to sustain those speeds across an Atlantic trip before running out of fuel?

Re:Mach10?!

[j3110]

That's certainly a very interesting thought... Unless you've played enough flight sims, or actually know about the real things, most people also don't consider that fuel weighs a lot. Having more fuel on a plane designed to be so aerodynamic will cause a shift in balance usually, which will cause it to be less aerodynamic, which will cause it to use more fuel for the same speed.

I think the general consensus is that we need a plane that's capable of going even higher into the atmosphere in order to get some place faster. Like the Borg show in star trek, it really doesn't matter how aerodynamic you are in space.

I assume that any plane capable of Mach 7 is going to be flying pretty high. Taking into consideration that the circumference of earth is greater at higher altitudes and that mach is slower at higher altitudes, I really wonder how much of a gain we are looking at in travel time. I know I'm not going to pay exponentially more for a flight that is linearly quicker. Hell, I prefer the greyhound. If only greyhound busses would float, I could afford to visit the far east like I've always wanted to. Greyhound looks a lot better these days considering you have to drive to the airport, and your travel time has been extended by 4h or more due to security. If you wanted to streamline travel, it seems to me that shaving some of those 4h off would be better than using more fuel to go marginally faster. Building a more secure plane would probably do more for travel times than a faster one with more fuel so that it is also more capable of destruction.

You know, considering that more people complain about jet lag than travel times, I think this is pointlessly academic. Anyone stupid enough to live in LA and work in NY deserves to not have a life.

Re:Mach10?!

[gnu-generation-one]

"As a previous poster stated, any vehicles that we launch into orbit need to attain a speed of 11.18 km/s, which is about mach 36, for escape velocity"

Ignoring the escape-velocity bit, 11.18 km/s in space isn't mach-anything, because sound doesn't travel at any speed there.

Re:Mach10?!

[DerekLyons]

Mach 10 is a record for powered flight; it is not even close to the record of a man-maned craft; IIRC that goes to the Apollo reentry capsules that routinely hit Mach 27 on re-entry. So the heat problem has been solved for quite a while.

Not really. Niether Apollo nor the Shuttle spent more than a few minutes at those speeds in the atmosphere, and when they are at those speeds they are much thinner atmosphere than any airbreather will likely ever fly in. The heat problem is not only not solved, but routinely handwaved away.

Re:Mach10?!

[phaggood]

Will those jets be able to sustain those speeds across an Atlantic trip before running out of fuel?
I thought this was cheap-space access. If so, then it's not a scramjet-only boost system but a combo thingy. Think 747 bolted on a shuttle liquid-fueled engine (the smaller ones, not the big-3) bolted on to a scramjet bolted on to (???, the last stage to orbit). The first two are fully tested, the third one was tested yesterday and shows you can get about +1Mach every 5 seconds (3500 to 5K in 10 secs is mach 5 to 7, right?) so if you run the scramjet for about 100 seconds you should get above mach 27; pretty close to the mach 36 you need for orbit. Someone said 2lbs fuel for 10 sec; that's 50lbs then for the 100 secs. Seems like somethin for nuthin.

Re:Mach10?!

[Anonymous Coward]

that's also why they flew over the Pacific - to have a large enough supply of cooling water.

Re:Mach10?!

[Anonymous Coward]

Rockets and other powered vehicles don't need to obtain escape velocity to obtain orbit, either. :)

Re:Mach10?!

[Anonymous Coward]

1) MS Flight Sim isn't an accurate predicator of flight characteristics. It's based on empirical models, which basically use lots of tables to compute how a plane should behave. It has no grounding in the actual aerodynamics of the question, which are too complicated to compute accurately for a mass market product like MS Flight Sim.

2) A rocket has to carry oxygen. You have to have 8x the mass of oxygen for each 1x mass of hydrogen. Because of that, that "puny" jet can carry a lot more than an equivalent rocket.

Re:Mach10?!

[Jim Starx]

No, exact escape velocity will put you into a perfect orbit. Anything above escape velocity will send you floating off.

Re:Mach10?!

[Jim Starx]

They do obtain escape velocity, it's just signifigantly lower then 11km/s because it's hit at a high altitude.

Re:Mach10?!

[teridon]

No, you're wrong. Read the definition again, until you understand it.

Escape velocity is to totally escape the gravitational influence of the Earth. Objects in orbit have by definition not escaped the gravational field, or they wouldn't be in orbit.

Re:Mach10?!

[Jim Starx]

Gravitational fields are infinite. You have never totally escaped, it's just become weak enough that its force is negligable. Definitions of escape velocity that rely on terms like 'totally escape' are outdated.

"Escape velocity is defined to be the minimum velocity an object must have in order to escape the gravitational field of the earth, that is, escape the earth without ever falling back." -Yasar Safkan, B.S. Phsyics Ph.D. Candidate, M.I.T.

If an object is in orbit it will not "fall back". It has escaped the earths gravitational field in the sense that the remaining effect of the field is no longer strong enough to reduce the altitude of the object.

At the present rate

[Fisher99]

when will we see warp engines? And ideas? Anyone from NASA working on this?

Re:At the present rate

[Boccaccio]

when will we see warp engines? Shortly after someone proves that its not impossible I guess.

Re:At the present rate

[Avian visitor]

Google for "nasa advanced propulsion" and "nasa breakthrough propulsion" for some answers.

I'm afraid we won't see anything like the warp drive in our life time though.

Re:At the present rate

[quetzalc0atl]

theoretical models HAVE been proposed, but they all make use of a) matter that is more dense than anything man has ever seen and b) a tremendous amount of energy, on the order of our Sun's total output.

Re:At the present rate

[Anonymous Coward]

There's this Zephram Cochrane guy who claims he has something, but he's a drunken loon. He really needs to find a companion and get a life.

Re:At the present rate

[alphorn]

it's not impossible, it's just infinitely improbable.

Re:At the present rate

[NeoThermic]

In 1994, a paper was written by Miguel Alcubierre which detailed a possible way of obtaining warp drive.

The current problem is that of relitivty, at which there is a certian point where energy stops creating speed, and goes into increasing the mass of the moving object, thus making light speed impossible.
Alcubierre's idea was that the ship doesn't move. Instead, it modifies the space around it much like an esclator. Since the ship doesn't move in relitive terms, it doesn't gain mass or suffer time dialation.

However, at this time, there was a problem with obtaining the required energy, which was quite alot [think total solar output of the sun in its current life, per second].
In 1999, however, Thomas Valone spotted an answer. Zero Point Energy. In a nutshell, one can theoretically harness the binding energy of a particle. This energy, if harnessed, would be enough energy to power an Alcubierre warp drive.

However, both ideas are still in the working stage, and I think we will see Duke Nukem Forever before we see warp drive from either of these two concepts.

NeoThermic

Re:At the present rate

[Walterk]

I've got one of those in my back yard. All it's missing is a Pulse Dimension Wrapping Modulator and a Plot Hole Compensator.

Re:At the present rate

[Anonymous Coward]

I think we will see Duke Nukem Forever before we see warp drive from either of these two concepts.

Now that is just way too optimistic. It's silly even. Have you no integrity?

Re:At the present rate

[blincoln]

Alcubierre's idea was that the ship doesn't move. Instead, it modifies the space around it much like an esclator.

I'm with you so far.

However, at this time, there was a problem with obtaining the required energy, which was quite alot [think total solar output of the sun in its current life, per second].

The main stumbling block to Alcubierre's drive is that it requires negative energy. My understanding is that the human race can't produce that right now, at least in appreciable quantities.

All of the FTL drive concepts that I've seen involve something currently unobtainable (or outright impossible) like this - infinitely long neutronium rods, creation of a pocket universe to put the ship in, etc.

In 1999, however, Thomas Valone spotted an answer. Zero Point Energy.

No. Pseudo-science can solve lots of problems theoretically, but it is not the answer to real-world problems.

Re:At the present rate

[Beryllium Sphere(tm)]

http://en.wikipedia.org/wiki/Alcubierre_drive

Re:At the present rate

[Anonymous Coward]

Personally, considering our current technology base, I'd be rather suspicious if we invented warp drive within our lifetimes. Breaking the known laws of physics, and developing a practical application, in under (some small number) decades? Now there's proof of alien intervention.

Re:At the present rate

[Anonymous Coward]

Actually, those models rely on either infinitely dense matter, not just much-more-dense matter, or infinite amounts of energy, or negative energy, or negative mass.

These sort of non-sense answers are equivalent to 'impossible' in the physical theories. (Although the existence of negative matter/energy hasn't been ruled out, and still remains a viable possibility.) They're mainly just fun thought experiments for physicists manipulating the equations. They don't actually mean anything.

Saying that these drives would work if you had such materials is like saying you could go to the speed of light if you could reduce your mass to 0. It's so beyond the realm of physical knowledge to say you could do that, that it's equivalent to saying it can't be done.

Stupid, Slightly OT Question

[dupper]

The news media keeps reporting NASA's previous failure to reach Mach 5. But didn't the X-15 do this in, like, the 60's?

And, to keep a little more on topic:
18 tiems the speed of light!

Re:Stupid, Slightly OT Question

[stripmarkup]

Yes, they did it in the 60s. They reached Mach 7 with a manned plane. This one is unmanned. I don't understand why it is such a big deal.

Re:Stupid, Slightly OT Question

[Boccaccio]

That was a rocket - this is an air breathing engine.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

Mach 6.70 IIRC. But that never got mated to the engine developed for it, which would have made it faster still. And that was manned. Now that dude had either some serious IQ issues, or one giant set of ICONEL X onions.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

Turns out oxygen is heavy, and kind of a pain in the ass to package anyway. It's much more convienent if you can just use the oxygen that's laying about, which is significantly more difficult that it sounds when you're traveling at hypersonic speeds.

Damn gravity.

Re:Stupid, Slightly OT Question

[Sepherus]

They reached Mach 7 with a manned plane. This one is unmanned. I don't understand why it is such a big deal.

It's a big deal becuase this is a scramjet, which doesn't need to carry oxygen and has the potential to go faster for much longer.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

x-15 == rocket powered
this time == jet powered

That is why this is different

Re:Stupid, Slightly OT Question

[peterpi]

You'll also find the lack of information about the X-15 in things like the Guiness Book of Records. I think this is because the speed the X-15 reached was unverified by an impartial observer, or something like that.

Another question: Doesn't the space shuttle enter the atmosphere at some crazy mach value like 20? At what point are you defined as being in space, I wonder?

Re:Stupid, Slightly OT Question

[mindstrm]

It's not. This whole experiment is not at all about speed, and everything about a new engine design.

IIRC, Mach5 is the speed at which the scramjet is released, and ignited... up until then it's just being boosted by a conventional rocket.
During the first test, the scramjet failed.

During this test, it worked, pushing the rocket up another mach or two.

This was not meant to be any kind of speed record.. that's just how fast you need to go to get a scramjet working.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

The big deal is the difference between Mach 6.72 and 7. And the speed was achieved with air-breathe engine (c.f., any rocket would exceed Mach 7 all the time, but then their engine does not intake compressed air to gain thrust).

I've been dreaming about a working scramjet since 80's. Well done guys at Dryden.

-b

Re:Stupid, Slightly OT Question

[Ogre-On]

The X-15 was fast, but it was also rocket-propelled. The X-43A uses an air-breathing scram-jet engine, which means it doesn't need to carry oxidizer on-board--it gets oxidizer from the atmosphere.

A reaction engine that doesn't need to carry its own oxidizer (oxygen) on-board has greater carrying capacity for fuel and payload.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

No, during the first test the rocket booster (the Pegasus) failed, mostly due to being released too low in the thick atmosphere. The entire package was destroyed by mission control before it went totally out of control.

Re:Stupid, Slightly OT Question

[the eric conspiracy]

I don't understand why it is such a big deal.

As some have noted, it's because of the engine type - air-breathing - that makes this so significant.

The economics of space travel are dominated by the cost to put something in orbit. Sitting on the launch pad, the payload to weight ratio of the Shuttle system is something like 1:50. Picking up the oxygen just lying around gives you a big increment in payload to weight ratio.

Re:Stupid, Slightly OT Question

[TehHustler]

Everyone says space is 100km, for the benefit of the X-Prize.

Nasa defines it as about 400,000 feet, when the atmosphere has a significant effect, and the space shuttle hits about Mach 25 on reentry. It orbits about Mach 24.5, but as you fall back towards earth on reentry you gain speed until the atmosphere slows you down

Re:Stupid, Slightly OT Question

[pfdietz]

Unfortunately, the drawbacks of airbreathing appear to outweigh the advantages, at least for vehicles intended to put objects into orbit.

The problem is that a scramjet trades a dense propellant (LOX) for more of a low density propellant (LH2). As a result, the propellant tanks on a scramjet vehicle would end up being larger (and heavier) than those on an SSTO rocket with similar payload. LH2 is also much more expensive than LOX, so your propellant costs go up (not that propellant cost is currently important, but your vehicle is also in a more aggressive thermal environment so it to will be more expensive.)

Worse, the effective Isp of a scramjet (after you take into account drag and gravity losses due to its lower acceleration) ends up being little better than the rocket. See Henry Spencer's comment on this.

About the only place scramjets may make sense is in hypersonic cruise missiles. The US military has a scheme for using hydrocarbon fuels, converting these fuels into hydrogen + CO in flight by partial combustion with a portion of the incoming air (that portion is slowed to a stop by a conventional ramjet inlet, with the fuel being used to keep the air relatively cool and the inlet from melting.) The H2 + CO + nitrogen is then injected into a scramjet for complete combustion.

Re:Stupid, Slightly OT Question

[Rank_Tyro]

This was done in the 60's, however the plane used was a rocket plane. The aircraft carried it's own oxygen and it's own fuel. Essentially, Willey Coyote strapped a big ass bottle rocket to his butt and was dropped from a B-52. This is the first time that these speeds were reached by an air breathing engine.

Re:Stupid, Slightly OT Question

[SnowZero]

I don't find this argument, or the one you link, very convincing. We need *real* data on scramjets to figure out how efficient they are, not guestimates from 1/1000 sec pulse simulations or extrapolations from relatively low speeds. I think that's exactly the kind of data the NASA project will get (along with another scramjet project from Australia; at UNSW IIRC).

With data in hand we can find out which simulation models are most accurate. Then we can intelligently decide whether something like NASP makes any sense, or if we are better off with just plain rockets.

And playing devil's advocate, what kind of rocket engine does Spencer's mythical SSTO use? Currently we need several engines tuned for different altitudes, necessitating multistage designs, and adding a lot of weight. Aerospike engines are the only possible solution I've heard of to date, but they are relatively new and only slightly more tested than scramjets. And the linear aerospike, proposed in several SSTO designs, has yet to work at all.

More research is needed, and then we can stop handwaving so much :)

Re:Stupid, Slightly OT Question

[BeerCat]

Not only was it done years ago (Mach 6.72, for the pedants out there), but the B-52 that was used to drop the X-15s is the same one used for the X-43. In fact, there was a piece about it here, in 1995 when the aircraft was only 40.

The NASA press conference about the X-43 was full of "100 years ago" type stuff, which is all well and good, but didn't say "49 years ago, the mother ship for today's flight was built", let alone "37 years ago, the X-15 went this fast with a guy on board"

I think what it really shows is that 100 years ago, the Wright brothers achieved powered and controlled flight, but most of the real "envelope pushing" advances were made over 40 years ago.

Re:Stupid, Slightly OT Question

[Grayraven]

liquid oxygen isn't a propellant, it's just the oxidizer. To go somewhere you also need a propellant, such as hydrogen.

Re:Stupid, Slightly OT Question

[pfdietz]

No, liquid oxygen is a propellant. Go read Sutton 'Rocket Propulsion Elements' (5th. ed.), chapter 7, section 1:

"The term 'liquid propellant' embraces all the various liquids used and may be one of the following: (1) Oxidizer (liquid oxygen, nitric acid, etc.) [...]"

Re:Stupid, Slightly OT Question

[pfdietz]

We could use real data, but there already is plenty of real data on things like hypersonic lift/drag ratios. Also, the numbers are not good even if you make optimistic assumptions about the performance scramjet engines. They are inherently lower thrust devices than rockets, since they are handling rather rarefied gases instead of the dense, high pressure gas handled by a rocket.

The upshot is that the engineers know this area is not going to live up to the breathless hype. But then there's nothing unusual about that in the space area -- it's like the word 'space' activates some sort of gullibility center in some people's brains.

Re:Stupid, Slightly OT Question

[Anonymous Coward]

As people have pointed out, the X-15 was rocket powered, not jet powered. It had to carry its own oxygen, unlike the scramjet on the X-43A. That's the whole reason why it's such a big deal: it's the first air-breathing engine to propel itself to those speeds.

Regardless of how fast it goes, a working scramjet is still interesting because you can presumably progressively develop into a higher speed version that will likely get the job done (aka, low stage booster).

Re:Stupid, Slightly OT Question

[richmaine]

The "destroyed by mission control" bit is BS. Yes, I saw it said that way in a new report, but the newa report was BS.

The vehicle very "nicely" tore itself apart. No intervention by mission control was involved.

Mach 10

[Boss, Pointy Haired]

is 3402 meters per second

or 12247 kilometers per hour

or 7610 miles per hour

Re:Mach 10

[bulletman]

And to put that in perspective, Earth escape velocity is:

11100 m/s 40200 km/h 25000 mi/h

So Mach 10 is almost a third of the velocity required to escape the earth's gravity.

See:What is escape velocity? for more info. for more.

Re:Mach 10

[Atzanteol]

People keep saying this... AFAIK "escape velocity" is the "muzzle velocity" a projectile would need to start with in order to escape the Earths gravity. But this doesn't apply to a projectile that accelerates with it's own power (ie. rocket).

Re:Mach 10

[dynoman7]

mach 10 = 20461245.5 furlongs per fortnight

Re:Mach 10

[Dutchmaan]

or two put it in our corporate masters terms..

"New York to LA in 25 minutes!"

Re:Mach 10

[Anonymous Coward]

Not at 95000 feet (the altitude the article claims). Assuming a standard atmosphere, the speed of sound is 315 m/s. So Mach 10 is 3150 m/s.

Re:Mach 10

[Anonymous Coward]

correct. mach is the speed of sound at a certain altitude, it is not universal.

Re:Mach 10

[Schaffner]

But chemical rockets do not run their engines continuously! They only have enough fuel and oxidizer to run for a limited period of time. The amount of "boost" you can get out of an engine is called the "specific impulse". Actually ion engines have a much higher specific impulse than chemical engines, but their thrust is very low, it's just that they can run for long periods of time.

Re:Mach 10

[BigBadBri]

20461245.5 furlongs per fortnight = an area the size of Wales

assuming a standard Norfolk plough and sufficient Shire Horses for regular changes.

Re:Mach 10

[Dun Malg]

Not at 95000 feet (the altitude the article claims). Assuming a standard atmosphere, the speed of sound is 315 m/s. So Mach 10 is 3150 m/s.

Calculating the Mach number from one's velocity in a vaccuum would yield a "divide by 0 error" then. But I guess they only use Mach numbers for aircraft, so that's unlikely to be a problem. You'd think they'd use the more concrete km/s scale rather than the Mach scale, but I guess people's eyes tend to glaze over when faced with large numbers.

Re:Mach 10

[Anonymous Coward]

No, they use Mach because it does mean something, and different things happen at different Mach numbers.

Sure, some of the big ones are in the transonic zone (~0.95-1.0 Mach), but other things, like "Compression lift", happen at ~Mach 3 if the plane is configured correctly, etc.

Re:Mach 10

[DgWatters0]

mach 10 = 20461245.5 furlongs per fortnight

tis true

Re:Mach 10

[Dun Malg]

No, they use Mach because it does mean something, and different things happen at different Mach numbers. Sure, some of the big ones are in the transonic zone (~0.95-1.0 Mach), but other things, like "Compression lift", happen at ~Mach 3 if the plane is configured correctly, etc.

Well, you learn something every day if you just pay attention.

ahem

[Anonymous Coward]

video plz?

How soon before...

[DoctorPepper]

I can get one of these for my Toyota Corolla? Man, that sure would cut my commute time down!

Re:How soon before...

[Knetzar]

But the traffic is going to get really bad 100,000 feet.

Re:How soon before...

[Anonymous Coward]

tsk tsk.

Smart enough to buy a toyota corolla but not smart enough to move to a place where commuting becomes unnecessary.

such a shame.

Re:How soon before...

[Ours]

And get you a nice shiny Darwin Award as well!

Speed of sound

[CaptBubba]

For those of you wondering how to convert between Mach numbers and mph or m/s, here's a nifty java tool that lets you see how altitude affects the Mach number.

basically the higher you go, the less air there is, and the slower sound travels. So, the mach number, which is the ratio of your speed to the speed of sound, will be higher at high altitudes if the speed is constant.

Re:Speed of sound

[mindstrm]

Common misconception.

The speed of sound in a gas is affected mainly by temperature... not density or pressure.

From the page you just linked to:
"The speed of sound depends on the state of the gas; more specifically, the square root of the temperature of the gas."

Mach at 35,000 ft is 663mph

Mach at 150,000 ft is 732mph

The reason higher aircraft hit higher mach numbers is due to decreased air resistance... concorde can hit mach at 50,000 ft, but not at 20,000.. not because mach is perceptibly slower, but because there is less drag.

Re:Speed of sound

[Anonymous Coward]

High shool physics: The speed of sound in a gas is proportional to the square root of the absolute temperature. That is, it is not a function of density or pressure but ONLY of temperature. This somewhat surprising result was known as far back as Isaac Newton (who notoriously make a small error in the calculation). So the speed of sound at high altitudes is not due to the drop in air density but to the drop in temperature. Baby its cold up there!

Re:Speed of sound

[Inspector Lopez]

To first order, the speed of sound does not depend upon the pressure at all; rather it depends primarily upon the mean mass density and the temperature.

The reduction of sound speed at altitude is due to the reduction of temperature. The temperature rises again in the upper stratosphere (ozone heating) and then drops down to its coldest temperature at the mesopause (around 120 K, at 85 km). However, the temperature increases rapidly above that, getting back to room temperature by 110 km, and heading for 1000k and beyond by the time you get to LEO.

At high altitudes the mass density is decreasing as you get more and more atomic species (e.g. O rather than O2) as well as larger fractions of light constituents (e.g. H2, H), so the speed of sound is quite high at LEO. At altitudes above the "turbopause" (somewhere around 105 km) the components of the atmosphere are no longer well-mixed, thus the different component gases stand at their own scale heights.

see scale height and speed of sound

Re:Speed of sound

[CaptBubba]

Yeah, you are right, that'll teach me to try and be smart in the morning before I've had any caffine. I wish I could split my post in two, the applet is nifty and useful, the other part needs to get modded down into oblivion.

The worst part is I really have no excuse for it. I was involved with a radiosonde launch last week that almost got to the altidue they are talking about. The pressure and temp at burst (almost 25km) were around 27mBar and -65C respectivly. That's damn cold!

Re:Speed of sound

[cartzworth]

Isnt the volume and pressure of a gas related to temperature though?

Re:Speed of sound

[Anonymous Coward]

Yes...

Pv=nRt

Re:Speed of sound

[Anonymous Coward]

The Speed of sound equation is
M=SQRT(Gamma R T)
Gamma = the thermdynamics ratio
R = Ideal Gas Constant
T = Absolute Temperature

Thus, looking at the RT, and yes we are talking about an ideal gas.
RT=PV/n
So the statement that it is the state of the gas is accurate.

As far as temperature, pressure or density, they are all considered since they are interrelated.

Re:Speed of sound

[Rich0]

Actually, the Concorde can't hit Mach at 50,000 feet - but it can sustain Mach at that altitude.

The concorde accellerates above Mach 1 at a lower altitude (probably 30-40k). It is probably near to Mach to by 45,000 feet, and it slowly drifts upward in height as it goes faster.

If you take a Concorde up to 50k feet at below Mach 1 (if it can even fly that high at that speed), you'd never be able to accellerate past mach 1. The drag on the aircraft builds as you near mach 1, and then goes back down once you pass it. At high altitude, the engine thrust is much lower (due to less air to breathe), and you can't pass the mach 1 barrier. Instead you pass it when the engines are at peak performance compared to drag due to being lower in altitude, and then climb to reduce fuel usage (once you are past mach 1 you don't need as much power to sustain speed, and you benefit from reduced drag in the less dense atmosphere at higher altitude).

Re:Speed of sound

[KD5YPT]

Read more carefully, the key note is that WHEN the pressure/density of gas is constant, the speed of sound in a gas is proportional to the square root of the absolute tempreature.

Re:Speed of sound

[ajw_h]

Am i drunk or is there a correlation between mass density of a gass and presure?

Re:Speed of sound

[Anonymous Coward]

Remember your chemistry classes? PV=kT.

So, you could factor speed of sound based on temperature for a given gas, and I could factor it based on pressure or volume as well.

Drag is also related to pressure and density (they really are the same). Baseballs hit on a cold day do not travel as far as baseballs hit on a hot day (hotter air is less dense).

And, Mach 2 at 50K is a bit slower than Mach 2 at sea level. Look at how big Project Pluto was (imagine a Bomarc missile the size of a DC-9...), and it was designed to fly Mach 2, at sea level...

And, at 50K, because the air is less dense, it then also takes less energy to maintain a given velocity, which means less fuel used, which means lighter vehicle.

Re:Speed of sound

[Anonymous Coward]

Pass your chemistry classes? PV=nRT for an ideal gas. Ignoring that air is not ideal, if a function exists that correctly determines Mach from T, then one could hypothetically use the gas law to create a function for Mach in terms of P, V, and n. But trying to compute Mach as a function of just one of those terms could only be possible in a special case, like a closed system, which doesn't much apply to aircraft in the sky.

Re:Speed of sound

[obirt]

Or, you could just go to google and type mach 10 in mph in the search box and hit return.

Re:Speed of sound

[tgrigsby]

Complete crap. The speed of sound is affected by density and pressure, not temperature. On the other hand, the density and pressure are affected by temperature, and thus the speed of sound can be affected secondarily by temperature.

A side note: why did scientists first postulate the existance of black holes? Because beyond a certain density of matter, sound waves would necessarily be able to travel faster than the speed of light. Since that's not supposed to be possible they conjectured that at a certain density neutron stars must collapse even further, etc.

Re:Speed of sound

[mindstrm]

Scientifically, the speed at which sound travels through a gas depends on 1) the ratio of the specific heat at constant pressure to the constant volume, 2) the temperature of the gas, and 3) the gas constant (pressure/density X temperature). This is represented by the formula:

a = Square Root(g R T)

where

a = speed of sound
g = ratio of the specific heat at constant pressure to the specific heat at constant volume
R = universal gas constant
T = Temperature (Kelvin or Rankin)

Fortunately, in the earth's atmosphere (a gas) several of these variables are constant. In our atmosphere, g is a constant 1.4. R is a constant 1718 ft-lb/slug-degrees Rankin (in the English system of units) or 287 N-m/kg-degree Kelvin (in SI units). With g and R as constant values, this results in the speed of sound depending solely on the square root of the temperature of the atmosphere.

Fast...

[Anonymous Coward]

...but does it run linux?

wtf are you babbling about?

[Anonymous Coward]

please refrain from posting until you are ready to make sense. kthx

Escape velocity

[MMC Monster]

Escape velocity is 7 miles per second (11.3 kilometers/second) That's Mach 34. Shoot me to the moon, anyone?

CNN gets it wrong

[AlecC]

It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours.

Considering Concorde did that in three hours, thit wouldn't be much achievement. I make it that it could do NY-LON in just over one hour.

What I think they should have said is that it could go from any point on the earth to any other, including the antipodes, in less than five hours.

Mind you, it would take three hours to get through security on departure and an hour on arrival to collect your baggage, if it had arrived with you.

Re:CNN gets it wrong

[openmtl]

The new trans-Atlantic flight time is now 6 hours....

Midtown to JFK - 1 hour (off peak)
JFK TIA/Homeland/Patriot-enabled security -> Plane seat - 3 Hours
US -> UK flight time in new Mach 10 rocket - 2 Hours

Total time 6 hours. Your bags though would arrive 2 days later assuming that they hadn't been blown up in an anti-terrorist "controlled explosion" at LAX.

Re:CNN gets it wrong

[davandhol]

One of the articles I had seen about the Mach 7 scramjet mentioned that it could transport between London and Australia in a few hours.

Re:CNN gets it wrong

[the_2nd_coming]

the trip to london is to short to benefit from a scramjet..

Re:CNN gets it wrong

[Anonymous Coward]

It is the first time a supersonic-combustion ramjet, or scramjet, which uses air for fuel, had traveled so fast, flight engineer Lawrence Huebner told reporters.

Pretty clever--using air for fuel. That ought to really cut the cost on the NY to London flight. I don't know why they didn't think of that sooner. I wonder if I can use air in my weed eater.

Re:CNN gets it wrong

[exp(pi*sqrt(163))]

They didn't mean anything. It was CNN. They switch of their brains the moment a news story contains scientific terminology like "miles per hour" or has too many figures in it.

Re:CNN gets it wrong

[ArsSineArtificio]

Total time 6 hours.

Gatwick -> central London via the Gatwick "Express" - 2 Hours

Total time 8 hours.

Re:CNN gets it wrong

[mabu]

Travelling to London faster is nice, but I'm holding out for technology that allows our baggage to travel just as fast.

Re:CNN gets it wrong

[KD5YPT]

That's a CNN screwup, but I think what they meant to say is "..., as an air breathing vehicle..."

Mach 10 enough to sail into orbit?

[SailfishMac]

Isn't this the whole point of this project? To get away from using the traditional rockets and create a space plane?

Re:Mach 10 enough to sail into orbit?

[TheRaven64]

Even if it can't get all of the way into orbit, it could go some of the way. Imagine this:

1. First stage, accelerate vehicle on a long maglev runway. 100% reusable, no fuel carried, speed of about Mach 1 reached.
2. Second stage, SCRAM Jet. Reaches about Mach 10. Then detaches and glides back to Earth on automatic. No oxygen carried, only fuel. Efficient and (apart from the fuel) reusable.
3. Third stage, rocket. Takes the plane the rest of the way into orbit.
4. Fourth stage, ion drive, takes the payload to a different planet (Mars anyone?). This would probably carry the payloads of several launches of a space plane.

Of course, you'll need to build a launcher on the destination planet, if you want to get back. And the SCRAM Jet is not going to be very useful on a planet with a thin atmosphere (but fortunately most such planets have low gravity, so it's less of an issue).

Re:Mach 10 enough to sail into orbit?

[Anonymous Coward]

Of course, you'll need to build a launcher on the destination planet, if you want to get back. And the SCRAM Jet is not going to be very useful on a planet with a thin atmosphere (but fortunately most such planets have low gravity, so it's less of an issue).

Also, this scramjet requires oxygen - there's no other planet with an oxygen-rich atmosphere. Wonder if an extraterrestrial airplane could carry oxygen in its tanks and use the atmosphere (methane on Titan, hydrogen in the gas giants, e.g.) as fuel?

The Mach 10 is not enouth...

[S3D]

Mach 10, projected speed to the end of the year is about 1/3 of the orbital velocity. While already in the same order of magnitude it is still a long way toward the space plane...

Great Things to Come

[Denix]

I think this finally points to a replacement for the space shuttle that was sorely needed. The shuttle is a decent space truck, but we need a cheaper (and safer) space "bus."

Hopefully it will be designed with a space station or dock in mind. It's my understanding that the shuttle was retrofitted for in-space docking such that the International Space Station almost had to be built around it.

"And how much more black could it be? None more black." - Spinal Tap

CNN slipping,...

[epicstruggle]

CNN in a poor programming decision IMHO, did not carry any news of this while it was happening. OTOH FoxNews did!! Which supprised the hell out of me. They did ask some expert a few times how this would mean that missiles (in the future) could hit Osama in 15-30 minutes instead of the 4+hours it takes today. But at least they did have someone talking about the technolodgy/science behind this, and actually showed the takeoff, and launch of the plane. Quite nice of them.

Kudos to Fox, to CNN: do a better job, or you will fall further behind FoxNews.

later,
epic

Re:CNN slipping,...

[dealsites]

Might be slightly off-topic, but I agree with this. I have enjoyed Fox's coverage much more than CNN's. Not only in this news event but also others. I have noticed that CNN is quite a bit more PC, while FOX news seems to give your the direct information.

--
Woot, Woot! Hot Sunday deals are rolling in from all the major deal sites. Slickdeals, Ben Bargains, Techbargain and more!

Re:CNN slipping,...

[dave420]

Yet Fox still managed to blame it not hitting mach 10 on the pink-commie-leftie democrats, and "their heathen ilk"...

heh.

Re:CNN slipping,...

[Anonymous Coward]

Fox News, because theres a little Red Neck Hick in all of us. Come on, be honest, Fox News is as news worthy as The Onion, and not as funny.

Re:CNN slipping,...

[mks180]

Yes, CNN is definitely slipping. They reported that it may be now possible to reduce the flight time from New York to London to less then 5 hours. The Concord, first built in the late 60's, was able to accomplish the same flight in 3 hours. Based on CNN's reporting, aerospoce technology seems to be making incredible steps forward. :)

Re:CNN slipping,...

[bombadillo]

News is supposed to be "PC". We don't need a TV network telling us what to think. After all how many times last year did Fox news anounce that WMD were found in Iraq?

Re:CNN slipping,...

[Gunark]

They had live coverage of the launch where I was watching (in Toronto).

Re:CNN slipping,...

[Anonymous Coward]

I am still trying to figure out how Fox news controlled by republicans, spewing republican propoganda is any different than the old Soviet Pravda, Iraqi News, or current chinese news! Each of these had opposition becuase we were beaming in neutral news into each place.

Re:CNN slipping,...

[Anonymous Coward]

Yeah, but what good does direct info do if it is simply propoganda? Lier!

Re:CNN slipping,...

[NewbieV]

That's not entirely accurate...

CNN did break in to their regular programming to show the B-52 in-flight, carrying the rocket and scramjet.

They also had a reporter on the air via telephone linkup handling some of the voiceover work.

The whole segment was aired at the time that the rocket detached from the B-52.

But I do agree that it didn't get as much coverage as other NASA-related news does... usually, Miles O'Brien takes over to add some background information, etc.

Re:CNN slipping,...

[ndinsil]

Boy, really? I missed out. For a couple hours on saturday I had the TV on and muted, flipping between news channels, waiting for the run itself (And doing other things, hence the mute.) CNN would periodically mention that the flight was upcoming, showing animations and stuff, whereas Fox didn't mention a thing. Unfortunately I had to leave before the action started.

So from what I know I don't think your characterization is completely fair. I'm guessing CNN was preparing for it and when it came time for the flight had something else going on they decided to cover instead, whereas Fox News didn't mention much about it before covering the flight itself.

As for comparing the networks' quality, I can see CNN falling behind Fox News when Fox switches to their upcoming split-screen format: all Iraq on the top, all celebrity trials on the bottom.

Re:CNN slipping,...

[Aku Head]

One of the news bimbos on Fox announced the story by stating that NASA had set a new speed record for air travel.

Others have pointed out that the speed was not a record.

My question is: Shouldn't there be a person on board for it to be considered travel?

How fast ..

[the eric conspiracy]

new speed record

African or European?

Re:How fast ..

[Anonymous Coward]

American..... you twit!

Re:How fast ..

[cc.chuck]

It was painted your favoite color.

Re:How fast ..

[BigBadBri]

And more to the point, what is the payload (expressed in coconuts, naturally)?

Re:How fast ..

[DarkSarin]

And just exactly how many coconuts are there to a VW? I want this in terms I understand, not some antiquated system of measurement.

Re:How fast ..

[Anonymous Coward]

Australian

10 seconds

[henryhbk]

Did anyone notice that the length of flight was 10 seconds? If it carried enough fuel for a sustained flight, it would be more impressive for a mach 7 flight. I realize this is a proof of concept flight.

Re:10 seconds

[Kiryat Malachi]

Proof of concept.

It worked for 10 seconds. That was all this design is supposed to do, and all it is likely capable of doing, but it proved their combustion chamber design works.

Now they can strap big fuel tanks on and go for a longer sustained burn, if they want to.

Re:10 seconds

[Sagarian]

It was only 10 seconds, but these sorts of early research-stage victories are the great things that we pay NASA to do. It'll take many years and/or decades to develop the technology sufficiently for interesting applications, but that doesn't take away from the triumph they've achieved. Hats off to NASA!

Re:10 seconds

[Jeffrey Baker]

Considering the vehicle would have been 32km downrange after 10 seconds, I'm fairly impressed. And I still haven't seen any mention of how they recovered the vehicle.

Re:10 seconds

[Anonymous Coward]

The article says that the carrier rocket boosted the X-43A to 5 Match. Then the scramjet worked for 10 second, and suddenly the plane reached 7 Match? +2 Match in 10 seconds? Sound fishy to me.

Re:10 seconds

[Chairboy]

What is this 'match' you speak of?

Re:10 seconds

[lommer]

In the scramjet reasearch buisiness, 10 seconds is an eternity. Most institutions who are researching this technology are universities and the like who don't have access to B-52s, rocket boosters, and the other equipment needed to actually flight test scramjets. Rather, they are forced to rely on less expensive wind tunnels. To simulate >mach 6 airflow (scramjet operational range), they either use an enourmous piston driven system, or a series of pressure build ups with a simultaneaous release. Regardless of the method, these techniques generally can't provide more than 5 milliseconds of flow time to test the engine. If you compare testing engines in 5 ms bursts to one sustained 10 s flight, the perspective kind of changes your opinion on how long 10 s is.

If you want a good paper on the subject, I suggest this one from the Australian National University.

Re:10 seconds

[Anonymous Coward]

Did anyone notice that the length of flight was 10 seconds?

CNN didn't notice:

After Pegasus released the X-43A, it flew under its own power for six minutes to do maneuvers over the ocean.

If CNN reports it, it's always more impressive - except for the journalism.

BTW, as someone pointed out, this isn't CNN's first error in this article.

Re:10 seconds

[Anonymous Coward]

There were discussions about making the vehicle a recoverable and reusable test system. However, with the increase in complexity, cost, and the need to fly in the area with heavy commercial air traffic (near LA) in order to land the X-43A, program official ultimately decided to make this version a single use engine test bed.
There were plans to build larger follow-on vehicles that are re-useable. I believe those plans are now are hold indefinitely as NASA shifts its focus to the moon and Mars missions.

Why its important

[Veteran]

SCRAM stands for Supersonic Combustion Ram (jet). What makes this different is that the combustion is taking place in air which is moving faster than the speed of sound inside the engine. Conventional Ram jets require that the air inside the engine be moving at less than sonic velocities for combustion to occur.

Conventional Ram jets are limited in top speed by the necessity to slow the incoming air down to sub sonic velocities.

Not only does the SCRAM jet have potential military applications, it can also serve as a 'midrange' stage for a lower cost to orbit booster.

Re:Why its important

[KD5YPT]

Actually, a different type of engine (PDE, pulse detonation engine) might be good for military for vehicle that doesn't need that high velocity but require a very long range. Bascially instead of burning the fuel (combusting it), it creates thousands of "bomb" per seconds to propell the vehicle. PDE have a ridiculously high fuel efficiency (80~90%) compare to other jet engine (~30% or even lower). So for military, especailly for surveillance, long range weapon, PDE might be a better choice then scramjet.

X 15

[p51d007]

Yeah, Pete Knight went to Mach 6.7 in Oct 67....STILL a record to this day, for a MANNED airplane (X-15 isn't "really" a traditional airplane since it is air launched). Also Pete Knight earned astronaut wings by flying the X15 near 300,000 feet. Several of the X15 pilots received astronaut wings by flying near or over 300,000 feet. Joe Walker, went the highest to 320,000 feet! Sadly, he was killed in the 60's when he was in a formation of planes for an Ad for the general electric engines that all the planes were flying. His "tiny" in comparison jet got too close to the XB-70 bomber (which was suppose to be a Mach 3+ bomber) and it went inverted and smashed into the tail of the bomber, and exploded. Sorry, the early years of test pilots, NASA has always fasinated me, and buddies of mine call me a walking encyclopedia of aircraft knowledge ;)

Re:X 15

[Anonymous Coward]

I hope it's not a psychic slip, but I misread the word "walking"...

Feasibiliy of High Speed Travel

[Faith_Healer]

Seems like if you travel at mach 7 there would have to be a massive acceleration/deceleration period if you wanted to survive the trip. Would it even be posible to make use of the capilibility to move a person at mach 7 if you wanted to take the shortest path from one place to another with out going the long way arround our little 8000 mile wide planet.

Re:Feasibiliy of High Speed Travel

[MajorDick]

I seriously hope this is a joke. This reminds me of the Back page of a 1957 Cars of Tommorow magazine, that was dealing with Drag Racing and Maximum speed, its claim laid out very scientifically with all kinds of formulas, was that a Drag car could never accelerate and stop beyond 200 mph in a 1/4 mile, because well it was just scientifically impossible.

Re:Feasibiliy of High Speed Travel

[mindstrm]

Not that massive.

Shall we calculate?

Let's say for rough estimation purposes mach is about 1000km/h, or 277.8 m/s
So mach 7 is 1944m/s

Let's say that G is 9.8m/s^2 (It is)

1944/9.8= 198.4 seconds

In other words, at 1G, after 3 minutes and a bit ,you will already be cruising at mach 7.

IN that time, you would have gone approximately 193km.

Factor in the same for deceleration... and we could say.

You could comfortably go 400km in about six minutes. Less than that and this speed is not practical.
For that matter, you spend more time in preparation and airports than you do on an aircraft for a 400km flight in the first place... so mach 7 would be really practical for longer flights.

Re:Feasibiliy of High Speed Travel

[Anonymous Coward]

What???

1G is 32 feet/second/second. Mach 7 is roughly 8000 feet/second. Let's say you restrict your acceleration forward to roughly 0.5 g, (which gives you a perceptible weight of sqrt(1.0^2 + 0.5^g), or sqrt(1.25) = 1.1 G perceived by your passangers, hardly enough to notice), then it takes you roughly 8000 feet/second divided by 16 feet/second/second, or about 500 seconds. That gives you almost 10 minutes to reach your desired speed, plenty to accelerate and decelerate for a shopping trip on the other side of the world. The overall trip would take (12,000 miles / Mach 7) over two hours, roughly 160 minutes not counting the time lost accelerating and decelerating.

Ye ghods, yes, this is possible.

Re:Feasibiliy of High Speed Travel

[quetzalc0atl]

i think that you misunderstood his (reasonable) question. the question is: is there enough "road" here on earth to actually fly this thing and take advantage of its mach 10 capabilities (while also taking into account for the limitations of a human being withstanding extreme forces). most ppl do not realize the tremendous physiological issue that fighter pilots deal with everyday.

as for your Cars of Tomorrow magazine, in fact what has changed is that the coefficient of friction for racing slicks is now 3 - 4. It was previously believed (and even still believed by many physics professors) that the c.o.f. was always less than 1. why does this matter? because physics _does_ say that a car that is propelled by frictional forces (i.e. tires) will never be able to accelerate faster than it's mass times it's c.o.f. doesn't matter how big the engine, how powerful the fuel, etc.

Re:Feasibiliy of High Speed Travel

[snarkh]

1G is not a comfortable acceleration for passenger travel.

Re:Feasibiliy of High Speed Travel

[mamba-mamba]

physics _does_ say that a car that is propelled by frictional forces (i.e. tires) will never be able to accelerate faster than it's mass times it's c.o.f. doesn't matter how big the engine, how powerful the fuel, etc.

Or in less scientific terms, it doesn't matter how much horsepower you have if you can't get hookup. You'll just sit and spin, turning expensive tire rubber into blue smoke.

MM
--

Re:Feasibiliy of High Speed Travel

[mamba-mamba]

The only thing is, during much of the acceleration time, they will have to use a different type of motor, since a scramjet motor will not work at lower speeds.

However they get up to minimum scramjet ignition speed, there is likely to be a pretty good kick in the pants when the scramjet ignites.

And the question of how they get up to that speed is a very important one to work out. If a rocket is used, then acceleration will be very brisk. Also, if you are going to use a rocket anyway, why bother with the scramjet at all? (In fact, a lot of people feel that scramjets are a solution in search of a problem.)

If a rocket is not used, then what will get you up to that speed? They could climb to 70,000 feet, then go into a power dive to start the scramjet, but can you imagine the G's when you pull out of a dive at hypersonic speed?

I'm not saying it can't work, I'm just pointing out that there are many issues to resolve before commercial flights are remotely feasible.

For very high speed travel, leaving the atmosphere may be the way to go. Hypersonic atmospheric travel is almost like constant re-entry. And designing a craft to get up to those speeds from horizontal takeoff is no joke.

Just some things to think about.

MM
--

Re:Feasibiliy of High Speed Travel

[quetzalc0atl]

no, that is not what that says.

what it says is that there is a _fundamental_ limit to the maximum acceleration that can be achieved, has nothing to do with spinning the tires, etc. this is assuming that you do not spin the tires at all, there is still an upper limit that is defined by your mass.

Re:Feasibiliy of High Speed Travel

[KD5YPT]

Actually if you count acceleration in a horizontal sense, earth provides 1G, 1G horizontal, the passenger will felt around 1.3G of force on them, which is not much. (Some people might get a thrill out of it "WEEEE!")

Re:Feasibiliy of High Speed Travel

[KD5YPT]

Human could withstand roughly 9G vertical (for a short period) in a flight suit without passing out. Astronaut can withstand around 13G since they're literally lying down. So with the right equipment, 9G vertical and 13G horizontal, of course, it'll be no where close to being comfortable.

Re:Feasibiliy of High Speed Travel

[snarkh]

Well,the horizontal component of the force will be equal to 1G times the mass of the passenger.

The absolute value (which is 1.4 G approx) is not important as we always have to bear the force of gravity in any case.

Re:Feasibiliy of High Speed Travel

[mamba-mamba]

I was assuming that what you were talking about was that the maximum forward force, assuming that the dragster has ample power, is dictated by the maximum frictional force of the tires on the pavement. This, in turn, is a function of the weight of the dragster and the friction of the tire on the pavement. (Increasing weight doesn't necessarily help you, though, because as you add weight, you also increase the force needed to reach equivalent acceleration.) Any application of power which causes the wheels to break loose (and therefore switch over to their dynamic coefficient of friction) will create an expensive blue cloud.

If you are talking about something else, then maybe you should explain in more detail where this fundamental limit arises from and how mass enters into the equation.

MM
--

Re:Feasibiliy of High Speed Travel

[mindstrm]

Yes.. I didn't want to get too detailed.

I realize that for joe average this would be straining after a time.. the point is that it's certainly not "far too much".

Re:Feasibiliy of High Speed Travel

[Anonymous Coward]

No it's not defined by your mass, but by the gravity force. With c.o.f.=1 you can accelerate no more than 1g = 9.8 m/s^2. At this point the force of acceleration = 1 x force of weight. If you increase force of acceleration more, the tire will start to slip. Mass cancels out of this equation because both force of weight (Fw = m * g) and force of acceleration (F = m * a) are proportional to mass. If you have a c.o.f. = 2 you can accelerate up to 2g, and so on. Another option to beat c.o.f. would be to use spikes (which is used in bike racing on ice).

Re:Feasibiliy of High Speed Travel

[Anonymous Coward]

horizontal acceleration of 0.5g corresponds to a car accelerating to 100 km/h = 60 mph in approx. 5.5 seconds. Only few of us have cars that are capable of that and I am pretty certain that you would notice such an acceleration. It would probably feel like tilting the seat backwards by 30 degrees (=arctan(0.5/1)).

Re:Feasibiliy of High Speed Travel

[esonik]

9G vertical (for a short period) in a flight suit without passing out.

have you seen videos from people at 9g? even for trained combat pilots it's hard to not pass out during a few seconds at 9g.

Re:Feasibiliy of High Speed Travel

[KD5YPT]

Emphasis on "short" period of time. Well... atleast you won't die at 9G... unless you experienced it for a long time (a few seconds IS long in that sense).

SCRamjet = Supersonic Combustion Ramjet

[amigoro]

So what's a Ramjet?

There's one fundamental difference between an ordinary jet engine and a scram jet engine: The Ramjet has no moving parts.

The all jet engines,operate according to Newton's Third Law of Motion:
For every action, there's an equal opposite reaction

The standard jet engine, invented by Sir Frank Whittle, sucks in air at the front. Then this air is mixed with fuel, and made to combust. The combustion causes the air to exit the engine at a velocity greater than when it came in, thus creating thrust. The escaping air causes the turbine to spin, and this intern activates the compressor, sucking more air in.

The Ramjet has no turbine and compressor unit. Ramjets fly supersonically and have an inlet which injests subsonic air after it goes through a shock wave in front of the inlet. The intake is slowed down aerodynamically, and then mixed with fuel and made to combust. But after about Mach 5, ramjets don't work so well.

The scramjet is almost but not quite entirely like a ramjet. The only difference being in a scramjet the combustion takes place as the air is travelling through the chamber at supersonic velocities.

More about the scram jet. Or another more concise explanation.

Moderate this comment
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Re:SCRamjet = Supersonic Combustion Ramjet

[Big_Breaker]

Efficient combustion requires that the fuel reacts with oxygen under a certain amount of pressureand for a certain period of time.

Regular jets need a compession step, using turbine blades, to create an effective combustion chamber.

Ramjets operate at a speed and altitude where these turbine blades are not necessary to create the necessary pressures.

Scramjet is a meaningful designation spearate from ramjet because it covers speeds at which the air is moving too fast for combustion to run to completion before exiting the exit nossle. Scramjets solve this with various aerodynamic techniques.

Re:SCRamjet = Supersonic Combustion Ramjet

[brucmack]

The escaping air causes the turbine to spin, and this intern activates the compressor, sucking more air in.

It is also important to carefully select the intern controlling the sucking, else risk legal troubles down the road.

Re:SCRamjet = Supersonic Combustion Ramjet

[Anonymous Coward]

All engines (jet or not) operate on the basis of Newton's third law, so this is a little bit pointless to mention.

You go higher... less air resistance, less heat

[Kjella]

Which of course also means less athmosphere for the engine to work with too, but oh well... Given enough speed it might also "leap" out into space where there's hardly any resistance at all, so essentially it'll just come back down to "breathe".

Kjella

Re:You go higher... less air resistance, less heat

[the_2nd_coming]

less air is not a big deal. combustion can be kept up as long as enough oxygen is entering the engine and at those speeds, the volume of air coming in is sufficient to do so.

Re:You go higher... less air resistance, less heat

[forlornhope]

Wrong, volume has nothing to do with it. Remember, as the density goes up the mass that a certain velume contains goes down. All that matters is the mass flow rate. That is the density times the velocity(parallel to the inlet) times the inlet area. For purposes of any air breathing engine its that value that determines if it can sustain combustion.

On a side note though, one of these combined with a Pulse Detonation Engine could be enough to create a truly reusable orbital vehicle, which would be mad cool(yes mad cool is an engineering term).

Re:You go higher... less air resistance, less heat

[the_2nd_coming]

excuse me, but as speed increases, the VOLUME OF AIR FROM THE ATMOSPHERE entering the intake goes up.

do you know what that means? that means that the volume of the swath of atmosphere is greater than the volume at a lower speed.

in the combustion chamber, the density of the air must be sufficient to maintain combustion, to achieve that, you must scoop up a greater volume of atmosphere, which is why the Scramjet works at such high altitudes, it is going fast enough to get enough oxygen into the combustion chamber to sustain combustion....super sonic jets are not capable of those speeds, and as such are limited to the altitudes they can reach.

Re:You go higher... less air resistance, less heat

[forlornhope]

Look in any compressible aerodynamics book or combustion and propulsion book, they dont care about volume because it doesnt mean anything. They care about mass flow rate.

Technically we are both talking about the same thing but you are looking at it from a very simplistic layman's point of view. Any true engineer will use mass flow rate over volume because it means more and carries with it more information.

Re:You go higher... less air resistance, less heat

[Anonymous Coward]

Oooh, let's see whose penis is bigger.

A true engineer will use whatever damn variable is most convenient for the computation at hand, as long as they lead to the right answer (give or take a few decimal places). A scientist might care about only using the politically correct figures. ;)

Re:You go higher... less air resistance, less heat

[Jim Starx]

I think your missing the entire point of a scramjet. It's designed to deal with the fact that airflow does matter.

no,

[Anonymous Coward]

the point is to gain the capability to bomb anyone in the world really quickly .

Re:no,

[Anonymous Coward]

Actually, it started out as research for a new form of a space plane. That has been changed in the last few years.

First Mach 10...

[Evanrude]

Then Quantum Leap. Where will Scott Bakula show up next??

Re:First Mach 10...

[Anonymous Coward]

who knows, he is a very enterprising fellow.

Re:First Mach 10...

[Anonymous Coward]

Amd if it were the Road Runner being chased by Wile E. Coyote, it would be Quantum Beep.

Re:First Mach 10...

[Anonymous Coward]

depends how fast it takes him to get up your buddys ass....

~GoAT~

CNN should take a look at the history books...

[Anonymous Coward]

Taken from the CNN article:

"It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours."

Wow... Concorde used to cover the distance in about 3.5 hours...With turbojets. Now that's progress!

A flight at mach7 between NYC and London should take less than an hour... with most of the time spent circling over the destination in the holding pattern before landing...

Re:CNN should take a look at the history books...

[wisebabo]

Yeah but they are going the long way around.

But it isn't nothing.

[Anonymous Coward]

Instead of a rocket launching this vehical, it's big brother could launch a rocket then return to earth for reuse. Bigger satellites, smaller cheaper, simpler rockets, both.

And BOOYA think of the cruise missles. KE=vmv/2.

Shit hits the fan, but the battle group isn't on station? No worries. Diplomacy is en route. Maybe paint a little picture of gerry-curl sam jackson smoking a cigar on the front of each one.

Commercial flights in the future

[armando_wall]

We'll soon be able to fly to Japan in less than two hours. It's going to be a truly small world for everyone.

Putting aside ticket prices and the uncertainty of how this will affect global economy (for good or for bad), there are more interesting times to come.

I hope I am alive and lucid by then.

Re:Commercial flights in the future

[slash.dt]

We'll soon be able to fly to Japan in less than two hours. It's going to be a truly small world for everyone.

Although technically we could fly to Japan in less than two hours, it won't happen for a number of reasons.

Firstly, cost. Still takes a lot of fuel to get you to those speeds. You need to get a lot of bums on seats, or at least enough people wanting to pay the price to fly that quickly to make it viable. How many of us were willing to pay for the shorter trip time on the Concorde?

Secondly (and more importantly) noise. The Concorde could fly to Tokyo from London or New York right now, except that the people under the flightpath don't like the noise. Ever noticed that the only regularly scheduled flights for the Concorde (when it flew) were over the ocean and not land?

Re:Commercial flights in the future

[Anonymous Coward]

Nope.

The biggest factor in commercial air travel is fuel cost. Profit margins are very narrow, so packing in a few extra passengers per flight can make a big difference, as can shaving some weight off the plane.

But flying faster just isn't on the metaphorical radar. People buy the cheapest plane ticket they can find, not the shortest flight time.

For these reasons, amongst others, Concorde could never compete with slower, cheaper flights.

In short: we ain't gonna see hypersonic airliners. Not in our lifetimes, and probably not ever.

It's the engine...

[Kjella]

Yes, we've done Mach 7 before. And the space shuttles & space probes go much faster. The big deal is the engine. It's like comparing a nuke to some kilotons of TNT. Sure they may have the same effect (Mach 7), but one is simply a gigantic waste of resources (fuel), the other is a valuable invention. And considering it's the military, for good or bad...

Kjella

Re:It's the engine...

[Anonymous Coward]

Acutally, space probes (once in space) aren't travelling at any Mach number. Mach is a ratio of the speed of sound. Sound doesn't travel in a vacuum, so any speed divided by zero is, well, a divide by zero error.

So when you say Mach, do you mean relative to Mach 1 at sea level? At the altitude the craft is traveling at?

Apples and rhinos people, apples and rhinos.

Re:It's the engine...

[Anonymous Coward]

In other news, NASA is not the military.

Adtional information on scramjets

[Faith_Healer]

If you want some something that will help understand the scram jet and you have a little aerospace knowledge check out this paper on combustion on a supersonic stream, http://www.anu.edu.au/Physics/aldir/publications/H yslop_hons_thesis_1998.pdf. Its amazeing that this jet can sustain a burn with out a flame holder, at least it looks like it does.

380,000 years to Proxima Centauri

[Anonymous Coward]

Let's see the nearest stellar neighbor, Proxima Centauri, is 4.3 light years away.

1 light year = 5.9 x 10^12 miles
(5.9 x 10^12 miles) x 4.3 light years = 2.5 x 10^13 miles

then

2.5 x 10^13 miles/7.6 x 10^3 mph = 3.2 x 10^9 hours
3.2 x 10^9 hours/24 hours = 1.3 x 10^8 days (give or take a leap day)
1.3 x 10^8 days/365 days = 3.8 x 10^5 years

380,000 years to nearest stellar neighbor

Don't forget the coffee-can exhaust...

[Anonymous Coward]

Don't forget the coffee-can exhaust and the 15-foot spoiler removed from an old 727 for the full effect.

I don't think so ...

[Anonymous Coward]

Unfortunatly the amount of fuel needed for such speeds would outweigh the time saved.

Re:I don't think so ...

[Big_Breaker]

Not necessarily. Airlines fly higher so that they can go faster with less drag. We'd probably see ramjets before we'd see scramjets.

Re:I don't think so ...

[KD5YPT]

I think Concorde already use ramjet.

THE PROGRAM IS BEING HALTED!

[wisebabo]

There's an old Airforce saying:
A new plane doesn't make a new engine possible: A new engine makes a new plane possible.

That's why when NASA went for the moon a critical development was the F-1 first stage rocket engine. Capable of 1.5M lbs. of thrust it allowed the Saturn V first stage to be built with only 5 engines. Compare this with the Russian failed manned lunar rocket the N-1 which had 20 engines. They never were able to work all together (vibrational problems) and abandoned it after several launch disasters.

So why is NASA stopping development? (The successor the X-43C will not be flown). Why are we freezing this enabling technology? Are we (under Bush's program) sacrificing everything to plant a flag on Mars and not making space flight practical? It might be worth it if we ever got to Mars but it looks highly doubtful that his proposal is a serious attempt at anything but votes!

Sorry for the (mostly) repost but I really wish we would move "faster" towards developing the technologies towards practical* spaceflight.

*As noted in previous posts, by not carrying the oxygen on board you save a LOT of weight. Remember the reaction is H2 + O = H2O (and energy) and since the atomic weight of oxygen is 16 compared to hydrogen for every kilo of hydrogen you carry you carry EIGHT of oxygen. The weight savings (could be in the millions of pounds) makes up for the turbo-fans/rocket engines you must carry for the takeoff/orbital transition parts of the flight.

Re:THE PROGRAM IS BEING HALTED!

[Krackbaby]

I think this programs future has been uncertain because of the uncertainty of its success. Remember what happened to the first one. Governments tend to be very wary of failure in expensive scientific endeavors, even if those failures teach us lessons necessary to succeed. Now that they've had a pretty stunning success, at the very least the millitary is going to be VERY interested in continuing this project (they're already funding this part) and even if NASA's budget doesn't allow for continuing this program with current priorities, I think the Military has been convinced this is a direction worth pursuing further. Just a guess on my part, but I bet you see new funding quite soon.

Re:THE PROGRAM IS BEING HALTED!

[demachina]

"So why is NASA stopping development?"

I'd rather doubt they are. If it can be made to work and there is a need, either the NASA program will be funded or it will disappear in to an Air Force black program and will just appear to have been killed.

It does appear it can be made to work and it would presumably add a new top end to Aurora or whatever the Air Force's current black program is.

Its use for civilian transportation is dubious. Its pretty dangerous and would take a LONG time to be made safe, cheap and comfortable. I'm also doubtful it will prove to be a great launch vehicle though you never know.

Its military applications are obvious. The DOD has a pretty desperate need to drop bombs on targets of interest that arise quickly and move around like Bin Laden. When they get intelligence he is at a place they need to drop ordinance there as quickly as possible before he moves and with some targeting flexibility. A manned or remotely controlled Mach 11 bomber would seem ideal. An RPV version of this could come to fruition a lot faster than a manned version, Cruise missiles, the stealth bomber etc are to slow to get to the target in time. Using ballistic missiles tends to set of alarm bells in Russia, China and everyplace else where governments have satellites watching for launch signatures. Targeting for ballistic missiles also can't be redirected at or stopped at the last minute.

It would also be priceless for strategic and tactical reconnisance. Spy satellites are to predictable and inflexible since they are locked in to orbits with limited manueverability. Most countries know the schedule and hide stuff when they are overhead. A Scramjet would be flying fast and high enough it would be hard to shoot down, or even detect until after its done the job.

NASA Dryden deserves a huge pat on the back for finally bending metal and flying something. They've been wasting money on computer generated fantasies for this concept for more than a decade and haven't done much to realize it. It would be fantastic if it lead to a better launch vehicle and civilian transport, I just doubt that it will.

Re:THE PROGRAM IS BEING HALTED!

[DerekLyons]

The weight savings (could be in the millions of pounds) makes up for the turbo-fans/rocket engines you must carry for the takeoff/orbital transition parts of the flight.

Actually, the weight savings is non-existent. Sure, you save about 25% of the LOX in your first stage, but that's more than made up by the increased structural weight and thermal protection. Fact is, when the numbers are added up, you frequently come out worse in both weight and cost.

Using a re-useable airbreathing first 'stage' is a powerfully seductive theory, but it simply doesn't work in reality. (Ever wonder why those stages appear now largely only in fiction, and have mostly dissapeared from serious proposals?)

really clean too

[frostycellnex]

Unless they're leaving something out about the fuel they're burning with the hyper-compressed air, this engine would be ultra clean too. Since the fuel is hydrogen (as shown by this NASA diagram), and the combustion agent is the oxygen in the compressed air, then the byproduct would simply be water. There would of course be some heat pollution, which is still actually a potentially serious pollutant, but only when the contrails created from such heat become as numerous as those from today's airliners.

Re:really clean too

[Uber Banker]

Except the production of hydrogen is not all that ultra clean.

Re:really clean too

[AndroidCat]

Under those conditions, I wouldn't be surprised if some Nitrogen got involved. (Hey, it's a hot high-pressure situation and you've got a split-second to grab a bondage date. It happens.)

Re:really clean too

[Doc Ruby]

It is when you crack water with solar-powered electrolysis. The hydrogen is the battery, not the power.

Re:really clean too

[pfdietz]

At hypersonic speeds, you're going to start getting NOx production just from the shock wave alone.

Yeah!!

[the eric conspiracy]

NASA overclockers RULE!!

smoke trail

[Anonymous Coward]

does a regular ram jet engine leave behind that odd puffy smoke trail? I was a little confused when i saw the video of the "2nd flight ever" of a scram jet becasue i saw that exact same smoke trail over my house a few years ago. If a regular ram jet left the puffy trail that would explain a lot.

Re:smoke trail

[KD5YPT]

ramjet and scramjet are essentially the same, they both compress air by their own velocity (unlike normal jet engine, which compress air with the engine's own turbofan, which cause a waste in energy).
The only difference is that...
Ramjet has a combustion chamber that slow the air down before combusting it. It's designed so that the fuel/air combo is combusted at subsonic speed.
Scramjet does not have a special combustion chamber, the fuel was combusted with air traveling the supersonic speed (hence the problem of the fuel being blown out the engine before it can be burned).
So I think ramjet would also make a similar puffy smoke trail as scramjet.

Re:smoke trail

[Artifakt]

That was actually light from Venus reflecting off swamp gas. Please remain at home while representitives of the US Air Force explain this further.

Re:smoke trail

[Anonymous Coward]

No, most ramjet engines have a movable spike at the front, that helps maintain the correct position of the shockwave so that it doesn't enter the engine.
If the shockwave does enter the engine, it flames out, because the shockwave chokes out the air.

Of course, this is taken mostly from descriptions posted in the past on the Skunkworks-L listserv, from people who flew/designed/etc. the SR-71, whose engines essentially were hybrid turbojet-ramjet engines that never fully went into ramjet mode.

Oxygen in space?

[Anonymous Coward]

Will this be used for space travel? Isn't there no oxygen in space?

Re:Oxygen in space?

[Anonymous Coward]

Not very smart, are you?

To put things into perspective...

[Xeo 024]

The circumference of the Earth at the equator is 24,901.55 miles (40,075.16 kilometers).

So traveling at Mach 7 (2382.03 miles per second), one could circle the entire equator in 4 hours 40 minutes and 23 seconds! That's fast.

Re:To put things into perspective...

[Anonymous Coward]

Erm...i think not. That would equate to 0.012c . METERS per second.

Re:To put things into perspective...

[elsegundo]

Well if it had wheels you could do that.

At 100,000 feet the circumference will be 24,961.06 miles.

So travelling at 2382.03 meters/sec or 1.48 miles/sec it would take 4 hrs. 41 min. 6 secs. Still pretty frickin' fast!

Yes, I'm anal. :)

Re:To put things into perspective...

[Punchinello]

Now that is cool. With enough fuel onboard You would be able to watch the sun rise in the west and set in the east.

science vs. lay

[MasTRE]

I clicked the first link and saw that NASA only used Mach units to report speed. Then, before clicking the CNN link, I made a bet with myself that they would include mph. Needless to say, I won :)

Armchair physicists are idiots

[Anonymous Coward]

Let's sum it all up. 1) Escape velocity is IRRELEVANT in the discussion. That applies to unpowered vehicles - not a vehicle under constant power such as this one.

2) As has been already posted. The speed record isn't for ANY vehicle. The record is for a vehicle with an air breathing engine (ramjet, scramjet, etc). It doesn't apply to vehicles such as the X-15, Apollo capsules, the space shuttles, etc as their speeds were/are either rocket powered or unpowered reentry.

3) During the first test the scramjet engine did NOT fail. It was never even fired. The booster engine that was supposed to get the scramjet to mach 5 is what failed. If I remember right the fins or something fell off and it went out of control so the remote detonated the booster and consequently the scramjet testbed attached to it.

4) The toyota corolla attachment won't be out until 2006.

Re:Armchair physicists are idiots

[Anonymous Coward]

If we really want to get to the truth, then I think the reason the first test failed was due to the engineers not fully predicting the flight caracteristics of a pegasus with X43A strapped to it. The pegasus flight control computer could not compensate enough, and the went outside its flight envelope, causing it to brake.

Re:Armchair physicists are idiots

[0x0d0a]

4) The toyota corolla attachment won't be out until 2006.

Bullshit. Toyota announced that they will not be selling *any* vehicles with the scramjet until it completes product safety retesting, which will be finished in 2008 at the earliest. Apparently, the flux capacitor doesn't perform as expected above about 88 mph.

Re:Armchair physicists are idiots

[the eric conspiracy]

Toyota announced that they will not be selling *any* vehicles with the scramjet

Yes, but Toyota Racing Division (TRD) is making these available as aftermarket add-ons.

Re:Armchair physicists are idiots

[mOdQuArK!]

1) Escape velocity is IRRELEVANT in the discussion. That applies to unpowered vehicles - not a vehicle under constant power such as this one.

Well, not exactly - since this is an air-breathing engine, escape velocity would become relevant when the engine can no longer suck in enough air to keep operating.

he's right here...

[jpellino]

Where else?

sorry. had to.. old childhood memory...

Holy wow. Mach 7!

[blair1q]

Could you imagine a beow<ABORT-ABORT-ABORT>

Scientists my eye....

[Nick Driver]

good work scientists :)

ENGINEERS had more to do with getting this ship up to Mach 7 that did the scientists!

Re:Scientists my eye....

[NuShrike]

The scientists were probably also the same team of engineers. That's how these research projects work.

Re:Scientists my eye....

[Anonymous Coward]

Get over yourself. Scientists have just as much or more to do with new technology as engineers do.

Re:Scientists my eye....

[dargaud]

Like they say:

"A scientist can discover a new star, but he cannot make one. He would have to ask an engineer to do that." -- Gordon L. Glegg, American Engineer, 1969.

Re:Scientists my eye....

[Anonymous Coward]

>ENGINEERS had more to do with getting this ship up to Mach 7 that did the scientists!

And how would you know that?? Considering someone (who??) modded you up to +5 insightful I expect you have a very, very good answer at hand.

Your are mistaken

[WindBourne]

I was watching CNN headlinenews yesterday, and it had a piece on it every 60 minutes. I saw it first at 9 AM(MST) and saw more at about 4 PM(MST).

As to hitting OBL, well, it will take about 5-10 years to get this into useable mode. If OBL is still running around, then something is way wrong with US politicians.

Big deal, Mitchell Gant hit Mach 6 back in '82.

[Anonymous Coward]

Big deal, Mitchell Gant hit Mach 6 back in '82.

Did the pilot have to think in russian?

Not exactly

[HangingChad]

Are we (under Bush's program) sacrificing everything to plant a flag on Mars...

Not exactly. We're sacrificing most everything for the Bush program to plant a flag in Baghdad.

Re:Not exactly

[Atzanteol]

Mods if you have any mercy, mark this as the flamebait it is...

Re:Not exactly

[Anonymous Coward]

mercy is for bleeding heart liberal traitors

From the CNN article

[badmonkey]

"The space agency's dogged pursuit of extreme speed, officials hope, will ultimately make space flight easier to accomplish.

It also could drastically cut the time of commercial flights -- perhaps shortening the trip between New York and London to less than five hours."

New York to London in less than five hours! That's heresy, that can't be done!

Re:From the CNN article

[Eslyjah]

By my count, 2 is less than 5, so the article is correct.

Throwing away information

[jmichaelg]

I'm perplexed by the fact that NASA intentionally threw away the plane before they'd done a post-mortem. The airframe could yield an awful lot of information about how well the craft stood up to the stress and yet they just let it sink in the Pacific. Seems to be either a waste of valuable information or suggests that this is more a publicity stunt than science.

Re:Throwing away information

[praksys]

Any idea what speed it was travelling at when it hit the water? How much extra weight would it have required to make it survive the impact and float? How much would it cost to have a recovery ship on station? What would the risks be of it being stolen while floating around at sea? How large an area might it come down in?

They wanted to test an engine. Adding crap to the vehicle, cost to the program, and an espionage risk, makes no sense at all.

Re:Throwing away information

[utexaspunk]

or, alternatively, they don't care what happens to the delivery vehicle- because this thing will be used in globe-crossing cruise missiles long before it goes into anything reusable...

Re:Throwing away information

[KD5YPT]

The reason is that they're not testing the airframe at all (it's built to be as simple and light as possible), they're just testing whether the engine can even light or not. That was their past problem, scramjet in past can't operate past mach 6.

Re:Throwing away information

[No. 24601]

The airframe could yield an awful lot of information

The simulations are probably more precise than getting your hands on the aircraft after flight. In fact, the simulations would not take into account other non-flight stress like hitting the water from that altitude ;)

Re:Throwing away information

[Anonymous Coward]

Are you kidding? Simulations are only simulations and need real data to be calibrated...

Re:Throwing away information

[Anonymous Coward]

Congrats! You've posted the most stupid comment in the entire thread!

Re:Throwing away information

[patternjuggler]

Seems to be either a waste of valuable information or suggests that this is more a publicity stunt than science.

I think it was a stunt to try to save the program, which last I heard NASA was pulling out of so it could focus on the 'New Vision'. Though it's likely the Air Force will pick up the tab for all atmosphereic propulsion technologies, in any case...

CNN Errors and the quarter mile

[Wingsy]

Looks like the guy who did this reporting for CNN isn't much of a techie. A few things he got wrong: (1) "scramjet, which uses air for fuel" -- quite a few people will read that as not requiring ANY onboard fuel at all. (2) "shortening the trip between New York and London to less than five hours" -- we can already do that in LESS than 5 hrs. (3) "it flew under its own power for six minutes to do maneuvers over the ocean" -- if you count gravity as its own power. It was only powered for 10 seconds under the scamjet, and "glided" the rest of the way to splashdown.

Now this intrigues me: It was taken to mach 5 by the Pegasus, then it accelerated under the scramjet to mach 7, BUT the engine was only lit for 10 seconds. Does that mean this succer gained nearly 1400mph in 10 seconds???? Wonder what it would do in the quarter? How many Gs is that?

Re:CNN Errors and the quarter mile

[ralphh]

One G is about 22 mph/s, so 1400 mph/10s is a about 6.4 G's.

Re:CNN Errors and the quarter mile

[mabu]

This really ticks me off. How tough is it for CNN to research their news so that they can avoid a ten second soundbyte being riddled with inaccuracies?

Re:CNN Errors and the quarter mile

[lfnoise]

It was taken to mach 5 by the Pegasus, then it accelerated under the scramjet to mach 7

This is not true. The pegasus booster took it all the way to mach 7. The scramjet proved it could make positive thrust, but it did not accelerate, it actually decelerated during those 10 seconds. Maximum speed was at booster burn out. This is according to their press conference yesterday.

Also, see this video: (remove the space in the URL)

http://www-pao.ksc.nasa.gov/kscpao/videos/metafi les/ksc_032504_x-43.ram

Re:CNN Errors and the quarter mile

[Anonymous Coward]

My physics are rusty. I got a question:

Gs are a measure of gravity right? And if gravity is an acceleration constant, shouldn't your units be in mph/s^2?

Your use of "mph/s" is a velocity.

Re:CNN Errors and the quarter mile

[man_ls]

mph/s is an acceleration.

mph is a velocity.

delta-v per second is acceleration

There wasn't anything left to examine

[Anonymous Coward]

Um, the airframe hit the ocean going several thousand miles per hour. There wasn't anything left larger than a dime.

Uhh guys...this has been done before

[shthd]

From cnn It is the first time a supersonic-combustion ramjet, or scramjet, which uses air for fuel, had traveled so fast, flight engineer Lawrence Huebner told reporters. The University of Queensland Launched the HYSHOT in July 2002. It Hit Mach 7.6. The first people who did this

Re:Uhh guys...this has been done before

[Stregone]

From what I can gather form that site, the HYSHOT only actualy ran for a few seconds. The x-43 apparantly ran for 6 minutes. By 'ran' I mean under its own power.

Re:Uhh guys...this has been done before

[Anonymous Coward]

Check this article for details, but apparently they used a 2 stage solid fuel rocket to accelerate the engine to Mach 7.6. Then they did a 6 second test of the scramjet.

Re:Uhh guys...this has been done before

[Anonymous Coward]

Not quite, according to the NASA link the scramjet ran for about 10 seconds out of the 6 minute flight.

Re:Uhh guys...this has been done before

[Chairboy]

Nope, the X-43 flew under its own power for 10 seconds.

Re:Uhh guys...this has been done before

[Anonymous Coward]

The Australian scramjet produced no net power (as it says on the website), so any acceleration was caused by gravity. NASAs produced net power (accelerating from Mach 5 to Mach 7 if I remember correctly).

Re:Uhh guys...this has been done before

[shthd]

Nope, X-43 did not accelerate from Mach 5 to Mach 7. The booster carried it all the way up to that speed. The x-43 got ignition going at mach 7 which is an incredible feat. When you read into the article that it accelerated from mach 5 to 7 it was the fault of crappy reporting.

Re:Uhh guys...this has been done before

[Anonymous Coward]

It sure as hell didn't accelerate by 1400 miles per hour in 10 seconds there, bud.

Re:Uhh guys...this has been done before

[Anonymous Coward]

Yeah, the NASA sites indicate the booster takes it up to Mach 7... and I must admit that Mach 5 to Mach 7 in 11 seconds would be pretty, er, amazing. What I was remembering was this bit (which I've seen in a number of places including the washington post):

"Flight engineer Lawrence Huebner said preliminary data indicated the needle-nosed jet reached a maximum speed of slightly over seven times the speed of sound, or about 5,000 mph, after a rocket boosted it to about 3,500 mph."

Re:Uhh guys...this has been done before

[Anonymous Coward]

That does seem a tad optimistic... some calculation:
Weight: 2,800lbf so we have a 87 slug mass
Delta velocity: 1400mph = 2100ft/sec, and duration = 11 sec, so:
Accel = 190ft/sec^2
Net thrust required = m * a
= 87 * 190 = 16,500lbf
Not too bad, but we have a little drag to contend with... at 100,00ft air density is roughly: 3.2e-05 slugs/ft^3
Cd (Coeff. of drag) = roughly 0.6 at Mach 7 for a blunt cone
Length = 12ft, width = 5ft, yields area of cone = 115ft^2
Drag = Cd * 1/2 * density * v^2 * area
= 60,000lbf

So the thing needs to generate on the order of 75,000lbf thrust...

A modern commercial jet airliner engine generates about 100,000lbf so it's not impossible but a bit unlikely... ;)

Re:Uhh guys...this has been done before

[shthd]

Pretty cool.... Yeah I'd say a tad unlikey since it only had enough fuel to burn for 10 sec.

Re:Uhh guys...this has been done before

[thepeete]

If it hasn't happened in the US, then, according to CNN, it has never happened.

Yeah, but...

[Anonymous Coward]

Does it run linux??? :)

but good acceleration

[MACC]

mach 5 to mach 7 in 10 seconds

660m/s / 10s ~66m/ss ~ 6G

quite good

This thing is (*TINY*)

[blair1q]

Take a look at the photo of the actual X-43.

All the pics were of the Pegasus booster rocket which was dropped from a B-52. You can't even resolve the X-43 in those photos.

That X-43 is smaller than most of the bombs that B-52 has dropped in its lifetime.

Recovery - they didn't

[Anonymous Coward]

There was no capability to recover the vehicle. This was a consious decision by the program team. It was planned to have it crash into the ocean when the mission was compelte.

A recovery system would have increased the weight and complexity (things to go wrong) of the vehicle. I assume the engineers and program managers decided that there were no significant benefits from examining the vehicle after flight to make the cost and compelxity of attempting to recover it worthwhile.

Speed Record

[Anonymous Coward]

I guess that this means that the SR-71 no longer holds the record for faster air-breathing plane!

Whoops

[The Tyro]

then drops down to its coldest temperature at the mesopause

Heh. For a second there I thought that said "Menopause"... many of my older female coworkers with hot flashes would disagree.

Sorry... it's early yet.

Re:Whoops

[ShooterNeo]

Glad to see you're back. So, umm, what's more exciting...trauma in the E.R. or the latest video game?

the scramjet did not accelerate to mach 7

[lfnoise]

According to their press conference yesterday, the maximum speed was attained at booster burn out. The scramjet achieved positive thrust, but it was decelerating the whole time (10 seconds). The speed was therefore the result of the booster and not the scramjet.

Re:the scramjet did not accelerate to mach 7

[lfnoise]

This NASA video confirms that it is the booster that got it to mach 7 : http://www-pao.ksc.nasa.gov/kscpao/videos/metafile s/ksc_032504_x-43.ram

Re:the scramjet did not accelerate to mach 7

[Anonymous Coward]

EXACTLY! The hype on this test is astonishing. Why can't these reporters ask the obvious question:HOW MUCH THRUST DID IT DEVELOP??????

Re:the scramjet did not accelerate to mach 7

[KD5YPT]

You're right, scramjet didn't accerlerate to mach 7, the only thing they're testing is that CAN scramjet operate when the air flowing through it is at mach 7. Because in the past, the major problem with scramjet is that when it approaches mach 6, the speed of the airflow literally snuff out the engine. Now they seems to be able to keep the scram jey burning at mach 7 (now they just need that thrust).

Aurora does this all the time.

[bondjamesbond]

You're comparing rockets to jets. Completely different. But, the Aurora does this all the time.

What we all want to know is...

[Anonymous Coward]

Suppose we can put HDs in this thing, what's the theoretical maximum sustained throughput in LOCs?

flyunder states

[Doc Ruby]

How about a scramjet-driven maglev loop across America? A 1000 ton freight train running NYC/LA in 1h (including de/acceleration) would reduce our dependency on the "heartland". And, if a straight tube were bored across the underside of the arc of the Earth's surface, the energy savings over a fleet of jet planes would pay for the drilling.

Re:flyunder states

[3waygeek]

It's been a while since university physics, but as I recall, you wouldn't need the scramjet or the maglev if you could get rid of friction. Gravity alone would get you from one end to the other in about 42 minutes, regardless of the tube's length.

Re:flyunder states

[Doc Ruby]

I like the "pendulum well" design, but "get rid of friction" is too much to ask, even from a maglev. The scramjet uses the frictional air to drive the system. But it is a hell of a lot louder, and less zen. BTW, nice "by construction" proof of the answer to the Question of Life, the Universe, and Everything.

Perfomance and economy

[soldeed]

Orbital velocity is damn near escape velocity, and thats the whole point. Getting to orbit economically is the key to making space travel pay instead of cost. It takes WAY more energy to get to orbit than to get from orbit to anywhere else in the solar system. Think about the Saturn V moon stack. You needed all the fuel in the 1st and 2nd stages, and most of the fuel in the 3rd, just to make orbit. only a small additional thrust from the third stage was required to send it on its way. We have all sorts of economical solutions for interplanetary travel, such as ion engines, solar sails, and nuclear engines. We need an economical booster technology, and this is it! 3500 mph to 5000+ mph in ten seconds with TWO POUNDS of fuel! Thats outstanding power and fuel economy In my opinion.

Re:Perfomance and economy

[corngrower]

Mod parent up. This is correct. Orbital velocity is the velocity an object needs to maintain an orbit about a planet (or another object). This is a tangential velocity. Escape velocity is the velocity necessary for escaping the gravitational pull of the planet (or other object).
Escape velocity is faster than orbital velocity. But like the parent poster says only a relatively small amount of thrust is needed to gain escape velocity.

Most of the energy in the fuel in a rocket is used to accelerate the remaining fuel in the rocket. Not having to carry along the oxidizer for the lower portion of the flight would save a lot of weight.
And with less oxidizer you need less fuel as well.

Re:Perfomance and economy

[pfdietz]

This is wrong. You actually need *more* fuel in a scramjet -- and the propellant tanks end up being much larger.

Airbreathing engines help the most early in the launch, since their Isp goes down with increasing speed. But early in the launch you don't care much about carrying oxygen, since it's used before the vehicle has accelerated much and therefore didn't require much previously used fuel to accelerate it.

Not exactly the same...

[Dan East]

http://www.mech.uq.edu.au/hyper/hyshot/:
As the spent motor and its attached payload falls back to Earth, they gather speed, and the trajectory is designed so that between 35km and 23km, they are travelling at Mach 7.6

http://www.uq.edu.au/news/index.phtml?article=3469 :
The recent HyShot(TM) launch was designed to take the scramjet engine to a speed of Mach 7.6 (or more than seven times the speed of sound) for the experiment, using a Terrier Orion rocket. The rocket and payload reached an altitude of 314km before the rocket was configured to fly in a new trajectory pointing the payload back down to earth.

HyShot was simply free-falling to earth in order to reach Mach 7.6 so the engine could be ignited. It achieved that speed regardless of whether or not the scramjet fired. The X-43 was flying horizontally, and was actually powered by the scramjet engine during a controlled flight.

So there is a difference between what was accomplished. The distinction is that HyShot achieved combustion, while the X-43 was the first scramjet powered craft to be flown.

Dan East

Re:Not exactly the same...

[Anonymous Coward]

Bullshit! NASA are always a step behind poorly funded universities.

Spacecraft

[Anonymous Coward]

Would it be possible to build a multi-stage craft that uses a scramjet engine for a part of the journey? A booster of some sort to get to scramjet minimum speed, and scramming till you can't really go faster due to low oxygen, and then turning on rocket engines to carry you to a higher speed necessary for orbiting. Let's face it, were using basically 50's technology rocket boosters to send up 70's technology shuttle to do work on a 90's spacestation nobody really cares for... okay, the rockets are better than then, and the shuttle has been updated, but still, we could do better.

Doubt it Re:10 seconds

[WolfWithoutAClause]

I've a sneaking suspicion that it would only work for 10 seconds- 'strapping on a bigger tank' would probably result in it melting. They've probably used heatsink materials to soak up some of the awesome heating effects you get at mach 7.

Besides, where would they put the bigger tanks? The thing is tiny; and hydrogen is seriously not dense; meaning very little fits into the vehicle.

Re:Doubt it Re:10 seconds

[KD5YPT]

They never put hydrogen as a gas in there. Even the rockets powering the space shuttle uses liquid hydrogen, which is actually very dense and heavy.

Re:Doubt it Re:10 seconds

[WolfWithoutAClause]

Um. No. Density of LH is a tiny fraction of gasoline- just 70kg/m^3.

Compare this to liquid oxygen which is (IRC) more like 1100 kg/m^3; or water 1000kg/m^3. Gasoline or kerosene is slightly lighter than water, but not a lot. Liquid Hydrogen is seriously not dense- that's actually the biggest problem with it.

Re:Doubt it Re:10 seconds

[Kiryat Malachi]

I wasn't seriously suggesting 'strapping on bigger tanks' to the existing design.

I meant something more along the lines of 'on the next design, knowing that the combustion will work, make the design large enough to be able to hold fuel sufficient for sustained combustion and appropriate heatsinking/materials to tolerate the sustained high speed'.

I just chose to contract it to 'strap on bigger tanks'.

Re:Doubt it Re:10 seconds

[KD5YPT]

I know that, What I meant is that compare to the gas itself, Liquid Hydrogen is much denser. Come to think about it... That's a no brainer...

What about the nitrogen?

[Stonent1]

Because of the high amount of nitrogen in the atmosphere, wouldn't this create a lot of Ammonia (Nitrogen + Hydrogen) as well as water vapor? They talk about oxygen all the time but that is only a portion of the atmosphere.

Re:What about the nitrogen?

[Anonymous Coward]

Nitrogen is far more difficult to dissciate (i.e. seperate the atoms), remember it's a triple bond, while oxygen is only a double bond. You need approximately twice as much energy to seperate a N2 molecule compared to O2.

Re:What about the nitrogen?

[Anonymous Coward]

Yes, high performance jets routinely create large amounts of nitrates (nitrogen + oxygen + hydrogen... just nitrogen + hydrogen is somewhat harder to make). It's a little mentioned but well known environmental problem with high performance jets, and one of the reasons why SSTs (supersonic transports) never really caught on.

Of course, it's not specific to the X-43A, and would probably be hard to measure, and the chemical reaction is actually a net detractor from total performance, so there isn't much point mentioning it.

Mod parent up.

[WindBourne]

ppl here seem to miss what was developed long ago. NASA may be faster and would supposedly be general knowledge.

Not trading for LH2.

[corngrower]

The problem is that a scramjet trades a dense propellant (LOX) for more of a low density propellant (LH2).

Not true. LOX is an oxidizer. LH2 is a fuel. Scramjets eliminate the need to carry the oxidizer. You would still need to carry the LH2 or other fuel in the rocket. Not only that but because you're also carrying the heavy oxygen, you need to carry MORE fuel. (and MORE Oxygen with which to burn it, (and MORE fuel ...))

Furthermore you want to carry with the vehicle a fuel that has a high energy to weight ration ( like LH2). You don't want something that is heavy (dense)with a low energy to weight ratio.

Re:Not trading for LH2.

[pfdietz]

I said propellant. Fuels and oxidizers are propellants. Scramjets reduce the need for the vehicle to carry oxidizer (one kind of propellant), but they increase the mass of fuel (another kind of propellant) that must be carried. Your claim that the scramjet vehicle needs less fuel as well is just plain wrong.

High specific energy fuels like H2 do give you higher specific impulse, but they also require the vehicle to have larger tanks, since their density (not coincidentally) is lower. This increases the dry mass of the vehicle, which increases the mass you are trying to put into orbit. If you are not careful you lose more from than than you gain from the Isp increase. This is a particular problem for scramjet launchers, where the amount of LH2 required can be several times that of an equivalent launcher with rockets.

It is not a coincidence that the first stages of multistage vehicles typically use a dense fuel like RP-1 instead of LH2 -- the density advantage wins over Isp for those. Some argue that even for rocket SSTOs hydrocarbon fuels beat LH2, since the wet/dry mass ratio can be much larger.

The tradeoff studies on scramjet launcher designs have consistently optimized to the 'rocket only' solution, I am given to understand.

Re:Not trading for LH2.

[srw]

Correct me if I'm wrong, but doesn't that big-ass tank strapped to the belly of the space shuttle contain LH2 and LOX? It seems to me that if you could reduce the amount of LOX you need (which is 8x as heavy as the LH2) you could significantly reduce the launch weight and therefore the amount of fuel required to get it to altitude. Or are you saying that scramjets are 10% as fuel efficient as the second-stage rockets on the space shuttle therefore you have to carry 10x as much LH2?

Of course, IANARS.

12-feet-long. Small in proportion

[johnjay]

I think the X-43 is 12-feet-long. This quote:

"The unpiloted 12-foot-long vehicle, part aircraft and part spacecraft, will be dropped from a B-52,aircraft. It will be boosted to nearly 100,000 feet by a rocket..."

from this NASA page is one source.

I think you are underestimating the size of the Pegasus rocket and B-52 bomber. I know I did. A quick google search found a page on the Pegasus rocket: it is 55.4 feet long and about 4 feet in diameter.

The USAF term for that is ...

[Artifakt]

the Mach 25 Orbital Dip Bomber. No, really. RAND corporation and DARPA were tossing that term around back in the 70's as a possibility if scram-jet research was funded.

More precisely

[olafo]

Mach 7 = 5 328.44936 mph (google.com)
The earth's circumference is 24,902 miles
=> 4.6737988 hours to fly around the earth (less flying east)*
=> 2.34 hours to reach anywhere on earth

(Note - altitude is insignificant in circumference calulations)

* earth rotates under aircraft

Re:More precisely

[SnowZero]

The Earth rotates eastward though, so don't you mean it'd be faster flying west? This is all assuming that the wind/jet stream/etc has more or less stopped at the altitude you are traveling at too. I'm not sure exactly how high you have to be for that to occur, but a scramjet can probably reach that altitude.

Either way, its pretty damned fast.

News is supposed to be "PC"

[Jodka]

"News is supposed to be 'PC'"

The term "Politically Correct" (PC) is a satirical epithet applied to liberal doctrine by conservatives. It mocks the presumption that liberal opinions are the "correct" opinions, in an absolute sense, not one perspective among many.

The term "PC" is made more amusing to conservatives by the liberals' conviction of their own political correctness preventing liberals from recognizing the joke that liberals' are unawaredly convinced of their own political correctness. "Of course our beliefs are the correct beliefs, why is that funny ?" ask the liberals.

Which brings us to your assertion that "News is supposed to be PC" What you are telling us ?

1. That news should be reported from a liberal perspective because...
2. Liberals are right and conservatives are wrong.
3. You are blind to the fact that you are promoting your own perspective in absolutist terms.

Note, "PC" denotes both the status of a particular belief as liberal and the associated presumption of correctness. For example, consider the statement "Johnny failed first grade, but he is African-American, therefore holding him back at that grade level would not be PC". In this sentence, "PC" serves to associate with liberals the principle that unqualified indviduals should be promoted if they are members of a particular ethnic group. But "PC" is also meant to characerize the attitude of those who would defend that principle as an absolutist faith that they are "right" and others are "wrong".

Fox News is unpopular with liberals not becuase it sets forth alnternative and consertavie "correct" notions, but because it undermines the very notion of correctnees in political discourse. Fox betrays the news broadcast tradition of delivering news in somber, ministerial tones which close off question and doubt; "Though shalt not question the word of Jennings". "The shalt now question the word of Brokaw." The informal on-air attitude of Fox news is like "Here are our correspondents and here is what they seem to to think is going on." It's more upbeat and friendly. We are allowed to ask questions. Fox news conveys to television viewers the dangerous attitude that what you see on TV is people telling you what they think is going on, not sacred and unquestionable truths. It undermines the notion of TV news as a conduit for absolute and correct truths, subverting the entire system of liberal propagandizing through control of unexamined "correct" news content.

News should not be PC.

Re:News is supposed to be "PC"

[bombadillo]

The term "Politically Correct" (PC) is a satirical epithet applied to liberal doctrine by conservatives. It mocks the presumption that liberal opinions are the "correct" opinions, in an absolute sense, not one perspective among many.

The term "PC" is made more amusing to conservatives by the liberals' conviction of their own political correctness preventing liberals from recognizing the joke that liberals' are unawaredly convinced of their own political correctness. "Of course our beliefs are the correct beliefs, why is that funny ?" ask the liberals.

"PC" is a pretty big tent. And thus can be interpreted and missused in many different ways. For example, PC can also be seen as pandering for votes. Many conservatives say "PC" things to hide a political agenda. What I was trying to convey was that news should be unbiased and impartial. That being said, your retort was also incorect. Conservatives are just as prone to being "PC" and believing that their view is correct.

"Which brings us to your assertion that "News is supposed to be PC" What you are telling us ? 1. That news should be reported from a liberal perspective because..."

The point is that news should be based on the facts from Both sides of the story. The news should not be used as a partisan tool. The true meaning of being PC is to not base opinions on steriotypes and to assist the downtrodden. For example my neighbor said that only blacks and mexicans can afford to be on welfare. That statement is not PC and is based on a steriotype. A news story that gives the downtrodden a voice and thus both sides of the story is PC. I think that you are thus again missuing PC and mistaking it for pandering.
You seem to have something against Liberals. You wrote a very long paragraph ranting about Liberals.

2. Liberals are right and conservatives are wrong.

There you go again. Wow you really do have something against liberals. Man you must hate the founding fathers of the U.S.A. All that talk of equality, seperation of church and state and seperation from the aristocratic policies of 17th century Europe. Hey why do we need the constitution and liberties when we have the magna carta! I think you need to ponder about your political affiliation if you believe in the ideals above. The plank of the conservative republican party is not about equality of races/sexes and not about seperation of church and state.
Besides what type of liberal are you talking about. I guess you are not talking about a financial liberal. Why is it that the Reagan/Bushes era is spending money so liberaly? I guess you must be talking about a social liberal? You know the type that want more civil liberties , etc... Since you went out on a limb and guesed that I am more of a social liberal, I will go out on a limb. I am guessing that you are probably not truly a conservative but a Neo-Conservative Facist .

3. You are blind to the fact that you are promoting your own perspective in absolutist terms.
If I am blind then you must blind and deaf as you are doing the same. Every one has their own perspective. We don't need a biased TV program telling us what to think. We need to be able to look at the facts and make up our own minds.

"PC" serves to associate with liberals the principle that unqualified indviduals should be promoted if they are members of a particular ethnic group.

Yeah, I used to think like you. Then I lived over seas for a while. I would always over hear ill comments towards American intelligence and way of life. That being said. You are probably also a member of an ethnic group that is the majority. Try living in a country where you are the minority. When you are back tell me how it feels. Then try to be a little intraspective and imagine if your skin was a different color, your ancesters were slaves and your parents remember a time when they had to sit in the back of the bus and weren't allowed to go to good schools. Th

What I really want to know about this technology.

[FauxReal]

Is... how will it affect the pizza delivery business?

Put these on the 747's!!!

[rice_burners_suck]

What they should do is start retrofitting Boeing 747's with about eight of the engines from the X-43A. That would make intercity travel a bit more convenient.

Imagine... instead of driving 45 minutes from Los Angeles to Burbank, you could drive to the airport (30 minutes), wait to check in (20 minutes), go through security (25 minutes), wait at the gate (40 minutes), get on the plane (20 minutes), wait on the runway (20 minutes), take off, fly, and land in Burbank (about 10 seconds), get off the plane (20 minutes), wait at the baggage claim (25 minutes), and then rent a car (30 minutes) and drive to your destination (25 minutes). Which would take about 4 hours, 15 minutes, and 10 seconds. Yes, I think this would be a very efficient way to travel, and it would definitely cut down on freeway traffic.

And of course, figuring out how to make the 747 withstand this kind of acceleration and speed without, uh, damaging the aircraft would, uh, create lots of jobs and make the economy strong again. Yeah. Good deal.

Re:Put these on the 747's!!!

[eclectro]

The reason that there are no supersonic passenger airplanes is that the economics is not feasible. Also they are very noisy, which is bad if you live near an airport.

The concorde is an example of this. Sure it worked, but it was not allowed to takeoff at most airports because of the noise.

The average ticket price to cross the Atlantic was $7,000.

The initial development and operating costs was paid entirely by the British and French governments. Without this the concorde never would have been possible.

Boeing has toyed with the idea of supersonic travel for ages. But for all of the above reasons, you will not see an actual airplane.

Re:Put these on the 747's!!!

[rice_burners_suck]

Apparently, some research has shown that the noise produced by supersonic aircraft can be drastically reduced by modifying the shape of the aircraft. I don't remember where I read it, but the big airplane manufacturers are spending enormous amounts of money to figure out how to do this.

Re:Put these on the 747's!!!

[Anonymous Coward]

You can't get around the sonic boom. By the nature of supersonic travel, you have to produce a shock wave, and it will travel all the way to the ground (unless you're flying straight up, maybe). Compared to that, you're not going to make things much quieter for folks.

completely offtopic but worth it

[crabpeople]

your definition of pc is biased and i would assume different from what people with sense assume the phrase "PC" to mean. I am pretty sure most people would agree that political correctness's goals are to create equality. in your wonderful example, the person is still being treated unequally. do things like that happen where you live? its probably closet racists or weird conservative converts or something.

also you are dumb because you are confusing the "face" of fox news, with what actually goes on there. Take for example the "investigative reporters" hired by fox to do a report on a steroid that is added to all american milk products. this steroid (rBGH i think it was called) has been proven to cause cancer and make people more resistant to antibiotics. When they found this out, fox fired them as it was too controversial for their pharmacutical industry (monstanto) backed news. LINK

i think its safe to say that if you have to go to so much trouble to promote yourself as hard hitting, indept and 'fair and balanced', your probably lacking in it.

as for news, all amerkian news is pretty much the same. i would suggest the bbc, or cbc for a bit more balanced reporting. and if you dont want to listen to me, i have found this conservative article lambasting them for doing what i would consider a more societally correct, good job.

"A BBC-type public broadcaster is responsible only to Parliament. Unlike its counterparts in most continental European countries, public broadcasters in the British or Canadian tradition report to no ministry of culture or information. British governments, democratically elected as they may be, can't tell the BBC what to do. If the BBC wants to engage in partisan politics, if it feels like opposing, discrediting, or undermining the government, it's in a good position to do so. Although a government might control the BBC's purse-strings through Parliament, and may give the board of governors some headaches at licence renewal time, no cabinet minister can give the BBC directives about daily operations, or about what it should put on the air, and how."

Re:completely offtopic but worth it

[Anonymous Coward]

Take for example the "investigative reporters" hired by fox to do a report on a steroid that is added to all american milk products. this steroid (rBGH i think it was called) has been proven to cause cancer and make people more resistant to antibiotics.

While I agree with your conclusion, I have some nits to pick with your example.

Bovine growth hormone is injected into cows, not added to milk. It has not been proven to cause cancer in humans or any other milk drinking animal. The argument against it is that it has not been proven safe. The Europeans had a big problem with importing our milk and wanted it certified as rBGH free before they would buy it. The U.S. pointed out the problem with this policy is that there is no test for rBGH in milk. This is the same problem with doing research to prove that it causes cancer. If you can't prove that it is there, how can you show causality?

I'm just guessing here, but I think that the reason that there is no test for it is for the same reason that there is no test to see if an athlete has been injecting testosterone. The stuff is in your blood naturally, so what would a test prove?

rBGH is not in "all American dairy products." It is quite easy to find organic milk from cows that don't use it. There is some doubt whether sufficient safeguards exist to prevent contamination with non-organic milk, however.

As to promoting the evolution of antibiotic resistant bacteria, I think that you are thinking of the antibiotics that are routinely added to animal feed.

Also, I think that it was a Fox affiliate in Florida, WTVT, and not the Fox News Network that authorized and then killed the story. But, I am sure that Fox network lawyers were behind the whole thing

Re:completely offtopic but worth it

[Anonymous Coward]

Those links there run the range from ignorant to patantly false.

Bovine growth hormone isn't even a steroid hormone. It's a protein, is naturally present in cows, nor is there any research proving links to cancer in any animals. As much as the Europeans, especially the European greens, would love to have something backing their ideology in banning this, it doesn't exit.

Heck, even if it was present in the milk an injected cow produced as a protein it would digested with all the other milk proteins in the milk. It'd be denatured and non functional in short order, it wouldn't have a single effect on your body whatsoever. It has nothing to do with antibiotic resistance either. Go read something other than biotech luddite propaganda.

Re:completely offtopic but worth it

[ukyoCE]

A few little picks to nit.

You didn't really clarify, but while yes, BGH is injected into cows, it comes out in their milk, and is therefore present in dairy milk consumed.

BGH is I believe very similar to human growth hormone, and is known(?) to affect the human body. I haven't ready about it in a while but it's stuff that MAY be safe, but certainly needs to be looked into.

The FDA didn't conduct tests on whether BGH is safe. The FDA requires these tests on any product sold as human food, but since technically the BGH is added to the cows, not their milk, BGH wasn't tested on humans before being included in human food.

This is why most people who know anything about it want it to be
1) tested thoroughly by the FDA
2) labeled on milk cartons containing it

Number 2 isn't *too* important, as you can at this point assume ALL milk contains BGH unless the milk carton explicitly states otherwise. But number 1 is definitely important.

(i welcome any additions as its been a while since I read up on the BGH issue. I'm lactose intolerant and don't eat dairy, so I'm not too concerned about the hormones and antibiotics and crap that people are drinking in milk)

Re:completely offtopic but worth it

[Anonymous Coward]

You should take some time to read ANY legitimate information on BGH. Your misguided idea that BGH is present in cows anyway and therefore can't be harmful is absolutely wrong. Most dairy farmer found that a variety of diseases increased dramatically once they began injecting BGH in their cows. Also, if BGH had no affect on cows, they wouldn't be injecting it in the first place. So as much as you seem to love drinking BGH, you should do a little research before flaming.

Re:completely offtopic but worth it

[Anonymous Coward]

Call it flaming, but I'll call it pointing out false or misinformed ideas...

Thanks for missing the point of what I said. I never said increased BGH in cows wouldn't cause any potential health risks to them. I pointed out that BGH has never been linked to causing health problems in humans by cosumption of milk from those cows treated with it. I also pointed out that it isn't linked to Antibiotic resistence problems that the prior post implied, nor was BGH even a steroid hormone (which can survive ingestion and affect humans potentially) but a protein (which can't survive the digestion process).

Now all the need to do is make the scramjet safe

[madcow15]

How safe are scramjets anyway I saw a test at an airshow one day and the whole engine overheated and blew up on of the operaters was very badly burnt. What would happen if this happened to a plane carrying a test pilot at 7000kph the result would be very tragic indeed.

DUPE!

[Anonymous Coward]

By NASA! :-)

Initial speed?

[SCHecklerX]

How fast was it already moving when the rocket separated and the scramjet took over?

It's not gullibility...

[Anonymous Coward]

it's hope. The extremes of material science have yet to fully say their piece. People look around, and the see a world they can fully make sense of in aggragate, there has to be something new.

The problems aren't going to be solved soon, probably not in my life time. But as long as one possible solution remains uninvestigated isn't it worth looking into? And what can sustain a person on difficult task that they almost certainly will not see the end up, and might be doomed to fail but hope? And what else could convince people en masse to spend their resources in the aid of someone else's esoteric pursuit?

If you want to be picky...

[idontneedanickname]

http://www.nasa.gov/missions/research/x43_soars_fe ature.html
"During the free flight, the scramjet engine operated for about 10 seconds."
(Emphasis mine)

It can just as well be said that the X-43A did not achieve "scramjet powered flight" as the scramjet engine was only operated for about 10 seconds out of the total flight time of several minutes. I'm not an aeronautical engineer, but it seems that NASA just used a different technique to get the aircraft to the speed at which it could ignite the scramjet engine.

Re:The Mach 10 is not enouth...

[Anonymous Coward]

it is still a long way toward the space plane...

ummm .. if the scramjet needs air to run, how could it possibly be used on a space plane?

headline should have read:

[jannesha]

The X-43A reached its test speed of Mach 7...During the free flight, the scramjet engine operated for about 10 seconds.

Zero to Mach 7 in 10 seconds.

Vroom.

Don't feel too bad,.Cowboy Neal

[Rogerborg]

I don't read michael's articles either.