Mach 10 X43A Flight Successful

Sector Bug writes "NASA's X43A research aircraft made its third and final flight today, firing its scramjet engine at Mach 10 (7,000 MPH) or close to it, setting a new record. "

Comments

Speed comparison question

[Drakonian]

A (possibly stupid) question: How does this compare to the speed of orbital rockets?

Re:Speed comparison question

[Eternally optimistic]

> How does this compare to the speed of orbital rockets?
Its slower.

Re:Speed comparison question

[Holi]

Not even close.

Hubbles orbital speed is approximately 16,900 miles per hour.

Re:Speed comparison question

[cephyn]

MPH? we still use that? I thought maybe in this age of newfangled units, we'd at least get like, .41 times that of the Hubble Telescope, or 34.7 times faster than a lambourghini diablo.

Re:Speed comparison question

[Tailhook]

LEO satellites move a bit faster than 17,000 Mph, or 2.4 times as fast has the X43A at Mach 10.

Re:Speed comparison question

[Anonymous Coward]

Orbital velocity at an altitude of about 150 miles is about 17000 mph (approx 242 km altitude at 27000 km/hr...checked my memory on howstuffworks), so the rocket was going about 0.41 of orbital velocity. In other words, you have only 17% of the kinetic energy you need to maintain an orbit (since KE=0.5*m*v^2). Unfortunately, you have to reach sufficient velocity to coast to the altitude and speed you ultimately want while there is still enough oxygen around you to make the scramjet work. Interestingly, the geosynchronous orbital velocity is only about 7500 mph, but you have to do more work against gravity to reach that altitude.

Re:Speed comparison question

[wviperw]

A related question, how does this (and the speed of orbital rockets) compare to the fastest man-made object (whatever that may be)?

Re:Speed comparison question

[peter303]

Shuttles re-enter at Mach 20. Atmospheric friction force is the square of velocity. So an orbital vehicle has to have four times the strength of X-43 and sixteen times Space Ship One.

Re:Speed comparison question

[Kehvarl]

What's that come to in migrating swallows?

Re:Speed comparison question

[Fnkmaster]

While that is true, this is the first real scramjet implementation. Apparently, people think scramjets will go up to about Mach 15, or over 10,000 miles per hour. While still not low earth orbital velocity, it doesn't have to get there to be useful in getting to orbit.

If a traditional rocket kicks in at Mach 15 to get the rest of the way to orbit, the savings in launch weight and thus cost from not having to carry all that oxidizer to get up to Mach 15 could still be quite large.

Re:Speed comparison question

[caluml]

A (possibly stupid) question:

The only stupid question is an unasked one.
Any fool can ask a question which the wisest of men cannot answer.
Too many cooks spoil... Wait, no, that's nothing to do with it.

Re:Speed comparison question

[Christopher Thomas]

A related question, how does this (and the speed of orbital rockets) compare to the fastest man-made object (whatever that may be)?

Particle accelerators accelerate anything from electrons and protons to ions close enough to C that the difference is academic.

For macroscopic objects, I believe compressed-gas guns used for simulating micrometeorite strikes and for producing shockwaves to study things like the metallic hydrogen phase transition accelerate projectiles to tens of km/sec, or larger than but of the same magnitude as orbital velocities.

Various other types of cannon (the so-called "ram accelerator", used to simulate scramjets, and various flavours of electromagnetic cannon) can also reach projectile speeds in the "greater than but still comparable to orbital" range.

Re:Speed comparison question

[AKAImBatman]

You need to ask yourself one question:

Relative to what?

*AKAImBatman hits wviperw over the head with a copy of Einstein's "Special Theory of Relativity"

Re:Speed comparison question

[DunbarTheInept]

Presumably you mean the fastest man-made object in relation to the solar system's frame of referece. (otherwise it is a harder question to answer because any object going in the same direction as the sun was drifting when it was launched will be going a heck of a lot faster than an object going in the opposite direction of which way the sun was drifting.) I don't know, for example, if the Voyager craft are headed in the same direction as the sun (in essence, blazing a trail in front of it), or if they are trailing behind it, or if they are flinging out perpendicular to it.

Re:Speed comparison question

[randomiam]

African or European?

Re:Speed comparison question

[frugle]

To allow particle accelerators you need to expand your parameters a bit to include natural objects accelerated by man.

The fastest "man-made" objects - I would hazard a guess at probes sent from Earth to other planets. Voyager 1 travels at roughly 17.4 km/sec or 38,923 MPH

This will all be put to shame by the Mini-Magnetospheric Plasma Propulsion system (M2P2) - which if it actually got into production and was launched could overtake Voyager1 (launched in 1977 with a 11 Billion Km head start) in 10 years.

This M2P2 drive in a nutshell would create a 60 km wide magnetic field filled with plasma behind it, trapping the solar wind and propelling it to a predicted 180,000 mph.

Let's just hope with all that trapped wind they have enough gaviscon to stop it when it gets where it's going...

Re:Speed comparison question

[JDevers]

Good post and all, but protons most certainly DO have mass... I think you mean photons, except that particular particle accellerator is known as a flashlight...or any other light source. Photons can ONLY travel at the speed of light because they ARE light (or at least "light" is a subset of the wavelengths possible for photons...).

Re:Speed comparison question

[Total_Wimp]

If a traditional rocket kicks in at Mach 15 to get the rest of the way to orbit, the savings in launch weight and thus cost from not having to carry all that oxidizer to get up to Mach 15 could still be quite large.

I've heard the idea of using three stages in scramjet orbital launches. The first and third are rockets and the middle is the scramjet. It makes me kind of curious about using chemical propellants, like in a giant howitzer, to propell the scramjet to it's initial speed.

I couldn't see this doing much for manned flight, but most of what we send up isn't manned anyway. It could also have some pretty kick ass millitary application, say for dramatically increasing the payload of current rocket propelled artillery rounds.

TW

Re:Speed comparison question

[Kehvarl]

African or European?

Yes.

Re:Speed comparison question

[interiot]

The article kind of hinted at something:

• "This flight is a key milestone and a major step toward the future possibilities for producing boosters for sending large and critical payloads into space in a reliable, safe, inexpensive manner," said NASA Administrator Sean O'Keefe.

So, for what it's worth, escape velocity is 25,000 mph, so a scramjet would be perhaps the second of at least three stages to getting into space.

Are there any Aerospace engineers who can comment? Are scramjets supposed to be more economical in some ways? Perhaps in that it's one way to get away from solid rockets?

Re:Speed comparison question

[Anonymous Coward]

Physicists use the metric system, but 16900 mi/h is indeed correct. To clarify this:

Acceleration of Gravity = Acceleration Centripetal

((Gm)/r^2) = (v^2)/r

G=6.67*10^-11
m = mass of earth = 5.98*10^24 kg
r = radius of Hubble from Earth core = 6980000 m

((6.67*10^-11)(5.98*10^24))/(6980000^2) = (v^2)/6980000)

v = 7559.373392 m/s or 16909.83 mi/h

Re:Speed comparison question

[Holi]

Actually I cheated and used Google to do my math.

Re:Speed comparison question

[foniksonik]

At least it doesn't refer to how many Horses equivalent are Powering the damn thing ;-p

Re:Speed comparison question

[mfago]

A related question, how does this (and the speed of orbital rockets) compare to the fastest man-made object (whatever that may be)?

I thought the fastest man-made object was Pioneer or Viking at around 45k mph. However, a quick Google indicates that Helios supposedly traveled at 150,000 mph.

I'm positing that the particles in particle accelerators are not "man-made" in this context.

Re:Speed comparison question

[FuzzyBad-Mofo]

I thought the standard measurement of speed was now Football Fields per Second (FF/s)..

Re:Speed comparison question

[mfago]

Doh! Pioneer or _Voyager_ -- and less than 45k mph.

Re:Speed comparison question

[Rei]

There's also some other proposals I've seen that use more stages - for example, turbojet->ramjet->scramjet->rocket, so the entire first stage is airbreathing. My favorite for (unmanned!!!) payloads is gun-launch -> scramjet -> rocket. You can to hypersonic velocities in a fraction of a second.

Re:Speed comparison question

[Rei]

Well... not quite, since the shuttle starts reentry in the sparse upper atmosphere. But the point is still an important one to make. :)

Re:Speed comparison question

[Rei]

IAMAAE, but the reason that they're more economical is that you only need to carry up ~1/9 of your propellant mass during the airbreathing stage. For example, a LH/LOX rocket uses 2 H2 + 1 O2 -> 2 H2O; For molecular weights, H2~=2, O2~=32; thus, the ratio is (32+4)/4 -> 9 times as much mass for the LH/LOX rocket.

More importantly, however, is the fact that the more mass your craft has, the more energy it takes to accelerate that mass; consequently, craft masses grow geometrically with a given desired increase in delta-V. The net benefit from only needing to carry up your fuel is staggering. Even if you use a hydrocarbon fuel (much denser, which is a very good thing, plus often not cryogenic), you're still going to get at least a 6-fold instantaneous mass difference (which, again, becomes more dramatic as you factor in how much it saves you from having to accelerate propellant).

Also, they're theoretically simpler, lower maintainance, and less likely to fail because of the reduced number of moving parts. They're just in general Good Things(tm). :)

Re:Speed comparison question

[F34nor]

http://science.slashdot.org/science/03/11/19/00920 1.shtml?tid=133&tid=134&tid=186

Re:Speed comparison question

[mintrepublic]

Well, it depends on its air-speed velocity while carrying a medium-sized coconut.

Re:Speed comparison question

[r_jensen11]

My friends and I have given up on inches, meters, yards, miles, etc, and have substituted them all with yey's. E.g: How big is book? About yey thick. How far away were you? About yey far. How fast did you end up driving? Meh, yey fast.

Re:Speed comparison question

[mazarin5]

To allow particle accelerators you need to expand your parameters a bit to include natural objects accelerated by man.

No no no, you're looking at it all wrong...

The particle accelerator is a man-made object accelerated to 0.99c.

You just have to use the electron's frame reference!

Re:Speed comparison question

[r_jensen11]

I remember seeing a story on the History channel about 3 stage rockets.... From the jist of the documentry, the soviets didn't have too much luck with it (Stage 2 burning before Stage 1 detaches, etc). All in all, they lost a lot of their engineers that way....

Re:Speed comparison question

[Guppy06]

Now all we need is a way to get up to Mach 10 without rockets. Right now your vision looks like:

1. ???
2. Scramjet from Mach 10 to Mach 15
3. Rockets from Mach 15 to beyond

Unless somebody figures out a jet engine that can combust in airflows at both subsonic and supersonic speeds (variable geometry?), phase 1 will be "rockets" for the time being.

Re:Speed comparison question

[drinkypoo]

hypersonic velocities in a fraction of a second.

I imagine this will be one of the first actual uses of a scramjet - by the military.

Re:Speed comparison question

[the_2nd_coming]

ummm.... the difference is 30 years of rocket since, very low oxidizer levels, and the use of some very familiar jet technology.

Re:Speed comparison question

[ducman]

But isn't Mach a rather odd unit, too? It's defined as the speed of sound, but the speed of sound varies a lot. 7,000 mph would be nearly Mach 10 at sea level, but what's the speed of sound at the 110,000 feet level the plane was at?

Re:Speed comparison question

[nofx_3]

What about a LIM to get the scramjet up to speed. I don't know enough about LIMS to know if they could propel the ScramJet up to the speeds it needs in order to work but it sounds like a good idea in my head. So the system would go like this LIM->SCRAMJET->CHEMICAL (or better yet NUCLEAR)ROCKET. Sounds good to me, now some rocket scientists need to get working on this to see if it is feasable.

-kaplanfx

Re:Speed comparison question

[mrgsd]

It's called Kilometres per hour :)

Re:Speed comparison question

[Jermonian]

A giant howitzer? The impulse would be huge! Almost anything you'd want to fire would be ripped to shreds.

Re:Speed comparison question

[Fnkmaster]

Or rail gun (i.e. electromagnetic propulsion launch) for the first stage. That would be frickin' cool. Rail gun->scramjet->rocket. And as a bonus, we could put Fed Ex out of business with a rail gun->scramjet unmanned terrestrial package delivery system using the same infrastructure.

Re:Speed comparison question

[angrist]

I've seen some research ( I believe it was done at Penn State) into using the scramjet chamber to hold rocket propellant.

Basically the first stage is a solid rocket, then when that burns out, the space where the propellant was is now empty, and becomes the combustion chamber. The application it was intended for was a rocket assisted, gun launched projectile for the military. But the same concept of dual purposing the chamber should be applicatble to most scramjet applications.

Re:Speed comparison question

[f()rK()_Bomb]

Not exactly. The HARP project did fire test probes out of a massive gun, with subsystems intact. Checkout this site

Re:Speed comparison question

[Da Fokka]

The light on my desk actually accelerates particles to c all the time.

Re:Speed comparison question

[gadget junkie]

"I couldn't see this doing much for manned flight, but most of what we send up isn't manned anyway. It could also have some pretty kick ass millitary application, say for dramatically increasing the payload of current rocket propelled artillery rounds."

Funnily enough, studies about that go back a long way, circa 1930. dr.Sanger eventually studied a Ramjet powered design, a model of which is in the Deutsches Museum in Munich, Germany. It would have been a cheaper alternative to the Space Shuttle, with a mother vehicle starting from a plain aerodrome and an orbital vehicle piggybacking on it. Basically the mother vehicle is the same concept inferred for the mysterious project Aurore Recce aircraft.

The military have always been attracted to these concepts, witness the Dynasoar in the late fifties, but the rationale is the same for civilian uses; higher efficiency and flexibility in bringing payloads in low earth orbit or suborbital flight.

Re:Speed comparison question

[TheKidWho]

Mach is dimensionless because it is a ratio.

Re:Speed comparison question

[CrimsonAvenger]

I imagine that a scramjet is a bit too expensive to make it worthwhile in that sort of application. A (cheap) rocket will do quite nicely.

Re:Speed comparison question

[CrimsonAvenger]

you only need to carry up ~1/9 of your propellant mass

one sixth. Typical H2/O2 rockets use a five to one ration of oxidizer to fuel. It's still a huge advantage, though.

All things being equal (they aren't, but it gets you in the timezone), an H2/O2 rocket massing 1000T at launch would mass only about 340T by the time it reached Mach 15. A 1000T scramjet would mass about 830T at the same point. From Mach 15, the flight profiles of both would be about the same (both using rockets from that point on, of course), and they'd both burn up ~55% of their remaining mass to get to orbit. So the pure rocket puts ~150T into orbit, the scramjet-rocket hybrid puts ~370T into orbit.

Note: Ignoring friction. Ignoring the atmosphere when convenient, and including it when helpful to do so. Ignoring the details of staging and such, and the extra mass of the airframe built around the scramjet stage. Ignoring the need of the scramjet to reach some high speed before it begins combusting. Ignoring [physical reality as much as possible]....

Re:Speed comparison question

[cluckshot]

I wonder with all of the money we Americans are spending on this fine research, ... ($Megabucks$ for really good research!) where will they build the planes/rockets etc that actually use this stuff? Could it be China? India? etc...

Does this mean Americans get the bill for the research and others get the profits? If so WHY would we spend for the research for others to get the "jobs of the future?" If this is the case, it would seem to be a bad investment. But really cool science!

Cool Invention doesn't pay the bills. Cool business does!

Re:Speed comparison question

[PHanT0]

A space shuttle upon rentry in to the earth's atmosphere has been clocked in excess of Mach 23.

Re:Speed comparison question

[The_Hun]

WHY would we spend for the research for others to get the "jobs of the future?"
This reminds me of the book "Unbound Prometheus" (by David Landes). It's mentioned somewhere in it that one of the reasons Germany developed faster than the UK after WW2 was that UK made more basic research - which could be later used also by German companies (that's my simplification of the text and I do not remember well).

Re:Speed comparison question

[stanmann]

Mach is usually(but not always) defined as SoS at sea level.

Re:Speed comparison question

[stanmann]

Just like the Speed of light as customarily memorized 186000 mi/s is defined in a vacuum.

Re:Speed comparison question

[drinkypoo]

Too expensive for the military, you say? What color is the sky on your planet? And how hard is it to get there? I've been thinking about relocating.

Re:Speed comparison question

[CrimsonAvenger]

Having been in the military, and watched some of the things they do, I can see your point.

However, one must remember that missiles/shells are "consumables".

And expensive consumables cut into training budgets in big ways. The Navy doesn't fire too many torpedoes in training (they cost too damn much, even if they are mostly recoverable), but the Army shoots a lot of artillery shells out their tubes (because, by comparison, an HE shell is cheap).

A scramjet will make a Patriot missile look like pocket change, and not be especially more capable. So it won't happen.

Re:Speed comparison question

[Rei]

2 H2 + 1 O2 -> 2 H20. That's the stochaistic ratio for hydrogen/oxygen combustion. Hydrogen has an atomic mass of ~1, and Oxygen ~16. 2 H2 = 4 * 1 = 4. 1 O2 = 2 * 16 = 32. For ratios, add together for the denominator - i.e., 4/(4+32) for hydrogen, and 32/(4+32) for oxygen. So, hydrogen makes up 1/9th of the propellant mass, and oxygen makes up 8/9ths.

Where do you get 1:5? Yes, rockets tend to run fuel rich to reduce nozzle corrosion, but usually just slightly. The level stated by you doesn't seem to make sense. Am I missing something?

Re:Speed comparison question

[Rei]

Scramjets are simpler than rockets in design; the hard part is getting the shape right (also, you tend to have to use relatively expensive/harder to work with alloys).

Re:Speed comparison question

[drinkypoo]

Actually, I think it's pretty likely that the scramjet will eventually be cheaper. It's only at this particular point in time - when they're brand spanking new - that they're expensive. Scramjets will likely make some types of weapon that we don't now have possible and make some types much more effective.

Re:Speed comparison question

[CrimsonAvenger]

Yah, they'll make some things possible that aren't possible now. I doubt they'll make anything that we already have more effective.

Keep in mind that one primary characteristic of military missiles is storability. Having to fuel it up just before launch (which you have to do with LH2) pretty well defeats the purpose.

At least, when it comes to consumables. A hypersonic stealth bomber (if it's possible at all) might be neat.

Re:Speed comparison question

[CrimsonAvenger]

Yes, you are.

You run H2 rich fuel mixtures to lower the average molecular weight of your exhaust stream, which increases the exhaust speed for a given combustion temperature. Exhaust speed is proportional to Isp, and high Isp is good.

I get that figure from the Space Shuttle and Saturn systems. Though I believe that there are some 1:6 ratios out there these days.

Keep in mind it's a matter of tradeoffs. 1:9 gives you smaller tankage, but lower Isp. Higher fuel:oxidizer ratios increase the size of the fuel/oxidizer tanks, but increase Isp. SO you aim for the "ideal" balance, and we seem to have settled around 1:5 as our ideal point.

Re:Speed comparison question

[Rei]

Wikipedia says that the shuttle uses a constant 6:1 ratio:

http://en.wikipedia.org/wiki/Space_Shuttle_Main_ En gine

Astronautix concurs. Also, this page states that you're wrong about the reason for running fuel rich:

http://yarchive.net/space/rocket/fuels/fuel_rich .h tml

Basically, as you reduce the molecular mass to increase ISP, you also reduce the flame temperature, so it's always a net loss. The benefit comes instead in nozzle efficiency, which is inversely proportional to the number of atoms per molecule.

Ah, practical considerations always have to interfere with basic chemistry ;) Now I wonder what the optimal ratio is for a waverider scramjet... it has a nonstandard asymmetric "nozzle", so I wonder if it goes back to 9:1, or at least approaches it? It'd be interesting to find out, because that's the number that really matters. In a waverider design like the X-43, it's the hypersonic shocks that do the compression for you.

Re:Speed comparison question

[CrimsonAvenger]

Ah, practical considerations always have to interfere with basic chemistry ;) Now I wonder what the optimal ratio is for a waverider scramjet... it has a nonstandard asymmetric "nozzle", so I wonder if it goes back to 9:1, or at least approaches it? It'd be interesting to find out, because that's the number that really matters. In a waverider design like the X-43, it's the hypersonic shocks that do the compression for you. For a scramjet, the whole question is moot. A scramjet doesn't carry oxidizer onboard, it uses the atmosphere. Most likely, it gets near 100% combustion of the H2. Of course, that is irrelevant, since it has an unlimited quantity of free oxidizer....

Wikipedia says that the shuttle uses a constant 6:1 ratio:

I'll take your word for that. It's been nearly 20 years since I cared enough to check this sort of thing. Perhaps the 5:1 was just Saturn, perhaps the original Shuttle mixture was changed in the decades since then.

Also, this page states that you're wrong about the reason for running fuel rich:

Interesting. Now I need to get the book referred to therein. Reason I gave was the one I got out of my college textbook, let's see, 25 years ago. From the beginning of the comment, it's still a not-uncommon belief, so whomever wrote that old textbook must not have been called on it often.

Re:Speed comparison question

[Christopher Thomas]

To allow particle accelerators you need to expand your parameters a bit to include natural objects accelerated by man.

How much tinkering needs to be done for an object to cease to be "natural"? We could accelerate ionized molecules with a molecular weight under about 100-200 using RHIC with no problems. That covers a wide variety of compounds that don't occur significantly in nature.

The fastest "man-made" objects - I would hazard a guess at probes sent from Earth to other planets. Voyager 1 travels at roughly 17.4 km/sec

I believe compressed gas guns can get faster muzzle velocities than that, per my previous posts. At minimum they can get in the same range.

This will all be put to shame by the Mini-Magnetospheric Plasma Propulsion system (M2P2)

Which would in turn be put to shame if anyone builds a maser-powered "starwhisp", or Orion, or any of a variety of other craft. If it hasn't been built yet, it doesn't count :).

Re:Speed comparison question

[jazman]

Damn, I must get my eyes checked. Perhaps I've got glaucoma coming on. I had to double-take cos I thought that said lambourghini dildo.

Re:Speed comparison question

[Rei]

The question most certainly is not moot. You release hydrogen at a carefully chosen rate to produce what you consider an optimal H2/air mixture. The faster you release your H2, the faster you run out of fuel, but it doesn't increase the amount of O2 to burn with it.

Re:Speed comparison question

[Guppy06]

When was the last time you saw an airplane that was built in China or India, supersonic or otherwise? Hell, when weas the last time you saw an airplane that was built in Japan? Not all high-tech is IT and just because IT jobs seem to be leaving for those places doesn't mean all high-tech industries are.

Besides, the primary customer for hypersonic planes for the forseeable future will be the United States government, specifically the military. The only military aircraft I can think of that we import is the AV-8B Harrier II built in the UK, and even then it's only imported to suit a specific need (VSTOL). You'll see the US government using French or Swedish aerospace equipment long before you see it use Chinese or Indian aircraft (which, again, they simply can't build).

Maybe in 50-75 years when hypersonic passenger service becomes a reality you'll find yourself in something built buy Airbus instead of Boeing or LockMart. Maybe.

Re:Speed comparison question

[CrimsonAvenger]

I should have said "someone building a launch vehicle with a scramjet doesn't care." The engine designer may care, but the launch vehicle designer just cares about his Isp and the amount of tankage he needs to design in.

With apologies to Marvin

[daeley]

X43A blurs past the camera. It is silent.

Marvin: "Where's the kaboom? There was supposed to be an earth-shattering kaboom!"

EARTH SHATTERING KABOOM!

Marvin: "At last!"

I guess it is the first 7000MPH post

[roman_mir]

we shall call it the ludicrous speed.

Re:I guess it is the first 7000MPH post

[Alien Being]

It went plaid!

Re:I guess it is the first 7000MPH post

[double-oh three]

To apply Spaceballs retroactivly;

At the breaking of the 60MPH:

We shall call it ludicrous speed.

At the breaking of the sound barrier;

We shall call it ludicrous speed.

At the breaking of the speed needed for stable orbitals;

We shall call it ludicrous speed.

The point is that we will always be breaking the limits we set now, so to call it ludicrous speed is ok, but the speed will likely be pedestrian in a few years. There's always a speed barrier we'll be breaking.

Re:I guess it is the first 7000MPH post

[DarkHelmet]

You stole the idea for my post, and I want it back!

Signed,
DarkHelmet

Re:I guess it is the first 7000MPH post

[roman_mir]

I guess you should have protected it with a better numeric combination then!

NASA sure has come a long way.

[Neil Blender]

Since their first scramjet, the A-1A, flew at 7 feet per second.

Re:NASA sure has come a long way.

[happyfrogcow]

from google calculator, and i'm too lazy to even verify it:

1 feet per second = 0.681818182 miles per hour

Re:NASA sure has come a long way.

[w42w42]

There is 5280ft in a mile, and 3600 seconds in an hour. 7/5280 * 3600 = 4.77 mph.

Re:NASA sure has come a long way.

[imsabbel]

Well, i dont think this is interesting, because the SC before the RAMJET means "supersonic combustion". So i dont know how your 7fps scramjet should archieve this speed inside the burning chamber.
Please enlighten me!

Re:NASA sure has come a long way.

[taylortbb]

The definition of a scramjet is that air enters at super-sonic speeds, if its not you have a ramjet (or if you slow air down before mixing the fuel). 7 feet per second is nowhere near mach 1. I think htat was likely NASA's first ramjet. (scramjet = super-sonic combustion ramjet, I did a project on scramjets a few year back before the first test flights) If I have been mis-informed, please do correct me.

Re:NASA sure has come a long way.

[radio.cgt]

Well done everyone for getting the joke there...

Re:NASA sure has come a long way.

[Idarubicin]

... flew at 7 feet per second...

...when it fell off the test stand?

Re:NASA sure has come a long way.

[coyote_oww]

... flew at 7 feet per second...

...when it fell off the test stand?

1/2at^2 = d

at = v

so... solving for d, where v = 7s, a = 32.2fps, we get...

a 1'6" high test stand, approx., and a 7.084s fall time.

Mod me up for nerdiness!

Re:NASA sure has come a long way.

[Suidae]

a 1'6" high test stand, approx., and a 7.084s fall time.

Not at an acceleration of 32.2ft/s/s you don't.

A drop from 1.5 feet ( 1'6" ) takes about 1/3rd of a second, with a terminal velocity of about 9f/s.

A 7.084s drop at 32.2f/s/s would be around 810 feet (disregarding atmospheric friction), with a terminal velocity of about 230f/s.

You would have to be on a small moon somewhere for a 1.5 foot fall to take 7.084 seconds, a moon with a surface gravity of about 1/16th that of Earth.

Also note that v=7f/s, not 7s.

Re:NASA sure has come a long way.

[SycoCowz]

Must've been a paper airplane some future NASA worker made in elementary school.

My SAAB!

[3770]

Man,

I need one of these engines for my SAAB.

Re:My SAAB!

[theguru]

Hopefully, it is one of these and not one of these

Re:My SAAB!

[antoy]

I need one of these engines for my SAAB.

If you were going for the Darwin award, someone beat you to it.

Re:My SAAB!

[plj]

Why? I thought it would be a great engine upgrade to this.

But more seriously, even if you'd fly Gripen afterburner on at it's maximum speed (mach 2), the speed would still be too low to ignite the scramjet engine. And even if you'd somehow manage to ignite it, the Gripen's airframe would then be utterly and completely shattered at once...

Re:My SAAB!

[theguru]

I actually prefer the Saab Sonett

News Delayed

[iamlucky13]

Meanwhile, CNN is still reporting the flight as being delayed on the front of their Science and Space page.

Re:News Delayed

[That's Unpossible!]

It takes a while for them to catch up because CNN is only operating at Mach 9.

Re:News Delayed

[iamlucky13]

On the contrary, CNN hasn't even reached 300 baud (for you non-technical readers, that's equivalent to the Library of Congress sliding down a 2% grade, assuming the coefficient of friction is 0.01).

Also last flight of the B-52B mother ship ...

[xmas2003]

The B-52B (tenth off the assembly line) first flew on June 11th, 1955 and among other things, has carried the X-15, Shuttle solid rocket booster, and finally the X-43A (on the same pylon as used by the X-15). Read more about the ol' BUFF at NASA.

Re:Also last flight of the B-52B mother ship ...

[dmanny]

Really? Could you elaborate on the aspect of last flight of NASA's B-52B? I haven't seen that mentioned anywhere. If so, I need to inform my father. He and his cronies did some work for the mods to that bird.

Re:Also last flight of the B-52B mother ship ...

[richmaine]

Yes. It is simultaneously a happy day and a sad one. Long time before we'll see a research flight to anywhere near that condition again. Some here wonder whether it is the last worthwhile research flight that will even be flown here.

But I didn't say that. Not in public. :-(

Re:Also last flight of the B-52B mother ship ...

[Wyatt Earp]

It's the last flight of the B-52B mothership, but it is being replaced with an H

http://www.dfrc.nasa.gov/Gallery/Photo/B-52/HTML /E C03-0258-04.html

Parts for the engine were becoming rare and costly for the B

Re:Also last flight of the B-52B mother ship ...

[cold fjord]

Good thing.

Now they should be set for another 20 to 40 years, along with the rest of the B-52H inventory.

Staggering to think that 80 year old bombers are currently what the US plans for the future.

Re:Also last flight of the B-52B mother ship ...

[ahbtbone]

possible source for explanation if really curious: http://www.stratofortress.org/forum/viewtopic.php? t=104&sid=7e2a812d1dc994caddfd613c42d540f6

Re:Also last flight of the B-52B mother ship ...

[Wyatt Earp]

It's a 60 year old design, not a 60 year old aircraft at the moment. The B-52s because of the size of thier avionics and electronics from the 50s are an easy to upgrade platform that allows them to remain functional. The B-52s and all US military aircraft for that matter, are terribly well documented.

I've read about the USAF sending teams down to AMARC in Arizona to look at B-52 Ds and Gs in storage to see what they find, for example, they discovered a leak in the roof lead to corrosion in the aircraft, so the USAF told everyone to look for leaks there in the A pillar of the cockpits and they found most of the aircraft in the fleet at the problem, so they were able to fix the problem before something disasterous happened.

Re:Also last flight of the B-52B mother ship ...

[Nemo Black]

Sad to see the "B" retire, but at least it will be replaced by an "H" It's amazing that the B52 in general has lasted this long. Says a lot about the design.

Re:Also last flight of the B-52B mother ship ...

[cold fjord]

It's a 60 year old design, not a 60 year old aircraft at the moment. I meant that they would be ~ 80 (+/-10) years old when they left service, not that they were 80 now. Sorry. I've read the same story about the leak. By the time they are retired the B-52 will have been an amazing success. Too bad we don't have anything with the bomb bay of the B-36 though.

Re:Also last flight of the B-52B mother ship ...

[iamlucky13]

Space.com reported several weeks ago that the White Knight (of Space Ship One fame) might be hired to do some drops for NASA after the retirement of its B-52B. In particular, a NASA spokesman stated that "cost analysis favored Scaled Composites," when talking about the X-37 program.

Mach

[MikeMacK]

"Mach Number" was named after the Austrian physicist Ernst Mach.

I understand he was a very fast guy, much to his wife's chagrin.

Re:Mach

[kris_lang]

and Mach also named "Mach Bands", a psychophysical illusion when gradients of light and dark are next to each other: the edge of the light region appears even brighter and the edge of the dark region appears even darker than it truly is. A series of graduated intensity bands will appear to be non-linearly illuminated because of the contrast-enhancement performed by ours retinas and cortices... (retinae?)

Hope for the future

[spawnofbill]

I really hope the aeronautical industry takes advantage of the testing done with the X-43A. Alot of ideas that were scrapped b/c of red tape and underfunding I.E. nuclear powered flight, true supersonic transportation, Pulse Detonation Engines (although the last one is seeing a revival) If applied correctly this could revolutionize the airline industry and make international travel quick and affordable over time.

Re:Hope for the future

[bananafish]

Um... beyond red tape & lack of funding, nuclear propulsion hasn't developed because it's REALLY FREAKIN' DANGEROUS, and thus banned (at least in space) by the Nuclear Test Ban Treaty...

Re:Hope for the future

[spawnofbill]

I was refering to atmospheric nuclear flight. Basically it uses a small nuclear reactor to power the engines, If you check out the latest Popular mechanics they have an article about lockheed delevoping something along the lines of this. The U.S. and russia both started projects that inserted reactors into large bombers, but both never flew due to unfounded worries over the crew recieveing harmful amounts of radiation. The worries are unfounded because Nuclear submarine crews with a mantained reactor recieve little to no radiation besides normal cosmic radiation.

airlines

[torrents]

how long before i can hitch a ride on something that can get be half way across the world before lunch...

Re:airlines

[corngrower]

Halfway? Hell, you'ld be all the way around and home before lunch.

Re:airlines

[Guppy06]

Depends: what's your credit limit?

Someone help me out here.

[Leroy_Brown242]

The rocket gets it up to speed, and the scramjet just maintains? Or is the vessel doing any of it's own acceleration?

Re:Someone help me out here.

[homb]

The rocket gets it up to the minimum speed at which the scramjet can operate: Mach 5-6.

Then the prototype separates and fires the scramjet to reach Mach 10. It is thought that a scramjet can operate at least until Mach 15.

Re:Someone help me out here.

[Leroy_Brown242]

Thanks.

I don't know if I just missed it or what, but I never caught that little tidbit.

Re:Someone help me out here.

[caluml]

Wicked! Soon the US will be able to get a missile to any point in the world in a few minutes. That'll help make the world a happier place.

Re:Someone help me out here.

[richmaine]

Please, if you are pretending to supply information, make it at least vaguely close to correct. :-(

The rocket boosted it all the way up to max speed. The scramjet wasn't even lit at quite the max speed, though close (the research vehicle decelerates slightly in the few seconds after separation from the rocket before the scramjet lights).

The scramjet *MAYBE* did as well as stopping the deceleration for a few seconds. One of the researchers, who I was talking to as we watched the B52 flyby and landing, said that he thought perhaps they got just a little positive acceleration (i.e. it sped up slightly), but small enough that he couldn't tell for sure from the quick look he took so far.

But then, that is what was being aimed for.

Re:Someone help me out here.

[Col. Bloodnok]

Wicked! Soon the US will be able to get a missile to any point in the world in a few minutes. That'll help make the world a happier place.

They already can.

You know, constant harping at our ally in this stupid conflict isn't going to stop those fucking jihadist nutcases from kidnapping and executing innocent aid workers. Targeted ordnance, while messy and unpalatable, does have a solid track record of changing the minds of those on the receiving end.

Good

[Dark Paladin]

Now, when I tell those guys I want my pizza in 30 minutes or less, there is no excuse!

Re:Good

[sik0fewl]

Unless, of course, you live on the far side of an airport and they can't get clearance to fly across it. In that case (assuming they had to fly all the way around the world the other way) your pizza would take about 3.5 hours to arrive.

Still better than some places I've ordered from.

Re:Good

[GreyWolf3000]

That stupid 30 minutes or less crap was done away with a long time ago.

Y'know why? Heh...there were incidents of drivers getting in huge car wrecks and their bosses running up to the scene, taking the pizza, and running to the customer's door to beat the time.

Re:Good

[drinkypoo]

Let's face it, until the pizza delivery company is owned by the mafia and issues you a jet black car with orange fire effects in the "grill" people just aren't going to get out of your way fast enough to let you deliver pizza in less than 30 minutes reliably. Personally I suggest we allow people delivering food to use a strobe and siren to clear traffic...

A loeeson in civics.

[standsolid]

Now just wait until some idiot puts that engine into his Honda.

Re:A loeeson in civics.

[flying_monkies]

Now just wait until some idiot puts that engine into his Honda.

Won't happen until they can come out with a "fart can" for the exhaust.

Re:A loeeson in civics.

[Megaslow]

You mean like this size?

Guinness Record

[Embedded Geek]

In case you're wondering, it beat its own world record (Mach 6.83, 5000MPH) set back in March.

By the way (and massively OT), doesn't a "Guinness Record" sound like something you'd like to break yourself, at least if it involved consumption?

Re:Guinness Record

[jelloburn]

Wasn't the whole point of that book to reduce the number of bar fights when drunks start arguing and betting about some wild rumor they heard. Do they list records involving their own product? (It is called the Guinness book for a reason.)

Re:Guinness Record

[corngrower]

The folks at NASA are probably in the bars right now celebrating and breaking their own Guinness records.

Re:Guinness Record

[Embedded Geek]

Not so much "bar fights," but I had heard it was indeed to settle bar arguments, especially about sports trivia. The fact that the word "Guinness" is proudly displayed was supposed to make the book into an excellent bit of advertising.

Whether or not that's true, the folks at the Guinness Book have chosen to dodge the topic (here):

In 1951, Sir Hugh Beaver, then the managing director of the Guinness Brewery, went on a shooting party and became involved in an argument. Which was the fastest game bird in Europe - the golden plover or the grouse? He realized then that a book supplying the answers to this sort of question might prove popular.

Re:Guinness Record

[Haydn Fenton]

Highly Off-Topic, but yes..

The McWhirter twins, IIRC. One (or maybe both) of them were obsessed with quirky facts. Then in 1950 they set up a business together to sell facts to newspapers. Roughly at the same time, the managing director of Guinness had an argument about the fastest bird in Europe but couldn't find any facts on it. Somehow, they ended up in contact with eachother and made the book we know as the Guinness Book of Records. Although they did have certain rules about what would and what wouldn't get put into the book.. no supernatural records (obvious reasons, I guess), no sex records (was to be a family book), no criminal feats (didn't want people doing illegal things to get into the book), and no records like eating the most marshmellows at once (didn't want people to die in the proccess). One died playing tennis, and one was killed by the IRA whilst offering £50,000 for information on terrorists..

Re:Guinness Record

[npistentis]

Fastest bird in Europe... could it be a Swallow perhaps?

This technology is all well and good but....

[banuk]

...can it get me around the world in 80 days?

Muuuuch better shot for scale...

[Anonymous Coward]

...had to hunt for it, but here it is:

http://spaceflightnow.com/news/n0106/02x43failure/ x43.jpg

Re:Muuuuch better shot for scale...

[demonbug]

Notice that in the picture the X-43 is the little black thing at the tip - the rest of the pod is the booster to get the X-43 up to speed before its scramjet can take over.

Re:Muuuuch better shot for scale...

[networkBoy]

That sucker is positively tiny!
looks like a toy.
-nB

Re:Muuuuch better shot for scale...

[MyHair]

It's 12 feet long. Small for a plane, but not "tiny". The B52 is friggen huge. The pegasus is pretty big, too.

Too bad there's not a person in the picture for reference.

Thanks for pointing out it was black. I couldn't figure out which part was the X-43A until you mentioned that; before it blended in with shadow.

Jobs

[Anonymous Coward]

Steve Jobs invented mach speed.

Re:Jobs

[Professor Oompa]

I thought it was Al Gore.

Re:Jobs

[chris_mahan]

no no no... Al Gore invented the Internet.

(Which was subsequently renamed Intarweb by GW)

Steve Jobs invented music downloads.

Sheesh, get your gross generalization straight...

Re:Jobs

[Drakonian]

I thought it was Avie Tevanian.

Re:Jobs

[Keitopsis]

If anyone cares:

Earnest Mach

--Kei

Re:Jobs

[SRain315]

That's not what Al Gore said...

Let's hope...

[HexaByte]

Let's hope that this type of engine isn't adopted by commercial arlines. If it were, a flight cross country would take less than an hour, and the flight crew wouldn't have time to get us all drinks and peanuts.

Re:Let's hope...

[corngrower]

I think you've figured out why the airline industry is pushing this technology. They could completely eliminate serving the drinks and peanuts and save beaucoup bucks.

Re:Let's hope...

[cplusplus]

My time is worth more than a thimble full of soda and small bag of peanuts :-)

Re:Let's hope...

[centauri]

To paraphrase a Museum of Flight poster about the Blackbird:

At Mach 10, coffee isn't served, it's vaporized.

Re:Let's hope...

[Guppy06]

They can give us drinks and peanuts while we're all waiting in line for our ATSB anal probes, which already are getting to the point where they take more time than the flight itself.

Re:Let's hope...

[fbg111]

I think you've figured out why the airline industry is pushing this technology. They could completely eliminate serving the drinks and peanuts and save beaucoup bucks.

Jeez, why was that rated insightful? Definitely +5 funny, but to be insightful it would have had to point out that the huge amount of money the industry will have to spend to get this technology working will more than negate the pennies they'll save by not passing out peanuts. And it would also have to mention the fact that such brief scramjet flights mean that only /.'ers will be able to join the milehigh club anymore. And then someone could make a funny post pointing out that /.'ers aren't elligible for the milehigh club anyway.

That 's around 12 000 Km/h

[ArcticCelt]

That's around 12 000 Km/h for those who use the more civilized metric system.

(sorry I know this debate is a classic but miles say nothing to me and I guess that many international slashdoters feel the same)

Re:That 's around 12 000 Km/h

[Anonymous Coward]

Which is 3.33 km/s. To leave the planet and stay in an orbit you need at least 8 km/s. So they need to go faster 2.4 times than right now.

Well still I have to congratulate NASA. Fine job :-)

Re:That 's around 12 000 Km/h

[marsu_k]

Mods, come on, that's hardly a flamebait. I for one found it informative, although I'd phrase it "more common metric system" (common as in the rest of the world, I do know most slashdotters are from the States)

Re:That 's around 12 000 Km/h

[Kehvarl]

I'm guessing the mod would have preferred knots per week?

Re:That 's around 12 000 Km/h

[clambake]

That's around 12 000 Km/h for those who use the more civilized metric system.

Is that metric hours?

Re:That 's around 12 000 Km/h

[JohnsonWax]

(sorry I know this debate is a classic but miles say nothing to me and I guess that many international slashdoters feel the same)

See, but we're Americans, so we don't give a shit about you - you're all 3rd world socialist pansies. Did you learn nothing from our election?

Around the world in 3.4285714285714285714285714285

[Marxist Hacker 42]

24000 miles at 7000 miles per hour means you'd be home in 3.4285714285714285714285714285714 hours.

Yes but...

[wviperw]

The important question is, what would Mach 10 be in warp speed?

Re:Yes but...

[otis wildflower]

TOS Warp or Next Generation Warp?

Re:Yes but...

[happyfrogcow]

TOS Warp or Next Generation Warp?

You should win a free slashdot premium subscription for that question.

Nerd of the Day honors to you!

Re:Yes but...

[Galuvian]

According to Google, mach 10 = 3.4029 kilometers / second Warp 1 = speed of light = 299,792.458 km/s Therefore Mach 10 is roughly equal to warp .000001

Re:Yes but...

[romrom97]

Waaaaaaaaa..... *is hurled off the cliff to the rocks below*

Re:Yes but...

[cold fjord]

The important question is, what would Mach 10 be in warp speed?

Release the docking bay clamps.

Re:Yes but...

[foniksonik]

I'd think you should be talking about Impulse speed, not Warp... I mean at low speeds they use Impulse engines right?

Re:Yes but...

[Rares Marian]

Um not quite. Warp numbers are exponents so... it would be log 3.4029 in base 299,792.458.

See each warp re warps the previous one so...

Now where's my autographed shot of Kirk telling Picard he was out saving the galaxy while his grandfather was in diapers?

Re:Yes but...

[Suidae]

You must be speaking of TOS warp. TNG warp is a bit harder to calculate. There is a graph in the manual though.

You know..

[bludstone]

For all the shit theyve been through, NASA still fucking rocks.

Kudos to the Alpha geeks.

We bow.

Re:You know..

[rritterson]

actually, you should have said:

for all the shit they've been through, NASA still fucking rockets (insert cymbal crash)

Thank you, thank you- i'll be here all week!

X-10?

[necro2607]

Did anyone else think of "X-10" when they saw this article's title? ... or even better... "We must destroy X-10... we must destroy all internet ad".. ??

Re:X-10?

[necro2607]

heh, I knew the word "pneumonoultramicroscopicsilicovolcanoconiosis" when I was in grade 5 (as well as "phthalylsulfathiazole", along with making all the spelling tests for my teachers since grade 3 because I knew words they'd never even heard of)... I think I can read well enough ;)

Re:X-10?

[passion]

Did anyone else think of "X-10" when they saw this article's title? ... or even better... "We must destroy X-10... we must destroy all internet ad".. ??

That's kind of an unfortunate take on that company. I certainly have a love / hate relationship with them. I hate their shady spam strategy, but love their simple home automation products. I don't know why they got into selling remote cameras, but I guess if you're paranoid about your shit, you need someone's eye to watch over it.

Re:X-10?

[necro2607]

http://artists.iuma.com/IUMA/Bands/kompressormusic /

Notice "WE MUST DESTROY X10"... listen to it. heh

My post was supposed to be funny, but no one seems to even recognize my allusion to this song... :\

More questions...

[EmbeddedJanitor]

The scram jet is air breathing. One wonders how much air is available to breath at 110,000 foot. Is there something majic about 110k feet? Is there too little air above this? Is this the altitude limit of jet technology?

Considering that GPS satellites are something over 20000 km up, 110k feet is only a fraction of a percent of getting there.

Re:More questions...

[TheAntiCrust]

Perhaps that is why it already needs to be going so fast?

Maybe it needs to make up for the thin atmosphere by going through a lot of it.

Re:More questions...

[spike hay]

110 thousand feet is almost space. The atmospheric density is about that of Mars. It couldn't go much higher than that, and the only reason it can travel that high is because this aircraft moves so fast. It can shove a lot of air in moving at 7000 mph.

WRONG

[Anonymous Coward]

Not even close.

Hubbles orbital speed is approximately 16,900 miles per hour.

You are not even close. He was asking about orbital ROCKETS! Not objects in orbit. Orbital rockets are the things that lift the satellites into orbit.

The space shuttle does not get anywhere near 16,900 mph on lift off. That is the speed it gradually gets to once in orbit, NOT ON LIFT OFF.

After 60 seconds, the Shuttle has accelerated to Mach 1 (the speed of sound). About one minute later (two minutes into the flight), the solid rockets burn the last of their fuel. By this time the shuttle is over 25 miles high. The now-empty solid rockets are released in order to reduce the weight carried the rest of the way to orbit. [They parachute into the ocean off the Florida coast, and are recovered to be refilled with fuel and used again.]

After the solid rockets are released, the shuttle is still attached to the external tank and its launch engines are still being fed propellants from the tank. When the shuttle reaches an altitude of about 57 miles, it changes trajectory to fly more horizontally, and pick up speed. In order to achieve orbit, it needs to accelerate to approximately 17,500 mph (~5 miles/sec). Once it reaches this critical speed (about 8-1/2 minutes after lift-off), the shuttle launch engines are shut off, and the shuttle separates from the external tank. The tank re-enters the atmosphere and burns up on re-entry. It is the only part of the Shuttle system that cannot be used again.

Re:WRONG

[bleckywelcky]

Well, if you're going to nitpick, the ET doesn't burn up on reentry. It breaks up and the pieces fall into the Indian ocean.

Re:WRONG

[drinkypoo]

The main tank could be used for something other than being thrown away, but we just jettison them. I'd like to see them taken to the ISS and made into modules, or at least placed in the path of orbital debris.

Re:WRONG

[the_2nd_coming]

ah, yes, the energy it would take to get them there would be greater than what is allowed a heavy payload to the ISS, and putting them in the path of orbital debris makes more orbital debris.... your not a smart guy are you.

Re:WRONG

[drinkypoo]

Maybe I should use shorter words... I mean, take them to the ISS and attach them to it and use them as a debris shield. Don't make assumptions, it makes an ass out of you, and umption.

Re:WRONG

[NateTech]

I gotta side with the other dude here, man. You badly worded your original message and he took it at face-value. I read your original that way too.

Plus it's still a retarded idea.

For any debris to be dangerous it would have to be travelling at a relative velocity to ISS to puncture it. The external tank of the Shuttle isn't much to stop that.

Large debris at slow speeds would just slam the ET into the station - so there's no point there other than spreading out the results of an impact.

If ISS needed a debris shield, I'm kinda betting that smarter folks would have already hung one on it. The thing is engineered to survive the average sized average speed debris it will encounter in its orbital lifetime, plus some.

So the real issue here is: Why do you assume the ISS needs a debris shield, and second, why assume that the very smart folks at a number of space agencies haven't already done hundreds of man-hours of work thinking about that very same issue long before you did?

I'd say you're the ass-uming person in this discussion, right from the start. The logic might escape you, however.

Instead of shorter words, perhaps less words and more thinking are in order.

Re:WRONG

[ParamonKreel]

Well if we're being really really super pendantic then either everything is moving because we're all moving in relation to the galactic core which is moving in relation to some zero point that is the global frame of reference or center of the big bang or somthing. Well, all except for me. I am the center of the universe so I'm not moving, everythign obviously revolves around me. Disprove it :)

Re:WRONG

[ParamonKreel]

Oh and the orbital escape velocity is Mach 26, you can convert that on your own. This is from all of the articles on the X43a

Re:WRONG

[M1FCJ]

Correct.
Shuttle does about 3g of steady acceleration (because of structural limits) After 1min, it would do around 635km/h. After 8 min, it would be around 5000km/h.

This is net 3g downwards, if it were going up all the time. As you described, it changes attitute which enables to convert acceleration to speed because it doesn't have to go straigt up and waste acceleration (less is used against the gravitational acceleration). Since Shuttle engines are throttable, they can ease on the acceleration any time they like.

Re:WRONG

[FleaPlus]

The idea I've mostly seen tossed around isn't to use the ET as a debris shield, but to actually turn it into a (very large) space station module.

In the 80s David Brin wrote a great short story, "Tank Farm Dynamo" (available online), which talks about a near-future space station using the technologies of external tank modules and electrodynamic tether propulsion. He assumed that electrodynamic tethers were a pretty "out there" idea and that external tank modules were a straight-forward no-brainer. Ironically, we've flown prototypes of the tethers on the space station and absolutely no development has been done towards external tank modules.

Re:WRONG

[HokieJP]

So how did the objects in orbit get to that speed if they weren't attached to rockets that were going that fast to begin with?

You're not really comparing apples to apples, since the shuttle has rocket engines of its own that provide a lot of the energy. The OP was talking about a satellite with only maneuvering thrusters.

Re:WRONG

[drinkypoo]

I agree that the best use for the tanks would be as modules for a space station. Personally I'd like to see a whole series of them linked into a ring and put under spin, with some number of spokes (three?) running to a centrally-located docking hub, which itself would probably be another tank. If we had been taking tanks into orbit with us every time we went up, we'd have enough for quite a sizable structure now. What the hell we would do with them and how we would make them livable is another question, and a serious one, but it might be a better use of the ISS to bootstrap another station than just to do the limited research we can do on the ISS with the tiny crew it can support. Let's bring down a scientist or two, and send up some welders :P

Re:Around the world in 3.4285714285714285714285714

[Kehvarl]

Assuming you didn't have to take off, land, accelerate or decelerate, you could circle the earth in pi hours at Mach 10.61.

At Mach 10

[boatboy]

So, at Mach 10, can anyone hear you scream?

Re:At Mach 10

[NeoSkandranon]

That would be some hellacious doppler effect.

Re:At Mach 10

[Anonymous Coward]

George, you know I was wondering, like if you were traveling through outer space, I mean like you're going real fast, like the speed of light, you know ...hoooohhhhh... and all of a sudden you started screaming ...aaaahhhhh aaaaahhhhh... Do you think your brain would blow up?

Re:At Mach 10

[drinkypoo]

Today, we're teaching poodles how to fly... at mach ten.

Re:At Mach 10

[DigiShaman]

The French?? What??? They will be rebuilding the Concord that flys at Mach 10? You don't say eh..... hmmmm

Maybe they will call it the "Phoenix".

I'm Not Impressed

[nate nice]

It's not like they put it into space, twice in two weeks, for under 10 million dollars.

Re:I'm Not Impressed

[nate nice]

Whoa, that's out of left field.

Re:Length?

[caffiend666]

The last flight was 11 seconds. Haven't heard on this one yet. See here.

Re:That camera angle

[ajlitt]

The name of the "Visine Commercial Dude" is:

is...
is...
had a short-running game show on Comedy Central...
anyone???
anyone???

Ben Stein.

And Ben Stein is best known for:

anyone???
anyone???
thundergeek???
thundergeek? ??

his appearance in Ferris Bueller's Day Off.

(sheesh, I know the average person around /. is ignorant, but the man had a critical role in defining the 1980's!)

Incorrect.

[i41Overlord]

On both flights, the rocket took the craft up to maximum speed and the craft merely sustained the speed.

Re:Incorrect.

[fozzy1015]

Sounds almost like one is trying to make a paper airplane with such finesse to it's form that it can fly straight and true when launched from a cannon.

Yes

[roystgnr]

But only if they're behind the shockwave.

Press Conference at 4 PST

[jmichaelg]

NASA has scheduled a press conference at 4 PST. It's available at http://www.nasa.gov/multimedia/nasatv/index.html

Computational Fluid dynamics modeling

[zymano]

Nasa is doing these tests because they can't model conditions with their computers.

I wonder exactly what about the scramjet that they can't model with the resources they have including plasma wind tunnels ?

But can it do...

[dark-br]

...the Kessel run in under twelve parsecs? ;)

Re:But can it do...

[bjhonermann]

What does that even mean? I know it's from Star Wars, but a parsec is a unit of distance, not time.

I guess it's possible that the Kessel run has some astronomical challenge that it must be done very quickly or a ship will actually have to travel farther to complete it. It just doesn't make much sense as a speed gauge though.

-Brian

Re:But can it do...

[KEVINWASH1]

Basically, it means the pilot and ship were both good enough to swing in closer to planets and other anomalies (such as anomalies), thus creating a shorter path. Perhaps even use a body's gravity field to slingshot around too (not really sure). So basically, fast and manueverable ship + skilled pilot = shorter distance required.

Re:But can it do...

[Lord Crc]

What does that even mean? I know it's from Star Wars, but a parsec is a unit of distance, not time.

AFAIK the kessel run involved a black hole intersecting the flightpath. So the closer you managed to travel to the hole, the less distance you'd have to travel in total.

Re:But can it do...

[Moonasaur]

Taking an opportunity to post off-off-topic... I had always assumed that the "Kessel run" line was was an egregious error on the part of George Lucas. But recently while browsing the actual script, I found something significant that I don't recall from seeing the movie -- been too long or maybe it was edited out -- that totally changes the scene, so that evidently this line was *supposed* to sound bogus:

HAN: Fast ship? You've never heard of the Millennium Falcon?

BEN: Should I have?

HAN: It's the ship that made the Kessel run in less than twelve parsecs!

*Ben reacts to Solo's stupid attempt to impress them with obvious misinformation.*

HAN: (continued) I've outrun Imperial starships [...]

(Emphasis added.) Apologies for posting this if others were already aware of it.

Re:How fast is 7,000 MPH

[JohnGrahamCumming]

> Circumference of Earth at equator = 24,900 miles = 3 hours 33min 26 seconds

Please, if you get a scramjet of your own, take the extra time to go around the earth and fly above sea level! You'll enjoy the trip a whole lot more.

John.

Some helpful links

[UnapprovedThought]

The article link doesn't have much in the way of interesting details, so, here are some slightly better links to hopefully raise the signal ratio:

• http://www.nasa.gov/missions/research/mach10_met eor.html
• http://www.nasa.gov/missions/research/x43-image- feature.html

The first one is an article with some details, the second is some artwork that explains the scramjet and the flight path.

From the looks of it, the scramjet engine doesn't appear to be a very sophisticated device. It's just a funnel that doesn't ignite the fuel until it has already reached supersonic speed.

The tricky part, if I'm guessing correctly, is building a vehicle that can withstand the 3600 degree heat of flying at Mach 10 in the upper atmosphere. It succeeded, but there was no human pilot inside of this one. I think that will be the next step: to build a craft, as small and light as possible, just to ferry crew into space, leaving cargo payloads to be sent up using a much cheaper but less safety constrained kind of lift capability.

Re:Some helpful links

[KoshClassic]

From the looks of it, the scramjet engine doesn't appear to be a very sophisticated device. It's just a funnel...

Actually, nothing could be further from the truth. Yes, it really doesn't have any moving parts, but designing it properly is an extremily complex undertaking. I believe engineers have compared it to trying to keep a match lit in the middle of a hurricane.

While the thermal issues are no doubt complex, that sort of problem has been tackled before (the space shuttle far exceeds Mach 10 during re-entry, for example).

Re:Some helpful links

[rebelcool]

Try keeping a flame lit in a 7000 mph wind.

Its taken decades of design and testing to figure out the geometry of the scramjet so that it actually works.

Re:Some helpful links

[Mulletproof]

"The tricky part, if I'm guessing correctly, is building a vehicle that can withstand the 3600 degree heat of flying at Mach 10 in the upper atmosphere."

Not only that, but the shape of the aircraft is critical to hypersonic travel. While it's been working thus far, there is something about the very design that becomes inherently unstable the larger it gets. There are serious concerns in building this thing to something of a more usable scale in the hypersonic community.

Re:Some helpful links

[corngrower]

Actually the air is slowed down quite a bit to compress it before combustion. But still the flow still remains supersonic and I'ld guess that would mean its flowing at at least 700 mph (1200 kph). The combustion needs a continuous source of ignition and, IIRC, some chemical that spontaneously combusts with air is injected into the flow along with the hydrogen fuel.

How do they keep the shockwave in place?

[homerito]

I looked at the pdf that shows how the shock waves propagate inside the engine. However the angle of those shockwaves changes with the speed of the plane.

They had the same problems with the sr-71 so the engine cone moves back and forth until the appropiate shock wave would form inside the engine. If the shock wave is not in the appropriate position then the combustion inside the engine stops and I dont think is easy to restart an engine at mach 3.

Anyhow, can please somebody give me an insight of the inner workings of the engine? One solution is that the plane would fly at a constant speed so the angles are always the same but that does not seem very practical.

Re:How do they keep the shockwave in place?

[Keitopsis]

Note that the inlet is built out of the forward body of the vehicle, so the shockwave is still external.
Its only the portion of the stream that enters the combustion zone that is being propelled, the rest can be reguarded as bypass air.
Also note the tail of the aircraft is formed to handle post/hyper-sonic exhaust.

--Kei

Re:How do they keep the shockwave in place?

[TigerNut]

The guy who designed the SR-71's engines ended up winning one of the most prestigious aviation prizes (no, I can't remember which) for the way that the movable engine inlets ended up being responsible for something like 80% of the thrust produced at high speeds. He later became director of the Lockheed Skunkworks in the era where they produced the F117A.

Re:That camera angle

[Anubis350]

how about as a speech writer for nixon? or as the host of win ben steins money? or lots of other things...

the man has had a damn versitile career, is very smart, and definately helped nshape both entertainment and politics for the last 2 decades. I agree with you, I cant believe that one cant come up with his name from the comercial

That's km/h

[SysKoll]

12000 Km/h is Kelvin times meter per hour. A Kevin is centigrages counted from the absolute zero. For laymen, the association of a temperature with a speed unit is a bit baffling, so let me explain. Km/h is a unit used exclusively to measure the speed reached by those people that run around at high speed while yelling "AAAAARGH! MY UNDERWEAR IS ON FIRE!!!". That's right, the dreaded Underwear Spontaneous Combustion Syndrome, often caused in young guys oogling all these hot chicks in Californian campuses. Witnesses of an USCS occurence generally scramble for water buckets.

An USCS episode can be dramatic, depending on the Km/h value. At high Km/h values, the victim is running so fast that the bucket carriers cannot catch him. On top of that, the wind of his frantic run vents the fire, which of course burns even hotter, quickening his race. After a certain threshold, the poor guy's genitals burns to a crisp. The critical speed is called "Mach speed" (pronounced Mack), after an early victim.

So unless you are referring to these sad but uncomon accidents, the metric unit you want to use is km/h, with a small k meaning kilo, not the capital K of Kelvin.

Re:That's km/h

[Captain_Chaos]

Isn't 12000 Km/h the same as 12288 km/h? ;-)

I beg to differ

[Atario]

Mach numbers are about as international as you can get.

Orbit with a scramjet is tough

[hpulley]

The scramjet is an air-breathing engine. That is its advantage over chemical rockets which must loft both fuel AND oxidizer while the scramjet just carries fuel, thus hopefully providing a better thrust:weight ratio. The scramjet gets its oxidizer from the atmosphere so unless it can reach escape velocity while deep enough in the atmosphere to get out (and overcome the remaining air resistance) it will need a different type of motor to kick it into orbit.

Re:G force?

[Matimus]

F = ma -> Force = Mass x Acceleration, I don't see where velocity comes into the equation? If it went from 0 ft/s to 10,266.25 ft/s in 1s, then it would be 318 Gs

no... X-Prize!

[freezin fat guy]

I suppose now NASA is kicking themselves for not entering the X-Prize competition.

Re:Length?

[Hobadee]

How much fuel do you have? No, seriously, that directly determines how long a scramjet engine will last.

Quick overview on how a scramjet works, for those of you who may not know. Basically, it can't work until it's already going really fast. All it does then is start a flow of fuel into the engine. The air flowing really fast through it ignites and burns, creating thrust. It's pretty much the simplest engine ever. The reason it took em so long to figure it out is that it has to be shaped perfectly and you have to GET it to ludicrous speed before you can maintain that speed.

No problem

[DaveAtFraud]

The flight crew will either serve them during the hour you're taxiing from the terminal to the runway and waiting for clearance to take-off or during the two hours you're waiting for your gate to open up after you land.

I doubt if the airlines would cut back on the serving size. A bag with just one peanut in it probably isn't cost effective.

But the luggage never showed up.

[NotQuiteReal]

And, there is a $1500 per bag liability limit, but if you don't have your check-in stub you are out of luck.

Rocket/scramjet/rocket???

[EmbeddedJanitor]

So basically scramjets can't replace rockets for space work. You's still need a scramjet + rocket.... and you'd still need a rocket to get going fast enough for the scramjet to work properly.

So you'd have a sequence something like: use rocket for take-off, switch to scramjet when fast enough, switch to rocket (likely a different one) when the O2 runs out. Is this really an improvement over, say, the space shuttle which only needs two rocket "stages".

I guess scramjets are potentially useful for high altitude aircraft, though they'd probably need rocket assisted take-off. If NASA is designing, I don't think I'm flying.

Re:Rocket/scramjet/rocket???

[the_2nd_coming]

they are useful for removing 80% of the oxidizer as well.

Re:How fast is 7,000 MPH

[Anonymous Coward]

>Circumference of Earth at equator = 24,900 miles = 3 hours 33min 26 seconds
Please, if you get a scramjet of your own, take the extra time to go around the earth and fly above sea level!
"it flew at an altitude of approximately 110,000 feet"

Circumference = 24,900 miles
diameter = 7925.9 miles
Radius = 3963.0 miles
110,000 ft = 20.8miles

So ((3963.0 miles + 20.8 miles)2)pi = 25031.0 miles

25031.0 miles / (7000 miles/hr) = 3 hr 34min 33 seconds

Diffrence: 1 min 7 seconds

Re:Computational Fluid dynamics modeling

[banz23]

I would think that they can and have modeled the conditions with their computers. Now that they have modeled the conditions they want to prove that they were correct in the real world. This is all about proof of concept.

Back in Time?

[dcollins]

Don't you go back in time if you go that fast? I thought I saw that in Star Trev IV...

Re:Back in Time?

[Bisqwit]

Speed of sound (~300 m/s) is much lower than the speed of light (~300'000'000 m/s).
Also, the trick used in Star Trek IV involved the sun somehow (flying behind it or something).

Re:Computational Fluid dynamics modeling

[rebelcool]

It doesnt fly until its flown, yeah?

Um, no

[PetoskeyGuy]

Parsecs per Millenium

The scram jet travels at a rate of 0.0035 parsecs per millenium. So to go 12 parsecs would take 3.4 Million Years.

Parsecs is a measure of distance, not speed. Han was just screwing with Luke. The Star Wars equivalent of headlight fluid, muffler bearings, knuter valves, and piston return springs.

How is 7,000 mph == Mach 10 at this altitude?

[GnuPooh]

So Mach number is related to air density (speed of sound). At 100,000 ft there's not a lot of air, so while the speed of sound is about 700 mph at sea level, it's not at 100,000 ft. Are they cookin' the books or am I missin' something?

Re:How is 7,000 mph == Mach 10 at this altitude?

[GnuPooh]

I think I got it. From this page: http://www.grc.nasa.gov/WWW/K-12/airplane/sound.ht ml Speed of sound is still 684 mph at 100,000 ft

Re:How is 7,000 mph == Mach 10 at this altitude?

[Keitopsis]

The speed of sound is approx. sqrt((gamma)RT)
Assuming Ideal Gas
Gamma (roughly constant for air (1.4))
R = Ideal Gas Constant
T = Absolute Temperature (relates to density, etc)
(somehow I knew those thermodynamics and aerodynamics courses would pay off someday)

At 100,000 ft, the temperature is only somewhat lower. This only marginally lowers the speed of sound, but also lowers problems with skin heating at high speed, parasite drag, etc.

So, no, noone is pulling a fast one. This is an impressive achievement for an air-breathing vehicle. Now if anyone can find an article detailing if they got any positive thrust out of it or if it was all the pegasus booster.

--Kei

Now that you are on the subject metric hours...

[ArcticCelt]

Now that you are on the subject I saw an interesting article about that. Just after the French revolution, the French government decided to put everything in metric. Not only the distances but also the time and the days of the week and time was then calculate by something factor of 10.

What made it fail is not only that it was a total pain in the ass to change every clock and calendars and get use to it but also that weeks were now lasting 10 day but still with only 2 days of weekends and workers were really pissed off about that. They were almost about to start another revolution so the French government decided to drop the metric system on time and dates.

Oh yea and also about my "civilized" comment: It was meant to be told with a wink, so please to the ones that are taking that personally I say go buy yourself a sense of humor somewhere, jee I didn't know that people where now so touchy about something so meaningless and futile.

orbital flight is a goal

[geg81]

Nevertheless, reaching orbit is a goal of this program:

"This flight is a key milestone and a major step toward the future possibilities for producing boosters for sending large and critical payloads into space in a reliable, safe, inexpensive manner,"

The scramjet may be used as an efficient booster, halfway between liftoff and full orbit.

Next year's headline

[serutan]

Burt Rutan builds 12-seat scramjet for $1 million, breaks Mach 15 on first attempt.

CNN Not Fast

[bill_mcgonigle]

Here's a snapshot I grabbed of CNN's page after the election. Kerry conceded the election before they called it. :)

Re:Computational Fluid dynamics modeling

[richmaine]

Yep. Or as our namesake (Dryden) put it:

"..to separate the real from the imagined, and to make known the overlooked and the unexpected problems"

That's about as good a statement as there is on what real flight research is about. You don't do that in a computer (though you use a lot of computers in the process).

Re:about 7000 mph??

[richmaine]

It would be if you did Mach 10 at sea level, which would be...um...exciting. :-)

The speed of sound varies with altitude. Not a huge amount, but some. I didn't bother to check the numbers amd I don't know them in MPH (no, those units aren't really used for technical work) off the top of my head. I'm sure the 7,000 is just a rough number for public consumption anyway.

And if you got your data from the NASA "Fact" Shhet about Mach number that I see was posted on the hyper-X page today, that fact sheet isn't quite so factual as it ought to be. (It says that Mach 2 means twice the speed of sound at sea level, which isn't true - it means twice the local speed of sound.) I emailed in a correction to the web page editor, but haven't heard a reply yet.

Death by Scramjet.

[Jafar00]

Hooray.
The Military application of this technology will be used many years before it is used for civilian things like transport.
Now unsuspecting populations can be blown to pieces even faster with new scramjet equipped cruise missiles.

Don't forget the B-70 Valkyrie

[Mulletproof]

The SR71 uses one of the more complex methods of maintaining high mach travel, but it isn't the only one. The B70 Valkyrie experimental strategic bomber solved the problem using wings that folded down vertically to encompass the shockwave beneath the fusalage and literally ride it. It's supremely ironic that this aircraft can outrun today's B1-b Lancer by a full two times the speed of sound using 1950s technology.

Some history on this forgotten, stunning piece of aviation engineering.

Snap, crackle, BOOM

[Mulletproof]

No, the airline industry isn't pushing this technology. Thry're pushing the technology that will allow an aircraft to create a quieter sonic boom over populated areas. A Mach airliner can be done. It can even be done affordably, if you can fly it over populated areas without a resounding 'thump!' everytime it passes overhead. The inability to use it's speed advantage over populations and subsequent lack of effecient route restrictions were key in killing the Concord, and it's one of the reasons why the industry hasn't taken off in the US. The cost to make the aircraft combined with the inability to use it effeciently makes it a money losing proposition everytime.

Skunk Works

[Airw0lf]

The guy who designed the SR-71's engines ended up winning one of the most prestigious aviation prizes (no, I can't remember which) for the way that the movable engine inlets ended up being responsible for something like 80% of the thrust produced at high speeds. He later became director of the Lockheed Skunkworks in the era where they produced the F117A.

The guy's name is Ben Rich, IIRC. He went on to write a very good book about his time at Lockheed-Martin. The book is called "Skunk Works." The title originates from the name of Lockheed's top-secret, advanced developments team...

Wasting nearly-Orbital Material

[AGMW]

Once it reaches this critical speed (about 8-1/2 minutes after lift-off), the shuttle launch engines are shut off, and the shuttle separates from the external tank. The tank re-enters the atmosphere and burns up on re-entry. It is the only part of the Shuttle system that cannot be used again.

What I don't understand is why you spend so much money in fuel and oxidiser to get the external tank nearly into orbit, then for the additional cost of presumably not very much (in the scheme of things), let the thing fall back to earth and burn up?

Would it not make more sense to take the tank into orbit and use it for something? It's got to be (at least nearly!) air-tight, why not add it to the Space Station as another module for something? Use it for spare parts - got a leak, hack a suitable sized bit off the old tank and stick it over the hole. Just stack them up in orbit somewhere for raw material to build a interplanetary space ship?

Re:Wasting nearly-Orbital Material

[DasBub]

"What I don't understand is why you spend so much money in fuel and oxidiser to get the external tank nearly into orbit, then for the additional cost of presumably not very much (in the scheme of things), let the thing fall back to earth and burn up?

Would it not make more sense to take the tank into orbit and use it for something? It's got to be (at least nearly!) air-tight, why not add it to the Space Station as another module for something? Use it for spare parts - got a leak, hack a suitable sized bit off the old tank and stick it over the hole. Just stack them up in orbit somewhere for raw material to build a interplanetary space ship?"

You're absolutely correct. Unfortunately, a lot of factors and events have stopped any of these things from happening.

The ET itself is completely space-worthy. It was designed to operate in space long after reaching orbit. Early plans for space stations and platforms included the ETs since they remain completely useable. What's more, the tanks still have a lot of H2 and O2 left after a launch. So in reality, the shuttle could reach much higher orbits if it _kept_ the ET attached on orbit. This was purposely designed-in, since the original plans for what's now the ISS called for a higher orbit than usual. So any visit to the space station would require one to keep the ET. Even if it was just hanging around LEO, the H2 and O2 in the tank are extremely valuable and are worth leaving in orbit.

So why don't they do this? Well, they just don't have a reason to anymore...

First, the shuttle no longer needs access to the higher orbit, since the ISS we have is in a much lower orbit. This was done to accomodate the Russian launch sites. This has crippled a lot of the usefulness of the ISS compared to it's original goals, but that's a whole other post.

Second, managing the ETs and their contents are more trouble than they're worth. What I mean is that the only immediate usefulness of the H2 and O2 would be for the ISS, but it's just less of a planning headache to have the supplies sent up by Progres than mapping out astronaut time to transfer stuff from the ET through the shuttle to the station (and having to manoeuver with the ET attached). We can say that making orbital warehouses of the tanks and their contents for future missions and projects is a great idea, but it brings up the question of where and how. Do you store them at the ISS, or at some designated point out of the way? If the ISS, you've just added another headache to the crew. If at some other point in space, you have to have station-keeping thrusters to maintain orbit and attitude. NASA has no need for any of these headaches currently.

Thirdly, the whole idea is moot since the shuttle's death warrant has already been signed. Well, it was signed a long time ago, but suffice it to say that the shuttle isn't going to be around much longer. There's no incentive to change their operations now, so they'll just keep chucking everything away until the program is over.

It's really quite sad to look back at the past thirty years* of the shuttle and ISS programs and realize how poorly they've been executed and how many opportunities and resources have been squandered needlessly. I have the utmost respect for the engineering teams and all the people who put the shuttles together and made them fly, but the shuttle program really has ruined NASA for decades.

Blah.

* - the shuttle fleet has only been flying since '81, but the design work began in the early 70's

Re:Wasting nearly-Orbital Material

[DasBub]

your right, next time they build a new bleeding edge revolutionary space vehicle thats is nothing like anything that had ever been tried before they should just do it perfect the first time and not add anything that will be under utilized because of the geopolitical situation 30 years later, but make sure to add everything they're gonna find out that they need after its built.

This is obvious flamebait, but I'll answer it anyway.

My comment about the shuttle hamstringing NASA for decades isn't a shot at the engineering teams or the assembly and operational staff. They've shown time and again that they're the cream of the cream in terms of ability and ingenuity.

My problem is with the whole space shuttle religion that encircled the project and led to a lot of needless waste and bad ideas.

The shuttle can perform many tasks, to be sure. But it does them at tremendous cost and adds human handlers to operations that can generally be done without human assistance or from remote operators. Think about how things were done before the shuttle; Saturn series boosters were able to deliver extremely heavy payloads to orbit without need for 2-7 humans onboard in a pressurized and man-rated environment. As soon as shuttle development began, all Saturn production facilities were dismantled, in order to give NASA incentive on the new project. This is one of the biggest mistakes of the project, not made by engineers, but by politicians. (Congress was unwilling to fund Saturn production concurrently with shuttle production)

Think about this logically. Why would you throw away such a tremendous launch capability when there are so many uncertainties about your new vehicle? The principle uncertainties being "when will we be able to use it?", "how much will it cost to use it?", and "what can we actually do with it?" As the old saying goes, "a bird in the hand is worth two in the bush."

By limiting NASA to the unbuilt shuttle they set the tone for the next three decades. Here's another fact: the shuttle was built primarily as a service vehicle for the american space station. This eventually meant that not only would it ferry crews and supplies to and from the station, but it would also be the sole launch capability for all of the station parts and modules. What does this mean for the station? Well, the modules are limited to the volume of the shuttle's cargo bay. Compare the size of that cargo bay with the size of the modules on SkyLab. SkyLab was a modified S-IVB booster (modified to live in). Much larger diameter, not the thin hotdog-shaped tube of the cargo bay.

I think I'll stop here for now.

A walk in the park

[Quai]

This makes Kallahar trip from Los Angeles to Oregon at Mach 9 look like a walk in the park...

Variable engine geometry

[cromagnum man]

By my understanding, a scram jet is the same as a ram jet but with a different internal shape.

What are the chances of coming up with a ram jet with a changable internal shape? (same kind of idea as swept wings on fighter planes I guess)

rather than leaving a card through the letterbox..

[RMH101]

...instead you'd have your house, garden and neighbourhood replaced with a huge crater with a squashed packet from amazon in the centre?

Re:How fast is 7,000 MPH

[jewf1sh]

Me to work = 36.8 miles = 18.9 seconds
Me to my parents' house = 545 miles = 4min 40.26 seconds
Me to my girlfriend's house = ....ok now I'm just making stuff up.

Re:Length?

[HokieJP]

It's about 10 seconds, because the X43A is rather small, and uses liquid hydrogen fuel. The follow-on project (X43C, before it was cancelled) was going to use Kerosene fuel, and a larger vehicle, so that it could remain under power for much longer periods. Aside from fuel, I guess the only limitation on how long you could run it would have to do with heat. As you might imagine, it needs some very aggressive cooling systems.

Re:about 7000 mph?? The Need for Speed

[richmaine]

And your point is?

I look forward to seeing your... well whatever it is that you plan to actually do. I'm a little unclear on the details of exactly what this plan of your is and how you are going to accomplish it. Anyway, whatever it is, I'm sure impressed. Go get 'em cowboy.

Amazing!

[caveat]

That's the same combination I use on my luggage!

Military security?

[CustomDesigned]

Wouldn't a terrorist love to modify the flight program of the unmanned craft to turn it into a cruise missile. No payload required, hitting something at Mach 10 will be quite catastrophic enough. The coexistence of terrorism and increasingly powerful commercial technology is scary.

Re:Military security?

[p3d0]

The coexistence of terrorism and increasingly powerful commercial technology is scary.

How many people have been killed by terrorism in the US? And how many have died in car accidents in the same period? How many have died from heart disease?

If you want to make yourself safer, eat healthy and take public transit. The benefits you'll get will far ourweigh the risk of terrorists flying a NASA scramjet into your bedroom.

Re: We're Americans, so we don't give a shit about

[ArcticCelt]

Did you learn nothing from our election?

What do that means? I don't know what did you learn but you seems kind of confuse and unable to express your opinions. You should use other material than MaxNews and Rush "OxyContin" Limbaugh as source of information. Me one thing that I remember is that the US dollar went down right after the election. Draw your own conclusions.

See, but we're Americans, so we don't give a shit about you.

Correction YOU are American, Slashdot have a great amount of American members but also a large international base. I don't know why you speak in the name of all Americans or all slashdoters for what I know you are not oficialy elected to represent anybody (maybe you are president of your local club of IBWHSAHA; Ignorant, Bigots, World-Haters, Sociopath Assholes Association). I also want to say that in the contrary to you I don't hate entire nations I only hate the small asshole like you who lives in them, so yes me I give a shit about the rest of the world.

you're all 3rd world socialist pansies.

What did you accomplish in life to think you are superior as an individual? You're country is indeed powerful but you as an individual are nothing for what I know! Only a small inconsequential clown. You are probably working at an unrewarding job (if you work at all) with people giving you shit all day or something like that... Well I have a secret for you: "You are a failure kid, stop hiding behind your country because you are probably a big time loser"

Enjoy your insignificant unfulfilling life.