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Scramjet Test Successful
An Anonymous Coward writes: "The Sacramento Bee is running this story about the first powered device to achieve "hypersonic" speeds in the Earth's atmosphere. In a series of DARPA-sponsored tests, at Arnold Air Force Base in Tennessee, a scramjet engine, encased in a titanium projectile, was fired from a 130-foot cannon, at an initial velocity of Mach 7.1. The scramjet's engines then ignited, and the object moved another 260 feet, in just 30 milliseconds, before it came to rest in a series of steel plates designed to halt the flight. Peak acceleration: about 10,000 G's. Elapsed time, including cigarettes & pillowtalk: less than a second. PS: According to this nifty page at NASA, Mach 7.1 is about 5406 MPH, whereas 260 ft, per 0.03 seconds, is about 5909 MPH."
Rent a Concorde and fill it with a lot of explosives. It's that easy ...
So, anyone want to set up a pool betting when the first "then we strapped a SCRAMJET on the back of Bob's old VW Bus" story appears?
Ladies and gentlemen, welcome aboard LotsaCashSpentDevelopingThis Airways.
Flight Attendant #1:
"Once we reach our cruising altitude we will begin our complimentary beverage service. Coke products are free while beer, wine, and liquor may be purchased for..."
(interrupted by Flight Attendant #2):
"LotsaCashSpentDevelopingThis Airways welcomes you to Paris DeGaulle Airport. The local time is 12:14pm."
seconds, is about 5909 MPH.
Well, given that the projectile in question was accelerating at ~10K G for that 260 ft, from a starting velocity of Mach 7.1, one would expect the mean velocity over the 260 ft to be somewhat higher, eh?
Very impressive indeed.
But if possible, could the posts include a conversion into metric.
Its just it takes me a little while to do the conversion on my slide rule.
I am sure the rest of the civilised world(ie SI unit using countries) can understand.
Thankyou.
But doesn't the speed of sound change with the air-pressure? If I remember highschool physics correctly, sound has a higher velocity in a denser medium.
--Ryv
The prototype, which resembles a gothic spire and measures just 4 inches in diameter, was destroyed when it punched through a series of steel plates designed to halt the flight. If this scramjet engine technology is so small, could this possibly be retrofitted, (I have no idea of the fuel needed to power this or it's economy, but im speaking theoretically) to give proper thrust needed for larger vehicles, such as, a jump-jet style civilian vehicle? The flying automobiles out of television sci-fi? Is this possible or am I just not getting the whole idea..
Is not life a hundred times too short for us to bore ourselves? -Friedrich Wilhelm Nietzsche
This is great - forget those stupid little rotor blades! 10K G from a small metal tube on his head - lets see Hobbes bounce him NOW!!!
Time to get to airport: 2 hours
Time waiting at airport: 1 hour
Flight time: 30 minutes (probably longer or shorter, depending on destination, weather, etc.)
Time waiting for bags: 1 hour
Time getting transportation: 30 minutes
Time getting to where you want to go: 2 hours
(Yes, all numbers are approximate. YMMV)
I don't think flying faster would help...
and...
"Please wait while our molecular reconstructor negates the effect of the 10,000G acceleration. We will begin by fixing our first-class passengers..."
I don't think that DARPA is using a stopwatch to calculate this to the nearest millisecond. They use very precise measuring tools that go to an accuracy far greater than a millesecond. The same goes for every number reported in the article. With all of these taken into account, the actual values probably differ than those reported by the illustrious 'sacramento bee'. Therefore, without the actual data, it is pointless to criticize or recalculate, since you are already using erroneous rounded data.
can't sleep. clowns will eat me.
Honestly, all I can think of is "what could I tie to that thing?"
It's like I'm 8, I have a box of GI Joes that need to be punished, 1 scram jet engine, and a role of grey duct tape.
"Things are more moderner than before- bigger, and yet smaller- it's computers-- San Dimas High School football RULES!"
260 ft is 79.25 m, 30 ms is 30 ms, so that's an average speed of 2.641 km/s or 9508 km/h. The initial velocity of 5325 mph is 2.380 km/s or 8570 km/h
Wow.
What's the point? Do you really think flying 10x faster will get you there much faster?
... :)
... was destroyed when it punched through a series of steel plates designed to halt the flight. "
I guess you've never flown from Australia to the UK (or vice versa). I'd tolerate quite a bit to reduce the ~22hrs spent in the air....
...although, judging from the acceleration rates, being squashed flat at take off like a cartoon character probably is a bit more than I'd put up with, not to mention the sudden braking at the destination
"The prototype,
Ouch!
Simon
I think that the market for these engines is not your average Chicago to New York flights, but your New York to Paris/Sydney/Hong Kong/Tokyo/[insert your favorite overseas city here] type of flights, i.e., those flights that are already over about 6 hours (closer to 10+ hours) with conventional aircraft. They have to be on those longer flights because they have to fly so high up before going supersonic to avoid having the shockwaves shatter every pane of glass from New York to Los Angeles. Besides, you can't just take off at mach 1 (much less mach 7.1); that would be kind of dangerous if you weren't in a space-shuttle quality harness...
--guru
Of course, if they are going to use these for commercial flights, I suggest we all invest heavily in steel plate manufacturing companies.
sig's not here
if such high velocities are required to ignite the scarmjet, how will they do it in the future. firing it out of a cannon doesn't seem reasonable for me if you want to transport fragile goods such das humans. i heard rumors of bringing the scramjet equpped vehicle to high stratosphere with a carrier aircraft and then drop it to gain speed, but that also seems to be a rough ride.
".Sig Stealer" was here
Alot of people complain about money spent on military/space research. I remember some outcry when the $125,000,000 (I think) Mars probe was left for dead and abandoned on Mars a while ago, and people bemoaned the waste of tax money. In this instance, $800,000, I don't think it's that big of a waste at all.
Let's see, Alex Rodriguez makes that much in 5 game days?
From the article
The prototype, which resembles a gothic spire and measures just 4 inches in diameter, was destroyed when it punched through a series of steel plates designed to halt the flight.
When and if they scale it up, I hope this part of the system is re-designed.
Get the EULA T-shirt
yeah, it did, but the x-15 was rocket powered and not jet powered
".Sig Stealer" was here
Yeah, sure, but what does all this stuff give in real scientific units (meters, meters/second, etc) ?
-- javaDragon is an instance of JavaDragon.
Imagine being able to fly from New York to LA in 30 seconds!!! Wouldn't that rock???
Sucks you have to be greated by sheets of steel to slow you down to below-puking speeds.
-EvilMonkeyNinja
Mild Mannered Host by Day
Wild Hammered Programmer by Night
'Cause if one of those things came strait for you at 8570km/h, you'd better...SCRAM!
Ah well, It sounded alot funnier before I typed it.
Looks like it's time for someone to invent the physics-defying-star-trek-inertial-damper things then.
:)
That reminds me.. Must send off for that patent.
You've got mail. Pattern baldness. - Crow
This will make countries even more trigger happy, since they have even less time to react to an incoming missile.
According to the article, the scramjet projectile was fired from a cannon at ~5400 MPH. From what I can gather, that much was done without any power from the scramjet system. At that initial velocity, 5400 MPH = 7920 FPS, it would cover the 260 feet in ~30 milliseconds, the total flight time of the projectile, according to the article. I'm not going to do the physics calculations, but I'm going to assume that in .03 seconds, wind resistance isn't going to have much affect on the velocity of the projectile, so what did the scramjet do?
Oops, sorry. I can read, though my original post wouldn't show that.. Let me toss some more numbers here, hopefully ones that aren't listed in the original post..
.03 seconds gives an acceleration of 24,591 FPS^2. Dividing by 32 FPS^2 (the force of gravity) gives an average acceleration of 768.5 Gs over the flight of the scramjet. Not that anyone else couldn't figure this out, I just figured I'd do the calculation for you, and maybe make up for my earlier post...
From 5406 => 5909 MPH is a change of 503 MPH, or ~738 FPS. Doing this in
Yeah, that would rock, except for the fact that you'd need to travel at least 360,000 miles per hour to pull it off. Unfortunately that would ablate/vaporize your entire aircraft/rocket and all organic matter.
What makes this any different from a base bleed boat tail artillary shell? Again DARPA misses the mark. And if the Auroura is not a scramjet, what is it? This test is smoke and mirrors.
If voting were effective, it would be illegal by now.
Hope it was wearing a seatbelt. :)
I can juggle for 30 milliseconds.
I can ride a unicyle for 30 milliseconds.
I'm as big a technophile as the next guy, but this smells like an $800k proof-of-concept, engineered to be a PR success?
Too bad there aren't any accompanying pictures, but with a flight time of less than a second, I guess they'd be hard to get.
Software Wars
Just a nitpick: if you want to use SI units of measure, take some time to get them right. The unit of acceleration you are referring to is "g", equalling about 9.81 meters/sec^2, while "G" is the gravity constant. Of course, then 10,000 g comes off rather misleadingly as 10 kg, which is why it's a good idea in the first place to use the official UM, meters per second squared.
Of course at 10kG, by the time they arrive in Paris, all passengers will have changed into some kind of schnitzel.
the goal is to get there.
Nobody said anything about mint condition 8)
It takes 40+ muscles to frown, but only four to extend your arm and bitchslap the motherfucker
Sure for shipboard use you'd want a sufficiently heavy object of small compass, such as a black hole...
Granted, getting such a system to work, is a tall order, but that's an engineering problem, not a physics one. ;-)
No, what irks me about the inertial dampers is the human factors thing; with the crew being thrown out of their chairs with every phaser blast, having to take precious time out to scramble back into them, why on earth don't they have seat belts? ;-)
Stefan Axelsson
can you say tank busting weapon? remember this is a projectile we're talking about, one thats only 4" in diameter. however the 130' cannon might be a liability on the battlefield.
<ramble>
on the aviation side, there have been rumors of hypersonic vehicles being tested at Area 51 for ten years now. as far as flying in one, i don't think acceleration to mach9 in less than a few mintues would be enjoyable to your average business passeneger.
</ramble>
this article at NASA gives a better explanation and has some QuickTime movies of the X43A.
...vividly encapsulates that post-Watergate/pre-punk/coked-up moment when you could trust no one, least of all yourself.
Flight time: 30 minutes (probably longer or shorter, depending on destination, weather, etc.)
;-P
And I always thought it was a stereotype that Americans didn't realise there were countries outside the States.
Oh, sorry, you've heard of Mexico and Canada too - I saw it on South park
>The Sacramento Bee is running this story about the
> first powered device to achieve "hypersonic"
> speeds in the Earth's atmosphere.
And I always thought current jet planes were "powered" too... It seems they aren't.
Donate free food to the hungry at The Hunger site.
Because of this, scramjets are critical for efficent, practical single-stage-to-orbit vehicles. The idea is that you operate in scramjet mode until the atmosphear thins out too much to sustain combustion, and then you start adding your own oxidizer. This will effectively turn the engine into a rocket motor. With scramjets, you could build a shuttle that would actually be fairly inexpensive to operate. Also, since the most expensive part of any mission is boosting into low earth orbit, any savings in the first stages of flight would dramatically bring down to costs for any mission, but especially heavy ones (like a manned mission to Mars).
The other reason to develop scramjets is for their raw efficenty. The use fuel at a fantastic rate, but at Mach 7, the fuel per unit distance is exceedingly good. Instead of supersonic (in this case hypersonic) flight being a luxury reserved for Concorde flyers, it would become the cheap, practical way of getting around. Of course, it would only make sense for the really long flights (like Chicago to Sidny), but the implications could be trans-global flights that cost less than regional flights.
Scramjets are very, very cool, and not just because they go fast.
In spite of the suggestions and all the tests that I have made, I have not cavato a spider from the hole.
ballistic missile defence network + scramjet
cruise missiles = a lot of very pissed-off
nuclear powers.
-- Proud descendant of semi-nomadic cattle-herders.
Well, as the Concordes are currently grounded, they probably wouldn't notice anything ;-)
"I'll just borrow it for a little while, OK ?"
But frankly, I'm more interested in that super cannon. Mach 7.1 is 7,500 ft/s (2,300 m/s) which is extremely high. It would have a max range (neglecting aerodrag) of 300 miles! Did they use a gas-gun?
...Now I won't be late for work again :-)
I was reading a research paper on scramjet technology, and according to their research it may be possible to scale these ships up to speeds of Mach 28.
That would mean be able to get anywhere in the world in less then 1/2 of an Hr.
That woud make for quite a plane ride- as other posters have said barely enough time for the stewardess to serve beverages. But think of the military potential- Near instant strike response. We could kill people and be back for dinner!
What makes this any different from a base bleed boat tail artillary shell?
It still accelerates after it has left the tube.
Secondly, WTF is a "base bleed boat tail" shell ? I've never seen anything (certainly not South African) that used both base-bleed and any boat-tailing together. Why would you ? If you use base-bleed you need the volume of a blunt-end, but you don't need the shaping.
Maybe it's just some 'Merkin deer-huntin' round...
Scramjets, or supersonic combustion ramjets, burn hydrocarbon fuel but scoop oxygen out of the atmosphere to combust it....
I'm sure i'm missing something fundamental here, but where the hell are spacecrafts supposed to get the oxygen from?
I guess they must just mean using scramjet untill leaving the atmosphere, and then use onboard oxygen, but it is a little misleading
Mind you, the date was supposed to be 2069.
I'd guess the same would be true with anything flying on wings and ambient oxygen.
-- Colin
Looks like it's time for someone to invent the physics-defying-star-trek-inertial-damper things then.
:)
That reminds me.. Must send off for that patent.
The project cost $800,000 according to that Sacramento guy, just to be destroyed in split of a second. Well smart project. If you invent any dumpers keep it GPL-ed please, or they'll rip us off. Got an affordable health/dental care plan for Joe Avearage ? Where ?
OK, the point is that this is a scramjet engine, not that it is going fast. The idea folks, is that in future vehicles you can take off to high speed using a mag-sled or a more conventional aircraft and achieve high velocity and high altitude using earths atmosphere and at the last possible moment switch to a rocket engine using Liquid O2 (LOX) that you store aboard.
Part of the reason launch is so expensive (and dangerous) is that we have to carry LOX from the ground up along with the propellant.
--mycr0ft
Me physicist. Me make rockets.
now all they need is a "flux capaciter" + someone stupid enough to drive it = THE FIRST INFINITE PROBABILITY DRIVE!!! :-)
"186,000 miles per second. It's not just a good idea, it's the law."
NASCAR gets to 3g pretty frequently on some flat turns. NASCAR's top speed is about the same as Formula One, so I don't think slow is the appropriate appellation.
Don't feel bad; both the other two responses to your comment and the NASA web page linked by the story also got it wrong... this is a common mistake. You can see this somewhat from their data. If you look at the chart labeled "I.C.A.O. Standard Atmosphere", note that the density decreases monotonically with atmosphere, but the speed of sound plateaus at the tropopause.
From a molecular dynamics standpoint, this make sense. The speed of sound is the rate that waves propagate through the medium, in the form of molecules bouncing against each other. Higher temperatures means the average molecular speed is higher, and a pressure wave therefore propagates faster.
"The simplest solution is to ignore your dead children."
Er, the UK is metric, you baboon. We still have Imperial measurements in things such as groceries and fuel, but they all come secondary to metric units (you get 568ml of milk which, oh, just so happens to be the same amount as a pint which people are used to). The only things I can think of that are still fully Imperial are pints at the pub (bottled stuff is all metric) and roads being measured in miles.
We use ISO paper sizes, our engineers use metric (hello NASA!), scientists work on metric (usually, or some weird magnitude of it multiplied by e or something), kids in school are taught in metric and only meet Imperial usually in "here's how we convert units" lessons, our weather (such as it is) is nearly always reported in Celsius (F is well and truly dying out).
You don't lose a unit system overnight but we've at least made the effort. Whilst we might say our car went xMPH, a brit scientist would be more likely to say "my scramjet achieved x m/s". Thankyou.
"Don't get mad, get a monkey!"
-- @rjamestaylor on Ello
And almost as cool as the LOSAT, which hits around 5000mph
They even have this video clip, but it doesn't look like much, I warn ya.
"The simplest solution is to ignore your dead children."
I can hardly wait for Estes' toy version. Zero to solar escape velocity in three seconds flat!
"How many light bulbs does it take to change a person?" --BMcC-->
Granted, getting such a system to work, is a tall order, but that's an engineering problem, not a physics one. ;-)
What about attending to a fundamental physics class?
You wrote unfortunatly utter nonsence.
If you have a black whole in front of you(or any mass), it does indeed attract you and your ship with the same force. So you fell floating in relation to your ship.
If your ship is accellerated with an additional 16g rocket/scramjet engine, the ship is pressed with 16g against your body.
The black hole in front of you does not change anything.
Regards,
angel'o'sphere
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
What about the Aurora? ;)
***
who is in turn interupted by Robotic Flight Attendant #3, who kindly requests that
"All disconnected body parts, included severed heads, arms, etc, caused by the massive acceleration and deceleration process must be carried off with each passenger. Thank you for flying LotsaCashSpentDevelopingThis Airways"
------
Let me give you the lowdown
This link
V I: www.washtimes.com/national/20010730-13752166.htm+r ussian+scramjet&hl=en)
(http://www.google.com/search?q=cache:JgNme-1tK
to a google cache (don't you just love those?) describes a for sure Russian scramject test this year and possibly two tests as long ago as 1995.
According to the show's original directors, it was so it would look better on TV. Basically the same reason that spaceships make a "whoosh" sound as they fly by in the vacuum of space.
Your right to not believe: Americans United for Separation of Church and
That kind of reminds me of Dan Simmons' Hyperion series. After finding a cross-shaped organism that can resurrect the dead, the Catholic Church devizes a great plan for sending emissaries somewhere fast: accellerate them fast enough to turn them into people jam, and then just resurrect them again on the other side. I'm not sure I'd want to go through that, but maybe for interstellar travel that might be the only practicable way to get there in a reasonable amount of time.
Your right to not believe: Americans United for Separation of Church and
The problem with pulse jets is that they are damned noisy. You can get them for small RC aircraft but your neighbours would become your worst enemy.
Sure. Like the way my car "came to rest" in a telephone pole after I tried to drive it home after a fifth of Chivas Regal.
As I see it is in less expensive surface-to-orbit vehicles. Use a standard RAMJET to acheive mach whatever-the-hell-you-need-to-start-the-SCRAMJET. SCRAMJET kicks in, and slingshots you out of the atmosphere, where conventional rockets can then manoeuver you. Hopefully, this could be made into a completely re-useable space shuttle.
Ideas quoted in this post are not mine, they come from a book called Silver Tower by an author I can't remember now. They used a magnetic launching track to get the shuttle up to the speed where the RAMJET would work, then the RAMJET until they could turn on the SCRAMJET.
It may look like I'm doing nothing, but I'm actively waiting for my problems to go away.
--Scott Adams
Is it just me, or do the phrases "came to rest" and "series of steel plates" just not belong in the same sentence?
I would quibble with your 'time waiting for bags' - in my experience it rarely takes more than 15 minutes, though when flying to the US I often have to queue for a long time at immigration before collecting my bags (after which it takes 5 minutes to collect the bags).
You forgot to include taxiing time which is often 30 minutes or more of the gate-to-gate time.
Still, I'd be happy to cut my 10 hour trans-atlantic flights down to 1 hour.
It seems that the human body may end up a bit more compact after a 10,000 g acceleration. If that's the case, the astronauts had better carry pictures of themselves to Mars, so that the martians won't think we are all a bunch of toothless midgets.
Do not taunt Happy Fun Ball(TM)
America ever hear of the decimal system?
SI units and whatnot...
Feet are things attached to legs (last I checked)
Can anyone convert the velocities to civilised modern measurements? Say meters? and kilometers per hour?
Next you will have them measuring speed in furlongs per forthnight!
-wink-
Silver Tower by Dale Brown, not bad although his later books have started to go downhill.
Kinky! I had GI Joes, but I never thought of... punishing them. :-)
My God man, what did they do - take the GI Joe tank out to town one night?
The revolution will NOT be televised.
He was my favorite Autobot! Congratulations!
AC's cheerfully ignored
We've known since the before the trials of the original supersonic planes that objects can break the soundbarrier in the atmosphere. Everytime you fire a gun it does it, thats how they knew there were building their planes wrong when they all ways fall apart because the sound wave begins to drag on the plane as you accelerate and if your plane isnt narrow enough to punch through the wall your dragging it will rip the wings off your plane.
Why do the kids in West Side Story have to join a street gang if they can afford $70 Gap khakis?
OK, so there are several countries out there that have the ability to destroy the world with a few nuclear bombs... well, that's just bad publicity these days, no government would want to wipe a country like Iraq off the map for good, what about all the innocent people that live there? Even though we have the "biggest guns" here in America, we continue to try and make newer, bigger, better ones, but now instead of blowing up an entire land mass we are making weapons that will be able to hit precise targets and travel at unimaginable speeds.
So here's the problem: just like every other new military technology, other countries will eventually get it. Hypothetically, let's say Russia makes a cannon that can fire an explosive projectile from Moscow to hit the World Trade Center in NY; they probably wouldn't do that (at least I hope not) but they would sell some of those to a bunch of small rogue countries out there who don't have "political correctness" or care about the welfare of a nation's innocent people. It all seems pretty scary to me. I mean missile defense sort of loses it's significance when the missile is travelling at mach 5.
What do we do? Well I guess we'd better make sure we have the biggest, best cannons and we have a whole bunch of them so all of those other countries will be too scared to use theirs.
~ now you know
how fast could I get to work on one of these babies?
Yep. If you read through the whole site, he's got a go-kart with a 100-lb thrust pulsejet.
Apparently, it can be heard miles away.
Here is a link to the AEDC press release with (fuzzy) pictures and video. -- mycr0ft
Me physicist. Me make rockets.
They used a very well designed potato gun, designed by the same guy who designed the Mach 1 potato gun reported on this site some years back.
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
Actually, the real story of interest here is that this scramjet apparently showed positive net thrust. This may seem academic, but the Russians sucessfully flight tested a scramjet more than 10 years ago. Unfortunately, it had a net negative thrust (could not overcome drag, even on the decending leg of a ballistic trajectory) and managed to bury itself quite completely in the permafrost after the recovery chute failed to operate.
Scramjets are not that exotic, just bitchin' hard to get to work. It's one of three types of internal combustion jet engines (turboprops don't count and cycle-type props are a totally different beast). You'll have to excuse any minor errors below...it's been a while since I've been through the nuts & bolts of aircraft engines (no pun intended):
Tradtional jets take in air and compress it mechanically, burn it with fuel in a combustion chamber, then pass the exhaust through a turbine to recover the mechanical work required to keep the compressor running. The "waste" exhaust is passed through a nozzle to optimize the thrust. Note: in a turboprop, the turbine also powers the blade rotor. The waste exhast still exists, but its momentum is negligible.
RAM jets eliminate the compressor/turbine system. The supersonic freestream flow is compressed at the engine inlet over a normal shockwave after a series of oblique shockwaves reduces the incoming flow to just above sonic. Note: oblique shock waves are relatively efficient at slowing down and compressing the flow, normal shock waves are "lossy" and the energy lost is proportional to the supersonic speed upstream of the shockwave. The compressed, subsonic flow enters the combustion chamber where fuel is added. The expanding exhaust is then returned to supersonic speeds through a converging-diverging nozzle. If it's been too long since you've had compr. aero, subsonic flows increase in velocity as the airstream constricts (aka Bernoulli's Principle), but supersonic streams increase in velocity as the airstream expands.
SCRAM jets (Supersonic Combustion RAM) are just RAM jets without the incoming air being dropped below the speed of sound. The combustion must then happen at speeds greater than sound - a tricky feat to accomplish. A diverging nozzle then allows the supersonic exhaust to accelerate out the rear of the engine. The SCRAMjet avoids the high energy loss (entropy gain) of the normal shockwave required in a RAMjet.
Is it just my observation, or are there way too many stupid people in the world?
This page has info on the gas gun (range G) used in the test, including many many pretty pictures (a shame to slashdot it!). The range (pictured, of course) is only 1000 feet long, so that's why the scramjet portion of the flight was only 300 feet. They also show loading and firing of the beast, but with probably a different payload.
At 2.4 km/s, it looks like this test was fairly heavy. The launcher can launch a 4", 2kg target to 6 km/sec.
HIV Crosses Species Barrier... into Muppets
You might want to rethink it a bit yourself.
As long as the gravitational force is exactly opposite and equal to the thrust from the engines, you'll feel no net force. So the greater the engine thrust, the closer you bring the black hole.
Of course, it would only work for a single distance from the black hole, so it wouldn't really work for a plane full of people. And you have to waste energy accelerating the mass of the black hole as well.
Uhh... pulse jets put the buzz in buzz bombs. I don't think anyone is interested in hearing those awful noises in the sky again.
-- Never hit a man with glasses. Hit him with a baseball bat.
You're both wrong. Black hole or not, what happens when the jet is standing STILL. Hmmmm... that could be BAD.
Killfile(TGK)
No trees were killed in the creation of this post. However, many electrons were inconvenienced.
In one of the Niven/Pournell novels (footfall?) they talk about "crowbars", which are weapons that are dropped from space and guided to a target, and using kinetic energy to distroy it.
How long before a scramjet is used to create this type of kenetic weapon. Get it going fast enough, and you would have a rather effective weapon, without needing to store any explosives. You wouldn't even need to drop them from space to get sufficient velocity. Probably good against tanks and buildings.
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
Actually, the real winner here is that crazy cannon. Doing a quick conversion we find that the initial velocity of the jet after being accelerated through 130 ft of cannon is 2380.4m/s. Now 130ft = 39.6m so using a = v**2/(2*x) with x = 39.6m and v = 2380.4 m/s we find a = 71,544m/s**2 . With g = 9.8 m/s**2 this means a = 7300.4 g. After being ejected the average velocity over the next 30ms is 2641.6m/s. Doing more calculations like the one above (assuming constant acceleration) gives a max velocity of 2902.8m/s which tells us that while the scramjet is operating the acceleration is a puny 1776 g. (a U.S. funded project produces the number 1776. Coincidence? I think not...) So, I guess that 10,000g number occured sometime in the cannon (acceleration cant be uniform there). Personally, I find 1776g acceleration from an engine to be completely amazing...
I couldn't find that Washinton Times story. Here is another news story which casts some doubt about the Russian scramjet this year:
http://uk.news.yahoo.com/010801/12/c04d7.html
If memory serves didn't the Germans have a cannon called "Long Max" aka "The Paris Gun" toward the end of WW1. That cannon had a 110 foot barrel that had to be trussed like a bridge to keep it from drooping. It fired an 8 inch pencil shaped shell with a 20 pound explosive charge. It could shell the city of Paris from a maximum distance of 80 miles. The muzzle velocity of this shell was about 5200 feet per second. Remember this was over 80 years ago. Except for the addition of the scramjet, it doesn't sound like much progress to me.
come on, scarmjets is old news. why? the u.s. goverment has been spending money on black budget programs. we already can achieve mach 50 or something like that. what do you think Area 51 is all about? long runway and underground facilities? yeah u know what i mean..
Abovetopsecret
Considering that 5909 mph is 3.17% of light speed, I'd be interested in seeing some tests done on time dialation factors and mass distortion.
um, NASA uses metric. The mars probe that crashed was developed by lockheed (I think) and they still use the Imperial system and forgot to convert to metric.
:)
for that matter, most US science classes teach in metric (except for a few conversions, all of my Physics classes were in metric). Many US machined items are now metric, as well. Yesterday I was digging through a hardware store trying to find a screw that didn't use metric threads and of the dozen or so types that still exist, none fit. Had the faucet handle used metric threads, I had about 400 different types to choose from.
US measurements that haven't switched to metric are mostly the everyday ones - Height and Weight of people and grocery items, distances on highways, and temperatures. If I remember, the excuse in the 80s was that the switch was too hard for the everyday American, resulting in the stoppage of the conversion from the mandate by congress (ah, the Reagan years...). To me, that means that most Americans are idiots because they can't pick up a much easier system. Now if I can just separate myself from the rest of my countrymen
Jetliner?: So instead of carrying an oxidizer, we carry along extra deadweight motors to get us up to the required speed and altitude necessary to fly the airplane without melting. This helps how??? Most of the cost of a commercial aircraft is the engines. We want to double up on engines with half the motors being dead-weight at any point in the flight?
Missiles?: This would have to be a staged vehicle. Some of the lowest sub-orbital rockets with more than one stage eject the first stage at 45000 ft (most stage higher). So how many SECONDS will the scramjet burn before it runs out of atmosphere? Plus at these burnout altitudes you then throw the engine away - costly.
Aero heating: If you can reach these velocities, why not just do a sub-orbital ballistic shot. Save the drag energy by poping into space. Why continue to incure the drag and heating when space is a few 10-thousand's of feet away?
About the only application where these make sense is in ballistic defense. You can loiter for maybe 10-50 seconds in the atmosphere and get some extra time to do target discrimination before you go in for the kill. But throttle-able ducted rockets are being developed simulateously that will probably also fill this roll for a whole lot less money.
My bets. Hydrogen peroxide mono- and bi-propellant motors and the ducted rockets (solid or liquid propellant using supersonic rammed air for the oxidizer). Both systems are being developed and FIELDED as we speak. Both are practical in some applications.
And yes, I am a rocket scientist (retired).
Religion and science are both 90% crap..but that doesn't negate the other 10%.
In its current form, this looks to be potential weapons technology. Relatively speaking, a very efficient interceptor, if electronics and guidance control can survive launch.
I'm never one to stand in the way of progress.
The above post is an editorial, the poster cannot and will not be held responsible for all or in part for it's contents
And I always thought it was a stereotype that Americans didn't realise there were countries outside the States.
<sarcasm>
Of course we know there are other countries. We can't exactly bomb ourselves, now can we?
</sarcasm>
Why is it that the proponents of "one nation under God" are so eager to get rid of "liberty and justice for all"?
If it only had to be that small and that brief, why didn't they just fire a bullet?! Heck, for that amount of money, I'll gladly give you MY gun and all the bullets you want!
Ladies and gentlemen, we'll soon be coming "to rest in a series of steel plates designed to halt the flight". We hope you enjoyed yourself and thank you for flying Scramjet Airlines.
This is a correction I couldn't let go.
Yes you are correct that energy is proportional to mass (linearly) and to the square of velocity, but you must have the 1/2 constant to get it right. If not, all the calculus gets screwed up.
Since we are only Mach 7, don't sweat relativistic corrections.
Me physicist. Me make rockets.
We know... we just don't care.
www.bannination.com Two things float to the top he
The mayor of Tullahoma, TN, decided to crack down on that damn noise ordinance again, and call his neighbors. They told him that they're the Air Force, and to go get stuffed.
Transferring the passengers while in motion is only another engineering problem. They don't stop the ISS or Space Shuttle to transfer passengers, do they?
Yeah, on TV it would be harder to make a battle interesting. It's more visually interesting to move things than to have everyone standing around while Spock says "Another hit, we now have 74 health points..."
Pulsejets are crap compared to scramjets.
.03 second scramjet flight.
Of course, pulsejets are also much cheaper and easier to build. For a hobbyist wanting to do something cool a pulsejet is fine. For a really high performance aircraft or SSTO spacecraft they aren't even worth considering. At the other extreme, scramjets are great but VERY hard to build because you basically have to create a standing wave of detonation in your engine. That is why everyone is so excited about even a
A nice compromise engine is actually somewhat related to the pulsejet; it is called the pulse detonation engine or PDE. It creates thrust by a series of explosions in the engine somewhat similar to the way that a pulsejet uses a series of flame pulses. Like pulsejet, the PDE is easier to build because you don't have to make the combustion stable and well-behaved like in a normal engine. Like a scramjet you get the efficiency of supersonic combustion (an explosion) instead of a subsonic combustion (a flame). But also like pulsejets, PDEs don't produce as much thrust because they are "on" only in brief pulses while a scramjet is generating continuous thrust. And of course you also have all sorts of fatigue and noise issues with the PDEs from all those pulses.
To simplify, Ramjet:Scramjet = Puslejet:PDE
For more info on PDEs, see:
http://www.grc.nasa.gov/WWW/AERO/base/pdet.htm
Expect to see a lot more about PDEs over the next 10 years.
Everyone seems so excited about the travel possibilities.
With an acceleration of 10000 G's, I will weigh 2,200,000 pounds during take-off. Exactly how is my body not going to be crushed to a thin paste before the 10-minute flight to London even gets started? That frog in that blender stood a better chance of survival than me in my trans-continental flight. Just a thought.
std::disclaimer<std::legalese> sig=new std::disclaimer; sig->dump(); delete sig;
Anyway, on the main point, it's much easier to force people to accept military-borne nuisance than commercial flights.
-- Colin
...but does it run Linux?
A friend of a friend of mine reported that this has actually been accomplished before. Apparently, he knows a guy who actually bought a scramjet which was accidentally sold at a NASA surplus auction. To test it, he tied it to the roof of his car! Don't believe me? Search the following site for "69 Chevy": Scramjet Car
Have you tried turning it off and on again?
Note: Don't try to convert Mach number directly to speed unless you know the atmospheric conditions in the test cell. They might not have been using air, and Mach also depends on temperature (remember, it is the ratio to the speed of sound in the conditions you are at).
The orbital use of scramjets was very attractive in the 70s and 80s (remember the National Aerospace Plane, NASP?). Now the aero engineers know better. Of course, that news doesn't make Popular Science.
Mod this parent up please!
My sig has a broken link in it.
"PS: According to this nifty page at NASA, Mach 7.1 is about 5406 MPH, whereas 260 ft, per 0.03 seconds, is about 5909 MPH."
.03279... would make it 5406 mph.
yeah maybe, but they're probably not flying that thing at sea level either. when you go fly around on an airplane you should notice your ears popping because the air pressure decreases with altitude. the speed of sound decreases as air pressure decreases, so logically mach 7.1 at altitude isn't as fast as mach 7.1 at sea level.
or maybe they just rounded off to the nearest hundredth.
Are you pondering what I'm pondering?
Since you want to be pedantic, the speed of sound is theoretically derived to be v = SQRT(gamma*P_0/rho_0) where:
Applying the ideal gas law, (obviously skipping some steps) this becomes v = SQRT(gamma*R*T/M) where:
So, for the purposes of aerodynamics, the speed of sound in a gas depends on the temperature, molecular weight, and molecular structure, but not on the pressure of the gas. For a given fluid, the speed of sound is preportional to the square root of the temperature.
It's too bad browsers don't implement MathML.
"The simplest solution is to ignore your dead children."
Well, since the end of the war, Paris has had a schnitzel shortage. Always look on the bright side.
If tits were wings it'd be flying around.
Reminds me of a great quote by an american comedian (I don't remember his name) when asked by a canadian interviewer, "What do americans think of canada?"
Answer: "We don't"
Carpe Cerevisi - Seize the Beer
Ah yes, the "balanced drive" from Charles Sheffiled's "McAndrews" stories. He didn't use a black hole though, IIRC it was a very massive disk compressed by electromagnetic fields. The stories can be purchased in ebook form from Baen here.
"Prefiero morir de pie que vivir siempre arrodillado!"
i'm afraid i dont know enough about diamagnetism to say for sure, but it's hard for me to accept that a magnetic force would effect every molecule the same way. Even the -slightest- difference in force at 10,000Gs would merely tear the passenger to shreds instead of flattening them like a pancake.
Even the inertial dampners from star-trek weren't perfect.
I think the path of least resistance in this case would be to take the approach taken in Event Horizon for rapid acceleration travel. The sleep pods the characters utilized in the movies not only cryogenically preserved them (which is out of the scope of this conversation), but it served to cusion them from the high G-forces by surrounding them with some sort of viscous liquid. Now, im not saying we fill the scramjet with peanutbutter and just sploosh the rider inside...
oh, wait, yes I am..
nevermind.