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Second Test of X-43A Scramjet Tomorrow
pinkUZI writes "NASA says its new Hyper-X, a jet capable of flying some 5,000mph - seven times the speed of sound - will be ready to take a test cruise across the Pacific this Saturday. This is actually NASA's second attempt; the first, in 2001, failed when stabilizing fins flew off the plane's booster rocket and controllers ordered the craft destroyed. CNN has the story." NASA's mission web page has more information, photos, etc.
http://science.slashdot.org/article.pl?sid=04/03/2 5/141238&mode=nested&tid=134&tid=160
Da-dum-ching!
Gordon D. Pusch wrote in sci.space.tech: "Hypersonic travel combines all the disadvantages of airplanes with all the disadvantages of rocket flight and all the disadvantages of re-entry --- continuously."
Um, this is primarily a test of an engine, not an aircraft.
The X1 was also launched from a plane and was the first aircraft to break the sound barrier. Planes such as the SR-71 have far surpassed this speed and takeoff in the conventional fashion.
I'm not sure what you're referring to when you state "always be launching them from the underbellies of a big plane".
They're not (directly) working on cruise missiles, although the tech could be used for that. They're trying to invent a cheaper way to get to orbit. This is just a test bed to figure out the scram jet. The plan is for a standard jet engine to get you to supersonic speeds, the scram jet to get you to hypersonic speeds and the edge of the atmosphere. Once you're going, say, Mach 7 and most of the atmosphere is below you, you fire the rocket engine to get you the rest of the way to orbit. This approach wouldn't require the rocket to carry as much oxydizer, thus less weight, less cost.
Obviously if this method of propulsion is used in aircraft that are anything but proof-of-concept, they'll have to take off on their own power. However most of these experimental aircraft are dropped from the belly of an aircraft already at altitude, even manned aircraft like the X-1 and X-15 (both rocket-powered, dropped from a B-29 and B-52 respectively). For the most part, getting the aircraft to the needed altiude on its own would require too much fuel (making the need to design a much bigger aircraft, etc.).
It's a test flight, not a full-fledged production vehicle we're talking about here. The plan is that eventually aircraft will take off under normal jet propulsion, use scramjets to accelerate to escape velocity, and use chemical-powered propusion once they have left the atmosphere.
http://www.questionablecontent.net
well, if you get your rocket to reach really high speeds at a fairly high altitude inside the atmosphere, you have less altitude for the rocket to fly and less energy that needs to be expended merely to accelerate the rocket. overall this means less rocket fuel needed to reach orbit. also, because you are starting your rocket at a higher altitude you can optimise your rocket motor for a higher altitude which would increase its effiecieny. overall, a Good Thing
Disclaimer, IANARSBIAITTBO (I am not a rocket scientist, but i am in training to become one)
Do not go gentle into that good night. Rage, rage against the dying of the light.
Slight off-topic, but why do I have to go to Jet Propulsion Laboratory to find out about the Mars rovers, and then I have to go to National Aeronautics and Space Administration to find out about fancy new jet engines?!
Is it a cunning plan to out-fox those secret stealing ruskies?
For those who want to know what a scramjet is, and how it works, check this page.
A ramjet has no moving parts and achieves compression of intake air by the forward speed of the air vehicle. Air entering the intake of a supersonic aircraft is slowed by aerodynamic diffusion created by the inlet and diffuser to velocities comparable to those in a turbojet augmentor. The expansion of hot gases after fuel injection and combustion accelerates the exhaust air to a velocity higher than that at the inlet and creates positive push.
Scramjet is an acronym for Supersonic Combustion Ramjet. The scramjet differs from the ramjet in that combustion takes place at supersonic air velocities through the engine. It is mechanically simple, but vastly more complex aerodynamically than a jet engine. Hydrogen is normally the fuel used.
This is all very different from conventional airliner engines, which are a gas turbine/fan nacelle called a "turbofan". (A "turboprop" is a gas turbine driving a propeller instead of a fan, BTW.)
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You know, if anything goes wrong with a regular transatlantic airliner while it's over the North Atlantic, I think it's fairly safe to say you're toast as well.
Granted, the nice stewardesses tell you that you can use your seat cushion as a floatation device, but two things strike me in that scenario:
1) What are the chances of surviving initial impact into the ocean when the plane is in a 600 mile an hour vertical dive
2) Do I really want to float around in the North Atlantic for several days, clinging to a pillow full of beer farts
And yet, we still do this on a regular basis because guess what - it's actually fairly safe. As will hypersonic travel be, once we get around to getting better materials etc.
In the 1700's people really believed that if you traveld faster than a horse, you'd die from the shock and that it would be impossible to build a heavier than air flying machine. Guess what - they were wrong, and you will be as well. Some day (if we don't manage to blow up ourselves first).
We do not live in the 21st century. We live in the 20 second century.
Wouldnt it have a problem with wing size?
flying at 5,000 mph, you'd basically have all the body lift yo'd need... the SR-71 (aka Habu or Blackbird) uses small wings and is very specialized.
The SR-71 has tiny wings, and consists of 2 huge engines.. it also leaks fuel onto the runway until the body heats up to running temperature.
The point being that the SR-71 has a very high take off and landing speed due to the small lift per mile figure. It will fly straight up and over a thousand mph until the engines run out of oxygen at nigh on 100,000 feet.
A aircraft using the scramjet capable of 5,000 mph would have to have very small wings for low air resistance and wouldnt need large lift per mile.
The ScramJet wouldnt work at low speeds, therefore the runway would have to be very long to take off using a conventional JATO (Jet Assisted Take Off) unit to get the ScramJet working. Getting a scramjet off the runway is going to be interesting!
BTW, what engine does the proposed (Active?) Aurora reconissance/spy plane use? It's supposed to have a very high speed (~3000-4000 mph?)
They don't need the B-52! Because of the power of the X-43a, it is taking off with a B-52 on its back just to show off!
Please don't mod this informative.
I think they're using it because its cheaper than designing a whole new rocket just for three flights.
Plus, the plane is the subject of the experiment, so you want to minimize the number of possible failure points in all the other systems. Using a booster thats already proven is a great way to do this. Of course, in flight one it was the booster that failed...