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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
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.
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.)