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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
Yes, you would hear the sonic boom of the test flight. (If you are close enough to hear it at all, of course).
At supersonic speeds, the edge of the soundwaves that are produced by an object is a cone in the object's inertial frame. Regardless of the speed. The speed only changes the angle of this cone..
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.)
In real layman's terms......
weigh yourself at sea level
then weigh yourself again at the top of mount everest
unless you are using *really* accurate scales the two readings will be the same.
now go back to both locations where you weighed yourself and measure the atmospheric pressure in both places.
unlike your weight you'll find the pressure is about a third of what it was at sea level.
pressure in a known and unchanged mixture of gases is another way of counting how many molecules of gas there are in any given cubic meter, or to put it another way, the mass of a given cubic metre.
so your aerofoil (wing) at the top of everest has about one third of the mass of gas to ride on as it does at sea level.... if your aerofoil is a fixed wing then you can always travel three times as fast (hence needing a scramjet) whereas if your aerofoil is a rotary wing (helicopter) you come up against a hard limit when the out edges of the rotors approach the speed of sound, hence the much lower maximum altitude ever recorded in a helicopter as opposed to a swing wing.
NB all of the above is really really simplified and therefore full of errors to a physicist / aerodynamics / bernoulli / etc etc etc
HTH etc
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the SR-71 (aka Habu or Blackbird) uses small wings and is very specialized.
The SR-71 has tiny wings,
Small wings? Have you ever looked at an SR-71? With a wing span of 55 and a half feet, and a wing area of 1795 square feet, its wings are far short of "small". A 737 only has a wing area of 1344 square feet.
Low lift wings maybe, making for less wind resistance and friction, but small, not hardly.
31,000 miles?
How do you work that out? a circumference of 25,000 miles gives us a radius of 3,978 miles. Go a mile up, and the effective radius is 3,979 miles, which gives us a circumference of...
25,006 miles. Not much of a difference.
evil math within Nature's Cubic Creation!