Posted on 11/10/2004 9:31:28 AM PST by the_gospel_of_thomas
washingtonpost.com With 'Scramjet,' NASA Shoots for Mach 10
By Guy Gugliotta Washington Post Staff Writer Wednesday, November 10, 2004; Page A01
HAMPTON, Va. -- They call it a "scramjet," an engine so blindingly fast that it could carry an airplane from San Francisco to Washington, D.C., in about 20 minutes -- or even quicker. So fast it could put satellites in space. So fast it could drop a cruise missile on an enemy target, almost like shooting a rifle.
Next week, NASA plans to break the aircraft speed record for the second time in 7 1/2 months by flying its rocket-assisted X-43A scramjet craft 110,000 feet above the Pacific Ocean at speeds close to Mach 10 -- about 7,200 mph, or 10 times the speed of sound.
The flight will last perhaps 10 seconds and end with the pilotless aircraft plunging to a watery grave 850 miles off the California coast. But even if the X-43A doesn't set the record, it has already proved that the 40-year-old dream of "hypersonic" flight -- using air-breathing engines to reach speeds above Mach 5 (3,800 mph) -- has become reality.
Unlike rockets, which must carry oxygen with them as a "combustor" to ignite the fuel supply, scramjets take oxygen from the atmosphere, offering a huge savings in aircraft weight, and researchers around the world would like to take advantage.
In northeast Australia, a scramjet team funded by the U.S. and Australian armed forces will try for Mach 10 next year as a first step in using a scramjet to put satellites in space. The U.S. Air Force hopes to demonstrate within five years a scramjet-driven cruise missile fast enough to drive explosives deep into hardened targets. Other projects are moving forward in France and Japan.
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(Excerpt) Read more at washingtonpost.com ...
I remember reading a sci fi book long ago that used the concept of flooding the passenger compartment in order to protect the passengers from extreme G forces.
The line that still sticks in my head, 30 years later, was asked by a character who was a skeptic and about to take his first trip. He asked "what happens when you drop a wrench inside of a submarine?"
"an object in water is immune to the effect of G-forces."
I'm not sure where you heard this alley tale, but if it were true, then humans wouldn't black out like they do at high g's - because your brain is immersed in fluid inside your skull.
Also acceleration and velocity are not necessarily related. The Earth is rotating at 1000 MPH at the equator, and zero MPH at the poles, but the g's are about the same on the entire surface of the planet.
Go USA. It's about time we had a breakthrough in technology. Now we need one in energy.
Or an inertia dampening field. I'm getting tired of waiting for all that UFO technology to come on line.
Why? Losers shouldn't be given hypersonic airplane rides. ;)
I see that knowledge of the subject matter is no impediment to finding a job. Where do they find these writers?
For those that are curious, a SCRAMJET (Supersonic Combustion Ramjet) is an engine that uses shockwaves created by the engine's internal geometry to compress the air entering it. The vehicle, of course, needs to be travelling at a speed which will produce shockwaves inside the engine. In contrast, a typical jet-engine has a rows of compressor blades and a turbine connected by a shaft which adds considerable weight. The SCRAMJET is, at the risk of over-simplifying, really just a hollow tube.
And aim it for the sun.
About eight minutes longer than it takes for my favorite Italian place to scare up a veal parmesan sub.
And yes, I made sure they serve dolphin-safe veal. :)
...and Han Solo's Millenium Falcon
Okay, so if Mach 5 is "3800 mph", how can Mach 10 be "about 7200 mph"?
> Active cooling is effective but it is not fuel efficient so it isn't useful load efficient and it isn't cost effective.
Depends on the method of active cooling. If you use transpiration cooling... yeah, yer throwing fuel overboard. If you use regenerative cooling, what you're doing is actually *improving* combustion efficiency by pre-vaporizign the fuel.
None of this is meant to suggest that this sort of thing is *easy.* jsut better than tryign to carve an HST out of a block of refractory metal of pyrolitic graphite.
> As I said, we are a long way off.
No disagreement there.
> Velocity has no bearing on perceived weight.
EEEEERRRR. Wrong, but generally not perceptible. If you are in steady, unacceleratign level flight... you are actually flying in a circle, with the center of the circle being the center of the earth. As a consequence, centrifugal force lowers the percieved weight. Fly fast enough, you are in orbit... percieved weight = 0. Fly slower than that, weight is reduced appropriately.
> Water does not cushion one from the effects of acceleration.
Water, no. But other fluids... yes. You need:
1) A fluid the same density you are
2) A fluid you can breathe (remember "The Abyss"?)
If you are neutrally and your lungs are full, you can take far higher accelerations than if you were self-supporting. However, this doesn't extend forever... various bits and pieces have different densities (bones, etc.) and thus you'd still feel the acceleration... but you'd feel it oddly.
I believe we already have the tech and have been flying it out of USAF bases for years. Aurora.
"Why? Losers shouldn't be given hypersonic airplane rides."
From the article..."The flight will last perhaps 10 seconds and end with the pilotless aircraft plunging to a watery grave 850 miles off the California coast."
> refractory metal is too heavy (dense) to be used as a heat shield or airframe in an aircraft.
Depends on your limits of definition of "aircraft." The X-20 and X-33 were to have refractory metal heat shields, but of course were not going to spend an hour plowign through re-entry.
> If one was to use regenerative cooling one would always have to have a reserve to keep the craft cool even after the boost phase of a mission.
For airbreathing hypersonic transport aircraft, there is no "boost phase." The engine is on the whole time. Only exoatmospheric craft have "boost phases," and if you're leaving the atmosphere, scramjets are a sucko way of going about it. Rockets rule.
Cmon. Don't you think that John F Kerry and Theresa Heinz Kerry are suitable punishment for each other? ;)
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