Scramjet Test Successful 300
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."
Re:Auroura (Score:2, Informative)
Well, this one carries fuel.
To some extent, so does a base-bleed shell.
Logistically, shells should be square-ended. You get more bang into the the chamber that way.
Aerodynamically, shells should be pointed at both ends, or in fact, even more pointed at the tail. The trouble with this is that it loses useful volume - although it's commonly done with small arms. The trick with base-bleed is that by burning a slow propellant in the tail of the shell, a high pressure gas plume is generated that makes the shell appear to be long-tailed, aerodynamically. You get the same compact shell layout (although you lose some space for propellant) and you get a long-range shell.
There are also rocket assist shells, but these are rare - they didn't work too well. They have some uses for heavy calibres with low muzzle velocities, but they lose in accuracy what they gained in range.
Air breathing high speed vehicles (Score:2, Informative)
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
Re:intended use (Score:4, Informative)
Heck, just a hypersonic projectile and/or missile would really change the landscape for Ballistic Missle Defense. Having a velocity several times faster than your target is a major advantage.
It wasn't mentioned in the article but the projectile used gaseous ethylene at 1000 psi, not hydgrogen, as its fuel. I love my Aviation Week subscription.
As mentioned in another posting hydrogen embrittlement would be a concern in a larger vehicle, this is a 20% scale model. The biggest barrier is heating. Atmospheric heating is a big deal at Mach 7+.
A more detailed article can be found here [aviationnow.com] at Aviation Weeks online site.
Gas gun: yes. Plus: link to video (Score:2, Informative)
They even have this video clip [af.mil], but it doesn't look like much, I warn ya.
Re:stupid question? (Score:3, Informative)
Imagine if your car/bus had to haul along it's own oxidizer in a honking big tank of super-cooled special-purpose gas next to the fuel tank, which is what all liquid-fuel rockets do today. Now imagine someone announced an engine that could possibly dispense with that heavy complex oxidizer tank that's been weighing down your car/bus and instead let the motor just suck in outside air - pretty exciting news eh?
Right now Scramjets are a tricky exotic tech requiring special materials and designs that push the envelopes for those fields. On the other hand the same was true for jet engines when they were developed yet all large and/or long distance aircraft use them pretty much exclusively today. This may be a technological blind alley or it may never be commercially viable but it's interesting stuff nonetheless, indeed exciting for the aerospace-heads.