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Australian Scramjet Launched
CaptainAlbert writes: "The University of Queensland, Australia is reporting the (possible) success of their "HyShot" scramjet test. The BBC have got this covered too. Apparently, they're now poring over the data loggers, trying to figure out if it actually flew under its own power." We had a story about these guys a while back.
We've bought a lot of bits and pieces off the shelf from automotive shops
I think they answered their own question.
They say in the BBC article that the US first achieved the supersonic combustion bit a few weeks ago. But, IIRC, the russians tested a ScramJet a while back, also from a rocket - and succeeded. Of course, poor funding probably delayed/cut further research, which is a shame - they're excellent at experimental (vs. theoretical, simulated) research.
I don't have references, unfortunately... but I'm sure google might provide some...
And let's not forget, ramjets have been in use for quite a while - again, the russians being in advance on the west, check out their air-to-air missiles.
Anyone reminded of those supercavitation torpedoes? Yet another area where those "technologically backward" russians are by far more advanced than the west...
Just how much brainwashing do we get?
My concern is whether there is actually a demand for supersonic flight, or whether the current conventional airliners represent the 'good enough' level of technology which means there is no incentive to replace them. The current state of the travel industry makes me think it will be a long time before we see a scramjet based airliner at JFK.
In the meantime, the Europeans seem to be about to revive the Concorde. Its a bit annoying that we don't have anything to beat that. Maybe these superjumbos will be as impressive, but they won't be supersonic
A bit of Googling revealed the following:
From The Ramjet/Scramjet Engine:
- a scramjet is a kind of ramjet
- "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."
Scramjet research seems to be a hot topic in the aerospace world - I saw references to projects underway in the UK, in the US Defense Department, at NASA, and of course Australia, all of which have claimed some or other big advances in the past year or so.Finally, here's Scientific American article that gives a bit more technical detail.
The first German rocket scientists supposedly freaked out the same way you did, when they couldn't figure out why their guidance systems still left their rockets apparantly wobbling in all directions. It turned out not to be the guidance systems at all - just the wind. The rocket paths were straight, but shifting winds at different altitudes blew them into crazy lightning-strike looking things as the rocket was still aloft. I'd be surprised if the same phenomenon wasn't the explanation for that photo.
Some posters seem to be under the impression that a SCRAMjet/RAMjet powered "plane" would need to spend an hour accelerating to speed in order to keep people from passing out or heaving guts, etc.
It's not nearly that bad.
People can generally withstand sustained G forces in the neighborhood of 8 Gs if properly supported. That works out to about 200 miles per hour per second. 5G to ignite the scramjet is about 3800 mph sea level, close enough to use 4000 mph back-of-the-envelope to get 20 seconds to scramjet ignition, maybe 40 seconds to Mach 10.
A two minute climb should be very endurable.
The limiting factor is more likely to be power-to-weight ratios than G-forces.
I bet it wouldn't be too hard to get that limit relaxed to something like no sonic booms below 15,000 feet (~4500m). A military plane once passed Mach 1 less than 2,000 feet (~600m) above the house of a friend of mine (at the time, he was living about forty miles west of Detroit in a rural area). He said it was really loud and shook the Earth, therein lies the problem. Moving it higher off the ground, is IMHO, a much better solution than an outright ban. In that regulatory environment, I can imagine the major hubs having regular supersonic connecting flights to each other, with conventional flights to all other airports. Think of it as a 'backbone network' for 'people packets'.
I like to play children's songs in minor keys.
"We're all sons of bitches now." --J. Robert Oppenheimer
many times
The US Space program used ordinary pencils in space throughout the Mercury and Gemini programs. Paul Fisher, founder of the Fisher Pen Company, spent over one million dollars of his own money developing the Fisher Space Pen before he came up with a working prototype in 1965, which he submitted to NASA for evaluation. NASA approved it for space flight in September 1965, and purchased 400 pens at $2.95 each in December 1967. The Soviet space program adopted them in 1968.
Why is it that the proponents of "one nation under God" are so eager to get rid of "liberty and justice for all"?
Accelerating at 1/10g (3.2 ft/sec/sec) to keep the passengers comfortable:
Mach 5 = 3000mph at high altitude = 4400 ft/sec
Time to reach this speed: 4400/3.2 = 1375 sec = 23 minutes
Distance covered while accelerating: 1/2(4400)(1375) = 3,025,000 feet = 573 miles
And your deceleration is going to be at least as long, so it's not worthwhile on trips much shorter than LA-NYC.
If the customers can be less comfortable, accelerate at 1g and your acceleration covers 57 miles in 137.5 seconds. But the ticket is going to be very expensive -- the plane has to go faster than most fighter jets BEFORE it can turn on the scramjets. So it needs ungodly big conventional engines, or else rockets. And the seats have to swivel around because you really don't want to hang from your seatbelt in 1g deceleration for 2 minutes.
Someone mentioned accelerating at 8g. This only takes 7 miles -- you could launch from an electromagnetic catapult to scramjet speed, IF the scramjets will run in thick air at low altitude. Of course, your passengers need a thorough physical, and there is still that deceleration issue.
Scramjets are not for airliners. The military applications should be obvious -- and you can use something like the space shuttle boosters in that case. Other than that, they might be useful for space launches -- get to Mach 5 with solid-fuel rockets, then use the scramjets to get to the outer fringes of the atmosphere at Mach 15 or so before you have to switch back to rockets. (The trouble with rockets is that they carry their own oxygen, which outweighs the fuel...)