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New Jet Engine Tested
SpaceAdmiral writes "A revolutionary new jet engine has recently been tested in Australia. It is hoped that the engine, designed by UK defense firm QinetiQ and capable of Mach 7.6, will pave the way for ultra fast, intercontinental air travel. Scramjet (supersonic combustion ramjet) engines have no moving parts and take all of the oxygen they need (to burn hydrogen fuel) from the air, allowing for larger loads than rockets which must carry oxygen for fuel."
First application for Mach 7+ won't be passenger travel, but military (if not already used) where it will not only be fast, but louder than heck - after all Jet Noise is the Sound of Freedom! ;-)
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Scramjet's are a revolutionary "new" type of engine, they have just been difficult to get from the concept to pratical stage.
The biggest problem is a way to compress enough oxygen at top speeds to feed the fuel reaction without needing to carry oxygen on board (which would be a rocket).
D.O.U.O.S.V.A.V.V.M.
" Scramjet (supersonic combustion ramjet) engines have no moving parts and take all of the oxygen they need (to burn hydrogen fuel) from the air, allowing for larger loads than rockets which must carry oxygen for fuel."
What??? I'll sue right now. This infringes on the name for my patented propulsion "Spamjet" (tm) system.... a revolutionary aerospace technology by which vehicles set up Hotmail accounts, and then propel themselves across the world by converting the lengthening promises of penis spams into actual thrust.
Scramjet (supersonic combustion ramjet) engines have no moving parts and take all of the oxygen they need (to burn hydrogen fuel) from the air, allowing for larger loads than rockets which must carry oxygen for fuel.
All jet engines take the oxygen they need from the air. Only rocket engines leaving the atmosphere require an onboard source of oxygen. Even the U2, which flew at > 40,000ft got it's oxygen from the surrounding air.
And the Scramjet is a jet engine, not a rocket engine. The difference you were looking for is that scramjet engines do not require a turbine to compress the surrounding air. This allows the engine to move at a much faster speed because turbine engines have an upper speed limit before the stresses pull them apart.
Also, theoretically if the compression was high enough the scramjet could burn jet fuel (kerosene) but there is probably technical difficulties with injection (ie. avoiding hot spots and detonation).
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Can anyone tell me why this engine is revolutionary? NASA has been testing these types of engine for some time.
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For example, the X-43 which hit mach 9.6.
[url]http://www.nasa.gov/missions/research/x43-ma
I'll bet it was a smashing success
If you're going to be hitting the ground at any speed greater than a few feet per second, you might as well make it Mach 7. Not like it's going to make a whole hell of a lot of difference anyway, and the crater will be a lot more impressive.
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Five blades is plenty for me. I want to keep my skin atleast.
More to the point, the distance between San Francisco (in California, USA) and London (in England) is about 5000 miles. That same passenger jet at mach 7 can bring its passengers from London to San Francisco in about 1 hour. The trip would be much cheaper than that offered by a subsonic plane because 1 hour is only enough time for cheap snacks like airline peanuts and Coca-Cola whereas a 14-hour flight would mean an expensive (but low-quality) dinner tray.
On the other hand, a 1-hour flight would facilitate global infidelity. An errant British businessman could fly to San Francisco, have dinner and sex with his squeeze, and then return to London within 4 hours.
"Can you find a 400 mile high hill, somewhere where there's no air resistance?"
In fact, when I was a young'n, the school was on top of that hill! We had to walk out of the atmosphere in freeze-drying temperatures every day! Kids, these days, get heated pressurized busses! They're spoiled, I say! There's nothing like a walk through the stratosphere to put the world in perspective!
Instead of getting people to consume more (faster) travel and burning up the ever decreasing oxygene of the atmosphere in the process, maybe the emphasis should be directed more on things like *reducing* the need for air travel? Just like instead of encouraging road travel, the opposite should be happening. Global warming, remember? Overly dependence on foreign oil etc?
Besides, when there were problems with making the Concorde profitable that flew at a mere mach 2, how in the hell is it going to be possible to create an aircraft that would be stable enough on ground level to take off and land, and still be profitable? The quantum leaps the material science has to make to meet such needs are huge.
Furthermore - a scramjet is nearly useless as the first stage of an orbital launcher, because it wants to cruise at a steady speed. An orbital launcher wants to be steadily accelerating.
That's not really true - or at least, it's highly confusing. All jet engines are accelerating whenever they are not idling: they exert a force on the craft causing it to accelerate at a rate of the force exerted divided by the mass of the craft. The apparent acceleration of the craft is reduced by drag and gravity. An orbital launcher has two requirements: that it gain sufficient height to reduce drag to near-zero, and sufficient velocity to actually be in orbit. There's numerous paths that will get you there and few of them involve 'steady acceleration' - a conventional 'great big rocket' launcher has steady thrust, but apparent acceleration to a ground observer is constantly changing with height, since the effects of drag reduce at higher altitudes.
A scramjet does not cruise at a steady speed. It runs at a fixed level of incoming air pressure. It has to run at that level because a scramjet does not contain moving parts to control the air flow. That means, as the surrounding air pressure decreases, the scramjet goes faster. It effectively operates at a fixed speed for a given altitude, and goes faster as you get higher. This is ideal for an orbital launcher.
However: the first stage of an orbital launcher is the one that gets it off the ground. A scramjet is completely useless as the first stage because it doesn't do anything when you aren't moving.
A scramjet path to orbit looks rather different to the old 'big rocket' system. You start with a conventional turbojet aircraft, which takes off and lands normally, using a horizontal path and wings. That's the first stage. You use it to climb to turbojet cruising altitude, and maybe accelerate to your maximum operating velocity (about mach 2 to mach 3). Then you fire a ramjet engine (or small rocket booster - this can be a solid rocket) to get you up to mach 5, which is the breakeven point for a scramjet. Then you fire the scramjet as the third stage, which carries you from mach 5 up to about mach 10 or 12, and most importantly, to near-orbital altitude.
At this point, the orbital craft that was piggybacking you breaks away, and boosts to orbit on one of the conventional late-stage rocket engines, like those used by the shuttle once it has discarded all its booster engines and is in the final orbiter configuration. It's already nearly there, so it doesn't need much fuel. The conventional aircraft that got it up here descends again and lands under turbojets, just like every other jet craft; the orbital craft has its own crew and operates independently.
The two advantages of this design are that it should be largely reusable (because you haven't discarded half the craft on the way up), and it requires significantly less total thrust to get up there. A 'big rocket' craft has to fight the force of gravity all the way up; an aircraft with wings is supported by aerodynamic lift, and merely has to accelerate. The disadvantages are that jet aircraft have more drag than rockets (but aircraft fly all the time; this isn't a fatal problem, it just reduces the advantage), and nobody knows how to build a useful scramjet aircraft yet (the X-43 testing craft just prove the scramjet concept, they aren't useful in their own right). Whether or not anybody can build such a craft that can lift a useful payload weight to orbit is unknown, but the theory says it should be possible.
Well if you were trying to get to Australia then it might be frustrating, but in fact two weeks on the open ocean is mighty fine. I did four weeks once and regard it as one of the best times of my entire life.