Slashdot Mirror
HyShot Scramjet Test Declared a Success
An anonymous reader writes: "ABC news is reporting
that analysis of the flight data from the recent
HyShot scramjet test (covered by Slashdot
previously) suggests that the test was successful and that the engine achieved combustion in flight after reaching Mach 7.6. The University of Queensland is also reporting the news."
The thing I don't like about Mach numbers is it's not consistent. Reason being, the speed of sound changes based on your altitude. Higher, where the air is thinner, sound travels slower. So Mach 7.6 at 50,000 feet is a lot slower than Mach 7.6 at sea level. Sure, it's a cool sounding number, but I wish we'd see these numbers represented in miles or kilometers per hour as well as a Mach speed. When the author of the article gave the comparison of a London-Sydney flight, (2 hours vs. 20), was he/she figuring that based on Mach 7.6 at sea level or at 75,000 feet? (not to metion it'll be decades before, if ever, we see passenger planes anywhere near this speed)
You are correct, from start to finish, if you are traveling at mach 7.6 the flight would take 2 hours. But the question was, how long would it take to get up to mach 7.6. How far along on your flight would you be before you reached that speed.
The test flight used a small craft, not a large passenger jet. It would be both easier and faster to reach that speed in a smaller light craft(and even then they used a MK 70 rocket engine, which I'm pretty sure isn't rated for passengers). Even if they were to just use a rocket or catapult(like on an aircraft carrier) to bring you to that speed faster, the G's would be immense, I'm not even sure if a G-suit would keep you from blacking out. And as stated earlier, if you gradually were to gain speed until you reached that point, you would be almost at your destination before you reached mach 7.6, and it would be time to start slowing down for landing.
Xaotik Designs
Mach 7.6 is right around 2,260 m/s (7,414 ft/s) or about 5,055 mph. It would still take you 5 hours to circumnavigate the globe. Plus you have to consider acceleration time - the rocket doesn't have to worry about killing people.
Realistically, we probably won't hit Mach 7 in commercial flights for some time, and there will probably be "low-speed" versions for shorter distances. As the article notes (emphasis mine):
--
Warning! Error reporting system failu
That what was all this school was for... to teach us how to solve our own problems. -- janeowit
Me too, but it is an expiremental craft, and there were problems launching the first one.
hmmm...
Add a warhead and you have one hell of a fast ICBM...
Xaotik Designs
Almost everything. Normal jet engines have lots of moving parts - turbines, compressors, etc. Ramjets and scramjets don't have any moving parts. They also require very high velocities to work properly, whereas a turbojet/turbofan is quite happy running all day long without moving.
Something like that would be impressive, and also would have definite mind bending impact on the popation below, just due to the sonic boom.
"It is a greater offense to steal men's labor, than their clothes"
Ever hit a speedbump at low speeds?
Not that bad.
Ever hit one at a higher speed? Say, at least twice it's rating (hitting a 15km/h bump at 30km/h, for example)?
It's not the most pleasant things.
Now, you're saying that "Planes don't have to worry about speed bumps!", and you're right.
But what about turbulence?
You can hit turbulence at Mach 0.76 that's pretty rough. What would that same turbulence to do a large plane at Mach 7.6?
Dark Nexus
"Sanity is calming, but madness is more interesting."
This is a really cool idea and I'm glad it's beginning to pan out. If the global scientific community wants to continue to move forward during this century as rapidly as it did during the last, it needs to tackle problems with innovations like these instead of simply trying to ameliorate other people's ideas.
For instance, a friend of mine thinks that the future of the computer industry lies in abandonning the binary basis that has been established and beginning to work with, perhaps, a 4-state diode... Granted, it's not exactly the best idea, but a good example to illustrate my point: it's only a matter of time before old ideas get stale. How many of us have even considered Base n != 2 computing?
...Whether my Maker is prepared for the great ordeal of meeting me is another matter.
Churchill
Um, just as a point of reference, ICBMs travel much faster than Mach 7. On suborbital trajectories from the other side of the globe, you might see a time of flight of 30 minutes or less. Think 20,000 km/hour.
Scramjets are not really interesting as strategic weapons. Extra-atmospheric vehicles (MVRs) are faster and proven 30-year-old tech. Scramjets are going to be useless for cruise missiles, because a Mach-7 shock cone will standout rather nicely even if the missile itself were stealthy. Depending on the altitude, it could also cause ionization of the atmosphere which would show up on radar!
Military applications here are going to be reactive in nature...fighter-bombers that can reach any corner of the globe in two-hours is a big selling point, as is the (literally) stratospheric flight ceilings such crafts would have. But I don't know what form a scramjet-based weapons system might need to take or what niche it might fill.
Very fast ramjet cruise missiles were under development in the 1950's, but they fell out of favor because ICBMs are even faster and just about impossible to shoot down. However, they did look way cooler than today's boring ICBMs.
I'm very impressed that this was headed by a University (versus, say, Lockheed-Martin or Nasa). The article says there were collaborators from around the globe, but who picked up the tab?