Slashdot Mirror
USAF Scramjet Hits Mach 6, Sets Record
s122604 writes "The [X-51A Waverider]'s scramjet engine accelerated the vehicle to Mach 6, and it flew autonomously for 200 seconds before losing acceleration. At that point the test was terminated. The Air Force said the previous record for a hypersonic scramjet burn was 12 seconds. Joe Vogel, Boeing's director of hypersonics, said, 'This is a new world record and sets the foundation for several hypersonic applications, including access to space, reconnaissance, strike, global reach and commercial transportation.'"
Why are these engines burning for such short times? Are these engines so early in development that they really can't get them to be stable and safe for more than 12 seconds? Sounds a lot like fusion: it works but it's not yet useful.
- Henrik
- when the Shadows descend -
From Wiki Answers:
So that's like going from Atlanta, Ga to Honolulu in just over an hour.
So not only does this do Mach 6, but it also uses its own sonic booms to help with propulsion? Or did they just choose Waverider because it sounds neat?
http://en.wikipedia.org/wiki/Waverider
Don't know something? Look it up. Still don't know? Then ask.
Commercial applications do usually follow. Whether or not you agree with it, military research has led to an enormous number of scientific advances that were initially used by the military but later disseminated more broadly. Jet engines, the Internet, cryptography, GPS, nuclear reactors, etc. Mach 6 might be inefficient overkill for Earth-side transportation, but it may provide a viable means of launching spaceflights one day.
$_ = "wftedskaebjgdpjgidbsmnjgcdwatb"; tr/a-z/oh, turtleneck Phrase Jar!/; print
...how quickly my home declined in value in 2008 and 2009!
Veritas patesco per quaestio questio. Truth is revealed through questions.
Mach 6 is still a long way from Mach 22. Mach 22 is orbital velocity.
Seastead this.
Boeing announcement here:
http://boeing.mediaroom.com/index.php?s=43&item=1227
"In its first flight attempt, the Boeing [NYSE: BA] X-51A WaveRider today successfully completed the longest supersonic combustion ramjet-powered flight in history -- nearly three and a half minutes at a top speed of Mach 5."
My understanding is that it didn't reach the 300 seconds Mach 6 burn it was hoping for. 200 seconds and Mach 5 isn't all that bad though...
More here:
http://www.theregister.co.uk/2010/05/27/x51_first_shot/
wot no sig
Questions
According to the article there's three more vehicles which will be tested in the fall.
Scramjets aren't exactly easy to test in the lab.
Hell, even normal jet engines are tough to test. Have you seen the equipment used to keep those things stationary while testing them? Holy fuck .
Living With a Nerd
Fine. Except for jet engines, the Internet, cryptography, GPS, and nuclear reactors what has the military done for us?
Little plastic Army Men
Living With a Nerd
It's amazing to me that they can make a machine who's parts are GLOWING they are so hot and the metal still functions without failing.
A work that expires before its copyright never enters the public domain and thus enjoys eternal copyright protection.
Assuming the acceleration is modest, her facial expression aqt Mach 6 should be identical to when she's sitting on her living room sofa.
Mac 5 melts aluminum steadily
Mac 6 melts steel
And don't forget that keeping this friction heat down also requires a good deal of power.
The differences are in how compact the engine is and exhaust velocity. Airliner engines are designed solely for efficiency and as such have bypass ratios that make start to look like a helicopter mounted sideways in a tube. The actual power generating bit of the engine is tiny and most of the thrust comes from shunting air through the outer parts at relatively low speeds without ever being compressed.
Generating exhaust simultaneously at high rate, high velocity and in a compact package is vastly different.
Hello,
The story is in error. Per this link, the plane only hit Mach 5, not Mach 6. This is still a pretty successful test, however.
Link: http://www.msnbc.msn.com/id/37377401/ns/technology_and_science-space/
--PeterM
Are you trying to point out that the internet wasn't a military innovation by stating its purpose was to track nuclear weapons (*military* nuclear weapons)?
And for what it's worth, the original purpose was to allow communication between points with no single path of failure (insert beneficial military application here like giving combat orders in the event of a nuclear strike); it started in universities, national labs, and large military bases who had the budget to pull the wires, and before we knew it there were all kinds of fun uses for it like MUD games and e-mail and slashdot and finally facebook; the ultimate military weapon.
Radial Engines, Kevlar, Ceramic Technologies, Radar, Microwaves, Food Preservation, Someone else keep this going.
Why is it so hard to only have politicians for a few years, then have them go away?
Brought peace!
Others have expressed the detail, so I won't be redundant, but the J58 is on the extreme end of Jet technology even today, and that was the point of my analogy. Those airliner engines you mention produce more thrust and are more economical to operate and to maintain, by a very healthy margin. However, they are only good up to about 500 kts or so, as opposed to the 2000+ kts the J58 is capable of. Nor will they function at all about 60000 feet, whereas the j58 will at full or nearly full thrust. So, in comparison, modern airline engines of which you speak are not in the same class of tech, nor would you expect them to be, since their purposes are far different. On a side note; it's note related to the tech of the engines themselves, of course, but those airline engines also will never push as pretty an airframe through the air, wich disqualifies them on the asthetic front too.... {smile}
A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort.
Even at Mach 3, you want a layer of foam to avoid burning.
Let's not stir that bag of worms...
The temperature of objects produces (from what i recall of physics) black body radiation - meaning it produces light wavelengths. Just because we associate melted iron being red hot, doesn't mean other metals melt when they start to glow. It just means they are hot enough to produce enough black body radiation that we can see. Look at mercury for example as an opposite.
..........FULL STOP.
I think you misunderstand his point (or perhaps I am giving him too much credit for asking a really good question). Mach speeds are a ratio of the speed of the aircraft to the speed of sound. Mach 6 therefore means "six times the speed of sound". OK, nothing difficult there; most people here probably knew that already. Here's the rub: what is the speed of sound? Hint: it's not the same at sea level and at the 0.1Mm you mention, because the speed of sound varies with the density of the atmosphere. In other words, Mach 6 at sea level (~4500 mph) is not the same speed as Mach 6 at, say, 100,000 feet above sea level (~4100 mph).
MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?
Well, for one, neither German, Japanese, nor Russian is my native language...
MCSE? No, sir...I don't do Windows. Yes, I am an idealist. What's your point?
you mean in the autumn?
or in the spectacular screaming descent towards land?
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Or you just lie flat on the earth and let gravity do about the same.