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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.'"
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.
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
According to the article there's three more vehicles which will be tested in the fall.
No it isn't. Mach is the speed sound travels in a medium (the atmosphere). As there is no atmosphere in orbit, you can't associate a mach speed value to orbital velocities.
-SaNo
Not only that, but you can't always be sure which part is the weak link, what will break. A few tests at hypersonic is guaranteed to make an engineer say "ok, that's an issue we weren't aware of", and confirm much of what they already knew. They may have to make some part that they *thought* would be ok out of a different, stronger alloy, etc. Of course, at this speed, every tiny error in engineering is amplified, as at Mach 6, you cross a lot of real estate in just a few seconds, so the word "precision" doesn't adequately describe the level of perfection required in the test system build.
Being a pioneer at anything guarantees surprises, and best of all, learning new things.
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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
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?
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.
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?
Atmosphere isn't just compression, it's reaction mass. The compression creates the conditions for acceleration when the fuel is burned, but it's heating of the compressed air that causes the high force that accelerates the air backwards, accelerating the vehicle forwards.
You can bring your own oxygen, but it's just going to make a pretty flame coming out both sides of the combustion chamber unless there's mass flowing into the inlet and being pushed out through the nozzle.
I said this above already, but what you do here is you use a first-stage rocket motor to get up to scram-jetting speeds. Then the second-stage motor gets you to a certain point in the atmosphere where it loses thrust. Then you light your third stage.
This makes sense only if the specific impulse (look it up) from the scramjet exceeds that from a rocket motor, or it's ridiculously cheap and still gets the job done. I'm guessing it's not ridiculously cheap. But given that you don't have to bring the reaction mass for the scramjet with you, it might be more efficient than a rocket of the same mass. Meaning you can omit a heavy rocket motor and use a lighter scramjet and put the saved mass into the payload.