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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.'"
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.
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
According to the article there's three more vehicles which will be tested in the fall.
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.
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Yes, but not scramjet technology that uses ordinary jet fuel to power the engine. Said scramjets used hydrogen instead, and can't maintain flight for long because of how bulky the large hydrogen tanks are.
Since the vehicle was deliberately crashed into the ocean and not recovered - there's nothing to examine for wear and stress, whole or in pieces.
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.
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Rocketry. 'Nuff said.
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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}
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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.
You start out in the atmosphere, chief. Also, Wikipedia specifies a Mach number for LEO.
Even in LEO, there is air- it's just very, very, very thin. The atmosphere doesn't end at a hard line.
Why do you think objects in LEO gradually slow down and re-enter? Answer: aerodynamic (and solar) drag.
Please help metamoderate.
If you're required to carry your own oxidizer, it's a rocket engine, not a jet engine.
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.
Assuming the acceleration is modest, her facial expression aqt Mach 6 should be identical to when she's sitting on her living room sofa.
Considering it accelerated from a maximum of about 650 mph (290m/s - crusing speed of a B-52) to about mach 6 (2000m/s) in a period no greater than 200s, that gives an average acceleration of 8.75 m/s^2.
That's roughly equivalent to accelerating in a car from a dead stop to 60mph (100 km/hr) in about 3 seconds. So, in order to see this face, I suggest you take her for a ride in one of the following vehicles, pinning the accelerator to grant maximum acceleration:
Bugatti Veyron 16.4 (2.6s to 60)
Lamborghini LP670-4 Superveloce (3.1s to 60)
Koenigsegg CCX (3.1s to 60)
My bet is that it looks slightly different than when she's on the sofa.
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).
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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.
Not to be a stickler, but mach is a relative number based on air density (altitude/pressure), so unless they tested the thing at 5' above the waves or something, it's more like 220 miles in that 200 second time frame (assuming 50,000 ft). That makes it way less cooler, I know.
!#&*
On a technicality, scramjets are actually a little bit crazier than even what you said. A turbojet (basic jet engine) indeed uses compressor turbines to compress the air it ingests. A ramjet flies fast enough that it can use the shockwave travelling off a forward point of the engine to compress the air without needing to use a compressor. A scramjet is short for "supersonic combustion ramjet" and in a scramjet the air never slows down below the speed of sound inside the engine and must be able to sustain combustion in the supersonic domain. o.0
The engines of the SR
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