Experimental Air Force aircraft goes hypersonic

[Baron Greenback]

An experimental unmanned aircraft developed for the U.S. Air Force has flown at more than five times the speed of sound in a test off California.

Read more at: http://phys.org/news/2013-05-experimental-air-airc... Air Force said in a statement Friday the X-51A WaveRider flew for more than three minutes under power from its exotic scramjet engine and hit a speed of Mach 5.1 or 1735.5 m/s!

The WaveRider was released Wednesday from a B-52 bomber 50,000 feet above the Pacific and was initially accelerated by a rocket before the scramjet kicked in. The flight ended with a planned plunge into the ocean.

It was the fourth and final flight of an X-51A by the Air Force

[Eric Mc]

I think that must be the first successful flight of a hypersonic scramjet. It's taken them long enough.

[Simpo Two]

Wow, had it had a pilot it owuld have taken the record by a country mile: http://en.wikipedia.org/wiki/Flight_airspeed_recor...

[Eric Mc]

It isn't that big.

I think we are still a few years away from building a manned hypersonic aircraft. Indeed, I expect this programme is more about developing the technology for unmanned drones of various sorts.

[Einion Yrth]

Eric Mc said:

I think that must be the first successful flight of a hypersonic scramjet. It's taken them long enough.

I read that it had been done before with hydrogen but that this was the first success burning kerosene.

[Eric Mc]

The X-15 did it as a pure rocket.

It's getting a sustained, managed jet type combustion going and maintaining aerodynamic control at those speeds which are the hard parts.

[anonymous-user]

I suspect that the aero thermodynamics are a real PITA at those sorts of speeds! I'm not sure at what altitude the max speed was attained, but I'd guess the thermal loading and dynamic pressure was pretty hairy :-)

[Eric Mc]

The slightest twitch and the vehicle is history.

[Gwagon111]

Eric Mc said:

I think that must be the first successful flight of a hypersonic scramjet. It's taken them long enough.

No, just the first one that the U.S.A.F. have openly admitted to.

[jmorgan]

This the one no one has seen but the internet says is real?

[Baron Greenback]

Tis a bit hard to see as dropped from 50k feet and traveling in a closed off area at mach5 for less than 3 mins!

The main problems is due to aerodynamic heating and shock wave interactions. This results in high temperatures which can exceed 1600c on the aero structure to occur and finding material strong enough is a tad hard to say the least while being light also.

[Eric Mc]

Gwagon111 said:

Eric Mc said:

I think that must be the first successful flight of a hypersonic scramjet. It's taken them long enough.

No, just the first one that the U.S.A.F. have openly admitted to.

Hard to hide something like that.

[Baron Greenback]

https://www.youtube.com/watch?v=cVhL7UAFdVA

Not bad acceleration!

[jmorgan]

Baron Greenback said:

Tis a bit hard to see as dropped from 50k feet and traveling in a closed off area at mach5 for less than 3 mins!

The main problems is due to aerodynamic heating and shock wave interactions. This results in high temperatures which can exceed 1600c on the aero structure to occur and finding material strong enough is a tad hard to say the least while being light also.

X15, some examples in there of what Mach 5 and upwards does.

[Eric Mc]

Initial acceleartion is provided by a solid rocket motor.

The X-15 achieved Mach 6.7 in 1968.

[jmorgan]

The Dryden flight centre had quite a good selection of images from the time including the ones with ablative coatings and the results of what that speed did to the craft. Looks like that site has been incorporated into the main NASA site and its a bit pants trying to find stuff.

[Einion Yrth]

Eric Mc said:

Initial acceleartion is provided by a solid rocket motor.

The X-15 achieved Mach 6.7 in 1968.

But as you say, it was powered by a rocket engine, so not strictly relevant.

[Eric Mc]

Hypersonic flight is difficult no matter what the power source is. Obviously, the ability to operate a form of jet engine at hypersonic speed is a breakthrough - although there is also a very long way to go before this technology can be put to any practical use. Hsaving said that, I am pretty sure that some ramjet powered missiles were operational in the 1960s (the Bloodhound and the Bomarc, for example). So jets have worked at high supersonic numbers before.

The other major issues of hypersonic flight are stability, control and airframe heating - all of which were tackled by the X-15 (not always successfully) and which which still need to be properly explored. In fact, from what I've seen, the previous tests of this hypsersonic scramjet vehicle failed not because of engine failure but because of loss of control at high mach numbers.

I think it is the aerodynamic control and stability issues which will make or break this project.

Edited by Eric Mc on Monday 6th May 08:56

[tapkaJohnD]

AHEM!!!
"Scramjet hits Mach 10 over Australia"
15 June 2007 - TWO THOUSaND AND SEVEN!
See: http://www.newscientist.com/article/dn12075-scramj...
And Mach 10 too.


OK, the U.of Queensland device was accelerated to the reqired hypersonic speed by being rocketed out of the atmosphere, and igniting its engine on re-rentry.
The USAF one was also boosted to hyperspeed by rockets. It's a development, and probably burnt for longer, but it's not the first, nor the fastest.
John

Edited by tapkaJohnD on Monday 6th May 13:12

[Gwagon111]

tapkaJohnD said:

AHEM!!!
"Scramjet hits Mach 10 over Australia"
15 June 2007 - TWO THOUSaND AND SEVEN!

See: http://www.newscientist.com/article/dn12075-scramj...

And Mach 10 too.

John

There have been numerous sightings of 'pulser' engined aircraft, which have had estimated speeds well into the hypersonic, since the 1980's. It's been getting harder to hide their existence since the proliferation of satellite technology.