# Jet engine tested at 10 times speed of sound



## syscom3 (Jun 16, 2007)

CANBERRA (Reuters) - An experimental jet engine has been successfully tested at speeds of up to 11,000 km (6,835 miles) per hour, or 10 times the speed of sound, during trials in Australia's outback, defense scientists said on Friday.

The experimental scramjet engine is an air-breathing supersonic combustion engine being developed by Australian and U.S. defense scientists that researchers hope will lead to super-high speed flight.

Scientists from Australia's defense Science and Technology Organization and the U.S. Defense Advanced Research Projects Agency (DARPA), used a conventional rocket to launch the scramjet high above the Woomera test site.

The engine was then tested as it reached speeds of Mach 10.

Scramjets need a rocket to propel the vehicle to high-speed before the engine can take over. They also need to operate in the thin atmosphere far above the altitude of commercial airliners.

"All the indications are it was a success, and we have some very happy scientists," an Australian defense spokesman told Reuters on Friday.

Flight data will be examined over coming weeks and compared to ground tests conducted in the United States, DARPA chief researcher Steven Walker said in a statement.

"We are pleased with this joint effort between the U.S. and Australia and believe that a hypersonic airplane could be a reality in the not too distant future," Walker said.

Scientists say the scramjet engine could lead to high-speed flights on long-range missions, as well as new low-cost ways to launch satellites into space.

Jet engine tested at 10 times speed of sound - Yahoo! News


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## Soundbreaker Welch? (Jun 16, 2007)

Hypersonic.........


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## FLYBOYJ (Jun 16, 2007)

Just read that - pretty wild...


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## R-2800 (Jun 16, 2007)

that's cool.


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## DerAdlerIstGelandet (Jun 17, 2007)

Very very cool.


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## Gnomey (Jun 17, 2007)

Cool, will be interesting to see how fast they can get them too.


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## HealzDevo (Jun 17, 2007)

Main problem would be the various metals and alloys for the other parts of the aircraft or whatever wouldn't it at that speed? The heat would burn it up pretty quickly wouldn't it unless it had very good heat-shielding. I mean the Space Shuttle gets exposed to very intense heat and only survives because it is for a very short period of time...


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## spitfire101 (Jun 17, 2007)

what do they mean by air-breathing exactly? does that mean it wouldnt be able to be on spaceships in space because theres no air?


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## syscom3 (Jun 18, 2007)

spitfire101 said:


> what do they mean by air-breathing exactly? does that mean it wouldnt be able to be on spaceships in space because theres no air?



It uses "air" from the atmosphere to support combustion.

Even at very high altitudes where the density is very low, it can "scoop" up enough air just from the velocity its going.


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## Matt308 (Jun 18, 2007)

Jet implies turbine in my definition. And it AINT a turbine engine. Think aerodynamically compressed air/gas mixture with an igniter. NOT a turbine compression of air, gas ignition that drives a secondary stage thus driving first stage compression.

Completely different concept SCRAMJET, thus you don't have them of subsonic to hypersonic capability. You need a starter for SCRAMJET speeds.


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## HealzDevo (Jun 19, 2007)

But that is just my point, even in the thin air at the edge of space wouldn't it get very hot on the outside metal travelling at 10 times the speed of sound?


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## k9kiwi (Jun 20, 2007)

Don't worry, if it fails it will cool down after it hits the sea.


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## SoD Stitch (Jun 20, 2007)

HealzDevo said:


> But that is just my point, even in the thin air at the edge of space wouldn't it get very hot on the outside metal travelling at 10 times the speed of sound?



Yes, it would, even with the air being as thin as it is 100 miles up . . . the scramjets I've read about are made of heat-resistant alloys, such as titanium or stainless steel. There is no limit to the theoretical speed at which a scramjet can operate - theoretical scramjets can operate at Mach 20 or 30; the limitation is with the materials used to build the scramjet. Even ceramics have a thermal limit.

There is also the problem of accelerating the scramjet to supersonic speeds in order to initiate combustion; this can only be done with either a supersonic "mother" craft (such as the Lockheed M-71), or with booster rockets, which are then jettisoned when the minimum combustion speed is achieved.


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## HealzDevo (Jun 20, 2007)

Ah, okay I understand now. So that is their main problem?


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## Gnomey (Jun 20, 2007)

HealzDevo said:


> So that is their main problem?


Yes, that is just what he said


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## DerAdlerIstGelandet (Jun 20, 2007)

HealzDevo said:


> But that is just my point, even in the thin air at the edge of space wouldn't it get very hot on the outside metal travelling at 10 times the speed of sound?



Yeah but they make them out of special materials. Look at the SR-71 it travelled so hot that it was known to glow sometimes, did it just melt and fall apart? No...


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## Lucky13 (Jun 20, 2007)

Cool!


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## SoD Stitch (Jun 20, 2007)

DerAdlerIstGelandet said:


> Yeah but they make them out of special materials. Look at the SR-71 it travelled so hot that it was known to glow sometimes, did it just melt and fall apart? No...



The SR-71 consisted of about 85% titanium alloy and 15% composite materials (mostly ceramic-based); titanium is probably the most durable metal in the world, especially in high-heat situations. Parts of the aircraft get up to 400 degrees Celsius during sustained Mach 3 cruising speeds at altitude; any other metal besides titanium alloy or stainless steel would probably disintegrate and/or be severely weakened at those temperatures.


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## DerAdlerIstGelandet (Jun 20, 2007)

Exactly...


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## HealzDevo (Jun 27, 2007)

Thanks, interesting. I didn't know the metal combination in the SR-71 Blackbird.


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