USAF working on mach 2-3 supercruise jet engines, page 1

posted on Jun, 3 2005 @ 03:39 AM

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Article

The ultimate goal according to the Air Force Research Laboratory, is Mach 3 supercruise.

posted on Jun, 3 2005 @ 04:04 AM

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Very interesting article. It mentions that since breaking the sound barrier 60 years ago, we are still stuck for the most part in the subsonic range. That is unexceptable, IMO.

I'm not very knowledgeable on the specifics, but I'm very interested to know: what is/are the reasons that combat aircraft can only fly supersonic for short bursts while the concord was able to sustain Mach 2 flight for 4+ hours?

And thanks for the post NWguy.

jonititan

posted on Jun, 3 2005 @ 06:02 AM

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Concorde engaged afterburners for the whole supersonic portion of it's flight
also it had 4 military designed jet engines olympia's i believe

when travelling faster than the speed of sound the engine can't alwasy cope with this increased pressue so the inliet is designed to cancel out the shockwaves and the airstream so that the pressure is lower and the engine can cope with it at subsonic speed

with an engine with supercruise it means i suspect that the flow is supersonic all through the engine
i predict low MTTF

backtoreality

posted on Jun, 3 2005 @ 06:25 AM

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Thanks for the info jonititan. That's simply amazing that afterburners could be engaged for a flight from London/Paris to New York. It really was a sad day for the state of civil aviation when the only supersonic public aircraft was scrapped. Let's hope that the dry spell won't turn into an Apollo-type situation.

Anyway, back to the topic: Mach 3 supercuise; can't wait!

RAB

posted on Jun, 3 2005 @ 06:27 AM

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One of the biggest problem will supersonic cruising is that the rear fans of to engine get VERY hot burning up oil, if you take the size of a modern plane e.g F16 or the Tornado I dare say that thay haven't got massive Oil tanks needed for sustained high speed flying.

Where as the B1B and Concorde were designed from dy one with that in mind.

RAB

waynos

posted on Jun, 3 2005 @ 06:44 AM

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Actually the above information is wrong. Concorde used afterburners to accelerate to mach 2 then 'supercruised' to maintain that speed. Had it kept its burners lit for the whole supersonic portion of the flight it would have run out of fuel very quickly and not reached New York!

That is the problem with supersonic flight, afterburning means exactly what it says in that large amounts of fuel are simply ignited in the nozzle to boost thrust in the same way as a rocket produces thrust. No aircraft can sustain constant buring off of fuel over long distances, whether it is 'unacceptable' or not it is simply a fact of life. The added problem with combat aircraft is that all those external weapons greatly increase drag and even more fuel has to be burned off to overcome it, hence the short bursts.

Canada_EH

posted on Jun, 3 2005 @ 07:42 AM

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Originally posted by waynos
The added problem with combat aircraft is that all those external weapons greatly increase drag and even more fuel has to be burned off to overcome it, hence the short bursts.

Hence the reason we see a plane like the F-22 Raptor that can cruise at mach 1.5 with no afterburner. Is the reason for that only because it doesn't have external stores?

waynos

posted on Jun, 3 2005 @ 08:00 AM

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Not entirely, nothing is that black and white. The Raptor is an extremely complex and advanced design, however when it is laden with external weapons its supercruise capability as well as its stealth profiile is seriously compromised and afterburning becomes much more necessary simply due to the higher drag at transonic speed.

jonititan

posted on Jun, 3 2005 @ 08:18 AM

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sorry i wasn't aware of that part
i'm only a 2nd year aero eng student but as far as i am aware they did indeed have fuel problems
when concord went from new york to paris it actually went without out enough fuel to meet the legal requirements
it didn't have enough safety margin
it did have fuel problems

waynos

posted on Jun, 3 2005 @ 08:25 AM

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even more reason not to keep the burners on all the way over the atlantic then

sminkeypinkey

posted on Jun, 3 2005 @ 08:26 AM

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There are also significant (airframe) heat issues in this too.
In fact kinetic heating is one of the biggest problems with sustaining high speeds over any significant period of time.

Concorde used a very elaborate system of pumping it's unused fuel around the aircraft to take heat away and out from around the aircraft (with it being a pretty large passanger liner it was a pretty major concern!
......and wow, was she pretty!).

[edit on 3-6-2005 by sminkeypinkey]

Canada_EH

posted on Jun, 3 2005 @ 10:38 AM

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......and wow, was she pretty!).

No argument there. as for the Raptors inablity to cruise at mach when its in a ferry configuration etc is it that big of a deal? personally i dont think so. I mean it likely would mean very little (extra time) when it comes to deploying to worldwide hotspots. the specs i saw for its ferrying configuration also gave it a huge range while still keeping its air to air role even if RCS becomes huge. speaking of RCS does anyone know what the raptors is suppose to be like? the B-2 is said to be that or a bike or the F-117 a bird but u havent heard about the F-22's

robertfenix

posted on Jun, 3 2005 @ 11:00 AM
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this quote bothers me,

This phase of the VAATE program is worth $5 million for Northrop Grumman. The overall indefinite delivery/indefinite quantity contract, which runs through 2011, has a potential value to the company of $20 million.

www.abovetopsecret.com...

$5 million or even $20 million of goverment money spread over 6 years is nothing, does not even pay for (1) engine prototype. Usually when you see something like this it's a slow leak and the technology is already fully operational. This is a leak from black to white, probably for the sake of the defense budget to give some tangible "technology advancement" and justfy next fiscal years budget spending.

Supercruise has been around in excess of Mach 2 for over 5 years...

Figher Master FIN

posted on Jun, 3 2005 @ 11:50 AM
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Read the article of "The Aurora" on this web site, and tell me wath your new opinion is...

waynos

posted on Jun, 3 2005 @ 01:21 PM
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Originally posted by Canada_EH

No argument there. as for the Raptors inablity to cruise at mach when its in a ferry configuration etc is it that big of a deal? personally i dont think so. I mean it likely would mean very little (extra time) when it comes to deploying to worldwide hotspots. the specs i saw for its ferrying configuration also gave it a huge range while still keeping its air to air role even if RCS becomes huge. speaking of RCS does anyone know what the raptors is suppose to be like? the B-2 is said to be that or a bike or the F-117 a bird but u havent heard about the F-22's

When I mentioned that I wasn't talking specifically about ferry configuration, but rather when actually carrying external armaments, missiles and bombs are more draggy than fuel tanks anyway. Neither was I pointing it out as some sort of failing, merely using it to illustrate the point of why military planes need to use afterburning, the Raptor is after all the exception that proves the rule.

I did hear somewhere about the Raptor having the RCS of a bumble bee, but I might just have dreamed that.

[edit on 3-6-2005 by waynos]

Canada_EH

posted on Jun, 3 2005 @ 01:54 PM
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I didn't mean for may comment to seem like it was attacking yours waynos. I missed which configuration you were talkin about. i was refering to the ferrying configuration in all my posts. oh and the RCS of a bubblebee is insane i have a hard time beliveing that but hey you never know.

TheeStateMachine

posted on Jun, 3 2005 @ 02:21 PM
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Originally posted by robertfenix
...does not even pay for (1) engine prototype. Usually when you see something like this it's a slow leak and the technology is already fully operational....
Supercruise has been around in excess of Mach 2 for over 5 years...

I believe the contract is more oriented to improving the fuel efficiency, MTTF, stress and heating of airframe components, take off noise, sonic boom characteristics, etc... as suggested by this quote from the article:

"attempted to design an aircraft that could operate efficiently beyond the speed of sound. Barriers such as takeoff noise, sonic boom, engine wear and fuel consumption make supersonic aircraft expensive to operate and maintain."

This makes even more sense considerring that Northrup-Grumman was never noted for engine design, as far as i know. They are likely working on new variable shaped engine inlet nacelles, shockwave contouring, etc... to achieve these advancements. Improving designs, and suggesting new design practices is much less costly than coming up with new airframes, new engines and entirely new technologies.

longbow

posted on Jun, 3 2005 @ 03:09 PM
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The reason why most todays planes fly subsonic, is the same reason why the cars speed is still only under 200km/hour - it is simply not worth to go faster. Even the best supercruise engines will still have higher fuel consumption than their subsonic equivalents. And as already said the fast traveling planes produce much heat, which causes structural problems and high IR signature.
Many people believe that future military planes(like possible b-3 bomber) will have much higher speeds (over mach 3) but I disagree with this opinion. Remeber that we are slowly moving from misilles to the energy weapons, by them the speed of plane is useless (because they have mostly have the speed fo light) so if they see you they can hit you. The stealth will be much more important(and the speed is not friendly to the stealth), so I think the future aircrafts will look more like advanced B-2 than like Blackbird or Aurora.