How is "SuperCruise" achieved??

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Well in normal jet engines the afterburners help the a/c in going supersonic...but in turn tend to guzzle the fuel. Can somebody please explain it to me that how the new phenomena of SuperCruise is achieved? i.e. how is the plane able to go supersonic without using afterburners and not finishing its fuel supply in like 10 minutes??

Thanks.

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I don't know. I thought it was a combination of high dry power and clever aerodynamics but truly I do not know. Interesting question.

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Engines, powerful enough in military thrust (NOT in afterburner), and low drag in supersonic . . .

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Re: How is "SuperCruise" achieved??

Originally posted by shamayel
Well in normal jet engines the afterburners help the a/c in going supersonic...but in turn tend to guzzle the fuel. Can somebody please explain it to me that how the new phenomena of SuperCruise is achieved? i.e. how is the plane able to go supersonic without using afterburners and not finishing its fuel supply in like 10 minutes??

Thanks.

Simple, you need a lot of power to overcome the drag. As you may know the drag will be increased exponentially with increased speed. Whether the power comes from the engines itself or from the afterburner it doesn't matter. You just need to have the power available to go supersonic. So a combination of low drag and high engine trust will do the trick.

Hope this answers your question.

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This isnt some magic new technology - its just that the current engines can produce enough thrust to make the plane go supersonic without relying on its afterburner (Which uses far more fuel) Current F-15E aircraft (-229 engine onwards I think) can go supersonic when not carrying any ordinance and I've been told stories that the EE Lightning could do the same almost 30 years ago.......

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Blimey I was right then?:D

Don't they have to do something with the airflow through the engines as well?

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Actually "superrcuise" isn't really new.

The "hard-wing" F-4's, in other words those without the new manuvering slats, were capable of going supersonic without any underwing/underfuselage stores attached.

What's new about supercruise is that now it's considered an important part of a new fighter (i.e. F/A-22) in that it allows the fighter to operate at supersonic speeds even with weapons onboard (of course these are internal of course), which drastically increases the effectiveness of the Raptor when performing its mission.

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new phenomena of SuperCruise

New!!!! Concorde has been doing it for over 30yrs!!!!

It uses afterburner to get it to Mach1 I beleive but once it turns it off it accelerates under normal poser to Mach2+

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Neither the Conorde nor the SR71 nor the XB70 ever did supercruise. Supercruise is also not primarily a function of thrust, though offcourse a lot is required to overcome the increased drag.

Supercruise is possible when the airflow through the engine is supersonic. In regular jet engines the inlet nacelle is designed to slow down the speed of the air at the low pressure compressor to subsonic speeds irrespective of the speed of the aircraft, thereby creating tremendous drag which could only be overcome by using afterburner.

Aircraft such as Concorde, SR71, Mig25 could sustain supersonic speeds through the use of turbo ramjets. These engines where afterburning turbojets but at speeds above Mach 1.5 or thereabouts a considerable portion of the air was diverted around the engine and ingnited to function as a ramjet. At no point however was the airflow through the turbojet supersonic. Ramjets are very efficient at speeds from M1.6 to about M3.5. This combination allowed respectable fuel consumption for its time. At higher speeds ramjets become ineffective because the air enters and exits the engine before the fuel can ignite. A problem that is being addressed by scramjets.

Supercruise currently uses low bypass fanjets. In a fanjet part of the air is already being diverted around the engine by the low pressure compressor and so it cannot also function as a ramjet. How the designers overcome the computational fluid dynamics of the attendant supersonic shockwaves within the engine is the secret that allows the F22 to supercruise effeciently without the use of afterburners.

A.A. Sharif

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LOL WHAT!!

AHUM....

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Originally posted by PhantomII
Actually "superrcuise" isn't really new.

The "hard-wing" F-4's, in other words those without the new manuvering slats, were capable of going supersonic without any underwing/underfuselage stores attached.

What's new about supercruise is that now it's considered an important part of a new fighter (i.e. F/A-22) in that it allows the fighter to operate at supersonic speeds even with weapons onboard (of course these are internal of course), which drastically increases the effectiveness of the Raptor when performing its mission.

As you said, it is better with weapons onboard :D

Sorry Cooper, I could not resist ;)

And just to add something which, apparently, has not been mentioned: the interesting thing about supercruise: using the afterburner uses a LOT of gas. so, if you can avoid that, you will be able to fly further without refuelling. And that is a huge tactical advantage.

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"Supercruise is possible when the airflow through the engine is supersonic. In regular jet engines the inlet nacelle is designed to slow down the speed of the air at the low pressure compressor to subsonic speeds irrespective of the speed of the aircraft, thereby creating tremendous drag which could only be overcome by using afterburner."

Hmm...no.

"Aircraft such as Concorde, SR71, Mig25 could sustain supersonic speeds through the use of turbo ramjets."

Neither the Concorde nor the MiG-25 nor the XB-70 for that matter ever used a turboramjet. Straight up turbojets.

Supersonic cruise and supercruise are not the same thing. The former is the ability to sustain supersonic speed. The latter is the ability to accelerate past Mach 1 and sustain supersonic speed without using afterburners. Concorde does the former, it has to sue 'burners to get supersonic. The F/A-22 does the latter.

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SOC then can you please explain how it is achieved?? I think the thing where the air enters the engine at supersonic speed...that engine is known as a scramjet i.e. which needs to be taken to super sonic speed (Mach1 and greater) by some other means and then only it turns into a scramjet. I think nobody has had much luck with those.

its just that the current engines can produce enough thrust to make the plane go supersonic without relying on its afterburner (Which uses far more fuel)

So you are saying that its just that now we have efficient engines; which go supersonic but without engaging afterburners and also without consuming much fuel??

A.A. Sharif you gave a very complicated explanation...care to elaborate on it please. :)

Thanks everyone.

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Originally posted by shamayel
I think nobody has had much luck with those.

Not true, iirc some missiles are using these Scramjets. and using Rocket mortors for the first stage.

SOC has the best explanation.

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Yeah SOC is right. SuperCruise is that a plane can fly at sustained speeds of over Mach 1 without the use of afterburner. How it gets there in the first place is by the use of afterburners.

I think currently only the Eurofighter and the Raptor are capable of SuperCruising. :cool:

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Shamayel, it does not use Afterburners at all thats the point of supercruise.

And its not just one single feature that gives you the ability. If you want to know i advise you to read some decent books.

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shockwave through the compressor?

I am sure you don't want supersonic shockwaves inside the compressor.. the flow will slow down after the shock.. you just don't want it near the turbine blades. I am not so sure that the flow thrugh the engine is supersonic..

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Originally posted by matt
Shamayel, it does not use Afterburners at all thats the point of supercruise.

And its not just one single feature that gives you the ability. If you want to know i advise you to read some decent books.

Dude but the Raptor still has afterburners. Its 35000 lb thrust rating is at full afterburner. Damn if it can go supersonic without afterburners then does anyone know what is the top speed with full afterburners engaged???

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Hey Shamayel and all,
yes the Raptor does indeed have afterburners, but that's not what's being discussed here. Afterburners are still important when turning hard and bleeding alot of energy during a dog fight. However, supercruise is about cruising supersonically WITHOUT afterburners. That makes the aircraft much more efficient at fast cruise, and still allowing it to have the necessary thrust in a dog fight. In a dog fight, or any other form of aggressive flying for that matter, top speed has no meaning. You know what I mean?
Best regards
Stephen

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20 years 7 months

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Originally posted by stephen
Hey Shamayel and all,
yes the Raptor does indeed have afterburners, but that's not what's being discussed here. Afterburners are still important when turning hard and bleeding alot of energy during a dog fight. However, supercruise is about cruising supersonically WITHOUT afterburners. That makes the aircraft much more efficient at fast cruise, and still allowing it to have the necessary thrust in a dog fight. In a dog fight, or any other form of aggressive flying for that matter, top speed has no meaning. You know what I mean?
Best regards
Stephen

Ok that has been established that SuperCruise is cruising supersonically without afterburners. But does the plane reach the supersonic barrier without afterburners or with afterburners in the first place???
I mean like in a car a person has to put the pedal to the metal to accelerate very fast but when a certain speed has been achieved you ease off and the speed becomes constant. Does supercruise work the same way?? i.e. that the pilot engages afterburners to go supersonic in the first place but when he/she gets there turns off the afterburners and starts supercruising due to the superior engine?? OR does the plane go supersonic without ever engaging afterburners??? :confused: :confused:

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The way to make your jet supercruise is to have an efficient engine, with a lot of dry thrust, good aerodynamics, and a good thrust/weight ratio.

That easy enough to understand?

The F/A-22's F119-PW-100 has max thrust output in burner of around 35,000 lbs. Haven't found a dry thrust figure yet.