3D Thrust-Vectoring and Supercruise

[EngTechno]

What is 3D thrust-vectoring and Supercruise ? I frequently see this terms in Military Fighter Aircraft data. I know nothing about it. Can you explain me in detail? Any website for it?

 

[enigma]

According to this page, supercruise means the "ability to... fly at supersonic speeds without using afterburners" (2nd paragraph).

---

Thrust vectoring is the use of flaps near the engine outlet to point the flow in a desired direction. This increases the possible turn and roll rates.

Here's a website with some pictures of 2D thrust vectoring. 3D just has side to side capabilities as well.

 

[griffin]

thrust vectoring can also be used to achieve vertical lift off, but unless it is truly essential to verticaly lift off the loss in efficiency when vectoring that much dose not make it worth the cost in efficiency

 

[DM]

According to this page, supercruise means the "ability to... fly at supersonic speeds without using afterburners" (2nd paragraph).

To some extent this is right.

Supersonic cruise requires the help of afterburners, no matter what.

 

[enigma]

To some extent this is right.

Supersonic cruise requires the help of afterburners, no matter what.

There are no planes which can fly supersonically at full throttle with just engines alone?

What mechanism is preventing supersonic flight without afterburners?

 

[DM]

Name an aircraft.

 

[enigma]

This site says that the Concorde uses afterburners in the transonic regime and then turns them off for supersonic cruising.

I'm not sure if it's accurate or not.

It's possible that fighter aircraft are engineered to rely on afterburners for supersonic flight, but I can't think of a reason why they'd be needed.

Heck, the X-43 doesn't use afterburners either, but it doesn't really apply.

 

[faust9]

YF-23: http://www.invisible-defenders.org/programs/yf-23/yf-23_flt-tst.htm

I believe the F-16 can achieve Mach 1 speeds without the use of an afterburner. Using an afterburner allows the F-16 to push to Mach 2+.

 

[DM]

Enigma, (sorry if this isn't your real name)

I can see your point of view towards afterburners, I suppose that you, just like I am, are worried about our environment. It's indeed very worrying.

However it is very hard to reach supersonic speeds without the use or help of afterburners. The reason I say this is because just like the concorde, fighter planes attempt and succeed reaching supersonic speeds as fast as possible.

If you think about it, a plane reaching supersonic speeds without the use of afterburners takes a long time. This would be extremely concerning towards fighter planes that have the goal of arriving at a place as quick as possible.

So concluding, the emphasis of using afterburners is in order to reach supersonic speeds as fast as possible. Ever wondered why the concorde used them? the promised 2h15m from EGLL (Heathrow) to JKFK (John Kennedy) would be dragged to at least 6 hours if the integration of afterburners never took place.

Daniel

 

[enigma]

Enigma, (sorry if this isn't your real name)

I can see your point of view towards afterburners, I suppose that you, just like I am, are worried about our environment. It's indeed very worrying.

Well, I'm an engineer. As an engineer, I'm always curious why things work the way they do, particularly aircraft (which isn't my area of expertise) and spacecraft (which isn't either, but I'm working on it...). I had never heard that there weren't any supersonic planes which did not rely on afterburners. Since you mentioned it, I wondered if you knew why there aren't any.

If you think about it, a plane reaching supersonic speeds without the use of afterburners takes a long time. This would be extremely concerning towards fighter planes that have the goal of arriving at a place as quick as possible.

I'm sure that a bigger reason would be the tremendous increase in aerodynamic drag in the transonic regime. That drag decreases again once you go past Mach 1.3 or so. I still don't see why they'd need afterburners for supersonic flight.

 

[russ_watters]

YF-23

Supercruise was a critereon for the design of the Advanced Tactical Fighter. I think that's where the term came from. The YF-23 was Northrup's entry into the design contest and Lockheed's was the YF-22. The YF-22 won and is now the F-22. It has supercruise and single axis (pitch) thrust vectoring.

If you think about it, a plane reaching supersonic speeds without the use of afterburners takes a long time.

Like enigma said, drag increases quickly in the transonic reason - this means that acceleration is pretty good right up until you get to mach 1.

I still don't see why they'd need afterburners for supersonic flight.

There may be an exit velocity/nozzle shape issue with some engines.

 

[rdt2]

Both thrust vectoring and supercruise are features of the Joint Strike Fighter (JSF). Thrust vectoring is what the AV8B uses to enable S/VTOL (as originally developed for the 'Harrier' on this side of the Atlantic). It also enabled the development (during the Falklands War) of a new tactic - 'vectoring in forward flight' (VIFFing) - to climb, brake and force pursuing enemy aircraft to pass on by and come into weapons range.

Supercruise is indeed the ability to sustain supersonic speeds without re-heat ('afterburners' on that side of the Atlantic). Do a google on 'JSF' for more information than you require.

 

[DM]

Like enigma said, drag increases quickly in the transonic reason - this means that acceleration is pretty good right up until you get to mach 1.

That's where afterburners increase from MACH 1.00 to 2.00.

And Enigma... there are planes in which do not use afterburners to reach supersonic cruise however these fighter planes are rather new.

I think I explained why afterburners exist for supersonic flight. I'm sorry if you can't understand it.

 

[russ_watters]

I think I explained why afterburners exist for supersonic flight. I'm sorry if you can't understand it.

Cool it, DM. We're all here to learn - even you.

 

[Sh0t]

The airfore recently messed up the definition of what supercruise meant to cover up the failures of the F-22

The real definition should be "the ability to cruise(cover distance economically) at supersonic speeds."
Not "supersonic flight without afterburners"

A real supercruiser in existence today would be the Mig-31.

Notice the fuel fraction of the Mig-31 compared to other fighters.

So pretty much discard the current USAF pushed definition of supercruise, it was done to coverup the failures of the ATF/JSF projects.

For a good overview of the F-22:
http://www.pogo.org/p/defense/do-000608-f22.htm

 

[KrazyIBKid]

First for an unbiased description (not read the other posts)..

Supercruise - Is the ability to accelerate pastand maintain trans and supersonic speeds without the use of afterburners

3D-Thrust Vectoring - It is the ability to rotate the Engine outlets amonst a 360* axis which allows for greater turn Radii and improve strike and life capabilities such as on the ATF F-22 raptor JSF (usa).

NOw to READ the posts...

Thrust vectoring is the use of flaps near the engine outlet to point the flow in a desired direction. This increases the possible turn and roll rates.

but not 3D thrust vectorin.. and it doesn't require the use of flaps to direct
the air a direction.. it has adjustable nozzles on the side.. such as on the Harrier Jump-Jet (britain)

Supersonic cruise requires the help of afterburners, no matter what.

Prove this... I have been taught and read that this is NOT true... link it please... if you COULD disprove it wiht a credible source.. please do, Becuz i have heard from an Air-Force Cheif (my Uncle) that this is NOT the case.. supercruise does NOT! require the use of afterburners

the emphasis of using afterburners is in order to reach supersonic speeds as fast as possible. Ever wondered why the concorde used them? the promised 2h15m from EGLL (Heathrow) to JKFK (John Kennedy) would be dragged to at least 6 hours if the integration of afterburners never took place.

The use of Afterburners is NOT primarily to reach supersonic spees AFAP.. but yet to Break supersonic speeds efficiently (well more so than conventional jets). Afterburn'ing' is a method of injecting fuel into the exhaust to create more thrust which is needed to acquire trans-sonic speeds (above mach 1.5), in level flight. the Concorde did not use its after burners until mach .8 (atleast) or it would have been unreliable and inefficient. And yes the concorde did turn off its afterburners after supersonic flight, however this is because they did not need to maintain those speeds any longer, in fact they had to Deccelerate to sub-sonic speeds before entering into US air-space (which i believe is 150 NM off the coast). technoicaly you COLD cruise for awhile at super-sonic speeds afterturning off afterburners, howevere you CANNOT maintain those speeds...
done... finally... for now atleast

 

[enigma]

...
trans-sonic speeds (above mach 1.5),
...

Trans-sonic is not above M#1.5. Trans-sonic is what happens near M#1 when portions of the airflow over the top of the wing reach supersonic speeds and form small oblique shock waves there. This increases drag immensely.

 

[KrazyIBKid]

o sorry.. musta been thinking of somethin else.. ill look into it for what i meant..

 

[enigma]

Maybe you were thinking of hypersonic (M#>5)?

Welcome to the forums, BTW...

Always good to have another aero-head here!

 

[KrazyIBKid]

Thx, no that's not what i was thinking of, but i can't find it anywhere.. I am sure it'll hit me. My uncle told me once and i looked it up somewhere, can't find it. I'll have to sak him next time i get around to it. I am 16 now and know way too much for my own good.. and I've wanted to fly and know why things fly for as ling as i can remember.. but that's the only thing wrong that i mentioned, because if I am wrong please do correct me, once again , I am only 16 but i still know a lot, however I am sure i don't know as much as a lot of you guys, so I am here to help AND learn

 

[red_fox77]

To some extent this is right.

Supersonic cruise requires the help of afterburners, no matter what.

Wrong. Just because you are above the mach doesn't mean you have to afterburn fuel. One has nothing to do with the other. Better engines, lighter aircraft. Hell, missles fly mach 2-4 without any kind of AB (or breathing air for that matter).

 

[red_fox77]

The airfore recently messed up the definition of what supercruise meant to cover up the failures of the F-22

So pretty much discard the current USAF pushed definition of supercruise, it was done to coverup the failures of the ATF/JSF projects.


You don't really know what you are talking about, basing information you read in the news is never a very good idea. The F/A-22 can supercruise, which means to fly above mach without the fuel-guzzeling afterburners. As far as failures, the real failure was in congress. The real reason the cost of the plane is so high is they cut orders from over 750 to under 280. The coast of the actual plan hasn't gone up much more than inflation. But when you include development costs in the cost per fighter, the reduction of aircraft really makes an impact on per plane cost.

That's really the only major problem with the aircraft, cost per plane.

 

[sigma]

That's really the only major problem with the aircraft, cost per plane.

The major problem? I'd say it's the only good and decent thing about it. That way, perhaps, they won't make so bloody many of them.
Heck. The MiG 1.42 is still way cooler. And better, as it is very unlikley to ever fight in a real battle, thus saving hundreds or thousends of human lives. The main drawback with all machines of destruction is that they are nothing but machines of destruction, monuments of our evil and bloodthirsty souls. "If you don't want anyone to drop the bomb, don't build the bomb" is the way we should think, not "lets build the bomb before anyone else does" because maintaining the terror balance is the easiest way to put everything else out of balance. We waste far too much energy and money on increasingly advanced and ingenious ways to killing each other, instead of trying to live in harmony.

And peace.

As for the subject question i have two points:
1. I find it hard to believe that it would be impossible to construct a jet engine capable of supersonic flight without the use of an afterburner.
2. The mechanics of directing the thrust, may it be flaps or a moveable nozzle, is of no importance for the definition of "thrust vectoring".

Cheers.

 

[russ_watters]

The major problem? I'd say it's the only good and decent thing about it. That way, perhaps, they won't make so bloody many of them.

I think you missed the point: the actual cost to manufacture a single plane is pretty low, but the R&D cost is high and fixed (its the same lump sum up front whether you buy 1 plane or 1000 planes), making the oft-cited "cost per plane" number highly misleading. Remember, the development of a plane takes upwards of 20 years and all of that is paid for before a single production aircraft is delivered.

Pulling some numbers out of the air, if R&D cost $1 billion and each plane cost $20 million to manufacture, the "cost per plane" of 10 planes is $120 and the "cost per plane" of 100 planes is $30 million.

Because of this, a tiny cost overrun or drop in funding results in a massive reduction in the number of planes built and a massive increase in the "cost per plane."

 

[russ_watters]

More:

The real problem here is the government procurement regulations. The process is so cumbersome that the F-22 has been in development since 1981(!) and is only just now entering service. Only 4 years of that ('86-'90) was from selection of the two teams to the first flights of the prototypes.

Contrast that with the F-117, which was developed largely without government obstruction since it was so secret few in government knew it existed. It started in 1975 with research into stealth, in 1976 Lockheed had a mockup undergoing radar testing, and by Feb, 1978 they had two flying prototypes (too small to be real combat aircraft). The F-117 itself began development in 1978, the first production plane was delivered in 1981, and the first combat unit was operational by '83.

Unit cost is listed as $45 million.

 

[sigma]

Okay. Great to know. How much is a F-16? An Apache chopper?

Still I think it is a waste of money. I don't want to guess how much of those AIDS brake drugs you could get for the price of one kickass fighter jet... or how many mountain gorillas you could save (probably more than there is alive today). Hope you don't think I'm way too much out of topic.

cheers.

 

[kurious]

Sometimes in photos of jet exhausts you can see dark and light vertical bands.
Is this a trick of the camera or sound waves or something else?

 

[russ_watters]

Okay. Great to know. How much is a F-16? An Apache chopper?

Still I think it is a waste of money. I don't want to guess how much of those AIDS brake drugs you could get for the price of one kickass fighter jet... or how many mountain gorillas you could save (probably more than there is alive today). Hope you don't think I'm way too much out of topic.

cheers.

It is off topic, but I'll answer: if the US military didn't exist, there would be no AID drugs because Hitler would still rule the world. War and the need to defend the US and the world are a fact of life, whether you like it or not and that means weapons are a necessary evil.

 

[russ_watters]

Sometimes in photos of jet exhausts you can see dark and light vertical bands.
Is this a trick of the camera or sound waves or something else?

Could you elaborate? I'm not sure what you mean here.

 

[LunchBox]

Sometimes in photos of jet exhausts you can see dark and light vertical bands.
Is this a trick of the camera or sound waves or something else?

I think I know what you're talking about here...

The exhaust gasses are exiting the engine nozzle at supersonic speeds and being dumped into stagnant atmosphere. So, the pressure difference causes a shock wave to form. These shock waves from the edges of the nozzle converge until they bounce off of each other and reflect. Then, the flow expands again until the flow bounces off the slip line created by the exiting gasses. The flow then reflects again until the waves bounce off each other again. This process repeats until enough energy is dissipated that the flow becomes subsonic. The dark and light bands you are seeing are due to the diffraction of light around the compression waves (higher pressure) and through the expansion waves (lower pressure).

Hope that explained it.

(See "Fundamentals of Aerodynamics" by Anderson for a more in depth explanation.)