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Eurofighter Typhoon TVC

SteveO

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Interesting Flight article on thrust-vectoring upgrade for the EJ200 http://www.flightglobal.com/articles/2009/10/18/333501/eurojet-pushes-thrust-vectoring-technology-for-typhoon.html

I wonder if there would be any benefits if a Typhoon fitted with TVNs could be tested with the fin and canards removed ???
 

SteveO

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Hmmm?

Thought I put this in the Eurofighter Typhoon Projects thread, didn't seem like enough new info for it's own thread.
 

saintkatanalegacy

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http://link.brightcove.com/services/player/bcpid18065281001?bctid=44876616001

interesting. . .
 

Scorpion82

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I don't think if there are any tests that they would be conducted without fins or canards. If the TVN would fail it would actually pose a serious problem to the aircraft, let alone that this would require some quite extensive redesign, whose cost would be certainly prohibitive.
 

Colonial-Marine

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I like the potential of this. Minimal weight increase, increased fuel efficiency, not to mention the additional maneuverability. Any chance a similar thrust vectoring nozzle could be developed for the F-35, but with LO characteristics like the current design? It still wouldn't enable super-cruise, but could it allow higher speeds at certain thrust levels anyway? Maintenance is probably a concern regardless of the aircraft it is fitted to, but I doubt maintaining a "normal" engine nozzle is a hassle-free task anyway.
 

mz

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All of this is not rocket science and is a basic effect of thrust vectoring... Why wasn't it done / researched earlier? A money or political question?
 

lantinian

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All of this is not rocket science and is a basic effect of thrust vectoring... Why wasn't it done / researched earlier? A money or political question?
I think they have. As far back as the early 80's you can find artist depictions of tailless TVC designs.

The one overwhelming problem is reliability. A jet exhaust has inherently more (and smaller) parts than a canard or a horizontal tail and on top of that its running hot. The probability for a failure and loss of aircraft control is significantly higher.

Also, loss of engine itself would eliminate your only control mechanism. In the latest gen of engine designs like the EJ2000, the F119 and the F135, reliably has improved so it makes economically feasible to make high end single engine jet designs like the F-35. Having two such engines makes it possible to "bet your control on their fate" as well. Remember the tailless F-22 designs proposals (aka X-44)...

I guess complex flight control laws were also an issue too, not to mention the design debate of stealth vs maneuverability debate. You just did not have a 3D TVC nozzle that was stealthy.
 

mz

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I meant TVC as an upgrade for the Eurofighter, keeping the canards, so not that much reliability issues. Even in the Flugwerft Schleissheim museum, X-31 and Eurofighter sit side by side, even look somewhat similar and it's a no brainer to think of it. What program were the Germans then going to apply their lessons from the TVC testing to, if not Eurofighter? It's not as if there are a bunch of modern fighter designs flying around in Germany? Exactly one.
Hence it's a bit of a surprise for me that this is presented as something of a new idea... :p

This from January 1990:
http://www.highbeam.com/doc/1G1-8333425.html
It is possible that technology gained by West Germany's MBB from its joint X-31 aircraft R&D program with Rockwell International, will be used for EFA's production-run updates, a German official tells Defense Daily. "Originally, MBB would have liked to see X-31 technology in EFA. But program slips have pushed up the (X-31's) initial flight date too far for any technology to be utilized now,"
 

F-14D

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mz said:
I meant TVC as an upgrade for the Eurofighter, keeping the canards, so not that much reliability issues. Even in the Flugwerft Schleissheim museum, X-31 and Eurofighter sit side by side, even look somewhat similar and it's a no brainer to think of it. What program were the Germans then going to apply their lessons from the TVC testing to, if not Eurofighter? It's not as if there are a bunch of modern fighter designs flying around in Germany? Exactly one.
Hence it's a bit of a surprise for me that this is presented as something of a new idea... :p

This from January 1990:
http://www.highbeam.com/doc/1G1-8333425.html
It is possible that technology gained by West Germany's MBB from its joint X-31 aircraft R&D program with Rockwell International, will be used for EFA's production-run updates, a German official tells Defense Daily. "Originally, MBB would have liked to see X-31 technology in EFA. But program slips have pushed up the (X-31's) initial flight date too far for any technology to be utilized now,"


It seems that the increased efficiencies hoped for come from independently varying the throat and exit areas. That can probably achieved without the complexities of actually vectoring the thrust.. So, what benefit does the thrust vectoring itself give Typhoon? It gives one more control mechanism in case of combat damage, but is that worth the cost? With modern fly-by-wire you can have the other control surfaces make up the function of the damaged one, to a certain extant, and a serious hit by a missile is going to make that academic, anyway. The other benefit is the ability to further point the nose away from the line of flight, something Typhoon already does quite well. At medium to long ranges, that isn't of any real value. For the short to medium ranges, in these days of Helmet Mounted sights and high off-boresight targeting and weapons (which didn't exist when serious investigations of TVC first began), a lot of the value of that has been reduced.

So the question has become, now with the introduction of other technologies is TVC worth the cost to Eurofighter?
 

mz

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F-14D said:
mz said:
I meant TVC as an upgrade for the Eurofighter, keeping the canards, so not that much reliability issues. Even in the Flugwerft Schleissheim museum, X-31 and Eurofighter sit side by side, even look somewhat similar and it's a no brainer to think of it. What program were the Germans then going to apply their lessons from the TVC testing to, if not Eurofighter? It's not as if there are a bunch of modern fighter designs flying around in Germany? Exactly one.
Hence it's a bit of a surprise for me that this is presented as something of a new idea... :p

This from January 1990:
http://www.highbeam.com/doc/1G1-8333425.html
It is possible that technology gained by West Germany's MBB from its joint X-31 aircraft R&D program with Rockwell International, will be used for EFA's production-run updates, a German official tells Defense Daily. "Originally, MBB would have liked to see X-31 technology in EFA. But program slips have pushed up the (X-31's) initial flight date too far for any technology to be utilized now,"

It seems that the increased efficiencies hoped for come from independently varying the throat and exit areas. That can probably achieved without the complexities of actually vectoring the thrust..

I think it also reduces trim drag if you vector it right in cruise, enabling higher supercruise speed or lower fuel consumption. Think Piaggio Avanti style where the three lift surfaces can be configured for minimum cruise drag, which would not be possible with two (at least not in a stable design AFAIK). This should be nothing new. AFAIK designers make compromises when setting the ordinary fixed engine exhaust angle - with thrust vectoring you can tailor it optimally for each flight situation. Takeoff, landing, cruise... This all coming from a basic physics / mechanics approach, I might be wrong.

So, what benefit does the thrust vectoring itself give Typhoon? It gives one more control mechanism in case of combat damage, but is that worth the cost? With modern fly-by-wire you can have the other control surfaces make up the function of the damaged one, to a certain extant, and a serious hit by a missile is going to make that academic, anyway. The other benefit is the ability to further point the nose away from the line of flight, something Typhoon already does quite well. At medium to long ranges, that isn't of any real value. For the short to medium ranges, in these days of Helmet Mounted sights and high off-boresight targeting and weapons (which didn't exist when serious investigations of TVC first began), a lot of the value of that has been reduced.

So the question has become, now with the introduction of other technologies is TVC worth the cost to Eurofighter?

That's another question by itself. But it really doesn't seem that complex of a technology for me. The mass is small, and the loads are always in the same direction. Compared to something as fundamental as variable geometry wings, it's much much less of a gamble in my view.

What big Europe really seems to lack compared to USA is stealth. Might be other areas too. But that's a much more expensive thing then...
 

Scorpion82

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mz said:
All of this is not rocket science and is a basic effect of thrust vectoring... Why wasn't it done / researched earlier? A money or political question?

TVC was actually part of MBBs early design concepts (TKF90) throughout the 70s. That this concept was working has been demonstrated with the X-31 and ITP and MTU started with work on a 3-D TV nozzle as early as 1994. The nozzle was extensively tested on the bench rig and even high altitude chamber. The nozzle was able to deflect 23.5° in any direction at speeds of up to 110°/sec. This was long proposed as a potential feature of Tranche 3 aircraft, but there was no operational requirement besides the customers so that the programme didn't progressed any further. At one point RR was working on a 2-D nozzle as well but abondoned it. In the meantime ITP has continued the work and presented the current concept. The reason why TVC wasn't considered before was mainly on cost/benefit grounds. The new nozzle is optimised for minimum weight penalty and low cost, by using as many parts from the existing nozzle as possible. The advantages might now offset the lowered tradeoffs.
 

F-14D

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Scorpion82 said:
mz said:
All of this is not rocket science and is a basic effect of thrust vectoring... Why wasn't it done / researched earlier? A money or political question?

TVC was actually part of MBBs early design concepts (TKF90) throughout the 70s. That this concept was working has been demonstrated with the X-31 and ITP and MTU started with work on a 3-D TV nozzle as early as 1994. The nozzle was extensively tested on the bench rig and even high altitude chamber. The nozzle was able to deflect 23.5° in any direction at speeds of up to 110°/sec. This was long proposed as a potential feature of Tranche 3 aircraft, but there was no operational requirement besides the customers so that the programme didn't progressed any further. At one point RR was working on a 2-D nozzle as well but abondoned it. In the meantime ITP has continued the work and presented the current concept. The reason why TVC wasn't considered before was mainly on cost/benefit grounds. The new nozzle is optimised for minimum weight penalty and low cost, by using as many parts from the existing nozzle as possible. The advantages might now offset the lowered tradeoffs.

It's certainly easier now than it was. Unquestionably a Typhoon with TVC will be able to point the nose better than one without. The central issue in 2009/2010 still remains, though. The other efficiencies discussed in the article can be achieved without actually vectoring the thrust The mechanism for vectoring the thrust can now be simpler and lighter than before, but it still adds weight and complexity to maintenance and more software to flight control laws. Given that high off-boresight targeting and weaponry removes much of the need to point the nose more than the Typhoon's already dramatic abilities and that increasing air-to-ground capabilities is rightly a much higher priority for the funds available to enhance Typhoon, is it worth it to go all the way to TVC?
 

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At only 88 pounds per engine, I doubt you would gain much of a reduction if you were to drop the 3D thrust vectoring capability. I have never worked on a turbofan engine before, but videos of the the F100 family in tests make it it clear that current variable axisymmetric nozzles are already pretty complex to begin with. Maintenance would certainly involve some changes, but I don't know if it would be more difficult and costly once ground crews got used to the change.

Honestly even in a day with high off-boresight missiles I believe we have not seen the last of gun engagements, and if you happen to be firing a medium ranged missile at short range, you certainly want to be facing the target too. Couldn't such thrust vectoring allow for somewhat shorter take-off runs too?
 

F-14D

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Colonial-Marine said:
At only 88 pounds per engine, I doubt you would gain much of a reduction if you were to drop the 3D thrust vectoring capability. I have never worked on a turbofan engine before, but videos of the the F100 family in tests make it it clear that current variable axisymmetric nozzles are already pretty complex to begin with. Maintenance would certainly involve some changes, but I don't know if it would be more difficult and costly once ground crews got used to the change.

Honestly even in a day with high off-boresight missiles I believe we have not seen the last of gun engagements, and if you happen to be firing a medium ranged missile at short range, you certainly want to be facing the target too. Couldn't such thrust vectoring allow for somewhat shorter take-off runs too?

Guns haven't been a major air-tor-air player since before the Vietnam War. While TVC may help a a defensive aid in defending against a gun attack, it would be a minor inconvenience to a highly agile missile (on the other hand TVC in the missile would make a noticeable difference). Even with a medium range missile at short range, TVC on the aircraft isn't going to make that much difference. There's no reason the aircraft's radar sweep or HMS can't "point" out the target to a medium range missile at shorter ranges. TVC on takeoff or landing will be a benefit only if the engine(s) exhaust at the center of lift (ala the original A-6 concept) or you have a canard configuration that has enough control authority at low speeds to balance the nose down pitch action of the TV nozzle (I'm excluding Harrier and F-35B concepts). In fact, given the rapid acceleration that modern fighters can enjoy (and USAF's disinterest in operating from short fields), TVC would mainly be a benefit on landing, providing the operator is interested in short landings.
 

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As stated in the article TVC can be used to reduce trim drag at supersonic speeds and improve thrust output in supercruise speeds. Reducing drag from the control surfaces will cause an overall drop of drag and thereby lower the fuel consumption as well. It's a fully integrated concept, not a simple nozzle with independant controls.
 

red admiral

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The main benefit that is currently being pushed is the reduced fuel burn due to vectoring in cruise, leading to cost savings that'll more than pay for the engine modifications. I doubt that the mod will be proceeded with, especially for the UK. There just isn't the capital available for it. Plenty of more important things to spend the little money available on like integrating Meteor and other stores. Beefing up the strike role with greater fuel capacity.

What big Europe really seems to lack compared to USA is stealth.

It only seems that way because Europe hasn't got any combat aircraft into production in the same timescale as F-22 or JSF. Eurofighter is earlier (but still incorporates enough stealthy features for useful impact). The UK studies that are concurrent with F-22 and JSF are classified, apart from the BAE RF signature model of about a decade ago. Stealth is expensive, in terms of money and performance, but things are going that direction for the future.
 

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