Thrust Vectoring for stealth fighters does it matter for China`s new J-20 and J-31?

Originally Posted by MiG-29

The use of an independently controlled divergent section
allows A9 to be optimised for any engine running condition
at any flight point, and has an improvement especially in
those conditions where one-parameter A9/A8 Ratio is not
optimized.
For example, for a supersonic cruise case (Mach 1.2, altitude
36,000 ft, engine at Max Dry condition) of EJ200 engine on
Eurofighter, the use of independent A9 control could lead to
an improvement of up to 7% in installed net thrust relative to
the current performance. This is due to the combination of
two effects: increase of nozzle internal thrust; and reduction
of nozzle external drag.
In addition to thrust increase, independent A9 control also
permits reduction in SFC for certain flight pointshttp://ftp.rta.nato.int/public//PubF...051-PSF-11.pdf



Mission Performance:
Reduced take off & landing distance.
Increased thrust and reduced fuel consumption by means of afterbody drag reduction at supercruise conditions and nozzle exit area optimisation for the whole flight envelope

ITP. Aeronautical engines and turbines manufacturer > Vectoring nozzle

read the whole papers kyanges

Are they saying they can change the shape of the nozzle to reduce external drag and provide optimal "nozzle exit area"?
If that IS what they're saying, I'm quite sure that all modern jet engines can do that.

there are somw fighter aircraft that does not need TVC,such as typhoon or F-16.
these aircraft are already highly manuever,adding TVC could do more harm to the pilot when attempting pull high G turn,creating a "black out".
problably why we do hear any news about TVC for J-10 .

Originally Posted by jobjed

Are they saying they can change the shape of the nozzle to reduce external drag and provide optimal "nozzle exit area"?
If that IS what they're saying, I'm quite sure that all modern jet engines can do that.

not all jet engines do thrust vectoring niether all thrust vectoring is the same
if you watch minute 7 of this video up　to minute 9 you will see Mikhael Pogosyan saying lower IR signature for the flat nozzle 2D but this system reduces thrust, for such a reason Russian fighters use axisymmetric nozzles but they pay with higher IR signature than F-22`s

Thanks for the links. I'm working through them now.

Originally Posted by MiG-29

not all jet engines do thrust vectoring niether all thrust vectoring is the same
if you watch minute 7 of this video up　to minute 9 you will see Mikhael Pogosyan saying lower IR signature for the flat nozzle 2D but this system reduces thrust, for such a reason Russian fighters use axisymmetric nozzles but they pay with higher IR signature than F-22`s

I'm not quite sure you get me, I asked whether the article meant that TVC increases thrust because it can change the shape of the nozzle, not whether all jet engines have TVC. The way I interpreted the article was that TVC increases thrust because it provides the optimal shape for air to produce thrust when exiting the engine. In that case, every modern jet engine can do that as seen here with this F-15, which can enlarge its nozzles for high thrust etc. F15 Rapid Ascent.mpg - YouTube

all fighter jet engines can modify the radius of its nozzles.

Originally Posted by jobjed

I'm not quite sure you get me, I asked whether the article meant that TVC increases thrust because it can change the shape of the nozzle, not whether all jet engines have TVC. The way I interpreted the article was that TVC increases thrust because it provides the optimal shape for air to produce thrust when exiting the engine. In that case, every modern jet engine can do that as seen here with this F-15, which can enlarge its nozzles for high thrust etc. F15 Rapid Ascent.mpg - YouTube

The TVC nozzles on the F-15 ACTIVE change shape as they vector thrust. (See below) However the flat nozzles of the F-22 are optimized for signature reduction so there may be a reduction in what pure thrust they can deliver. Tradeoffs




F-15 ACTIVE on a test stand showing its 3D Pitch Yaw Balance Beam Nozzles (P/YBBN). These nozzles are mounted on the stock F100-299 engines and provide 20 degrees of thrust vectoring in any direction.

And thank you MiG-20 for the new thread

Originally Posted by jobjed

I'm not quite sure you get me, I asked whether the article meant that TVC increases thrust because it can change the shape of the nozzle, not whether all jet engines have TVC. The way I interpreted the article was that TVC increases thrust because it provides the optimal shape for air to produce thrust when exiting the engine. In that case, every modern jet engine can do that as seen here with this F-15, which can enlarge its nozzles for high thrust etc. F15 Rapid Ascent.mpg - YouTube

Originally Posted by Vini_Vidi_Vici

all fighter jet engines can modify the radius of its nozzles.

You guys nailed the point.

Thrust vectoring works by manipulating the direction of thrust, not the nozzle's exit area. Variable convergent-divergent nozzle works by changing the exit area, but not the direction of thrust. You can have both on an engine, but MiG-29 is being very disingenuous by misrepresenting a function of a variable convergent-divergent nozzle as that of TVN.

Originally Posted by NikeX

The TVC nozzles on the F-15 ACTIVE change shape as they vector thrust. (See below) However the flat nozzles of the F-22 are optimized for signature reduction so there may be a reduction in what pure thrust they can deliver. Tradeoffs



F-15 ACTIVE on a test stand showing its 3D Pitch Yaw Balance Beam Nozzles (P/YBBN). These nozzles are mounted on the stock F100-299 engines and provide 20 degrees of thrust vectoring in any direction.

And thank you MiG-20 for the new thread

Here is a video of the changing nozzle on a regular F-100 engine. No TVN is necessary to accomplish this.

Originally Posted by Engineer

You guys nailed the point.

Thrust vectoring works by manipulating the direction of thrust, not the nozzle's exit area. Variable convergent-divergent nozzle works by changing the exit area, but not the direction of thrust. You can have both on an engine, but MiG-29 is being very disingenuous by misrepresenting a function of a variable convergent-divergent nozzle as that of TVN.

That was exactly my point.

Around 97/98 I saw some amazing "Discovery Wings" programs that showed some amazing footage of the F-15 ACTIVE nozzles but never got to see the ever again Not even on YouTube But, fortunately there some F-16 MATV footage.

NF-16, F-16 VISTA/MATV : Link-1, Link-2,

@Engineer: I think you can see in the following diagram and pictures a convergent / divergent nozzle being used to do thrust vectoring. And I believe that this type of system MiG-29 was referring to

Notice how the nozzle changes shape as it cycles through its thrust vectoring routine

It seems PRC has been messing around with TVC nozzles at least since 1995. Some stuff I collected from the WWW :

Mid 90s 2D nozzles :



Early 2000s 3D nozzles :




2010+ 3D nozzles :

Originally Posted by NikeX

@Engineer: I think you can see in the following diagram and pictures a convergent / divergent nozzle being used to do thrust vectoring. And I believe that this type of system MiG-29 was referring to

Notice how the nozzle changes shape as it cycles through its thrust vectoring routine

See my reply in post #9.