J-20... The New Generation Fighter III

siegecrossbow said:

TVC may not just be good for improving manoeuvrability. Sweetman said that employing the TVC during the cruise phase of the mission will decrease the usage of flight control surfaces and lower the chance of radar detection.

Click to expand...

what I should said was 3D TV or not.

Yes, that's one of the advantage of 2D TVC, you can be in a "Cruise stealth Mode" in your flight control where your try to minimize surface deflection. with 2D TVC that's possible. I mentioned that in Key forum couple days ago, anyways, almost a open secret now.

also good for at really high AOA/low speed you can point your nose, but IMHO when you are at those low speed, you just did something you shouldn't do anyways. you are sitting there like a dead duck with very low energy.
and any one with a decent high off-bore sight AAM can kill you at ease.

for big boys like F-15/Su-27/F-22/T-50/J-20, keep your speed up! that's the ticket for your survival against F-16s and J-10s of the world.

and
I really don't see the advantage of a 3D vs 2D, weight and complexity pentalty for what? so you can size the Vertical fins a little bit smaller? no. not worth it.

i.e. said:

what I should said was 3D TV or not.

Yes, that's one of the advantage of 2D TVC, you can be in a "Cruise stealth Mode" in your flight control where your try to minimize surface deflection. with 2D TVC that's possible. I mentioned that in Key forum couple days ago, anyways, almost a open secret now.

I really don't see the advantage of a 3D vs 2D, weight and complexity pentalty for what? so you can size the Vertical fins a little bit smaller? no. not worth it.

Click to expand...

Yes. Well then it's a shame we haven't heard or seen anything about the chinese testing 2D tvc nozzles.

If 3D is so much more complex than 2D tvc why did the russians opt for the former on most export fighters and only tried the latter on a few testbeds? :/

Bltizo said:

Yes. Well then it's a shame we haven't heard or seen anything about the chinese testing 2D tvc nozzles.

If 3D is so much more complex than 2D tvc why did the russians opt for the former on most export fighters and only tried the latter on a few testbeds? :/

Click to expand...

true 3D nozzles (what I really meant is axis symmetric) will come into being when next generation fighter comes, high performance and no vertical tail.

a good 3D axis symmetric demand some pretty nasty plumbing for the actuation, the stuff Russians put in MKI's engine uses fuel pressure I believe. not exactly a good solution as the pressure is not enough. and I think it is only 2D. no?

of course you can go for paddles (shinshin, x-31) but loss in thrust is too much.

a 2D round nozzle is much simpler.

Also
while we are on MKI.

our indian friends prob don;t like to hear this,

but.
I just read some material which led me think that,
The stall barrier system that MKI's flight control has is much less sophisticated than J-10's

J-10 has a true AOA Limiter, where pilot can pull full aft stick in normal conditions and get to ragged edge of aerodynamic performance, and still not worry about getting over the edge. (Lei Qiang has some description on how to defeat the system, system like this that can always be defeated, what's remarkable is, if the description is correct, it is a pretty hard and sophisticated system to defeat. and on par with the absolutely the state of art in the west, kudos.).

MKI as far as I can tell has a stall barrier system that relies on increasing stigck pressure, it is not truly controlling up to the aerodynamic limit of the aircraft. almost like stick pusher in old civil air liners.

IMHO, when in a close in dog fight. I rather be in a J-10. it is much more forgiving.

don;t bring this up over in Keys though, will get banned real quick.

erased double post.

i.e. said:

I am just happy with a bigger engine. TV or not.
Bigger engine... higher top speed. more war loads.

Click to expand...

Bigger engine=/=top speed (unless you mean that more thrust can overcome airframe drag to more closely reach exhaust impulse)/

i.e. said:

I really don't see the advantage of a 3D vs 2D, weight and complexity pentalty for what? so you can size the Vertical fins a little bit smaller? no. not worth it.

Click to expand...

3D might marginally open maneuvers and flight envelopes 2D couldn't.

latenlazy said:

3D might marginally open maneuvers and flight envelopes 2D couldn't.

Click to expand...

latenlazy said:

3D might marginally open maneuvers and flight envelopes 2D couldn't.

Click to expand...

where?

At high aoa low speed conditions where one can argue that they can save some vertical tail size
also at high speed one can argue again one can use 3-D nozzle to generate side force and yawing moment for artificial directional stability. thus save some rudder and Vt size. or even get rid of it.


that is about it.

but to take advantage of those drag/weight savings fully by removing the Vertical Tail, they have to absolutely sure one can use them all the time or else everytime they don't work, the user is looking at a airframe loss.

so unless one is prepared to fully ditch the Vtail and really capitalize/invest in a high-availblity 3-D nozzle. it is not worth it yet.

i.e. said:

where?

At high aoa low speed conditions where one can argue that they can save some vertical tail size
also at high speed one can argue again one can use 3-D nozzle to generate side force and yawing moment for artificial directional stability. thus save some rudder and Vt size. or even get rid of it.


that is about it.

but to take advantage of those drag/weight savings fully by removing the Vertical Tail, they have to absolutely sure one can use them all the time or else everytime they don't work, the user is looking at a airframe loss.

so unless one is prepared to fully ditch the Vtail and really capitalize/invest in a high-availblity 3-D nozzle. it is not worth it yet.

Click to expand...

I agree. The key word in that comment was marginal. I could also see a sophisticated 3D TV aid complex maneuvers while climbing, but a lot of this is FCS specific, and the software--and even hardware (mechanical responsiveness)--challenges may be difficult to overcome.

latenlazy said:

3D might marginally open maneuvers and flight envelopes 2D couldn't.

Click to expand...

I think that as the Indian's found out during Red Flag, opening those envelopes have steep costs as they loose speed and power miserably fast when doing it, and ended up as sitting ducks to 'enemy' guns.

Its about as useful as the cobra or the F22 'hover' trick is in real combat. If you try it, you better have your hands on the ejection handle as chances are you will be needing it real quick.

The biggest operationally relevant use of TVC is to improve supersonic maneuverability, but 2D is more than sufficient for that, and canards probably achieve a similar goal anyways.

The WS15 is still easily half a decade away, if not further off, that is plenty of time to develop a suitable stealthy engine nozzle, even if it isn't TVC. In the meantime, CAC and the J20 has plenty of more important things to do than worry about such a small detail that can be addressed later when the final operational engine is ready for integration.