J-10 Thread IV

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Tirdent

Junior Member
Registered Member
While the J-20 and J-10 share a canard aerodynamic layout, there's also the engine installation to consider. On a twin engine aircraft you can use TVC asymmetrically for roll control, but the J-20 with its closely spaced engines is possibly too different from a Flanker for this to matter.
 
T

Tirdent

Junior Member
Registered Member
taxiya said:
Besides "strain gauge", could it be air pressure sensor? I have seen such sensor as thin as the old camera film.
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I've seen that kind of thing done on a British Typhoon prototype (I believe it was DA2), but they plastered numerous sensors all over the airframe to characterize the entire flow field - such that they painted the whole thing pitch black, so it wouldn't look like it had some kind of disease. Measuring just a tiny area on the wing tips doesn't really make sense to me for aerodynamic purposes.

EDIT: Yeah, DA2 and about 500 (!) transducers, apparently:

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Air Force Brat

Air Force Brat

Brigadier
Super Moderator
ougoah said:
Butt wouldn't that mean it's better to test it on a Su-27 and J-20 if the TVC is meant to those type of fighters? Wouldn't it be easier to test FCS for the planes the engine is meant for? This indicates it is indeed either also for J-10 or they want to evaluate TVC for J-10.



But we haven't seen one yet where it is deflected during flight. Might be saving it for the show.
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Actually Sino Soldiers does appear to have a slight downward deflection, which would be depitching the aircraft, you wouldn't see a lot of this inflight, unless you were recovering from very high alpha, or
even post stall recovery.

and thank you, this is exactly what I was looking for, as the aircraft is pulled to very high alpha, we should see a large deflection of the nozzle upwards, I'm gonna ck out Siege's practice flight video next.
 
Air Force Brat

Air Force Brat

Brigadier
Super Moderator
siegecrossbow said:
Video of the first practice flight. Pretty dull and disappointing to be frank.

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I just watched Siege's video here, and while it looks like a "snoozer" compared to the F-22 or Su-57 high alpha, low airspeed pass, its not really bad, just not a lot of "hanging it" up on the pipe high-alpha low speed pass? I would remind everyone that the J-10 is a still a 4th Gen airframe, and while OVT is still a game changer, the J-10 airframe may not like those very low airspeeds we see with the F-22, Su-57, even F-35A with no OVT...

All that would change if a couple were installed on the J-20, if indeed the Chinese OVT is 3D like the Russians OVT, but as others have reminded its more to develop FCS rules and coupling's? I will continue to remind all, looping the OVT into the FCS is a lot of work, it is a very complex and precise process, but even once that's done, the airframe on which its installed still has the same aerodynamic limitations, it just that the OVT allows you to "push" the airframe into areas of flight where it would be in trouble without OVT...

OVT on the J-20 would likely provide the kinds of thrill you are expecting Siege, and I do look to see that in coming days, but I'm not sure if the Chinese will find it to be "worth it", as air combat logically seems to have moved away from "super-maneuverability" towards more BVR engagement...
 
by78

by78

General
One more...

(2048 x 1366)
30759086707_74ac88bed2_k.jpg
 
T

taxiya

Brigadier
Registered Member
Tirdent said:
Just to clarify, that's not quite what I mean.

Going by the patents posted earlier in this thread, the WS-10 (unlike the Eurojet nozzle) has separate throat and exit section sync rings like the 'classical' (if you can call it that, given that it never went into production) AVEN/PYBBN design. I merely think it adopts a short divergent section like the PW1120 (as well as F135 and R-79, but ground clearance in STOVL mode was the driver here, a concern which doesn't apply to the WS-10) to save weight.

My point was that combining both the short divergent section and Eurojet's simplified actuation mechanism would yield what is likely the lightest and least complex TVC implementation. All of the designs implemented to date (including the actual WS-10 configuration) probably fall somewhere in between this notional concept and the Saturn ball joint at the other extreme in terms of the thrust penalty versus weight/complexity trade-off.

Also, define 'short' - while I'd estimate the WS-10 TVC nozzle has a shorter divergent section than the AL-31F (which is probably one of the longest out there), it may well be longer than on the F135 or R-79. Short or long isn't a binary thing.
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I didn't really follow your posts and @latenlazy, so I don't know either of yours' position. That said, I searched and found this document from EJ200's TVN designer.
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According to my understanding:
Saturn's ball type TVC has both more weight and thrust penalties

If we focus on 3-D, Con-Di military aircraft TVNs with mechanical actuation, there are several ways to materialize the vectoring:
  • Deflect whole nozzle. The disadvantages arc: a large mass has to be moved; and there is a big impact on performance upstream of the nozzle.
  • External Flaps. The disadvantages are: there is a need for additional mass; and the efficiency of vectoring is very
  • Deflect Divergent section. This is the preferred solution. the size of the nozzle is optimized and the effect on performance is negligible. The ITP Nozzle is of this third type.
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Also, Eurojet is aware of the disadvantage of their design (single combined A8/A9 actuation) compared with independent A8 and A9 actuation.
Depending on the level of control upon this divergent section, variable geometry Con-Di nozzles can be of two types:
  • One-parameter Nozzles: also called I-DOF nozzles; the Convergent section (hence Throat Area) is fully controlled, and Divergent section (hence Exit Area) follows a pre-defined relationship to the convergent section behavior (throat area). The current EJ200 nozzles of this type.
  • Two-parameter Nozzles: also called 2-DOF nozzles; the Convergent section (Throat Area) and Divergent section (Exit area) are fully controlled independently. This type can match the Divergent section to the exact flight [condition in order to obtain an optimized thrust.
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Nozzle Exit Area Control

As described in the Introduction to military aircraft nozzles, in one-parameter Con-Di nozzles the divergent section (hence A9) follows a pre-defined relationship to the convergent section (hence A8). This relationship is optimized for an average of all missions, which normally means low A9/A8 Ratio for dry operations (without reheat) and high A9/A8 Ratio for operations with reheat.

In rough terms, this is reasonably optimized for low speed dry operations (cruise, climb, etc...) and for high speed reheat operations (high speed strike, etc...), but is not optimized for low speed reheat operations (take-off) and high speed dry operations (supersonic cruise).

The use of an independently controlled divergent section allows A9 to be optimized 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.
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I think the J-10 TVC designers choose to not to make any performance compromise if possible. The only compromise compared to Eurojet is increased weight of the A8 actuators.

P.S. Eurojet's TVN has three variants, the split-ring design is one but not the only (final) one. I haven't get time to understand why the "split-ring" improves thrust in certain conditions though.
 
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