Trident is arguing that the length of the divergent section of the nozzle in Convergent-Divergent can affect thrust efficiency, specifically that shorter divergent sections sacrifice thrust loss. His argument is that TVC nozzles in the form and style of the EF (which Trident puts in the same category as the WS-10’s) saves weight and complexity but penalizes thrust, while a ball pivot as used by Saturn’s AL-31s preserves thrust but has greater weight and complexity. I’m questioning whether the divergent section (which, typically speaking and seems to be the case here judging by the pictures, starts around where the nozzle petals start) of the TVC version of the WS-10 is really shorter than what we see in other engines with convergent divergent nozzles.Ähhhm, maybe in case I missed something, but are you guys really comparing a non-TVC-AL-31-nozzle with the TVC-WS-10-nozzle??
Why?
J-10 Thread IV
- Thread starter Jeff Head
- Start date
Dizasta1
Senior Member
Well that just about settles the argument in so far as Pakistan Air Force is concerned. What could J-10s offer that JF-17s don't except for extra range.
A J-10 with AESA & TVN is something JF-17 has no change of matching. If Pakistan Air Force is ever to actually pursue a Gen-4+ procurement, once JF-17 Block-lll production run commences. Then I would say that J-10s with AESA+TVN would be the first choice, no question about it. Subject of course, China's approval of the sale.
I don't think they plan on putting TVNs on production model J-10s. The J-10B used for TVN testing is obviously a tech demonstrator for future J-20 (J-20B/C) variants.
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.
I’m glad we’re on the same page about qualifying length though from what I can tell, if the WS-10 TVC divergent section is shorter than the AL-31F’s it’s not by much. On the technical details I don’t think we’re actually that far off in our technical understanding of where the TVC WS-10 strikes its balance between weight and thrust penalties. It’s a matter of qualifying how much thrust loss or weight gain is “a lot” and how much is “minimal”, and without measurements and numbers I don’t think either of us can say.
Most likely strain gauges and associated wiring bonded to the skin to measure aeroelastic response. With TVC, this aircraft will reach much higher angles of attack than taken into account during its design, exposing the airframe to patterns of separated airflow and resulting excitation of structural oscillations it was not originally supposed to experience.
I thought it had something to do with the different forces the wings would experience with TVC flight characteristics but hadn’t thought of strain gauges. My first thought was maybe some changes in the internal wing structure but strain guages probably make more sense.
Besides "strain gauge", could it be air pressure sensor? I have seen such sensor as thin as the old camera film.