That tumble roll is *really* interesting.
J-20 5th Generation Fighter VII
- Thread starter siegecrossbow
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Climb when rolling
J-20s from 1st Brigade allegedly training at Gongmiaozi AB in Inner Mongolia while home base near Anshan under renovation.
Begging the PLA to let the J-20 fly a different routine.
L
To help illustrate just what an impressive display of control authority this is, imagine this maneuver going in the reverse direction, where the J-20 is descending instead of climbing. The basic control dynamics should be more or less identical, but in the descent direction you have gravity providing you the energy for the maneuver and you only need to recover enough lift to control your nose pointing. For a climb you have to be able to sustain enough lift at the stall limit to keep initiating the climb while also having enough energy and control authority to keep executing the rolls against gravity. We knew that in theory the J-20 was supposed to have controllability at very high angles of attack while preserving good control characteristics even without TVC, but this display is a subtly stunning demonstration of this attribute.
Coincidentally this maneuver also closes the loop on the other maneuver we saw earlier in the week where the J-20 looked like it did a very low speed flip at high angle of attack before recovering to level and flying off. In fact that maneuver is exactly the same maneuver as this one, except executed at much lower speed and with a slower climb, thus without the momentum to do the sustained rolls that we saw at the air show. That video was probably in actuality showing us the pilot practicing this maneuver for the show, and either they were intentionally going at slower speeds just to practice the controls for the maneuver, or what we saw was a failed example of that maneuver where the pilot didn’t collect enough speed and energy before the climb to do more than one roll.
Yeah this article mirrors a lot of my observations about this maneuver. It’s actually not that visually striking to an average person but if you think carefully about what’s going on with the plane’s kinematics it’s kind of a holy smokes moment. Normally when you try to execute a sustained roll at such a high angle of attack you’re hugging the stall limit if not going past it, and when you hit that limit the nose wants to dip down. You’ll typically lose altitude and pitch angle in that situation and the subsequent roll after is used to recover the plane. The J-20 here seems to be engaging in that kind of behavior *but it keeps climbing while recovering its angle of attack* as it continues each subsequent roll maneuver.
To help illustrate just what an impressive display of control authority this is, imagine this maneuver going in the reverse direction, where the J-20 is descending instead of climbing. The basic control dynamics should be more or less identical, but in the descent direction you have gravity providing you the energy for the maneuver and you only need to recover enough lift to control your nose pointing. For a climb you have to be able to sustain enough lift at the stall limit to keep initiating the climb while also having enough energy and control authority to keep executing the rolls against gravity. We knew that in theory the J-20 was supposed to have controllability at very high angles of attack while preserving good control characteristics even without TVC, but this display is a subtly stunning demonstration of this attribute.
Coincidentally this maneuver also closes the loop on the other maneuver we saw earlier in the week where the J-20 looked like it did a very low speed flip at high angle of attack before recovering to level and flying off. In fact that maneuver is exactly the same maneuver as this one, except executed at much lower speed and with a slower climb, thus without the momentum to do the sustained rolls that we saw at the air show. That video was probably in actuality showing us the pilot practicing this maneuver for the show, and either they were intentionally going at slower speeds just to practice the controls for the maneuver, or what we saw was a failed example of that maneuver where the pilot didn’t collect enough speed and energy before the climb to do more than one roll.
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Indeed, it is interesting and even if some surely will claim it is nothing in comparison to the Su-57 or F-22 it is anyway a first IMO:
If I'm reading this correctly then for the first time the PLAAF took the J-20 a little more "off the leash" at the 2022 Changchun Air Show after all previous flight displays were rather tired flybys:
here a different video of the same maneuver
If I'm reading this correctly then for the first time the PLAAF took the J-20 a little more "off the leash" at the 2022 Changchun Air Show after all previous flight displays were rather tired flybys:
here a different video of the same maneuver
Yes, I think definitely the first time they’ve let it off the leash a bit more. I think this maneuver is actually not the lesser of what we see with the Su-57 or F-22 in terms of showing the plane’s flight characteristics, and in some ways may be more impressive since it’s doing this without TVC, even if it’s not as visually attention grabbing.
Not sure if this link works but here’s yet another angle. I think this one shows just how aggressive the maneuver is a bit better than the others.
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