Thrust is a very dynamic variable. And it changes with altitude and inlet design. At high altitude and high speed, most of the thrust comes from inlets. For mach 2.5 and above, one really needs large, long, spacious inlets that can take lots of air, alongside with various mechanisms inside inlets to manage the air flow. In that regard, J-20 certainly has the potential to have inlets more optimized for high speeds than F-35, for example.
Aerodynamics thread
- Thread starter siegecrossbow
- Start date
@latenlazy That's equivalent to saying the J-20 isn't subsonically maneuverable, though, since the F-16 is an antiquated 4th generation, not 4.5th or 4++, platform. The figures, for me, only make sense relative to the WS-10 / AL-31. When upgraded to WS-15, that should rise up to 9G sustained turn rates at 10k ft, if the F-16 is capable of 7G sustained turn rates at 10k ft at Mach .85.
The F-16 is considered by most to have the best subsonic sustained turn rate of all 4th gen fighters (and the author of the Guancha piece emphasizes how good that's supposed to be by suggesting this makes the J-20 the best gun fighter, even if it doesn't have a gun). I've heard that in sustained turns the F-16 can keep up with the Eurofighter below 10k feet, but putters out a bit above that due to outdated aerodynamics and weaker engines. I don't think it's a stretch to posit that such an altitude limitation isn't as applicable to the J-20, given the other parts of that comment praising its aerodynamics (it includes a blurb about how the J-20 can do near impossible high alpha maneuvers at stall speeds).
Anyways, I won't pretend to be an aerodynamics expert. Nor do I think we should lavish such a conceit upon the author of that Guancha piece. We don't have any flight envelope charts to make hard comparisons, so I'd recommend that we all try to avoid committing to excessive speculations about how different fighters perform relative to one another. I think these two posts from Keypub, by Andraxxus and Peregrinefalcon, are instructive here.
The above is, in fact, another source suggesting that the J-20 may already supercruise with the AL-31, since Total Drag is slightly lower between about Mach 1.0-1.4.
Together with the calculations of the paper from Virginia Tech, as shown in message #2902, there are at least 2 independent sources now supporting the same.
I wouldn’t take the VTech paper seriously. Their model looks woefully simplistic and imprecise to the J-20’s actual geometry, and there are no control comparisons to gauge how well it fits with reality.
I don’t believe anything about that paper. I don’t think it tells us anything about the J-20. Rule of thumb for all models is garbage in garbage out, and oversimplified assumptions often generate garbage. This paper might as well not exist.
I do actually. Just look at the physical geometry of the J-20 model they’re using.
Does it look like the J-20 to you? No? You can’t get an accurate aerodynamic assessment of an object if you don’t have an accurate model of that object’s geometry.