The center of gravity is not the same as the center of lift.
J-20... The New Generation Fighter II
- Thread starter Asymptote
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Engineer
Major
Does any of these have anything to do with the fact that SR-71 is longer than F-22 and could significantly fly faster? No it does not. Does any of these have anything to do with the fact that Mig-25 is longer than F-22 and could also fly sigificantly faster? Again it does not.
Which brings us back to the problem: your argument about a plane being longer results in more drag thus lower top-speed is flawed. Top-speed, as you have even admitted yourself, does not depend solely on length of the aircraft. You thus cannot conclude that J-20 would be slower than F-22 based on their length.
MiG-29
Banned Idiot
now it does not, and it has rounded nozzles, rounded nozzles keep thrust well, flat nozzles lose thrust, but cool better the exausting gases, then the IR signature on the J-20 is higher as well its Radar cross section.
the main point will be is the J-20 going to supercruise?
being larger and heavier with less powerful engines and larger radar and IR signatures than the F-22 and still do you think it is a match for the F-22?
it is also easier to spot at naked eye
Engineer
Major
This does not alter the fact that you have no information about the aerodynamic center of the aircraft, thus precluding from making any conclusion regarding the longitudinal stability.
MiG-29
Banned Idiot
my statement is simple, it has less thrust than the F-22, it is bigger and larger, has larger cross section and can not be all composites so it has similar at best construction technics than the F-22, it has canards that add more drag than tailplanes that is the reason it uses a delta wing with lower drag, how it will be lighter and have similar performance?
Engineer
Major
The canards, vertical fins, and in the future thrust vectoring will be used in pitch control. But these are irrelevant with regards to radar signature, because radar signature is optimized for when the aircraft is in criuse where flight controls deflection is minimal.
Engineer
Major
Your statement does not have anything to back it up. You have no information regarding the current available thrust on the J-20 prototype, nor do you have any information on the final achievable thrust once WS-15 engines are fitted. Your claim that J-20 has larger cross-section contradicts your own earlier statement about J-20 having similar cross-section as the F-22. You also do not have information regarding the drag coefficient on either the J-20 or F-22 for you to make comparsion regarding the top-speed between the two planes. Finally, no one here claimed J-20 is ligher than F-22. It's only you right now who are desparately claiming that J-20 is heavier and slower, and you have no proof to back it up.
MiG-29
Banned Idiot
uhmmm i see now you will claim it is superior to the J-10, the J-10 and Gripen have wings closer to the center of gravity than the AJ-37 Viggen and J-20, therefore the J-10 and Gripen are highly unstable and their canards are not as loaded as the canards on the J-20 and Viggen
The only advantage of the J-20 over the J-10 is the use of a V tail that can be used as pitch control, this will allow a triplane type configuration but will increase drag, as long as the J-20 remains hidden from the J-10 is an advantage, but a J-10 with 3D vectoring nozzles will beat a J-20 in close combat.
The AL-31 gives the J-10 a TWR near 1:1 and higher at combat weight, the J-20 won`t have a 1:1 TWR at max weight and at combat weight will have lower TWR than the J-10
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Engineer
Major
It will have to for it to be considered a 4-th generation fighter.
You have no proof that J-20 is heavier, no proof that the production version will have less powerful engines, no proof that J-20 has significantly larger radar signature and IR signature.
The J-20 seems to have silver coated nozzle petals. The petals look very similar to another kind of IR reducing stealth technology we saw on the stealth blackhawk used to nab Bin Laden. We also know there are multiple types of IR suppressing solutions. For example, the YF-23 didn't use flat nozzles but an exhaust lined with ablative tiles and air cooling vents.
Stealth copter picture here:
Supercruise is determined by aerodynamic design and specific exhaust velocity without afterburners, not the overall thrust. There's a reason why the F-35 can't supercruise. The T:W ratio of the plane (and therefore its maximum thrust and weight) has nothing to do with whether it can cruise at supersonic speeds.
We do know for a fact that as of right now the J-20's engine is an interim engine. The WS-15 which is intended for the J-20 is still being developed. Also a larger radar array (especially if it's an AESA) is probably better not worse (but it also depends on the T/R module sizes). Finally, which plane is better is not something you can eyeball. Heck, it's not even something we can assess just by knowing the exact specifics of each design. It's about the overall system which the planes are situated in, including support, and weapons systems.
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