How effective is the J-20 without the WS-15 ?
I would argue that the current non-supercruise capable J-20 probably would not be able to outperform the F-22 (which would probably be the best fighter plane up until the late 2020's, when the WS-15 version of J-20 and upgraded Sukhoi T-50 become available). However, the J-20 should be able to at least match the performance of the F-35A and have superior combat radius. The F-35A isn't designed to supercruise.The added thrust will increase it gross weight, climb rate, and sustained turn rate, the J-20 is NOT grossly underpowered in its present configuration! In fact the performance appears very good, it will also likely supercruise once the WS-15s are installed
I would argue that the current non-supercruise capable J-20 probably would not be able to outperform the F-22 (which would probably be the best fighter plane up until the late 2020's, when the WS-15 version of J-20 and upgraded Sukhoi T-50 become available). However, the J-20 should be able to at least match the performance of the F-35A and have superior combat radius. The F-35A isn't designed to supercruise.