Simultaneous development of two stealth fighters indicates the allocation of enormous resources by China. But if the country is to continue to catch up to Western fighter technology, it probably cannot afford first to get the J-20 into service and then to move on to a smaller aircraft as a replacement for Chengdu’s J-10. The J-10 began large-scale entry into service in 2006 and is unlikely to be considered fit as a first-rank aircraft in the late 2020s.

Also, China will want a domestically built fighter for the aircraft carrier it is now testing, as well as any follow-on ships. The J-20 is probably too large for carrier use. On the other hand, views of the truck-hauled object suggested that the Shenyang fighter had only a modestly sized wing; carrier aircraft need relatively large wings. Conceivably, a big-wing carrier version of the new fighter could be built, like the F-35C.