That's OK. We all know this is a very challenging business.
Thanks, ... so by now we have actually "only" 4 confirmed aircraft, since '20001' became 781, and then we have 783, 785 and now 788.
The problem with these serials is that they are simply no Xi'an c/n's. The first serials '20001' was such a number but right after this first prototype was assigned to the CFTE it gained a CFTE-serial similar to the many other's we know: the Tu-204C testbed for the J-20 with serial 769, the famous Y-8-radar testbed 079, the KJ-500 '737', the Y-8GX-6 '731' and '732' even the new Z-20 has the serial '632'.
As such the new prototypes usually get numbers within a series/row if they are of the same type of aircraft, so no. 01 Y-20 = 781, no. 03 Y-20 = 783 and most likely no. 02 Y-20 would have been = 782 if it was not the static test frame.
So is anything known about these missing numbers 782, 784, 786 & 787 ?? were they just skipped similar to J-20 '2014' or are they even very different types with these numbers at the CFTE ?
Deino