Originally Posted by
ORAC
Easier, and better, to start with a clean sheet of paper and design an aircraft around modern engines and avionics - with an open architecture - to meet the required specifications.
Maybe. Maybe not. USN scaled up the classic Hornet to get the Super Hornet and it looks like they're going to keep improving the Super Hornet and keep it in production for another decade or so. And the B-21 by all reports appears to be a down scale of the
original B-2 bomber design. (By original I mean the design Northrup came up with decades ago as a high altitude penetrator and then USAF bastardized to give it a low altitude penetration capability.) So clearly there's much to be said for using a mature, known design over an all new clean sheet design. And you don't need a clean sheet aircraft design to use the most modern engine technology available. The same goes with avionics. A mature airframe design can employ both a leading edge engine design as well as leading edge avionics.
And perhaps the best argument for using a mature airframe design is production. The biggest headache in any new aircraft design is maturing the production systems, including all the suppliers.