Originally Posted by
mr_matt
Drag goes up as a square law. You need 4 times the thrust to go twice as fast.
So all else being equal (very important point), the 42 pounder will only be 15% faster.
I can't guess what ducting would do for drag, but I would never run anything open with one of these giant rectangular cross section fuselages. I myself might make a single duct/bypass, discretely block the other inlet and run a single turbine out one is the outlets.
+1
The extra static thrust would help most with verticals vs straight speed.
With full ducting the EDF Byron F-15 Lock has now goes into the 140s 150s iinm, not sure it can get up there without the ducting.