The engine we're looking at was for a supersonic cruise missile anyway.... At least before they put better materials in it to make it have an appreciable lifespan. While "simple" intakes can work on slower planes, they're also working their butts off. A variable geometry intake is "easy-ish" to do, and can be designed to be self correcting. The big benefit there is you get some really serious pressure recovery of the air going into the engine, which would do some really good things for range. So... Sonic flight is ok, so long as you're high enough the boom won't reach the ground. I bet, if you could demonstrate the boom was less noisy than say... a C172 at 1500' you'd get permissions opened up all sorts of places. HHHmmmmmmmmmmm So were do we find a billionare who's looking to be a millionare so we can publish plans?