Scramjets don't even become operational until mach 5. How would they get this plane off the ground in the first place? The logical answer is a combined-cycle e

Scramjets don't even become operational until mach 5. How would they get this plane off the ground in the first place? The logical answer is a combined-cycle engine, but there are slim pickings here. The X-43 used a combined-cycle rocket/scramjet, but had to be dropped from a B-52. It did hit around Mach 9.6 though The Chimera engine is a turbojet/ramjet engine under active development (it or something similar is likely going to power the NGAD), but it most likely won't go faster than Mach 5-6. They aren't considering a couple important realities though. First, the US government isn't letting advanced engines get put into civilian airplanes. There's just too great a risk of them falling into Chinese or Russian hands and giving their fighter programs a massive leap forward. Second, physics aren't in their favor. A large passenger plane means lots of air resistance and lots of weight. Getting all that moving at Mach 2 in the Concorde was a huge task on its own. Moving up to Mach 9 increases the number of issues exponentially. It takes decades to get this working with a tiny plane (eg, all the NASA experiments). The time to scale that up would be even more. Third, there is ZERO economic possibilities here. The total SR-71+A-12 development costs have been estimated at around $16.5B dollars not to mention $200k per hour to fly. Let's say this company makes 100 of these planes at a similar cost (despite them being much more exotic and larger than the SR-71). The planes will cost $165M each and probably only hold less than 30 passengers/crew. If they are selling 25 tickets and flying that 1-hour flight at $200k/hr, tickets would cost $8,000 just to cover operating expenses. If they expect 20,000 flight hours per plane, that's an additional $8,250 per ticket. I'd guess minimum ticket price would be about $25,000 using these numbers. But in reality, there's not a market for 100 of these planes. The R&D costs would probably be much higher and the cost per flight hour would certainly be massively higher too. It's all snake oil.