You can watch them kick in on the telemetry (which goes from "100%" to "A/B" for all three engines) at the bottom of the video around the 58:35 mark. https://www.youtube.com/live/-qisIViAHwI?feature=shared&t=35...
1: Well, their Plan B intended engines. Their Plan A was that one of the Big 3- RR, PW, GE- would make engines for them, but none were interested in taking the risk that a difficult engine could be designed and built in enough volume to make the investment back.
2: Their biggest legal question is over-land supersonic regulations. Their biggest economics question- and probably the biggest and most important of all of them- is how much will people pay for civil supersonic?
Do we know how much more it's likely to cost? I could easily see people paying 1.5x - 2x.
Anything beyond 2x I imagine would start to price out the average person and anything beyond 5x would probably price out the vast majority of potential customers.
People pay more than that for domestic first class, which doesn’t even have lay-flat seats. $2,500 or even $5k for a New York <> San Francisco 2-hour flight would absolutely sell.
I don't know if those theorized efficiencies will be delivered (a lot depends on that engine) or if airlines will price tickets at that level. But it's the theory so far.
The original plan was a commercial partner for the engines, but the big three - Rolls-Royce, Pratt & Whitney and General Electric - turned them down. It's one of the biggest remaining question marks in the entire project.
There IS no production plane, nor can there be. The last company they wanted to use for engines dropped them as a client years ago (others did earlier): https://english.alarabiya.net/business/aviation-and-transpor...
