I think the bigger question is whether either of them will make the business deal with Boom, or if they both deem it too risky and too expensive.
Going back to the analogy from before, you can go to companies which specialize in chip design and development, and you can pay them to design a chip that will meet your specifications and make it in small quantities. It is economical for these companies to keep the technical staff and equipment on hand for this highly specialized work, because they use them for more than just one AI startup's need.
Perhaps an easier analogy would be legal services: every startup needs them at some point or another, but it doesn't mean every startup needs to or should build up an internal legal team. You hire the pros when you need them, and since you're not their sole source of income they can maintain a much better legal staff than you could every support internally. Even for companies where legal expenses are frequent, if the legal services are merely enabling something else then you still shouldn't be a law firm.
Likewise, Rolls Royce has years of engine development experience, it has the tools to manufacture and test prototypes, and it has the facilities for mass production already, and it uses those same expertise and tools for many product lines serving a wide swath of the aviation market such that no one aircraft needs to pay for it all. For Boom to acquire this same capability would be orders of magnitude more expensive than paying RR to do it for them.
The deal has not fallen apart because the development can't be done or because RR doesn't have the capability to do it; the deal has fallen apart because boom is unwilling to pay whatever price RR has named for it providing this service. Boom didn't decide to build the wrong thing, they are just unwilling to pay a required business expense.
We don't know why the deal has fallen apart. We just know that it has. There is no engine. No one is planning on developing it. No amount of argument here on HN will change that. Boom should have built the engine if they wanted the engine, instead they bet their startup on buying something not available for sale.
Sure RR would love to do preliminary investigation. But what is the opportunity cost for RR to design and manufacture these engines versus devoting those resources to engines for Boeing and Airbus? How many of each does it project it can sell? What harm would it do to RR if it were to fall behind P&W on jet engines for commercial jets?
And having a civilian suoersonic turbofan engine nobody needs or wants doesn't get a comoany anywhere.
