Its not a crazy idea, its a smart idea. There are two things that aim against it, export regulation. These could be overcome but it would require a lot of politics and cooperation.
Second, Europe has NIH syndrome and until reticently were 100% convinced that they were simply superior and would never have even considered it even if the US was open to it.
But not reinventing the wheel on the engines and things like that would make a lot of sense. Its just not practical in the current environment.
Up until severe sanctions started in 2022, Arianespace launched soyuz rockets out of guyana they bought from russia.
Were it not for ITAR, and probably spacex's business model, I'm sure they'd love to buy a bunch of falcon 9s, and barges to go with them. That site would likely be the most payload you could get out of one of those rockets, prograde.
And the thing is, depending on how you do the agreement. Europe could produce the engines themselves, they only would need plans and help with manufacture.
This isn't unprecedented in the space industry. Its how India and China worked with Russian engines. And it also happens between commercial companies.
In case of a complete breakdown of relation Europe could continue to manufacture the engine.
This would allow for in-depended access and still produce jobs in Europe. This could serve for both a large, medium and small rocket. Additionally it could allow for learning to do landing. Also, Europe has a decent second stage engine that they could have combined with that first stage.
Europe has to get away from solid fuel boosters and hydrogen main engines, its totally the wrong architecture and moving away from it would have been smart. Sadly they domed themselves with the Ariane 6 and Vega designs.
If not the US, you could have done the same with something like the RD-191 or something like that.
Second, Europe has NIH syndrome and until reticently were 100% convinced that they were simply superior and would never have even considered it even if the US was open to it.
But not reinventing the wheel on the engines and things like that would make a lot of sense. Its just not practical in the current environment.