/sci/ - Science & Math

>>16096295
I guess you could build a worse version of Starship that uses simpler gas generator engines. It used to be Relativity's plan with Terran-R. It is similar to CAS Space's plan with Kinetica-3. They say 1.5MN kox engines (GG or ORSC, they don't say), diameter 6.6m, liftoff mass ~1,950t, payload 20t. Although they don't have any hardware for it yet; they just have a rough notional render.

However, with a worse engine, your payload mass will be worse. This is especially painful when so much mass on your upper stage is already dedicated to reusability. So the benefits of full reuse become a lot less. I also think an FFSC engine is very beneficial for long engine life, quick turnaround and minimal refurbishment, because it sidesteps the issue of interpropellant seals starting to leak, and turbopumps can run at lower temperature and pressure.

So such a half-way solution with GG engines might be hard to justify if you have to face direct competition from SpaceX. And that kind of investment into reusability would still be hard to justify unless you have a large amount of guaranteed payloads that are safe from competition from SpaceX, allowing you to have the high cadence that lets you to reap greater benefit from full reusability than the price you pay for it.

>>16056605