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> an aerospike-based Starship wouldn't need both vacuum and sea-level engines and could use the same engines in space as it would use to land. In vacuum, an ae
by Tuna-Fish 5y ago
> an aerospike-based Starship wouldn't need both vacuum and sea-level engines and could use the same engines in space as it would use to land.
In vacuum, an aerospike will not be as efficient as a maximally expanded traditional nozzle. If you could conjure an aerospike raptor from thin air, you'd still probably want the vacuum engines there, but you'd of course want to replace the sea-level ones with the spikes for higher efficiency immediately after stage sep (when all 6 are firing).
- panick21_ 5y agoI agree, but I don't think its worth it. At sea-level you rather have a sea-level optimized engine then a spike as I understand. So you would actually lose landing efficiency, and that is the most important place to save energy. I'm not even sure if Starship will light all 6 engines on separation. Its a question of gravity loses vs lower ISP of sea-level engine. Maybe they turn them on for a initial boost and then turn the center 3 engines off.
- rbanffy 5y ago> immediately after stage sep (when all 6 are firing) And don’t forget the landing. Aerospikes are easier to justify if you are doing a propulsive landing.