cross-post:
How are Raptor engines restarted in vacuum? Must they use Helium from COPVs, or can they do something else?
The reason I ask is that if they use Helium, then it constrains the number of times the SS can restart its engines before Helium replenishment.
This affects the design of a replenishment depot for SS such as Starship HLS that do not return to Earth.
cross-post:
How are Raptor engines restarted in vacuum? Must they use Helium from COPVs, or can they do something else?
The reason I ask is that if they use Helium, then it constrains the number of times the SS can restart its engines before Helium replenishment.
This affects the design of a replenishment depot for SS such as Starship HLS that do not return to Earth.
Thanks, Jim. As you are aware, I'm not a rocket scientist and I have no clue how hard it is to spin up those turbopumps. Is there extra hardware involved, or is this just an additional capability of the existing turbopumps?
Head pressure
Forgot to add start tanks.
http://www.apolloexplorer.co.uk/pdf/saturnv/saturnv.htmF-1 engine head start (just tank pressure and gravity)
J-2 engine start tanks (tanks reloaded from the turbopump)
Has any "start tank" hardware made an appearance at Boca Chica? For engines the size of Raptor, how much capacity (size and pressure) does a start tank require?