Re:SpaceX Soft Lands Falcon 9 Rocket First Stage
by Gravityloss on Wednesday July 23, 2014 @02:07PM
(#8075898)
Returning to launch site doesn't require that much fuel as the first stage is really light after separation.
Barnaby Wainfan patented an interesting alternative: after staging, re-enter, then do a burn and fly ballistically back to launch site. This kills the horizontal speed with air resistance instead of propulsion, potentially saving fuel. You have to regain the altitude though.
They intend to do a return to launch site--at least eventually. There will be several intermediate steps to prove the system. If it proves unworkable, always landing on a barge is better than not, I guess.
RTLS will certainly require a good deal of margin (by rocketry standards), but first stages usually have some margin already, and SpaceX will have a nice range of options once the F9H comes on line so that they don't have to fly a rocket "fully loaded" except for certain extra-large payloads.
I imagine they can also optimize most flight profiles for RTLS, by sending the first stage more than usually straight up--which is close to the case anyway. Lateral velocity is mostly the job of the second stage.
While it's never been done before, it's not an unheard-of concept. One of the potential evolutions for the STS was "fly-back boosters".