A reusable second stage would be actively guided it its landing zone, just like the first stage. No need to drop it in the ocean. It could land back at the launch site or on a barge.BTW, this is the MCT speculation thread, so why are we having what seems to be a F9/FH discussion?
Quote from: RonM on 07/31/2016 03:53 pmA reusable second stage would be actively guided it its landing zone, just like the first stage. No need to drop it in the ocean. It could land back at the launch site or on a barge.BTW, this is the MCT speculation thread, so why are we having what seems to be a F9/FH discussion?Agreed, it's in the wrong thread, I suspect it spun off the Raptor powered upper stage discussion. It should probably be moved.Whilst the stage could be actively guided in the landing zone, for a GEO launch, the zone itself would be determined by the highly elliptical orbit after launching the satellite, and how quickly that orbit decayed. It can take years for that to happen, so there probably wouldn't be any fuel left for landing.
Quote from: Impaler on 07/29/2016 02:18 am... it is totally unstable, the engine is most massive part of a 2nd stage and this will dictate an engine first entry....False. On a Dragon to ISS mission the residual propellent outweighs the entire second stage, and it only takes 1% of the initial 100 tonne propellent load to outweigh a Merlin.At atmospheric drag will settle the remaining propellent in the nose long before it's significant enough to overpower the RCA thrusters, resulting in a quasi-stable configuration that cold be controlled by either RCS or small active aerodynamic surfaces during re-entry.
... it is totally unstable, the engine is most massive part of a 2nd stage and this will dictate an engine first entry....
Does the mass of the heat shield exceed the mass of the fuel required to create a sufficiently large "bubble" ?Please show your working
Is this a SSTO? How do you get enough Km/sec to reach LEO, etc?How do humans get from the living area to/from escape pod with heat shield in between?
Quote from: matthewkantar on 07/29/2016 08:41 pmIf second stages are going to be reused and deliver worthwhile payloads, I think most of the braking will need to be done with friction and not propulsion.MatthewHow about like this?
If second stages are going to be reused and deliver worthwhile payloads, I think most of the braking will need to be done with friction and not propulsion.Matthew
Quote from: OneSpeed on 07/30/2016 05:08 amQuote from: matthewkantar on 07/29/2016 08:41 pmIf second stages are going to be reused and deliver worthwhile payloads, I think most of the braking will need to be done with friction and not propulsion.MatthewHow about like this?It has to turn around for landing, I think retro propulsive braking test give them numbers that propulsion is good enough to build shield.
Don't assume the EDL takes as long as a manned capsules entry, deceleration can be VERY fast if your coming in steep it just makes for very high g-forces and a tank can tolerate that.
Quote from: Impaler on 08/05/2016 09:39 amDon't assume the EDL takes as long as a manned capsules entry, deceleration can be VERY fast if your coming in steep it just makes for very high g-forces and a tank can tolerate that.The crew can tolerate a 20G entry.