Quote from: Lars-J on 04/02/2017 10:02 pmQuote from: guckyfan on 04/02/2017 10:08 amSo if you have the fuel for RTLS, do that and maybe only reduce the reentry burn to 1 engine. But on marginal missions for downrange landing do a lower trajectory, that is where saving is most needed.No, you don't seem to understand. The higher trajectory *IS* the optimal one. The stage isn't thrusting upwards... It merely cancels and reverses its horizontal vector. The same apogee would have been reached with or without a boost-back burn. Doing a shallower boost-back profile does in fact consume MORE propellant. I am wondering if with the new larger and more heat resistant grid fins there is enough control authority to actually turn, not just slow down by getting some lift. If you could turn around you might be able to RTLS even with a less lofted profile. Wings by any other name? Probably not.
Quote from: guckyfan on 04/02/2017 10:08 amSo if you have the fuel for RTLS, do that and maybe only reduce the reentry burn to 1 engine. But on marginal missions for downrange landing do a lower trajectory, that is where saving is most needed.No, you don't seem to understand. The higher trajectory *IS* the optimal one. The stage isn't thrusting upwards... It merely cancels and reverses its horizontal vector. The same apogee would have been reached with or without a boost-back burn. Doing a shallower boost-back profile does in fact consume MORE propellant.
So if you have the fuel for RTLS, do that and maybe only reduce the reentry burn to 1 engine. But on marginal missions for downrange landing do a lower trajectory, that is where saving is most needed.
Sigh, if something has lift and has control authority why can't it turn? Things with actual wings turn all the time. They bleed off speed turning and they bleed off altitude too (or more speed if you "set the flaps" higher)
Sigh, if something has lift and has control authority why can't it turn? Things with actual wings turn all the time.
At present that suggests the refurb team can do 3 stages a year, but we don't know how big that team is or how many teams they can form. If it's 100 strong you don't want too many such teams. If it's just a couple of guys then you could have dozens of them.
I the presser Musk said the refurb took about 4 months of actual time and the replaced pretty much everything that looked even slightly worn. The jokers in this process are 1)How many staff did it take 2)How variable can it be. Consistency really helps in staff planning. 3)Once they are satisfied most stuff does not need replacing what could it go down to?At present that suggests the refurb team can do 3 stages a year, but we don't know how big that team is or how many teams they can form. If it's 100 strong you don't want too many such teams. If it's just a couple of guys then you could have dozens of them.
Quote from: john smith 19 on 04/03/2017 06:31 amAt present that suggests the refurb team can do 3 stages a year, but we don't know how big that team is or how many teams they can form. If it's 100 strong you don't want too many such teams. If it's just a couple of guys then you could have dozens of them.Did you miss that the refurbishment time is already down to 6 weeks, even ahead of block 5 which is supposed to make it much easier?
Quote from: guckyfan on 04/03/2017 02:02 pmQuote from: john smith 19 on 04/03/2017 06:31 amAt present that suggests the refurb team can do 3 stages a year, but we don't know how big that team is or how many teams they can form. If it's 100 strong you don't want too many such teams. If it's just a couple of guys then you could have dozens of them.Did you miss that the refurbishment time is already down to 6 weeks, even ahead of block 5 which is supposed to make it much easier?Yes. Where was it reported?
a few months back I toyed with the idea of using the legs to generate lift and control...
Quote from: Rocket Science on 04/02/2017 11:30 pma few months back I toyed with the idea of using the legs to generate lift and control...Mechanically, current legs are a non-starter on this. I don't know whether Block 5 will have automatically retractable legs, but probably not.And aerodynamically...no, I don't think this works. Even with the COM being so far forward, the drag on those legs at anything over a few km/s would flip the stage like a shuttlecock.
Quote from: sevenperforce on 04/04/2017 05:26 pmQuote from: Rocket Science on 04/02/2017 11:30 pma few months back I toyed with the idea of using the legs to generate lift and control...Mechanically, current legs are a non-starter on this. I don't know whether Block 5 will have automatically retractable legs, but probably not.And aerodynamically...no, I don't think this works. Even with the COM being so far forward, the drag on those legs at anything over a few km/s would flip the stage like a shuttlecock.Elon Musk has just said, the gridfins become a lot larger and provide more drag. That could counter some more drag of the legs. Or just one leg. He did announce too that the rocket can do some more lift as well. I don't believe that helps on ascent but can increase drag on the way down. The increase of capability must come from somewhere and not from more engine thrust alone.