The BFR & BFS are supposed to have a more squat profile, which would make them less "tippy" when they land, so it would make sense for SpaceX to investigate legless landing capabilities. But the Falcon 9 is very slender, and I just don't see that it is a good candidate for legless landings. Not until they can perfect it for wider base rockets at least.
Quote from: guckyfan on 07/12/2017 05:30 amI have no idea if it will be done. But it would secure the stage on the barge, better than the Roomba/Octocrab can. It would make turn around easier than with legs. They could be on the way back an hour or two after landing. It would save some weight. But can they come down precisely enough that the thrusters can do the fine tuning? The last two landings at the limits of what can be done, were not that precise. We will see if they can improve at the limits with practice.I wonder if they could modify the He-pressurization for the legs for at least initial tests, before they install cold gas thruster in the thrust structure area.IMO the catching mechanism will have a substantial structure, both for last-inch alignment, and for arresting vertical motion (which the legs kinda do today).That said, there are some advantages for doing it far off shore.
I have no idea if it will be done. But it would secure the stage on the barge, better than the Roomba/Octocrab can. It would make turn around easier than with legs. They could be on the way back an hour or two after landing. It would save some weight. But can they come down precisely enough that the thrusters can do the fine tuning? The last two landings at the limits of what can be done, were not that precise. We will see if they can improve at the limits with practice.I wonder if they could modify the He-pressurization for the legs for at least initial tests, before they install cold gas thruster in the thrust structure area.
I vote for the Grasshopper 2 approach. Raptors, methane and BFR diameter.
They are already experimenting with a "booster grabber". Wouldn't it be likely to be extended to cover this?
Quote from: Space Ghost 1962 on 07/12/2017 06:04 pmThey are already experimenting with a "booster grabber". Wouldn't it be likely to be extended to cover this?I'd think some sort of roomba version would be in the running. Able to make quick adjustments in its position as the Booster is landing.
Perhaps the development sequence:1. "Auto jack stand" to mechanically constrain freshly landed stage as a part of automated "safeing" at sea.2. GNC improvements to reliably land within a fraction of a meter at sea and land.3. Reversable "launch mount" clamp downs with jack stand's "adjusters" that seat/align vehicle in LZ-1 deployable platform.4. Reconfigured/new pad with above mentioned mount that can be secured, TE/L lowered, booster returned to HIF.
Quote from: meekGee on 07/12/2017 07:29 amQuote from: guckyfan on 07/12/2017 05:30 amI have no idea if it will be done. But it would secure the stage on the barge, better than the Roomba/Octocrab can. It would make turn around easier than with legs. They could be on the way back an hour or two after landing. It would save some weight. But can they come down precisely enough that the thrusters can do the fine tuning? The last two landings at the limits of what can be done, were not that precise. We will see if they can improve at the limits with practice.I wonder if they could modify the He-pressurization for the legs for at least initial tests, before they install cold gas thruster in the thrust structure area.IMO the catching mechanism will have a substantial structure, both for last-inch alignment, and for arresting vertical motion (which the legs kinda do today).That said, there are some advantages for doing it far off shore.I think it could be a substantial, but simple system. I've attached my pet idea of using counterweights on 'see-saws'Getting it out of there without relaunching would require a crane, but so do the legs.F9 doesn't have a frustrum like that on the end, but it's just an example, and any GH type flight would just be for experimentation anyway so there'd be a lot of modifications to get it working.
I'm not going to pretend I can draw, but given the ground structure doesn't have to be small couldn't you extend your cone vertically (or have four arms) and have a series of lightly sprung guide vanes at various points along it.
..or simply land in different place.
Quote from: alang on 09/02/2017 05:10 pmI'm not going to pretend I can draw, but given the ground structure doesn't have to be small couldn't you extend your cone vertically (or have four arms) and have a series of lightly sprung guide vanes at various points along it.I think the phrase you're looking for is "compliant coupling" Holes with rounded corners and tapering the entry area to a hole for a bolt or screw are classic tactics to simplify robot arms locating fasteners to holes. The jokes in this pack is that what you're talking about has to stay in place during takeoff, with 28 million lbs of thrust. Might be possible if the structure is vented, but it's going to be very large and very heavy.
What about a landing structure that will move in after launch, before landing occur?
How much payload capability would F9 have without legs?