Unless cores are being refurbished in a matter of days (we'll see whether that happens) and there is a very high launch cadence (which is currently restricted by pad turnaround) and there is an insufficient number of cores in existence (which seems unlikely, even if do keep dropping them into the sea) - then there's no real benefit in cutting a day or so off turnaround times.
Why does Blue Origin want to do Booster landings on a moving ship rather than a barge with thrusters to keep it a GPS position?
Suggest it is to allow recovery irrespective of sea state, so that even in poor conditions the valuable, always meant to be recovered, overbuilt to allow very large number of uses booster - will be recovered. Not the same as Falcon's "opportunistic' approach to recovery, with expendibility if things don't work out, which has happened.
Also for faster return of the booster, which always lands downrange and never RTLS, and which always lands far downrange.
It would take a towed barge well over a week to return.
I don't doubt that that was also a consideration, but for the same reason I've just expected NG to only launch when recovery has good chances to succeed. i.e. BO's Launch Commit Criteria will very explicitly include hard limits for landing area conditions.
With the possible exception of a rare mission with a hard launch window (like some planetary launches, etc).
If they're lucky, SpaceX will move toward including something along these lines so that the market has already had a chance to get used to the idea some by the time that NG starts launching. Let SpaceX get all the flak and then come online and just say, "Well that's how everyone does reusable launches." Gradatim, For The Win.
For SpaceX, it might be a progressive evolution. Start with a sliding price scale where if you got a low price (only offered for missions where recovery is possible), then that has baked into it that SpaceX can delay in order to optimize for landing conditions but gives the customer an option to launch anyways for an added "non-standard service price " of $X.
Keep in mind, you could likely field quite a number of barges for the cost of a ship. And just leave them there, serviced by fast ship(s), as an after the fact means to handle the recovered booster fleet.
Quote from: envy887 on 03/13/2018 06:06 pmIt would take a towed barge well over a week to return.Note also that a fast return ship also would work for SX too in the same sense.
All I'll say is that SpaceX already know how hard it is to land on a (almost) stationary platform.. and landing on a moving one ups the difficulty to a whole other level never before seen by mankind.
I think you're getting carried away. The precise landing time and location is known, and programming the ship's autopilot to intersect at both is a solved problem.
Quote from: CameronD on 03/14/2018 03:26 amAll I'll say is that SpaceX already know how hard it is to land on a (almost) stationary platform.. and landing on a moving one ups the difficulty to a whole other level never before seen by mankind.I think you're getting carried away. The precise landing time and location is known, and programming the ship's autopilot to intersect at both is a solved problem.
The ASDS has no control authority in the vertical direction, only X & Y translation. The deck will be pitching as a function of wave period vs. hull dimensions.
A ship with stabilizer fins has the vertical control authority to null out this pitching.
A well-designed autopilot will be able to contend with instantaneous changes in current and wind, especially if controllable pitch propellers are used for propulsion.
This leaves the rate of travel itself, which is well within the capability of a gimballed rocket engine to match at touchdown. The landing platform is more stable overall, at the cost of being installed on a larger and more expensive hull.
Cadence is limited by the slowest operation divided by how many of them you are executing in parallel.Cores can take a month to refurb and if you have 10 of them, you can do a 3 day cadence based on core refurb.With only one ASDS, there is a limit to how close in you can do two ASDS (not RTLS) missions of a week or more. Faster transit/return times reduce this. But I suspect buying a whole second set offers a better reduction. Especially if you have to buy a second set anyway for FH.
I remember that a looooooooooong time ago on this forum (SpaceX time: barely two years) we discussed one heck of an exciting idea. That is, a Falcon 9R stage that had landed on the drone ship could be automatically refueled with some kerolox and fly itself back to the Cape in a brief hop. Did Musk ever considered that option ? and what would the FAA think about it ? can't be worse than the twin booster landing at the Cape...
Quote from: Archibald on 03/15/2018 06:10 pmI remember that a looooooooooong time ago on this forum (SpaceX time: barely two years) we discussed one heck of an exciting idea. That is, a Falcon 9R stage that had landed on the drone ship could be automatically refueled with some kerolox and fly itself back to the Cape in a brief hop. Did Musk ever considered that option ? and what would the FAA think about it ? can't be worse than the twin booster landing at the Cape...Musk originated that speculation with some rather off-the-cuff comments soon after the first barge landing. The idea is not quite that simple. The booster is not very aerodynamic with the open interstage and extended legs, so those would have to be capped and closed. The booster needs more than just RP-1 and LOX: TEA/TEB, nitrogen, helium, at least. The barge would need to supply those, and also have a launch mount with hold-downs, and a flame deflector installed. All of this would have to be operated either automatically, or by crew from the support ships.
The booster needs more than just RP-1 and LOX: TEA/TEB, nitrogen, helium, at least. The barge would need to supply those, and also have a launch mount with hold-downs, and a flame deflector installed. All of this would have to be operated either automatically, or by crew from the support ships.
Never bothered to ask how many hours does OCISLY and others needs to drive themselves back the from landing zone to Cape Canaveral. At some point in the future, with very high flight rates, all those hours lost in transit times might become an issue... or maybe not. QuoteThe booster needs more than just RP-1 and LOX: TEA/TEB, nitrogen, helium, at least. The barge would need to supply those, and also have a launch mount with hold-downs, and a flame deflector installed. All of this would have to be operated either automatically, or by crew from the support ships.be creative ! hint: Sea Launch rebuild an entire burned-up oil rig to launch a rocket (of course it did not exactly ended well for them) I remember the first time I red about Sea Launch, 1997, in the pre-history of the Internet. I thought the guys were completely nuts or insane. Launch a rocket from a rebuild oil rig, what can possibly go wrong ?
Quote from: envy887 on 03/15/2018 06:55 pmQuote from: Archibald on 03/15/2018 06:10 pmI remember that a looooooooooong time ago on this forum (SpaceX time: barely two years) we discussed one heck of an exciting idea. That is, a Falcon 9R stage that had landed on the drone ship could be automatically refueled with some kerolox and fly itself back to the Cape in a brief hop. Did Musk ever considered that option ? and what would the FAA think about it ? can't be worse than the twin booster landing at the Cape...Musk originated that speculation with some rather off-the-cuff comments soon after the first barge landing. The idea is not quite that simple. The booster is not very aerodynamic with the open interstage and extended legs, so those would have to be capped and closed. The booster needs more than just RP-1 and LOX: TEA/TEB, nitrogen, helium, at least. The barge would need to supply those, and also have a launch mount with hold-downs, and a flame deflector installed. All of this would have to be operated either automatically, or by crew from the support ships...and, in the end, it was easier, simpler and safer to tow the entire thing back to shore and forget about it.
Just to return to the opening post.Theoretical hull speed is a recognised phenomenon, but not everyone understands why it exists ...
(Snip)With reduced hull motion, it's arguably easier in a SWATH or similar high speed hull, however the mass and final position of the rocket's landing on the vessel would result in a significant near-instantaneous increase in displacement/trim and a corresponding near-instantaneous decrease in speed which could be enough to topple the stage. It would feel like the ship hit a brick wall..In summary: It's a nice idea that perhaps holds merit but, as I see it, SpaceX have far fewer variables to contend with in the present design.
Quote from: CameronD on 03/15/2018 12:17 am(Snip)With reduced hull motion, it's arguably easier in a SWATH or similar high speed hull, however the mass and final position of the rocket's landing on the vessel would result in a significant near-instantaneous increase in displacement/trim and a corresponding near-instantaneous decrease in speed which could be enough to topple the stage. It would feel like the ship hit a brick wall..In summary: It's a nice idea that perhaps holds merit but, as I see it, SpaceX have far fewer variables to contend with in the present design.I only regret that I have but one like to leave for my colleague. (To paraphrase Nathan Hale)This commentary has been a long time coming. Musk is a physicist and a “first principles” guy. He reduces problems to their simplest and peals away at the obstacles, the degrees of freedom. A stationary barge drives many DoFs to zero, or close enough in the case of vertical motion. A moving ship adds many more to that also need to arrive at zero, but now they have to do so at one precise moment. The issue of a slow barge (ASDS if you wish) return is much simpler to “solve” than the very complex control issue.