I'm currently trying to wrap my head round how SpaceX plans to launch a full-stack BFR in the near future, it's not the rocket itself that's bothering me (as SpaceX have shown they can build rockets) but the infrastructure needed to support a BFR launch. >
>SpaceX is also considering building their own new facilities, although this will not be a launch complex but rather a factory to build their future BFR vehicle. The company is talking with NASA and Space Florida about obtaining land for the new factory, likely be located near or right next to Blue Origin’s existing New Glenn factory. >
I believe they will have a T/E to bring the vehicle to/from the pad to cover initial vehicle placement and return to hanger for maintenance. This T/E will not be a TEL -- launches/landings are from/to the launch mount. This same equipment could deliver and erect the BFSs in the same manner. A crane has been shown moving the BFS from a side pad to mate to the booster.
Quote from: AncientU on 03/17/2018 01:33 pmI believe they will have a T/E to bring the vehicle to/from the pad to cover initial vehicle placement and return to hanger for maintenance. This T/E will not be a TEL -- launches/landings are from/to the launch mount. This same equipment could deliver and erect the BFSs in the same manner. A crane has been shown moving the BFS from a side pad to mate to the booster.So, if I understand correctly you are thinking about a single T/E that can be used alternatively to transport/erect the booster and the spacecraft.Why not use a simple transporter and erect both with the crane?You need the pad crane from the beginning in any case (for stacking ops) and they already have the former orbiter transporter system that I think could already transport both the BFS and the booster.This is ok for the booster that only has to be lowered occasionally, but a bit impractical for the BFS. All things considered I think they may use this approach for the first few flights only. For mature operations I'm more and more convinced that VI of the spacecraft is the way to go.
Quote from: AbuSimbel on 03/17/2018 01:54 pmQuote from: AncientU on 03/17/2018 01:33 pmI believe they will have a T/E to bring the vehicle to/from the pad to cover initial vehicle placement and return to hanger for maintenance. This T/E will not be a TEL -- launches/landings are from/to the launch mount. This same equipment could deliver and erect the BFSs in the same manner. A crane has been shown moving the BFS from a side pad to mate to the booster.So, if I understand correctly you are thinking about a single T/E that can be used alternatively to transport/erect the booster and the spacecraft.Why not use a simple transporter and erect both with the crane?You need the pad crane from the beginning in any case (for stacking ops) and they already have the former orbiter transporter system that I think could already transport both the BFS and the booster.This is ok for the booster that only has to be lowered occasionally, but a bit impractical for the BFS. All things considered I think they may use this approach for the first few flights only. For mature operations I'm more and more convinced that VI of the spacecraft is the way to go.Stabilizing a large heavy vehicle hanging on a cable to the precision required for stage mating is not easy. It's likely much simpler to lift the BFS from below with a transporter/erector. The same T/E could potentially move/erect the booster alone, or the full stack as well - allowing mating to be done in the HIF under more controlled conditions.The only way a crane would be simpler if if the BFS lands close enough to the pad that they never have to break it over between flights, except for rare maintenance. SpaceX did show this in the P2P video last year, but I think that operational concept is somewhat further in the future. For the near term they will use what they learned with Falcon.
So the general consensus seems to be, no matter what SpaceX decides to do in regards to launch infrastructure they will have to install a large crane. A while back I read an article about how the airforce had given a SpaceX a contract to install a crane on 39a for vertical integration of military payloads. Could this crane also be used in the future for assembling the BFR stack?
They have to design the system for vertical integration of the spacecraft on the pad from the beginning IMO.The question is: what are the technical challenges exactly?
They want to get rid of the TE altogether:-The booster always remains vertical on the pad except for occasional maintenance (it only needs to be lowered/erected once in a while, every X launches);-The launch/landing cradle supplies everything to both stages;-The stacking is done directly on the launch mount.The only things needed on the pad would be the crew access tower and a really big crane to mate the second stage and occasionally lower/erect the booster (or maybe something that serves both aims).The question is: is this technically feasible, and how?
Quote from: HeartofGold2030 on 03/17/2018 02:19 pmSo the general consensus seems to be, no matter what SpaceX decides to do in regards to launch infrastructure they will have to install a large crane. A while back I read an article about how the airforce had given a SpaceX a contract to install a crane on 39a for vertical integration of military payloads. Could this crane also be used in the future for assembling the BFR stack?Very good point. Unfortunately we haven't heard much about that project after the initial news. That crane was intended for FH/9. To me it's possible that SpaceX has ditched those VI plans for F9/H and moved them to BFR similarly to what happened to FH crew and dragon propulsive landing.If a crane has to be designed and built on 39A it's likely it will be the BFR one, given how the planned timeframe for BFR on 39A is now 2020/2021. When would the first VI NSS mission have launched on falcon 9?
Quote from: envy887 on 03/17/2018 02:08 pmQuote from: AbuSimbel on 03/17/2018 01:54 pmQuote from: AncientU on 03/17/2018 01:33 pmI believe they will have a T/E to bring the vehicle to/from the pad to cover initial vehicle placement and return to hanger for maintenance. This T/E will not be a TEL -- launches/landings are from/to the launch mount. This same equipment could deliver and erect the BFSs in the same manner. A crane has been shown moving the BFS from a side pad to mate to the booster.So, if I understand correctly you are thinking about a single T/E that can be used alternatively to transport/erect the booster and the spacecraft.Why not use a simple transporter and erect both with the crane?You need the pad crane from the beginning in any case (for stacking ops) and they already have the former orbiter transporter system that I think could already transport both the BFS and the booster.This is ok for the booster that only has to be lowered occasionally, but a bit impractical for the BFS. All things considered I think they may use this approach for the first few flights only. For mature operations I'm more and more convinced that VI of the spacecraft is the way to go.Stabilizing a large heavy vehicle hanging on a cable to the precision required for stage mating is not easy. It's likely much simpler to lift the BFS from below with a transporter/erector. The same T/E could potentially move/erect the booster alone, or the full stack as well - allowing mating to be done in the HIF under more controlled conditions.The only way a crane would be simpler if if the BFS lands close enough to the pad that they never have to break it over between flights, except for rare maintenance. SpaceX did show this in the P2P video last year, but I think that operational concept is somewhat further in the future. For the near term they will use what they learned with Falcon.The thing is that having a T/E for the full stack completely disrupts BFR operations, not only for P2P. Why land on the cradle if you have to lower the booster and mate it with the BFS inside an hangar?They have to design the system for vertical integration of the spacecraft on the pad from the beginning IMO, otherwise the concept doesn't make sense. And building a gargantuan TEL for a 110m, >100 ton SHLV just for the initial phase, only because you're afraid of the challenges of VI on the pad would be an error NASA can afford (see SLS' MLP), but not SX with their limited budget. The question is: what are the technical challenges exactly?
Landing precision is the main issue determining the BFR ground infrastructure. Falcon 9 first stages land with precision of a few meters. Intuitively, it seems to be a fantastic achievement. Not long ago we were quite happy when the stages missed the barge by a few tens of meters only. However, the few meters precision is probably not enough for the BFR landing: it risks the outer engines to collide with the cradle accepting the outer skin of the rocket. What kind of precision we can envision? If it is e.g. 0.5 meter, then we need a way to take care of that 0.5 meter.
What kind of precision we can envision? If it is e.g. 0.5 meter, then we need a way to take care of that 0.5 meter.
To the first order, about how heavy would BFR booster be if the 42 raptors were not installed into the octoweb until after the booster is vertical in the launch clamps? Would it be comparable to an unfueled BFS?