ThatGuyWithALongUsername Posted November 19, 2018 Share Posted November 19, 2018 21 minutes ago, tater said: A good point was made regarding the delightfully counter-intuitive, radical changes to BFR design over at NSF. Since they are working on BFS (note the S) right now, already, what's to say the change isn't to the BFBooster part of BFR, not the spacecraft? They've built exactly nothing for the booster yet, it's considered the short pole, since it's F9 writ large. What could be delightfully counter-intuitive in that part of the vehicle (assume BFS remains unchanged until they do testing with fins on F9 stage 2 next summer)? People there were suggesting multiple F9s to launch the thing (a booster built like Saturn 1b), but I think that is unlikely. Still, that makes his tweet a lot less radical overall. Ditching landing on launch clamps couldn't hurt, for example. Makes sense. The design of the BFB hasn't changed at all from 2017, and not that much from 2016. It seemed a bit placeholder-y in the 2018 presentation, as we didn't really get any more details on it. Grid fins were accidentally completely forgotten in the first renderings, which could hint that this design isn't going to stay. This seems epecially likely since the BFS is nearing the next phase of development, with testing starting hopefully within a year and parts of the design becoming more concrete, while the BFB is still neglected. Development on the BFB, although assumed to be "easier," is clearly not at the same stage as the BFS and is thus a prime candidate for more design change. It's also a bit less insane than changing a two-month-old design. Quote Link to comment Share on other sites More sharing options...
tater Posted November 19, 2018 Share Posted November 19, 2018 44 minutes ago, ThatGuyWithALongUsername said: It's also a bit less insane than changing a two-month-old design. That said, other interesting ideas are out there than don't change the footprint much. Like putting the engines on the outside as a possibility (cargo, etc at the bottom vs the top, for easy unloading). LOL. I wish the launch today had not been moved, we'd have something real to discuss, instead. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted November 19, 2018 Share Posted November 19, 2018 1 hour ago, ThatGuyWithALongUsername said: Makes sense. The design of the BFB hasn't changed at all from 2017, and not that much from 2016. It seemed a bit placeholder-y in the 2018 presentation, as we didn't really get any more details on it. Grid fins were accidentally completely forgotten in the first renderings, which could hint that this design isn't going to stay. This seems epecially likely since the BFS is nearing the next phase of development, with testing starting hopefully within a year and parts of the design becoming more concrete, while the BFB is still neglected. Development on the BFB, although assumed to be "easier," is clearly not at the same stage as the BFS and is thus a prime candidate for more design change. It's also a bit less insane than changing a two-month-old design. BFB is an scaled up Falcon 9 first stage, yes it will obviously be new issues but far less than with BFS, lots of the issues will also show up on BFS. Assume they will also do grasshopper testing with the BFS. Quote Link to comment Share on other sites More sharing options...
tater Posted November 19, 2018 Share Posted November 19, 2018 Quote Link to comment Share on other sites More sharing options...
tater Posted November 19, 2018 Share Posted November 19, 2018 The "Skydiver" profile has the vehicle go from (looking end-on, planet is DOWN): | / \ to: | \ / right? (this was all we had for graphics back in the day ). The hinge is a possible set of failure modes. If it freezes in either position, on even one fin, it's a loss of vehicle, and if crewed, loss of crew. What if the fins are fixed? You cover the whole thing with TPS, then you go from: | / \ to: \ / | Now we still have the skydiver profile, but no moving parts. You can roll to maneuver (maybe small inputs on canard, or use grid fins up front (perhaps rotated 90 degrees)). Quote Link to comment Share on other sites More sharing options...
Mad Rocket Scientist Posted November 19, 2018 Share Posted November 19, 2018 That seems like it would be uncomfortable for the passengers, especially since they experience G's from two directions at 180 degrees apart. If you mounted the fins at 120 degrees apart, you could get close to that by only rolling 60 degrees, requiring much less extra TPS and reducing the discomfort. Instead of full g-load both eyeballs in and out, you have full g at 30 degrees to the side of eyeballs in. (Assuming the passengers are lying down in line with the ship) Quote Link to comment Share on other sites More sharing options...
tater Posted November 19, 2018 Share Posted November 19, 2018 The people sit with their backs down. The craft never rolls more than a little to maneuver, there is no 180 degree roll (except maybe in zero g). Quote Link to comment Share on other sites More sharing options...
magnemoe Posted November 19, 2018 Share Posted November 19, 2018 56 minutes ago, tater said: The people sit with their backs down. The craft never rolls more than a little to maneuver, there is no 180 degree roll (except maybe in zero g). Yes, its move with back towards direction of movement nose up. At the end your are pretty parallel with the ground and the nose goes up for powered landing. Quote Link to comment Share on other sites More sharing options...
tater Posted November 19, 2018 Share Posted November 19, 2018 39 minutes ago, magnemoe said: Yes, its move with back towards direction of movement nose up. At the end your are pretty parallel with the ground and the nose goes up for powered landing. Yeah, in this case if you imagined it on its side like Planet Express, the tail would in fact be down, not up. The windows would be on the up side of this Y (opposite of where they are in the current design) (or almost all aircraft). Quote Link to comment Share on other sites More sharing options...
tater Posted November 19, 2018 Share Posted November 19, 2018 (edited) Edited November 19, 2018 by tater Quote Link to comment Share on other sites More sharing options...
DDE Posted November 20, 2018 Share Posted November 20, 2018 12 hours ago, tater said: People there were suggesting multiple F9s to launch the thing (a booster built like Saturn 1b) Or... or... After all, they already have Falcon Heavy. How many Falcons do they need to replace one BFR? I see an immediate and obvious flaw: the structural loads will be very different. Cluster’s Last Stands rarely make it from the drawing board. I specifically mean that and not series of strap-ons. Last one to my memory was an early Zenit design, which used two parallel stacks with their own fuel and engines. Then Glishko smacked them over the heat with an RD-170, grossly overpowered for the Zenit proper but essential for a certain bigger project, and they abandoned the “flatfish” for the “log”. Quote Link to comment Share on other sites More sharing options...
tater Posted November 20, 2018 Share Posted November 20, 2018 FH gets S2 props + 64t to LEO. Staging is about the same. Presumably F-superheavy (4 side boosters) could do it. Maybe they'd make a "quadroweb" to bolt them together, top and bottom, then put legs on, and land all 5 at once (use multiple engines on the central core to land, and maybe some per side booster for the entry burn?). The booster doesn't need to be terribly complicated. Such a short-term version, using capability they already have (a F9 factory) could get a BFS into orbit perhaps faster than dev on a similar booster (even if the booster is relatively easy compared to the ship because EDL is so much more gentle at 2.x km/s than 8. Quote Link to comment Share on other sites More sharing options...
ThatGuyWithALongUsername Posted November 20, 2018 Share Posted November 20, 2018 Uh Elon what Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted November 20, 2018 Share Posted November 20, 2018 I hereby propose that the first Starship be named "Jefferson!" And we can build this thing together, stand the stormy weather... Quote Link to comment Share on other sites More sharing options...
ThatGuyWithALongUsername Posted November 20, 2018 Share Posted November 20, 2018 (edited) WHAT EDIT: I thought this would merge, sorry- blame @CatastrophicFailure Edited November 20, 2018 by ThatGuyWithALongUsername Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted November 20, 2018 Share Posted November 20, 2018 Quote Later versions will Well, he did say it was a pretty radical and counter-intuitive change... Quote Link to comment Share on other sites More sharing options...
tater Posted November 20, 2018 Share Posted November 20, 2018 No chemical rocket (or even fission rocket) is taking anything meaningful to another star system in a timeframe that matters. It's a crappy name, just as bad as "Starliner" for CST-100. It needs a more functional class name. General Transport Unit or something (Culture names are always good). I assume the name comes more from the look... His use of "Super Heavy" seriously implies the Falcon Super Heavy could be the booster. That slides the timeline left. They have data on FH, and it flies twice in the next X months. If the acoustics are not awful, they could possibly bolt them together and land as a unit. I think this would be required, since the upper stage is really heavy, no way it sits on top of a F9 core. Quote Link to comment Share on other sites More sharing options...
ThatGuyWithALongUsername Posted November 20, 2018 Share Posted November 20, 2018 1 minute ago, tater said: No chemical rocket (or even fission rocket) is taking anything meaningful to another star system in a timeframe that matters. It's a crappy name, just as bad as "Starliner" for CST-100. I think it's supposed to match with "starlink" more than anything. No idea what the last comment was about, probably just wild future speculation... 1 minute ago, tater said: His use of "Super Heavy" seriously implies the Falcon Super Heavy could be the booster. That slides the timeline left. They have data on FH, and it flies twice in the next X months. If the acoustics are not awful, they could possibly bolt them together and land as a unit. I think this would be required, since the upper stage is really heavy, no way it sits on top of a F9 core. I don't think this is the case here... "Super Heavy" simply means it is... well, super heavy. Quite a bit heavier than, say the (Falcon) Heavy. This tweet seems to back up the single-stick design: Quote Link to comment Share on other sites More sharing options...
tater Posted November 20, 2018 Share Posted November 20, 2018 Maybe the spaceship will be a saucer. Launched sideways on top of the booster. Engines in the middle. In deep space, they can spin it. Crew sits with their backs down at launch, and on EDL, they are seated normally (feet and butt down). Why not just speculate like crazy at this point, LOL. Quote Link to comment Share on other sites More sharing options...
ThatGuyWithALongUsername Posted November 20, 2018 Share Posted November 20, 2018 2 minutes ago, tater said: Maybe the spaceship will be a saucer. Launched sideways on top of the booster. Engines in the middle. In deep space, they can spin it. Crew sits with their backs down at launch, and on EDL, they are seated normally (feet and butt down). Why not just speculate like crazy at this point, LOL. LOL, maybe Elon Musk is just trying to drive us all slowly crazy at this point... (IT'S WORKING) Quote Link to comment Share on other sites More sharing options...
ThatGuyWithALongUsername Posted November 20, 2018 Share Posted November 20, 2018 The Wikipedia discussion page sums this all up perfectly: "unsure if Elon is high right now." https://en.wikipedia.org/wiki/Talk:BFR_(rocket)#Requested_move_20_November_2018 Quote Link to comment Share on other sites More sharing options...
Rakaydos Posted November 20, 2018 Share Posted November 20, 2018 46 minutes ago, tater said: His use of "Super Heavy" seriously implies the Falcon Super Heavy could be the booster. That slides the timeline left. They have data on FH, and it flies twice in the next X months. If the acoustics are not awful, they could possibly bolt them together and land as a unit. I think this would be required, since the upper stage is really heavy, no way it sits on top of a F9 core. It doesnt have to sit on just one F9 core. 7 stage separation pushers on the booster, each one to a Raptor bell. Just put 1 pusher per Falcon core. Quote Link to comment Share on other sites More sharing options...
tater Posted November 20, 2018 Share Posted November 20, 2018 20 minutes ago, Rakaydos said: It doesnt have to sit on just one F9 core. That's what I said, they'd have to be bolted together. Quote Link to comment Share on other sites More sharing options...
Rakaydos Posted November 20, 2018 Share Posted November 20, 2018 2 minutes ago, tater said: That's what I said, they'd have to be bolted together. That doesnt actually need to follow. They can be attached at the BFS, with a FH-style decoupler spar at the base. Quote Link to comment Share on other sites More sharing options...
tater Posted November 20, 2018 Share Posted November 20, 2018 2 minutes ago, Rakaydos said: That doesnt actually need to follow. They can be attached at the BFS, with a FH-style decoupler spar at the base. I think the acoustics would mean that they should be pretty rigid vs just pushers at the Raptor bells. You could have clips on the bottom of the BFS, but then you have to make sure those don't interfere with refilling, etc. Quote Link to comment Share on other sites More sharing options...
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