Quote from: TripleSeven on 09/16/2018 03:27 pmthis is a completely new vehicle with new shapes, new engines, new everything; almost nothing will come from the 9 or FH and in my view they are still paying off the Falcon "cost". the level of composite composition of the vehicle is several times higher than anything that has been done in a working vehicle...and all those things have driven a lot of manufactors from airplanes to ships "cost through the roof"Now, remember the margin.Many aspects of BFS can fail utterly and it still succeed as a ridiculously capable launcher.All that needs to work is reliability and reflight cost.If the dry mass is double the expected, or the heatshield is only good to 5km/s, not 11km/s, or ... almost nothing changes in the business case.If the 787 had come in at 100% overweight so it could only carry 50% of designed cargo, and used the same amount of fuel, it would have been laughed out of the industry.If BFS does the same, it beats every single launcher hollow in almost every single aspect, and the ones it doesn't beat on every single aspect it can beat operationally using propellant transfer far cheaper than they can..
this is a completely new vehicle with new shapes, new engines, new everything; almost nothing will come from the 9 or FH and in my view they are still paying off the Falcon "cost". the level of composite composition of the vehicle is several times higher than anything that has been done in a working vehicle...and all those things have driven a lot of manufactors from airplanes to ships "cost through the roof"
Quote from: KelvinZero on 09/16/2018 08:43 amQuote from: tyrred on 09/16/2018 08:38 amTriple duty, including exhaust shaping, thermal radiation, and engine shielding... Sounds quite within the realm of possiblity of something Elon & Co would think up.Hey, totally random thought.. If they did all that, maybe you could do away with any swivel mechanism on the 7 engines? (I think I remember some statement about all engines swivelling though)Oh, so you think that with this kind of macro-nozzle thing, then none of the engines would have to gimbal? Could the macro-nozzle thing achieve the required control authority on its own, particularly during landing?
Quote from: tyrred on 09/16/2018 08:38 amTriple duty, including exhaust shaping, thermal radiation, and engine shielding... Sounds quite within the realm of possiblity of something Elon & Co would think up.Hey, totally random thought.. If they did all that, maybe you could do away with any swivel mechanism on the 7 engines? (I think I remember some statement about all engines swivelling though)
Triple duty, including exhaust shaping, thermal radiation, and engine shielding... Sounds quite within the realm of possiblity of something Elon & Co would think up.
This leads me to think that there would be plenty of other opportunities to support multiple other mission objectives other than tourism.I would hope that the announcement covers that and also that, if anyone from NSF is given the opportunity to ask, they would press SpaceX to discuss any such plans.
the F9 booster would come completely apart had it to reenter from orbital velocities as I suspect they have found out the second stage would as well
Quote from: TripleSeven on 09/16/2018 12:28 amthe F9 booster would come completely apart had it to reenter from orbital velocities as I suspect they have found out the second stage would as well I don't recollect if this idea has been brought up before, so I apologize if I'm repeating it. Could a BFS returning from BEO get refueled in earth orbit before reentering the atmosphere and landing retropropulsively? I suppose the question is whether it would take more fuel to go into orbit than it would to power a landing with fuel reserves left over after Mars or lunar departure. SpaceX has experience with retropropulsion, and perhaps applying the techniques it has learned with F9 to slowing down the interplanetary vehicle would make more sense than equipping it with extra-robust shielding.
Quote from: WindyCity on 09/16/2018 08:16 pmQuote from: TripleSeven on 09/16/2018 12:28 amthe F9 booster would come completely apart had it to reenter from orbital velocities as I suspect they have found out the second stage would as well I don't recollect if this idea has been brought up before, so I apologize if I'm repeating it. Could a BFS returning from BEO get refueled in earth orbit before reentering the atmosphere and landing retropropulsively? I suppose the question is whether it would take more fuel to go into orbit than it would to power a landing with fuel reserves left over after Mars or lunar departure. SpaceX has experience with retropropulsion, and perhaps applying the techniques it has learned with F9 to slowing down the interplanetary vehicle would make more sense than equipping it with extra-robust shielding.good question. If a BFS was returning from BEO and could enter earth orbit at an altitude that could be reached by a tanker then without a doubt; if the basic refueling system works then it could easily be refueled for a propulsive landingwhat would be interesting to explore...from a fuel etc viewpoint what would be the affect on fuel etc of using the atmosphere to "aerobrake" into some high eccentric orbit (ie one with a high point and a low point but a very high point) do a few more aerobrakes (maybe with some propulsive burn) to circularize and then refuel for a landing. it would take some serious orbital mechanics work to figure out the pros and cons of that.direct entry is always less expensive on fuel than any orbital manuevers (to then land) but you dont have the same heat issues.good question.
I would hope that SpaceX would consider a lifetime NSF member with engineering degrees as possible crew.
what would be interesting to explore...from a fuel etc viewpoint what would be the affect on fuel etc of using the atmosphere to "aerobrake" into some high eccentric orbit (ie one with a high point and a low point but a very high point) do a few more aerobrakes (maybe with some propulsive burn) to circularize and then refuel for a landing.
Is it reasonable to think that the shielding necessary for aerobraking maneuvers and refueling would be less massive and complex than what would be required for direct entry from BEO? If true, could that translate into a capacity to return larger payloads to earth?
I've known the SSME could operate SL to vacuum with no problems recently I read on how it did it.The nozzle was the ideal vacuum shape so it would operate over a wider pressure range at the cost to efficiency.Carrying engines BFS couldn't use seemed wasteful......
t to efficiency.Carrying engines BFS couldn't use seemed wasteful......
the parallel-looking gaps between the petals would in general imply only a small amount of radial movement to close up the gaps (maintaining same cone angle), assuming no petal overlap is created by mechanism.If they are a nozzle extension of some sort could they be set up to fold into a lobed cone shape around the engine bells to be more conformal to the bells than a simple cone would be? Use of 2 petals per engine suggests that this could be part of the solution. Could they be designed to work as Expansion-deflection nozzles? The ring of raptors being gimballed outwards to each fire against the 2 deflector petals for just that engine, mostly independent of other engines (so that only 2 engines need be fired at once). Middle engine could/would be shut down for this. I like the idea that they might also shield non-firing engine nozzles from debris during a Mars or Lunar landing.
Oh Monday, deliver us.
Quote from: meekGee on 09/16/2018 10:19 pmOh Monday, deliver us.I expect an update, I do not expect all these details to be explained, especially if there is not a Q&A session. If there is a Q&A session, and all the pre-approved questions start with "How do you feel now that..." I'm going to freak :p