It only takes one engine to explode out of 30 to bring down an LV. I believe this happened to at least one of the N-1's. Anyone including SpaceX even attempting something like the N-1 beggars belief. >
And announces a >F-1 thrust version of Raptor to keep no. of engines on BFR to no more than 9.
...
Also for purposes of reliability and repair.
Production Raptor goal is specific impulse of 382 seconds and thrust of 3 MN (~310 metric tons) at 300 bar
Chamber pressure is almost 3X Merlin, so engine is about the same size for a given area ratio
Quote from: DJPledger on 09/25/2016 01:32 pmAnd announces a >F-1 thrust version of Raptor to keep no. of engines on BFR to no more than 9.Why do you assume early Sixties engine logic still applies? The base principles of rocketry do indeed move that slowly. The engineering, materials science, and practically everything else, do not.
Quote from: GORDAP on 09/24/2016 01:03 pmMy best guess1 - a (BFS 2nd stage is MCT) 2 - 46x raptor on 1st stage, multiple used for landing, for redundancy3 - 15m4 - 120 MN SL thrust 5 - Redundant raptors on MCT for LAS / no LAS needed6 - c7 - a (or combination with b where there is more than one pass through atmosphere before landing)8 - a / c
Quote from: GORDAP on 09/12/2016 06:32 pm1) Overall Launch Architecture a) MCT is composed simply of a BFR 1st stage and BFS 2nd stage/spacecraft b) Boost phase consists of 2 stages, which put the BFS into orbit c) Other: 3rd stage, 'half' stages, drop tanks, etc.Going with (a)2) Number of Raptor Engines on BFR (1st stage)< 30, my best estimate is 25-27 if thrust stays close to 230 tonnes range3) Diameter of BFR (1st stage)Range 12.5m-15m, best estimate 15m 1st stage4) Total Raptor 1st stage thrust (sl)60 Meganewtons and T/W > 1.35) LAS Architecture a) No LAS - BFS is the escape mechanism b) Traditional LAS - above BFS and is nominally jettisoned during launch phase c) BFS contains smaller 'ejection pod' where humans reside during launch d) Other, non-traditional LAS designBest guess is (a)6) Shape and Landing Mode of BFS a) Capsule (perhaps elongated), w/ TPS on base b) Cylindrical or biconic - horizontal landing c) Cylindrical or biconic - vertical landing d) OtherGoing with (c), definitely no horizontal landing7) Mars and Earth return a) BFS does direct entry into Mars and Earth atmosphere b) BFS does orbital capture before performing entry burn and landing c) Same as b, but upon Earth return, stays in orbit for next synod(a) Use of non-chemical thrust a) Not part of the plan b) Will use SEP for some/all of the big transits c) All chemical for now, but plans to incorporate SEP down the road(c) strongly favorCan anyone think of more/better questions?Predict Musk will miss 1st crewed landing by >= 3 synods5-6 Rvacs on BFS stage 2Raptor sea level will have 10s of tonnes thrust more than the 230 tonnes mentioned by ElonEntire BFR/BFS GLOW masses under 5.000 tonnes; my estimate ~4,500Height of BFR/BFS stack under 120m; my estimate <100mCargo version, tanker version, crewed version of BFS1st crewed landing on Mars 8-12 humans plannedJust over 48 hours until Musk makes fools of us
1) Overall Launch Architecture a) MCT is composed simply of a BFR 1st stage and BFS 2nd stage/spacecraft b) Boost phase consists of 2 stages, which put the BFS into orbit c) Other: 3rd stage, 'half' stages, drop tanks, etc.Going with (a)2) Number of Raptor Engines on BFR (1st stage)< 30, my best estimate is 25-27 if thrust stays close to 230 tonnes range3) Diameter of BFR (1st stage)Range 12.5m-15m, best estimate 15m 1st stage4) Total Raptor 1st stage thrust (sl)60 Meganewtons and T/W > 1.35) LAS Architecture a) No LAS - BFS is the escape mechanism b) Traditional LAS - above BFS and is nominally jettisoned during launch phase c) BFS contains smaller 'ejection pod' where humans reside during launch d) Other, non-traditional LAS designBest guess is (a)6) Shape and Landing Mode of BFS a) Capsule (perhaps elongated), w/ TPS on base b) Cylindrical or biconic - horizontal landing c) Cylindrical or biconic - vertical landing d) OtherGoing with (c), definitely no horizontal landing7) Mars and Earth return a) BFS does direct entry into Mars and Earth atmosphere b) BFS does orbital capture before performing entry burn and landing c) Same as b, but upon Earth return, stays in orbit for next synod(a) Use of non-chemical thrust a) Not part of the plan b) Will use SEP for some/all of the big transits c) All chemical for now, but plans to incorporate SEP down the road(c) strongly favorCan anyone think of more/better questions?
Quote from: Oersted on 09/26/2016 02:59 amAlso for purposes of reliability and repair. That's what I meant, wouldn't it take longer to repair/inspect 30 engines on one stage compared to 9 or 20? Extra person-hours required for turnaround, etc.
Quote from: Pipcard on 09/26/2016 03:29 amQuote from: Oersted on 09/26/2016 02:59 amAlso for purposes of reliability and repair. That's what I meant, wouldn't it take longer to repair/inspect 30 engines on one stage compared to 9 or 20? Extra person-hours required for turnaround, etc.I'm guessing now that this won't be a very huge problem (or will it?), because when Falcon 9's first stage has 9 engines, people aren't talking about how this is harder to maintain than one big engine + at least 2 small engines on the sides for landing; people instead talk about how it is more expensive to maintain production of multiple engine types instead.