Isn't the real long pole item Raptor? I would think the tanks, thrust structure etc. would be pretty straightforward. M1D is pretty much done, and SuperDraco is a few months from the pad abort test. After that's locked down the propulsion guys will need something to do - if they haven't started modeling it already. Two questions I have is would M1D's hydroforming construction translate to Raptor production? Could that speed its development?Then there is Musk's testimony before the Texas legislature where a factory was mentioned for Brownsville.
Quote from: docmordrid on 05/20/2013 12:15 amIsn't the real long pole item Raptor? I would think the tanks, thrust structure etc. would be pretty straightforward. M1D is pretty much done, and SuperDraco is a few months from the pad abort test. After that's locked down the propulsion guys will need something to do - if they haven't started modeling it already. Two questions I have is would M1D's hydroforming construction translate to Raptor production? Could that speed its development?Then there is Musk's testimony before the Texas legislature where a factory was mentioned for Brownsville.bump -- bold mineHow scale-able is the tank and thrust structure design of the F9? Of course, new tooling, bigger assembly building, transportation issues, etc., but is there anything about the fundamental F9 balloon tank design that can't be scaled? And what else of F9 existing technology (avionics, launch facilities or concepts, whatever) can be used for a BFR?
I think they want 50 tons of cargo to Mars per shot, with no orbital assembly.
deltaV - What would the numbers be for a single core version?Also, I couldn't resist... Fun with photoshop - Here is a 7m "MCT" with 7 raptors compared to F9 and FH.
deltaV - What would the numbers be for a single core version?
Don't focus too much on expendable performance; the methane/Raptor vehicle will probably be reusable for the start.
Quote from: Lars_J on 10/24/2013 01:47 amdeltaV - What would the numbers be for a single core version?Also, I couldn't resist... Fun with photoshop - Here is a 7m "MCT" with 7 raptors compared to F9 and FH.Very impressive, though given the Raptors' thrust & Isp, it seems like a very large rocket to only get ~ the same payload into LEO as the Falcon Heavy. If the Raptor is only putting out 293 tf of vac thrust, I would strongly expect that there absolutely has to be a minimum of 7 Raptors on the 1st stage. I still think 9 is more likely to avoid cannibalizing the Falcon Heavy's market. Any chance you could create a triple-core heavy version of this rocket?
Quote from: Hyperion5 on 10/24/2013 02:01 amQuote from: Lars_J on 10/24/2013 01:47 amdeltaV - What would the numbers be for a single core version?Also, I couldn't resist... Fun with photoshop - Here is a 7m "MCT" with 7 raptors compared to F9 and FH.Very impressive, though given the Raptors' thrust & Isp, it seems like a very large rocket to only get ~ the same payload into LEO as the Falcon Heavy. If the Raptor is only putting out 293 tf of vac thrust, I would strongly expect that there absolutely has to be a minimum of 7 Raptors on the 1st stage. I still think 9 is more likely to avoid cannibalizing the Falcon Heavy's market. Any chance you could create a triple-core heavy version of this rocket? I think cannibalizing FH would be perfectly fine with SpaceX. While larger, it would be a simpler vehicle (7 vs 27 engines), less components, AND easier to reuse. Once this "MCT" entered service, FH would be phased out.
Also, I couldn't resist... Fun with photoshop - Here is a 7m "MCT" with 7 raptors compared to F9 and FH.
Would there be any advantage to a "Heavy" version of this beast?
Quote from: Lars_J on 10/24/2013 01:47 amAlso, I couldn't resist... Fun with photoshop - Here is a 7m "MCT" with 7 raptors compared to F9 and FH.That's hot.Quote from: SpacexULA on 10/24/2013 04:17 amWould there be any advantage to a "Heavy" version of this beast?Similar to FH you'd think.
Why would it replace F9? If there is a market for it, they would keep it.
If we assume that the MCT is sized as a SSTO Mars-Earth return vehicle, and that the second stage of the launcher is the EDS, and that the EDS is integrated into the MCT, then back-of-the-envelope calculations give the following.For the return flight:if you assume 7000 m/s delta-v from Mars' surface to Earth and 380 s Isp, you get a propellant mass fraction of ~0.85. Assume a T/W of 1.5 at take-off, 2.5 MN thrust for a single Raptor and 3.7 m/s2 gravity on Mars. That gives you a gross take-off weight of 450 (metric) tons, out of which 380 tons is propellant.For the outward flight:Assume 6000 m/s delta-v and 380 tonnes propellant. Propellant mass fraction ~0.80, gives IMLEO is 475 tonnes. The MCT would launch dry and be refuelled at a propellant depot. At Mars top-of-the-atmosphere mass would be about 150 tonnes, 55 tonnes of which is propellant for landing from about Mach 5.If we guess that the stage + ship has a dry mass of 50 tonnes, playload Earth-Mars is 45 tonnes and Mars-Earth is 20 tonnes.The MCTSingle Raptor engine. About 40m long and 10m diameter of approximately fairing shape. Direct entry at Mars, aero-brakes to about Mach 5, then uses propulsive descent. [vertical or horizontal landing?]Aero-brakes into Earth LEO on return, small amount of propellant used to circularize orbit below radiation belts. Refuelled and refurbished for future missions. [or perhaps lands back on Earth?]The LauncherLauncher needed is 95 tonnes to LEO for the integrated stage+ship and payload, as the stage part is 20 tonnes, the launcher is in the 75 tonnes/LEO range. So assuming 30% payload loss for 1st stage reuse that is about 110 tonnes to LEO non-reusable. Assume a 2nd stage reuse penalty of 50% and a tanker version of the 2nd stage, this can place about 37 tonnes of fuel into LEO. This is similar to the performance a 9 Raptor 1st stage would give.So each Mars mission would consist of one MCT launch and 11 tanker flights. [Alternatively, a heavy version could place about 110 tonnes of fuel into LEO so 3 or 4 heavy launches would be needed][Some of these calculations were initially done by Joel]
Quote from: Lars_J on 10/24/2013 05:16 amWhy would it replace F9? If there is a market for it, they would keep it.I was sort of joshing but more seriously, they would if there was a case for it. Although the move from F1 to F9 wasn't quite as drastic. Just saying.