Someone has probably already asked this but I wouldn't know how to find it: How short could you plausibly make the full-diameter BFR? Im just thinking a lot shorter and symmetrically remove some engines.
Yes, if you could make it wide but short for a Mini-BFR with say 9 Raptors, then stretch the tanks and add the remaining engines for a full BFR. Same with a second stage, one Raptor and a short reusable stage, then stretch with more engines for an MCT or tanker. I would say at least 10-12m in diameter. 3.7m tankage could be made at Hawthorn to fit inside the upper stage with remaining space on a stretched MCT version for cargo or crew.
The only way I could see this being worthwhile is if it used almost all the same major components from the ITS spaceship.
convert the thrust structure to hold 21 Raptors
Quote from: envy887 on 10/03/2016 04:52 pmThe only way I could see this being worthwhile is if it used almost all the same major components from the ITS spaceship.Well that is the idea. Essentially the propulsion section of ITS (second stage) starts life as the first stage of smaller beast.Same tanks, same engines, same handling and transport systems.Quote from: envy887 on 10/03/2016 04:52 pmconvert the thrust structure to hold 21 Raptors21?
21 SL Raptors is based on the idea that the second stage is the same as the ITS ship. The total GTOW would be about 4500 tonnes, so at least 20 Raptors are needed. 21 packs a little better.I don't see the point of wasting resources making a smaller dedicated second stage. Just put the big ITS upper stage on top and stage lower. As long as the booster gets it up 30 km they can light the Raptor vacs.
It doesn't sound like everyone is on the same page as SpaceX. They intend to build and sub-orbitally test the Ship first. Once that's accomplished there will be time for them to decide whether going for the final Booster design, or building a shorter "Booster Block 0" makes more sense.
Quote from: sdsds on 10/09/2016 06:55 amThey intend to build and sub-orbitally test the Ship first.Does ship mean upper stage? Where can I read about this?
They intend to build and sub-orbitally test the Ship first.
Quote from: KelvinZero on 10/09/2016 07:33 amQuote from: sdsds on 10/09/2016 06:55 amThey intend to build and sub-orbitally test the Ship first.Does ship mean upper stage? Where can I read about this?Well yes it would mean that, if it were a standard launch system. It's an upper stage of a launch vehicle, a trans-planetary habitat, a planetary lander, and a single-stage-to-orbit (from Mars at least) ascent vehicle. You can hear more about it in ... the speech Musk gave announcing the ITS. Look particularly at the timeline graphic which shows which systems are developed when....
Quote from: sdsds on 10/09/2016 08:02 amQuote from: KelvinZero on 10/09/2016 07:33 amQuote from: sdsds on 10/09/2016 06:55 amThey intend to build and sub-orbitally test the Ship first.Does ship mean upper stage? Where can I read about this?Well yes it would mean that, if it were a standard launch system. It's an upper stage of a launch vehicle, a trans-planetary habitat, a planetary lander, and a single-stage-to-orbit (from Mars at least) ascent vehicle. You can hear more about it in ... the speech Musk gave announcing the ITS. Look particularly at the timeline graphic which shows which systems are developed when....I just meant the top bit (as distinguished from the bottom bit) Ok, I found the timeline inside the speech.https://www.youtube.com/watch?v=IFA6DLT1jBA?t=3157It is saying top bit first, possibly in 4 years, mentions vague possibility of suborbital flights as a service as well as for testing. Mentions possibility of at least tanker being single stage to orbit.I didn't see mention of a shorter block 0. Were you just referring to what is being discussed on this thread?I had been discounting the SSTO, especially due to the mention of not being able to bring it down, but I guess there is one reasonable use if you can just get the non-tanker version to orbit: You could avoid developing the tanker or booster at all until flight rate is high. Instead you launch SSTO with no cargo and use many launches of you F9R to refuel it. You could also use F9R to get 6 crew to orbit, plenty for an early mission. Maybe the safety would be the most important factor. The booster does sound pretty simple once you have the space ship and the F9R very likely would still not be fully reusable.
What kind of performance would you get out of a 9+1 Raptor, 12m diameter, TSTO launcher?
I didn't see mention of a shorter block 0. Were you just referring to what is being discussed on this thread?
Yes, someone should think about a refuelable SSTO excursion vehicle for interplanetary missions.
But what if the first Ship they build doesn't have quite the performance capability they currently say the final version will have? Wouldn't it then be interesting to supplement its capabilities with a minimalist, reusable version of the Booster? That would allow them to fly fully reusable missions to Earth-orbit....