Now I have a confession: I never tested if the Crew Dragon 2022 fully replaced the DM2 Dragon & Inspiration4 addons...I have to confess I missed out that the version v2.0 of the Deep Space Dragon was already based on the new DM2 (now Crew Dragon 2022) capsule. I flew some mission segments, including the Asteroid approach and it looks excellent!
This was also a test if the new Crew Dragon 2022 fully replaces its predecessor, and it does. No problems whatsoever.
Exploration. That is what.What the heck am I doing here? This is a pretty lonely place, far from home.
I'd prefer to have more than one engine to rely on the return flight.
The trick here is that the trunk mounted SPS uses CTF as the oxidizer for this mission. CTF is a real beast to deal with, and any engine that uses the trunk fuel supply has to deal with it. It attacks anything remotely organic vigorously and runs at an extremely high chamber temperature.It might make sense to have more than one engine for deep space missions. Even airliners flying on long-range ETOPS routes must have two. Orion has a set of ATV-type thrusters as backup, if its AJ10 main engine fails.
Based on the organization of Dragons systems in quads, I would opt for 4 smaller engines for deep space propulsion.
I think the Orion back-up thrusters use the same fuel source as the main engine. So if the main engine fails, nearly the same dV can be achieved, although at longer burn durations.
If the secondary propulsion system of a Deep Space Dragon uses different fuels, it might be difficult to come back to Earth in case the main thruster fails in mid-flight.
Exactly. Keep all the trunk prop system separate. The trunk uses CTF, while Dragon uses NTO. The 4 smaller APS thrusters would use the big fuel tanks in the trunk just like the main engine.The proposed 1 + 4 layout. May need to check the achievable dV with the back-up thrusters.
That would be great, except... The Dragon's prop system could never handle CTF, and even if it could, there are no prop lines from the trunk to the Dragon so a redesign of the umbilical would be in order. Even so, I don't really want CTF lines running anywhere close to the crew... Or to have CTF contaminated plumbing onboard for entry, splashdown, and recovery. Better to let all the CTF stuff burn up on entry.Use Dragons nose thrusters as back-up. They are there anyhow, and might do the job.
That would be good except for the lunar lander mission, where I unfortunately need all that thrust for LOI with the lander docked.2 or 4 smaller CTF engines. Smaller engines might be easier to design, and the loss of a single engine would not kill the mission.