Starship design challenges

 Simulation of a cylindrical shaped shield reentry with V=6000m/s, P=15 Pa. Flow of  0.02 kg/s 100K cold methane is injected on 50 mm slice. This does not take into account the phase transferee energy of methane - 510KJ/kg.K. If we take into account the phase transferee energy, even 0.01 kg/s could be enough. For 60 meters length of Starship we have 12kg/s total methane consumption for cooling. If we consider 15 min. reentry we get 10.8 tons methane in total, but to be on the safer side I think 20 tons would be wiser. If  HASTELLOY   alloy is used for the shield it could withstand multiple reentries as it keeps enough strength and oxidation resistance at 1300K. However,  for a reentry shield  I consider the cylindrical shape mildly said inappropriate. 

 This is a cross section of the shield with simplified but principally correct geometry. The liquid methane is ejected through a single "pipe" directly over the most heated part of the shield. The methane vapor is ejected through a gas "trap" (View A) in radial direction towards the upper part - after many experiments this redirection of the vapor seems most logical, as it helps cooling the upper part without creating excessive force in the reentry direction. The temperature of the exhausted methane is still low enough - about 170-180 K

 Much more refined fluid simulation of Starship reentry with liquid-vapor cooling. About 5 0000 000 fluid and solid cells and 8 hours CPU time. The shield temperature is acceptable, despite that it will still glow red. About 20kg/s methane without considering the  methane  phase transferer energy - 510 KJ/Kg.K. The simulation study does not allow that. If we consider the  phase transferer energy, the total methane consumption will decrease significantly. As well the heat transfer efficiency in the shield can be further optimized. Considering about 20 minutes reentry cooling I can approximate that 20 tons of methane should be enough for a first /still risky/ reentry attempt. The necessary cooling power is approximately 3000 kW .

 A rough approximation of a liquid-vapor methane cooling. Same reentry conditions as the previews post. Up to 30 tons methane required for cooling. In this simulation I am injecting the cooling fluid from a single collector "pipe" directly over the bottom part through the entire length of the double bottom shield space. The methane vapor vents through channels on the upper horizontal part of the shield. I am working to refine the cooling system. 

Surface temperature plot of Starship /tile protection/ top and bottom part with very mild reentry conditions - only 5000m/s speed, AOA=70 degree and  atm. pressure only 10 Pascals. As it is seen the shield temperature well exceeds 3000K in about 40-50% of the surface.

 Possible design of the retractable leg:

 Rough design of the new shield:

 Possible construction of a fully protected retractable catch hook - it is possible only with similar shield design:

 Possible construction of the habitat module:

  Starship cargo/habitat module on Mars surface:

 Starship habitat/cargo module landing on Mars:

  Starship first unmanned flight to Mars with three habitat and/or cargo modules:

 Starship in space:

  Starship on Mars surface with retractable legs and solar panels extended.

 Starship shield upgrade which would decrease the thermal load in critical areas as flap hinges. As well this design makes the Starship aerodynamically stable during the reentry, which allows to replace the rear driven flaps with fixed wings as a part of the shield. The forward flaps would be enough to keep the angle of attack and perform the belly flop maneuver.