Wu14 and DF ZF:
The problem is cooling the warhead
You can use ablative materials or, for mach 20, air film cooling
The paper says:
Objective To put forward a new approach of active thermal protection system termed as film cooling for future hypersonic vehicles (Mach 20 flow) and validate its performance by CFD. Methods By solving Reynolds-averaged Navier–Stokes equations, the finite-rate chemical reaction model with Park-I 5 components (N2, O2, N, O, NO) 17 equations was used to investigate the real gas effect. For the typical blunt body, a numerical study of the effectiveness of film cooling was presented for
Mach 20 flow at 30 km, with the special designed micro inject hole located at the stagnation point. Results The reduction of heat flux on the isothermal wall (300 K) with film cooling at the vicinity of the hole could be as much as 90% compared to that without film cooling, and the covering area of the coolant flow could be 10 times larger than the out area of the hole. Conclusion The study showed promising prospect of film cooling for heat proof of future hypersonic vehicles.