Fig.3.4 gives the shock layer temperature distribution of 3250K at the
stagnation point and 3050K at both ends of the shoulder region. This
gives a temperature distribution at the shoulder ends as 94%
(3050/3250) of the maximum (stagnation point) value. Fig.3.5 gives the
wall temperature distribution as a ratio of shoulder end distance (s) to
nose radius (Rn) taken from stagnation points. From the
prototype design of Orion MPCV heat shield in Fig.3.1,
‘Rn’ is 60mm and‘s’ is 25mm giving ‘s/Rn’ ratio of 0.416 (25/60). Tracing the
Tw curve of 5s in Fig.3.5 using ‘s/Rn’ ratio of 0.416
gives an approximate value of 91.6% (1100/1200) of the stagnation point
value. There is no shoulder region temperature lower than 90% of the
stagnation point temperature by repeating this process for all other
curves in Fig.3.5.
However mere looking at the temperature distribution curves in Fig.3.3,
tungsten rods of diameters 6mm, 8mm, 10mm, 20mm, and 40mm seem to
satisfy the 90% maximum temperature values at the shoulder regions.
This is not true due to some individual temperature analysis in Fig.3.6.