The drag coefficients for cones with hot and cold walls and different bluntness ratios have been found experimentally. There is a small wall temperature effect which can be accounted for by the change in the pressure drag that occurs in the free molecular limiting flow. The results from the Monte-Carlo calculations agree well with the experiments and they show that the flow field is characterised by the free molecular behaviour at least as far as Knudsen = 0.02 (based on bade diameter) and that the shear drag is the predominant force. From the experimental results it seems reasonable to conclude that the flow fields are characterised by the free molecular behaviour down to the lowest value of Knudsen number tested, which was 0.006. The nose bluntness effect on the measured drag can be correlated by normalising the coefficient by the value in the free molecular limit and by defining a Knudsen number based on the cone lengt
