Problems

Problem 2.1. During re-entry of a RV the density at 70 km altitude is 10 per cent lower than assumed. The actual drag hence is 10 per cent smaller than the nominal drag (D = 0.5p^v^CD(a)Aref). The vehicle flies with an angle of attack a = 45°. We assume a constant velocity vTO, the reference area A is constant anyway. How must the angle of attack a approximately be changed in order to recover the nominal drag?

Problem 2.2. Take from Table 2.1 the density for a) 30 km and b) 80 km altitude. Compute for both cases the partial densities pN2 and po2 and determine the partial pressures pN2 and pO2. Compare the results with the density and pressure data in Table 2.1.

Problem 2.3. The Knudsen number of a nose cone with a diameter D = 0.3 m at 70 km altitude is Kn = 0.0029. It is to be tested in a ground-simulation facility. Pressure and temperature in the test section of the facility are p = 50 Pa and T = 100 K. What is the mean free path in the test section? What nose cone diameter is needed in the facility in order to have the same Knudsen number as in the flight situation?