A chemical rocket is used for launch into earth orbit. At the end of the combustion chamber the stagnation temperature is 3000 K. The molecular weight of the combustion products is 26. The gases expand isentropically as an ideal gas mixture with specific-heat ratio 1.2. The area ratio Ae/A* of the nozzle is 20, and the throat diameter is 0.1 m. Determine: a. The stagnation pressure if the expansion is correct at sea level; b. The rocket thrust at sea level, 15-km, 30-km, and 60-km altitude