Peculiarities of gasdynamics of descent and landing on planets with rarefield atmosphere

TSNIIMash was one of the first scientific centers were such investigations had been started dealing with force and heat loads from the engine jets acted on the space vehicle structure during soft landing on the lunar and Martian surfaces. Interaction of single/multiple jet with oncoming flow or surface is characterized by appearance of a large number of shock waves contact surfaces separated zones and other peculiarities and this defined the necessity of fulfillment of extensive experimental studies. For these aims U-22 and U-22M vacuum chambers were created in TSNIIMash in 1970-ies and 1980-ies. Some results regarding drag coefficient of the space vehicle with working jets are presented below.