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Technical Note — The impingement of underexpanded axisymmetric rocket motor exhausts and cold jets on flat plates

Rocket motors are used to provide propulsive thrust for various types of aerospace vehicle. The thrust is developed by the supersonic jets of hot gas emitted through the rocket motor exhaust nozzles. Usually, for most flight trajectories of rocket-propelled aerospace vehicles, the exhaust jets expand freely into the ambient medium. There are, however, instances where the exhaust jets impinge on solid obstacles which are either unavoidably or deliberately positioned in the vicinity of the rocket motor exhaust nozzles. In these cases, the exhaust jets are deflected from their normal paths. When a rocket exhaust jet is deflected in this manner by a solid obstacle, the situation is usually referred to as rocket exhaust impingement.