Pogo oscillation

The Pogoeffekt is a resonant vibration of the engine performance liquid rocket during flight. Can be triggered such an oscillation by pressure changes in the engine, which then lead to increased fuel flow rate ( decreasing chamber pressure ) or a reduced fuel flow can cause ( increasing combustion chamber pressure), which in turn attracts a pressure change by itself. Does such a vibration, a resonance frequency of the forest or the fuel system, so the vibration may increase to such an extent that the vehicle is thereby destroyed itself.

The Pogoeffekt takes its name from the English pogo stick ( pogo stick ).

The first and second stages of the Saturn V rocket were relatively susceptible to the Pogoeffekt, since in each case the central engine of the five cross-shaped engines of these stages was not directly connected to the rigid outer structure of the stage and therefore prone to vibrations, to which is fuel lines affected. This led to problems when unmanned test flight of Apollo 6 The premature shutdown of the second stage inner engine at flight of Apollo 13 went back to the Pogoeffekt, which remained beyond consequences.

Several total losses of unmanned launchers, particularly in the 1950s and early 1960s were due to the occurrence of the Pogoeffekts.

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