Pogo effect

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The pogo effect is a resonant fluctuation in engine performance in liquid rockets during flight. Such an oscillation can be triggered by pressure changes in the engine, which can then lead to increased fuel throughput (increasing combustion chamber pressure) or reduced fuel throughput (falling combustion chamber pressure), which in turn results in a pressure change. If such a vibration hits a resonance frequency of the overall structure or the fuel system, the vibration can increase to such an extent that the vehicle is self-destructive.

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

The first and second stages of the Saturn V rocket were susceptible to the pogo effect, since the center engine of the five cross-shaped engines of these stages was not directly connected to the rigid outer structure of the stage and was therefore prone to vibrations that were reflected in the fuel lines affected. This led to problems during the unmanned test flight of Apollo 6 . The premature shutdown of the inner engine of the second stage during the flight of Apollo 13 was also due to the pogo effect, which had no further consequences.

Several total losses of unmanned launch vehicles, especially in the 1950s and early 1960s, were due to the occurrence of the pogo effect.

Individual evidence

  1. ↑ Wernher von Braun: The Perils of Pogo. In: Apollo Expeditions to the Moon. NASA, accessed March 13, 2012 .
  2. ^ Courtney G Brooks, James M. Grimwood, Loyd S. Swenson: Pogo and Other Problems. In: Chariots for Apollo: A History of Manned Lunar Spacecraft. NASA, accessed March 13, 2012 .
  3. ↑ Tom Irvine: Apollo 13 Pogo Oscillation. (PDF; 1.0 MB) In: October 2008 Newsletter. Vibrationdata, pp. 2-6 , accessed March 13, 2012 (English).

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