Talk:Pogo oscillation

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Is this really a stub? It says just about all there is to say about pogo oscillations ... Richard W.M. Jones 18:53, 29 Jan 2005 (UTC)

Why is it capitalized? The article notes that it isn't an acronym, and therefore shouldn't be written all-caps. But if it's named after a pogo stick, shouldn't it be "pogo"? (As opposed to a phenomenon named after the Walt Kelly comic strip.)

The Apollo 13 article links here, and it's capitalized there, too. It seems that they should both be changed.

Lets keep it as POGO that way it is unique to rocketry (liquid fuel propulsion at least) and prevents any confusion with any other future space experiments using pogo or oscillating experiments. John E Greenwood

[edit] I don't understand this explanation

Quoth the article:

This structure was an "X" of two I-beams, with an engine on each beam and the center engine at the intersection of the beams. The center of the cruciform was unsupported, so the central F-1 engine caused the structure to bend upwards. The "Pogo" oscillation occurred when this structure sprung back, lengthening the center engine's fuel line below (which was mounted down the center of the cruciform), temporarily reducing the fuel flow and thus reducing thrust. At the other end of the oscillation, the fuel line was compressed, increasing fuel flow - causing a sinusoidal thrust oscillation during the 1st stage ascent.

I don't understand how there is negative feedback here. Let's say that the centre engine is pushing hard upwards on the X-cruciform beams. The fuel line is, as it says, compressed, increasing fuel flow. So the engine thrusts more and pushes harder upwards, compressing the fuel line further. That's positive feedback, not negative feedback surely? Richard W.M. Jones 11:41, 11 October 2006 (UTC)