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Old 06-11-2018, 07:48 PM
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BEC BEC is offline
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Join Date: Feb 2009
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Well, yes. But I’m thinking use a fairly large T-pin rather than a small sewing pin. In other words, something on the order of 1/32 of an inch in diameter or perhaps a little smaller. As a long time aeromodeller I have lots of big T-pins and I use one like that for this purpose.

Basically what you are trying to do is provide enough of a leak path for air inside the payload compartment to get out and allow the pressure to equalize at apogee before the model has fallen back so much as to mess up your reading unacceptably. If you do the math and assume a ballistic path (and neglect drag), you fall back 16 feet in the first second after reaching apogee (1/2at**2) where a in this case is the acceleration due to gravity. In the first half second it’s 4 feet.

So you want the payload compartment to “leak down” pretty quickly.
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