#### sunderll

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The sampling port calculator I use says .28. So your .29 would be in-line with that. This is based on a four hole scenario with roughly 500ish cubic inches of volume in your AV bay. What I normally do is look for the next up-sized drill bit, in this case 5/16 or 9/32.

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I kind of like Joel Schiff's, from the Apogee

Using your numbers, and assuming three holes, we get

dN = 0.022 * 7.5 * sqrt (12/3) = 0.165 * sqrt (4) = 0.165 * 2 = 0.33

5/16 is 0.3125; 3/8 is 0.375; 11/32 is 0.34375

So I would probably just go with 3/8 to be sure. Remember that the calc is for the

Quickly, if you choose to go with four ports, then you need 0.165 * sqrt (3) = 0.286, so go with 5/16.

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A single 7/16" diameter hold would have a 0.88 second time constant. (4) 7/32" diameter holes equally spaced around the airframe has the same area and has a common mode time constant of 0.88 seconds but offers a 3.5 second differential gust time constant.