Vent holed for ebays

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Jan 19, 2009
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So, I have noticed the sizes are rather small in the instructions compared to what I remember them being. Perfectflight says .033 per hole for a 2" bay....I remember using 3x.125 for the same size. Also, what does telemetrum recommend? I didn't see anything in the manual about vent sizing.

This is what happens when I look at directions for something I have been using successfully for years :)
Hi Chris,

I consolidated several Excel workbooks published by other rocketeers and you can find them posted here As you know this is not an exact science, or I should say for anything reasonable at our hobby level it certainly isn't, and from my experience close enough is good enough when it comes to this topic.

The worksheet from that workbook that you would want to look at is the "Altimeter Sampling Hole Calc" and you simply input the diameter and length, then select the number of holes you want and choose the drill-bit. I have used this as a guide for 3 - 5 hole AV bays and I have yet to have an issue with the numbers, as a matter of pride my apogee events are bang on.
Thanks, I'll use this now. It's crazy how long it's been since I looked at this stuff, still flying, just haven't built in a while I guess.