To vent, or not to vent - that is the question...

bsexton · Mar 31, 2003

At what point (read that as altitude) should you consider vent holes in the booster and payload sections of a 4" diameter rocket? I am working on a modified "stretch" version of the PML Pterodactyl Jr. with a 16" payload section. I plan on dual deployment and projected altitudes of 4,000 - 5,000 feet with a Pro38 J class motor.

Picture attached.

Thanks,

daveyfire · Mar 31, 2003

I'd recommend a couple 1/8" to 1/4" vent holes in anything that size going up to that altitude, it can't hurt and it may prevent a pressure separation. However, I've found that where vent holes are really needed is in rockets going very high very fast. See my post "High Speed Vents" under the Small Endeavour thread. That Pterodactyl is a very nice looking rocket!

bsexton · Apr 1, 2003

Just wanted to confirm that multiple vent holes may be required:

Static port or altimeter vent holes and
Air vent holes

I am using a Missle Works RRC2 altimeter and the User's Manual has a formula for calculating the "static ports". They say "more" is better than "one". Do you agree?

daveyfire · Apr 1, 2003

I would tend to agree, but I don't think it should really matter much, just as long as you don't have one BIG one right over the altimeter's pressure sensor. Then Bernoulli might come into play and you'd pull a vacuum over the sensor, giving a false reading...

HTH.

To vent, or not to vent - that is the question...

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To vent, or not to vent - that is the question...

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