Brain Freeze on Sampling Port Sizing

[jmmome]

Here's what I want to do- four (4) sampling port holes for an 8" dia electronics bay which is 13.5" long. I tried to use the calculator referred to below, but it isn't making any sense to me:

https://www.rocketryforum.com/threads/vent-hole-size-calculator-spreadsheet.42898/
Also tried using the rocketrycalculator.com Altimeter Vent Port Sizing, but "number of quarters per hole" of 1.3 makes no sense to me either.

What diameter should the four sampling port holes be? Sorry for the brain freeze!

 

[rcktnut]

4 at 5/16ths in. dia is what it comes out to. To be exactly right on you need 21/64ths. and a 64th of an inch ain't going to make any difference!!

 

[tsmith1315]

"number of quarters per hole" of 1.3

Quarter = quarter inch

each hole is 1.3 quarters... so each hole is 1.3(0.25") = 0.325"
...aka 1.3/4

 

[rcktnut]

Here's what I want to do- four (4) sampling port holes for an 8" dia electronics bay which is 13.5" long. I tried to use the calculator referred to below, but it isn't making any sense to me:

https://www.rocketryforum.com/threads/vent-hole-size-calculator-spreadsheet.42898/
Also tried using the rocketrycalculator.com Altimeter Vent Port Sizing, but "number of quarters per hole" of 1.3 makes no sense to me either.

What diameter should the four sampling port holes be? Sorry for the brain freeze!

View attachment 500475

You arrived at the correct total area needed just had to divide by 4. .3125 (5/16ths) x4 = 1.25
.3281(21/64ths) x4 = 1.3 No need to be sorry at 66 I get my share of brain freeze and farts.

Thanks for bringing this up was unaware of the rocketry calculator. Nice and easy, I did it the hard way, using the math. The rocketry calculator is right, and now book marked here!!

 

[jmmome]

Thanks guys!!!!!!!!!!!!!!!!!!!!!!

 

[jmmome]

You arrived at the correct total area needed just had to divide by 4. .3125 (5/16ths) x4 = 1.25
.3281(21/64ths) x4 = 1.3 No need to be sorry at 66 I get my share of brain freeze and farts.

Thanks for bringing this up was unaware of the rocketry calculator. Nice and easy, I did it the hard way, using the math. The rocketry calculator is right, and now book marked here!!

Age 68 for me, and now taking an epilepsy anti-seizure med, so the grey matter computer isn't working quite as well as it was 40 years ago.