shear pins with motor eject
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jeff2space
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Don't usually put shear pins in booster/coupler section. Only use them to hold nosecone to payload section in dual deploy. Does your booster have that much drag you need shear pins in it?
Titan II
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I use two or three 2-56 on "all" of my rockets between 38mm and 4 inch. I like the consistency of shear pins to friction fitting.
Pro38 motors contain 1.3 grams of FFFFG black powder if you want to do deployment tests.
Pro38 motors contain 1.3 grams of FFFFG black powder if you want to do deployment tests.
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Coop
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Question is: which motor size are we talking? Second question is what is the volume you're pressurizing with the motor eject? Third question is what size shear pins are you using, and the fourth is how many.
The calculator here: https://www.info-central.org/?article=303 might give you some insight...
Later!
--Coop
The calculator here: https://www.info-central.org/?article=303 might give you some insight...
Later!
--Coop
RKeller
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my example for needing them would be when using a longer delay on motor eject as a backup to the altimeter. with AT you can put in the same amount you use for the primary charge, but for CTI the amount is fixed. I see Pro38 contains 1.3g and pro 54 contain 2g. what about 29mm? the particular rocket I'm thinking about is a 54mm body tube with a 29mm motor (DD wildman sport) I plan on using three 2-56 nylon screws. looks like as long as there is more than .8g it should be fine.
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RKeller
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ok, after much more searching, I found a post from 2013 by Bobkrech that says,
"CTI ProXX motors use FFFF BP ejection charges. The charge weights are: Pro24 = 0.6 g; Pro29 = 1.2 g; Pro38 = 1.3 g; Pro54 = 2.0 g."
as long as this is correct I should be fine. also should be fine for my 38mm with two 2-56 screws.
"CTI ProXX motors use FFFF BP ejection charges. The charge weights are: Pro24 = 0.6 g; Pro29 = 1.2 g; Pro38 = 1.3 g; Pro54 = 2.0 g."
as long as this is correct I should be fine. also should be fine for my 38mm with two 2-56 screws.
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JimJarvis50
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The instructions for Pro29/38/54 state that if you want to add more BP, add it above the white cap and then seal the cavity with tape. So, you can use whatever amount of BP that you want.
Jim
I find it interesting that the 29mm and 38mm amounts are almost the same. It would be interesting to find out what criteria they used to come up with those values.
dingle
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I'm still confused, you are worried about drag separation of the drogue deployment? Typically the main deployment is the one that contains the shear pins as you don't want that coming out at apogee accidentally. With the drogue though I can't see a use for shear pins unless you think it will drag separate but not have enough drag/force to fully deploy the drogue laundry?
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