[roc-chat] Re: BP for Deployment of Main Question
- From: Chris J Kobel <Chris.J.Kobel@xxxxxxxx>
- To: roc-chat@xxxxxxxxxxxxx
- Date: Thu, 8 Dec 2011 11:26:09 -0800
I would second David's recommendation of 4 grams, which should give about
200 lbs of ejection force at 5000 AGL, with the 3 2-56 shear pins
requiring about 100 lbf to overcome.
Chris
From: David.P.Smith@xxxxxxx
To: roc-chat@xxxxxxxxxxxxx
Date: 12/08/2011 11:10 AM
Subject: [roc-chat] Re: BP for Deployment of Main Question
Sent by: roc-chat-bounce@xxxxxxxxxxxxx
I use the "rule of thumb" on this site.
http://www.vernk.com/EjectionChargeSizing.htm
So, by that site you would need 4 grams of ffffg black powder.
Remember that you are looking at a lot of area to apply the ejection
pressure to. A 7.5 inch circle had a bit over 23.5 square inches of are.
So 10 psid will give you 235 pounds of ejection force.
What is the shear force rating for your pins?
David P Smith
NAR 78668 L2
Amateur Extra, W6DPS
The opinions expressed in this email are my own and do not necessarily
represent the positions, strategies or opinions of Southern California
Edison, its parent company Edison International, or any of their
affiliates.
From: Richard Dierking <redierking@xxxxxxxxxxx>
To: <roc-chat@xxxxxxxxxxxxx>
Date: 12/08/2011 10:10 AM
Subject: [roc-chat] BP for Deployment of Main Question
Sent by: roc-chat-bounce@xxxxxxxxxxxxx
Say your main deployment section is 7.5" diameter, 24" long and using
three (3) 2-56 nylon shear pins. How much BP?
Also, what's the advantage of using two or more deployment canisters
instead of just one? For multiple canisters, would you wire in series or
parallel? (One 9 volt battery and Perfectflite WD altimeter with main
deployment at 1100'.)
Richard Dierking
BTW: Kurt, we're not intending to turn the nose into a second stage :-)
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