[roc-chat] Re: BP for Deployment of Main Question
- From: Geoff Huber <ghuber@xxxxxxxxxxxxx>
- To: "roc-chat@xxxxxxxxxxxxx" <roc-chat@xxxxxxxxxxxxx>
- Date: Thu, 8 Dec 2011 21:29:35 +0000
Do the math and then ground test and adjust. The math always assumes a
spherical chicken. YMMV
Geoffrey Huber
(530) 891-0853 ext 3030
Geoff.Huber@xxxxxxxxxxxxx<mailto:Geoff.Huber@xxxxxxxxxxxxx>
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx] On
Behalf Of David.P.Smith@xxxxxxx
Sent: Thursday, December 08, 2011 11:17 AM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: BP for Deployment of Main Question
Arghh. Do you math self-check before sending....
Let me try one thing again. A 7.5 rocket is a bit over 23.5 inches in
circumference. The area is a bit over 44 square inches. Therefore 10 psid
gives us 440 pounds of ejection force...
Hey, who does math at lunch time???
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: David.P.Smith@xxxxxxx<mailto:David.P.Smith@xxxxxxx>
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Date: 12/08/2011 11:12 AM
Subject: [roc-chat] Re: BP for Deployment of Main Question
Sent by:
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________________________________
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<mailto:redierking@xxxxxxxxxxx>>
To: <roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>>
Date: 12/08/2011 10:10 AM
Subject: [roc-chat] BP for Deployment of Main Question
Sent by:
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________________________________
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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