[roc-chat] Re: BP for Deployment of Main Question
- From: Richard Dierking <redierking@xxxxxxxxxxx>
- To: "roc-chat@xxxxxxxxxxxxx" <roc-chat@xxxxxxxxxxxxx>
- Date: Thu, 8 Dec 2011 11:35:09 -0800
Wow, 4 grams BP is about one half what we were coming up using the web and a
reference book I had.
Richard
Sent from my iPhone
On Dec 8, 2011, at 11:26 AM, "Chris J Kobel" <Chris.J.Kobel@xxxxxxxx> wrote:
> 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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