[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 12:43:48 -0800
So Dave, how much BP would you suggest for a 7.5" diameter x 24" long
compartment with three 2-56 shear pins?
Richard
Sent from my iPhone
On Dec 8, 2011, at 12:19 PM, "Dave McCue" <dmccue@xxxxxxx> wrote:
> Please remember that electric match makers alway say to put matches in series
> - it takes no more than a 1.5V AA cell to light one, so putting two or three
> in series is no problem. THis also solves the problem of monitoring two or
> more matches, sine a loss of continuity anywhere will be detected by the
> electronics.
>
> I do series match wiring all the time when I use multiple ematches to light
> big liquid propulsion engines. See links below:
>
> http://www.youtube.com/watch?v=FlkMiCtCxg0&feature=related
>
> http://www.youtube.com/watch?v=jOiaxfGpudM
>
> You can also see the unusual recovery system I came up with for these
> rockets: side deployed! This is because the rocket is big and heavy, and
> needs to land on it's side to avoid unplanned damage; we assume we will break
> two fins upon landing.
>
> By the way, the big 1000 square-foot parachute is deployed by BP charges that
> push out the pilot chute, with HPR recovery electronics making the decisions.
> This was one of several low altitude flights to test the recovery system.
>
> Dave McCue
>
> On Thu, 8 Dec 2011, Richard Dierking wrote:
>
>>
>> One possible failure mode: If it's in parallel, if one of the matches is
>> bad and doesn't have continuity, you will not know, because the altimeter
>> will detect continuity in the second and indicate that everything looks OK.
>> So one canister would go, but probably not be enough BP for a successful
>> deployment. We tested two matches in series yesterday, and they both went
>> fine. I've been using series for airstarts and haven't had a problem (up to
>> 4 engines). I thought people were crazy when I first heard about using
>> series, but when a match lights the "plasma ball" becomes very conductive
>> for a moment. However, I have not used series for deployment charges, so
>> thought it would be a good idea to hear from people that had experience with
>> this. Richard > From: xsive.guy@xxxxxxxxx
>>> Date: Thu, 8 Dec 2011 10:39:46 -0800
>>> Subject: [roc-chat] Re: BP for Deployment of Main Question
>>> To: roc-chat@xxxxxxxxxxxxx
>>>
>>> Definitely in parallel. Otherwise, when the first one burns out the
>>> rest would stop getting current. By wiring them in parallel even
>>> after the first one goes the rest continue to get current.
>>>
>>> I'd like to know the answers to your other questions though.
>>>
>>> Thanks,
>>> Mike
>>>
>>> On Thu, Dec 8, 2011 at 10:09 AM, Richard Dierking
>>> <redierking@xxxxxxxxxxx> wrote:
>>>> 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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>>>
>>
>
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