[roc-chat] Re: BP for Deployment of Main Question
- From: Richard Dierking <redierking@xxxxxxxxxxx>
- To: <roc-chat@xxxxxxxxxxxxx>
- Date: Thu, 8 Dec 2011 21:31:49 +0000
I've had the police respond one time because the HOA called them. The officer
was here about 1/2 hour because he thought it was so cool. Next time, I might
not get someone that thinks it's cool. Richard
> Subject: [roc-chat] Re: BP for Deployment of Main Question
> From: allen.farrington@xxxxxx
> Date: Thu, 8 Dec 2011 13:29:10 -0800
> To: roc-chat@xxxxxxxxxxxxx
>
> Richard -
>
> By now, if your neighbors are still freaked out by small explosions, then you
> should move. ;-0
>
> Allen
>
> On Dec 8, 2011, at 1:22 PM, Richard Dierking wrote:
>
> > Other than the time it takes for a ground test and that sometimes stuff is
> > damaged and must be repaired; there are other considerations. Some of my
> > neighbors are already a little freaked out about the large rocket projects.
> > So, setting off a 4 gram BP charge would not be advised. We could go to a
> > City park, but previously, we were asked to leave by the City's park
> > enforcement officer (details only around the campfire). If we did the test
> > at a school field, I would probably end up in Quatmo.
> >
> > So, between advice, formulas, and our gut, we'll come up with the correct
> > amount. ;)
> >
> > Richard
> > To: roc-chat@xxxxxxxxxxxxx
> > Subject: [roc-chat] Re: BP for Deployment of Main Question
> > From: Chris.J.Kobel@xxxxxxxx
> > Date: Thu, 8 Dec 2011 12:59:56 -0800
> >
> > Here's the relationships I use: (I believe Dave Flynn is the source)
> >
> > E-charges: BP(g)=.00051xLength(in)xForce(lb)x(Peak Alt ASL/10K+1) ; 150-200
> > lbs
> > 2-56 nylon bolts for shear pins; 35 lbs shear force each; 100 lbs w/o
> > pins, 200 lbs with
> >
> > Only separation force, length, and altitude are input variables. The
> > diameter factors out.
> >
> > Time for a ground test....
> >
> > Chris
> >
> >
> >
> > From: Richard Dierking <redierking@xxxxxxxxxxx>
> > To: "roc-chat@xxxxxxxxxxxxx" <roc-chat@xxxxxxxxxxxxx>
> > Date: 12/08/2011 12:44 PM
> > Subject: [roc-chat] Re: BP for Deployment of Main Question
> > Sent by: roc-chat-bounce@xxxxxxxxxxxxx
> >
> >
> >
> > 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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