[roc-chat] Re: Dual Deployment advice
- From: Lakestake Rocketry <lakestake@xxxxxxxxx>
- To: roc-chat@xxxxxxxxxxxxx
- Date: Wed, 13 Jun 2012 17:31:50 -0700
Oops, I realized I didn't answer your question.
'that depends on the cannister'
I use the plastic micro centrifuge tubes in small projects because they're
cheap and convenient. I do not use them above 7000 feet or on large
projects.
Without knowing the container you are considering this is just opinion, not
engineering.
You don't want to reenforce the cap to be stronger than the cannister. You
want the flame front to burn into the powder. If the match is at the
bottom of your charge (or if the bottom of the tube blows out before the
cap) the remaining unburnt powder will be scattered. This effectively
reduces the size of your charge, possibly to the extent that it can not do
its job.
In your ground testing inspect the airframe after each test. You should
not see damage (dents) or black unburnt powder. If so your charge is
poorly contained.
Matt
P.S. I loved the previous picture of the ejection cannister punched through
the airframe!
On Jun 13, 2012 2:53 PM, "Jeff Gortatowsky" <indanapt@xxxxxxxxx> wrote:
> So can I draw a conclusion that says disposable canisters are fine, but
> put a wrap of tape over the canister cap to contain the charge a little
> longer?
>
> I learned my lesson from Kurt. Put in what you need, then double that. :)
>
> ---------------------------------------
> Jeff Gortatowsky, Redondo Beach, CA | Twitter: JeffGortatowsky | Yahoo:
> indanapt
> "(Scientific) Skepticism is not a set of beliefs, it is a set of methods
> for asking questions about reality." -- Doctor Steven Novella
> ------------------------------
> *From:* Lakestake Rocketry <lakestake@xxxxxxxxx>
> *To:* roc-chat@xxxxxxxxxxxxx
> *Sent:* Wednesday, June 13, 2012 12:34 PM
> *Subject:* [roc-chat] Re: Dual Deployment advice
>
> Hi Bob,
> Dave Flynn and I did vacuum testing of ejection charges a couple of years
> back.
> We found that both black powder and smokeless powders work best if
> properly contained. In a five sided solid aluminum tube they produced fine
> grey ash with a complete vigorous burn even under full vacuum.
> BP when 'loosely' contained in a hard plastic tube still lit under vacuum,
> but scattered much of the charge unburnt with a lot of black sticky
> residue. Pyrodex powder did worse.
> The take away is that smokeless powders are fine to use for rocketry and
> leave less mess. Any ejection powder should be solidly contained for any
> use to aid cleanup and for all use over 10000 feet.
> The sixth side of the solid containment chamber used in our testing was 3
> layers of good electrical tape. Fewer did not work consistently.
> The match was placed on top of the powder nearest the open side of the
> cannister and all remaining space in the ejection cannister was packed with
> non-flammable wadding to keep the match in contact with the top face of the
> charge.
> Hope this old info helps some of our newcomers, if I've skimmed over
> anything of interest ask away.
> Matt
> P.S. Allen, this message was typed on my Android phone with no spelling
> assist/mangle by an annoyingly eager OS. ;)
> On Jun 13, 2012 11:45 AM, "Michael Klett" <xsive.guy@xxxxxxxxx> wrote:
>
> And don't put 2 1/2 grains in a "small"ish rocket either. :-) Ground
> test with smaller values working your way up.
>
> Thanks,
> Mike
>
> On Wed, Jun 13, 2012 at 10:41 AM, Jack Garibaldi <jackgaribaldi@xxxxxxx>
> wrote:
> > I like the disposable ones whether you make them or buy them they are
> easy
> > quick and disposable, I sale the quickbusrt EZ-Cannisters the have a
> small
> > which holds up to 3 grams and they have a large which holds up to 12 gram
> > charges (Gugisburg Style)
> >
> > Jack G
> >
> > -----Original Message-----
> > From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:
> roc-chat-bounce@xxxxxxxxxxxxx]
> > On Behalf Of Bob Brown
> > Sent: Wednesday, June 13, 2012 10:10 AM
> > To: roc-chat@xxxxxxxxxxxxx
> > Subject: [roc-chat] Dual Deployment advice
> >
> > Even though I am level 3 and made dozens of launches over many years
> almost
> > all of my experience has been with Public Missiles that use piston
> > deployment. My avionics experience is also with the Public Missiles
> design
> > that includes their own BP holders. I am planning now to build a Madcow
> > Rocketry fiberglass kit and need some advice on the deployment. I have
> both
> > a Missile Works and Perfectflite computer than I can use but am not sure
> of
> > a design for holding and igniting the BP. I've seen online the Blastcap
> > http://www.blastcaprocketry.com/index.html and Pratt Hobbies ejection
> > canisters http://www.pratthobbies.com/ejection_canisters.htm Any advice
> > about these or other systems would be appreciated . Hope you all had some
> > successful launches at Roc Stock.
> >
> >
> > Bob Brown
> > http://us.imdb.com/name/nm0113141/
> > http://www.tripoli.org/ #9186-L3
> >
> >
> >
> > --
> > ROC-Chat mailing list
> > roc-chat@xxxxxxxxxxxxx
> > //www.freelists.org/list/roc-chat
> >
>
>
>
>
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