Here's a photo of one of Ned's perforated hemis for the inner pistil:
--- In PrairieThunderPyrotechnics@yahoogroups.com, "Andy Holcomb" wrote:
> Hi Dean
> 1. A strobe rocket does produce a small amount of net thrust during the
> strobing stage, but not enough to really be meaningful. The original creator
> of the strobe rocket, William (Doc) Barr (not ex PGI president Bill Bahr)
> actually made his rockets with the entire fuel grain being strobe comp. They
> didn't have much thrust, so you couldn't really even put a small header on
> them. Steve LaDuke and a few other guys came up with the idea to use whistle
> fuel as a "booster".
> 2. The first trick is to pack the shell so full that the contents can't
> shift around during pasting/handling; I think that's the important part, and
> use a layer of tissue paper across the top of one of the hemis to keep
> everything solid when you close the two parts together.
> On shells 5" and above, most guys use a perforated inner paper hemisphere.
> The best results come from "pasting" (2-3) layers of gummed paper tape on a
> plastic shell of the appropriate size for your pistil, the first layer
> sticky side out, and the others sticky side in. After it's dry, you slice
> the shell in half to form a thin set of hemis, perforate them with whatever
> your chosen method, and assemble the inner petal just like you were making a
> smaller shell inside. The perforations let the fire propagate more evenly.
> Jim Widmann was selling commercial perforated hemis from 4"- 8" a few years
> ago, that had 5/16" holes punched in them, so I suppose you could use a step
> drill to recreate those. Ned uses one of these to perforate his inner hemis:
> If you want some inspiration as to what's possible, check-out this guy's
> video of his 4" shells: http://youtu.be/Ypm6kP7XSrc , and
> http://youtu.be/R59unyXC3vQ Amazing!
> 3. Low humidity been my issue lately. The paper tubes shrink when they dry,
> and everything is stressed. I've even had the tube split/crack on the
> outside. I keep motors sealed in Ziploc bags now.
> -----Original Message-----
> From: PrairieThunderPyrotechnics@yahoogroups.com
> [mailto:PrairieThunderPyrotechnics@yahoogroups.com] On Behalf Of deanw3576
> Sent: Saturday, January 19, 2013 4:20 PM
> To: PrairieThunderPyrotechnics@yahoogroups.com
> Subject: [PrairieThunderPyrotechnics] PYRO SECRETS OR QUESTIONS
> I have some questions that i would like to throw out to the group.
> #1 Does a strobe rocket produce thrust in the STROBING stage of the burn?
> #2 How do you maintain a symmetrical pistil in a ball shell?
> #3 what do you think would cause a PROVEN whistle rocket to cato after
> storage(3 months)?
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