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  • andys_junk_address
    Here s a photo of one of Ned s perforated hemis for the inner pistil:
    Message 1 of 5 , Jan 25, 2013
      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:
      > http://compare.ebay.com/like/290407649600
      > 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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