Help Support RocketryForum by donating using the link above or becoming a Supporting Member.


Page 3 of 3 FirstFirst 1 2 3
Results 61 to 67 of 67
  1. #61
    Join Date
    18th January 2009
    Location
    Southern Indiana
    Posts
    3,528
    Quote Originally Posted by kuririn View Post
    Is dog barf the same as cellulose insulation? I've seen mostly negative reviews of dog barf, seems the ejection gases can blow by the clumps and melt the parachute. Your experiences with this, please.
    Yes, they are the same. I usually use one or two squares of estes wadding (depending on diameter) and fill the center with dog barf. The paper and barf together act like a plug and hold together until they leave the tube. But this way I use a lot less paper wadding than I would otherwise.

    Greg Poehlein

    Member of Launch Crue - http://launchcrue.org/

    Hint #1: Do not use magician's flash paper for recovery wadding!

    Hint #2: Clean your shoes after flyin' in that cow pasture - that ain't no dirt clod on the sole!

  2. #62
    Join Date
    30th June 2009
    Location
    Framingham, MA
    Posts
    261
    Quote Originally Posted by kuririn View Post
    Is dog barf the same as cellulose insulation? I've seen mostly negative reviews of dog barf, seems the ejection gases can blow by the clumps and melt the parachute. Your experiences with this, please.
    Iíve never heard anyone have anything bad to say about dog barf. They keep a trash can full of it at CMASS launches for anyone who wants it. The only problem they have is if someone thinks itís a trash can for throwing away trash.

    I use nomex blankets in most of my larger stuff, usually with a bit of dog barf for good measure. In larger Estes rockers where Iím not using a chute protector, I use straight dog barf. Seems to be fine. My guess is people arenít using enough. As long as you leave it loosely packed you can pretty much fill Ďer up, minus the room for the chute.

    One note about nomex. Someone earlier said they wrap it around the chute. I would do that and still get crispy chutes. Then I Read The Freaking Directions and they say to put it in before the chute like wadding. Had much better luck.

    Landing in trees since 1992.

  3. #63
    Join Date
    19th January 2009
    Location
    Southern California
    Posts
    8,362

  4. #64
    Join Date
    18th March 2012
    Location
    Oregon City. OR
    Posts
    2,524
    +1 on the Dog barf / insulation ; used it on everything from lil Estes on A's through to 4" diam HPR rockets. If you buy a bale, you can afford to use a LOT of it in your rockets... which is what I end up doing, get enough of it down there, and pack it in solid, then add more, etc., and you will STILL end up trying to give old catlitter buckets full of it to your club, friends, and neighbors.

    Beware... if you get a compressed full bale of this stuff, it is actually alive, and will continue growing once you open it. You reach in to scoop it out, and the rest grows to fill the gap. 5 years on, and multiple bucket donations... still over 1/2 a bale left!

    It also works fantastically as packing for any Secret Santa gifts to other forum members (oh, gonna get more hatemail for that one!)
    Rob Appleton
    "That Crazy Brit"

    - - -
    Team Numb
    -exploring the possibilities-
    L3 - TRA 13815 - NAR 87999

  5. #65
    Join Date
    10th July 2007
    Location
    Melbourne, Australia
    Posts
    1,219
    I use party crepe paper streamers from reputable suppliers. If you get the cheap and cheerful Chinese stuff it might not have flame-retardant in it. I use Lombards or Spotlight here in Australia for a reliable source.
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  6. #66
    Join Date
    6th June 2009
    Location
    Middle of the Mitten, MI
    Posts
    2,312
    Dog barf sometimes needs to be "fluffed up" a bit before use as wadding.

    If you grab a fistful right out of the bale, it can be compacted pretty thickly and serve, basically, as just a plug, and ejection gases can leak around the "plug" and scorch the chute.

    So when you grab your dog barf out of the bale, squeeze and release it a few times in your fist in order to fluff it out and make it fill up more of those gas gaps.

    It's also a good idea to use a combination wadding recipe: a couple of BT diameters of dog-barf, and then wrap the chute in a single sheet of fireproof crepe paper as a "chute bag." The extra thickness of one sheet of flame-resistant paper should catch any burning hot propellant particles that sneak around the dog barf.

    That's kind of a vestige of the old old-school method from the 1950s/early 60s of cutting "chute protectors" out of sheets of typing paper (as described in the first edition of the HBOMR). This was used before flame retardant wadding was invented about 1965 (I believe).

    The chute protectors didn't catch on fire outright too often, but they did come down to the ground smoldering sometimes. I would guess some grass fires probably ensued.

    But making your chute wrapping out of flameproof paper should get rid of that problem.

  7. #67
    Join Date
    20th April 2012
    Location
    Fredericksburg VA
    Posts
    1,528
    Quote Originally Posted by r12ski View Post
    . . .One note about nomex. Someone earlier said they wrap it around the chute. I would do that and still get crispy chutes. Then I Read The Freaking Directions and they say to put it in before the chute like wadding. Had much better luck.
    Nomex is fire resistant but if it is sitting directly on top of an ejection charge the charge can still blast holes in it.

    NAR Level 2 #96210

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •