05-21-2007, 08:33 PM
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BARCLONE Rocketry
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Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
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Quote:
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Originally Posted by Doug Sams
Hi, Craig,
I wanted to say something, but since Sol mentioned dog barf, I let it go.
But, now that you brought it up  I do use dog barf, usually in birds ~1.3" diameter and larger. My experience with it is that it appears to not block the flames and hot gasses well when used by itself; it needs to be used along with some wadding or a chute protector to work well.
I will often make a piston by placing a ball of barf in a sheet of wadding and putting that in first, then more wadding, shock cord, etc.
For HPR, dog barf with just a chute protector works well. For MR birds ~2" and under - whether it's dog barf, Quest wadding or crepe paper - I tend to get the best results when using a little Estes wadding in the mix
Doug
Hoping I'm not repeating myself... |
Doug,
I appreciate your observations, and don't mind any "repeats" of information. I've noticed from time-to-time an occasional hole in a parachute that I attributed to just not having enough barf shoved into the tube. Most of the time the shredded newsprint works well; I think it fills in the gaps better than does the sheet style. But there are those odd moments when the parachute comes back with damage that was not there pre-flight.
The downside to the ShredCel wadding is packing it into the less-than-1" tubes, like ST-7 and BT-20. I tend to pack it down a bit tighter than I should, resulting in the occasional blockage near the end of the tube, even to the point of blowing out the motor as often as it blows out the laundry.
Your "piston" idea is similar to Bit Eimer's Teflon pompom, just not as permanent. I may have to go re-read his construction sequence on the BARCLONE site and try it out on a few. |