Re: Heat-PROOF engine mount tubing?
- From: "Fred Shecter" <fred.e.shecter@xxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 30 Aug 2006 16:44:32 GMT
The ejection charge is not roasting the stuffer tube - the delay afterburn is roasting it.
bad on all motors but worst on special composite motors. Also the most vulnerable tubes
are those with thin walls like standard Estes BT-5, 20 and 50. BT-55 thickness is a bit
more. MRC tubes were the thinnest ever.
Google Hibachi Effect.
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLR,GGL...
http://www.apogeerockets.com/education/newsletter28.asp
-Fred Shecter NAR 20117
http://search.ebay.com/_W0QQfgtpZ1QQfrppZ25QQfsooZ1QQfsopZ1QQsassZshreadvector
--
"""Remove "zorch" from address (2 places) to reply.
http://www.sirius.com/
<syncbus@xxxxxxxxx> wrote in message news:1156947993.967815.96610@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Keep in mind that the flame path is coming up to temperature at about
the same time as the event is over- the temperature is spiking. I
wonder if you're seeing charring near the end of the tube from
unconsumed ejection particulate finally mixing with a suitable
atmosphere?
At any rate, I vote for the lightweight heat shield too :-)
CA glues will produce noxious fumes when heated and aren't heat
resistant in this range anyway. Epoxy will soften but the heating
event duration is so short it won't occur in this range, still over
time there will be a degradation of it's surface so that negates the
zero maintainance you're going for.
Mike Doyle
Gordon S. Hlavenka wrote:I've been experimenting with a no-wadding chute packing/deployment
method and run into a snag.
What I've done is to run a stuffer tube all the way up to the nosecone,
then pack the shock cord and chute around the stuffer. The nosecone has
a plug attached to the center that mates to the stuffer. So the
ejection gases pop off the nose, and it pulls the chute out after
itself. The shroudlines are wrapped around the chute so that it gets
completely out of the body before opening.
This scheme has worked nicely, with one problem: I'm using Estes BT20
for the stuffer, and it burns completely through after 4 or 5 flights.
Apparently the BP is hanging around too long and frying the tube. I
still get a recovery under 'chute, but the bird has to be rebuilt to fly
again. This puzzles me, since I have other models with stuffer tubes
(albeit not all the way to the nose) and they don't burn through even
after dozens of flights :-/
I coated the stuffer with CA on the first rebuild but that burned
through also. So I guess I need a stuffer tube made out of something
that just plain doesn't burn. Or some way to get the hot stuff out
before it starts burning the stuffer. It seems to me this problem must
have come up with baffle designs also, so there should be some useful
wisdom out there.
Suggestions?
--
Gordon S. Hlavenka http://www.crashelectronics.com
If your teacher tells you to Question Authority
Should you do it?
.
- References:
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- From: Gordon S. Hlavenka
- Re: Heat-PROOF engine mount tubing?
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