[RocketsNW] Fins on a Minimum Diameter

[Fred Azinger]

And remember when you take it out of the oven to set it on the kitchen
table. 

-----Original Message-----
From: rockets-bounces at rocketsnw.com [mailto:rockets-bounces at rocketsnw.com]
On Behalf Of Scott Berfield
Sent: Tuesday, February 02, 2010 10:33 AM
To: 'Christopher Guenther'; 'Julian Picard'
Cc: 'rockets'
Subject: Re: [RocketsNW] Fins on a Minimum Diameter

I recommend that if you plan on using the kitchen oven, you wait until the
wife is out.

-----Original Message-----
From: rockets-bounces at rocketsnw.com [mailto:rockets-bounces at rocketsnw.com]
On Behalf Of Christopher Guenther
Sent: Tuesday, February 02, 2010 10:03 AM
To: Julian Picard
Cc: rockets
Subject: Re: [RocketsNW] Fins on a Minimum Diameter

I wrapped a coupler with a waxy freezer paper and went completely through
the wall to the paper and 30 minute epoxied the fins into place.  When the
epoxy had set enough to hold and still be a tad pliable I removed the
coupler with the waxy paper then popped the fincan into the preheated oven
at 250 for about 30 minutes.  (be sure to constantly check to make sure you
are not starting to darken the tubing or smoking)  If the fincan is to long
for your oven door to shut that is fine just make sure you have lots of
ventilation in your kitchen.  Then after it has been oven hardened I started
layering epoxy mixed with milled fiber (you can get milled fiber from Tap
Plastics) along the fin root to even it out and to build the curve from the
fin to the body.  (Fiber Glass and Carbon Fiber do not like to form to sharp
corners very well.)  With each layer I oven hardened again, and remember to
give a light sanding in beteween each layer it will help smooth out any
dimples/bubbles etc... and make it easier for the next epoxy layer to bond.
After I reached a point that I was satisfied with my layered curve I spread
a layer of epoxy from fintip  to fintip and set my Fiber Glass in place.
(remember to measure twice and cut once leaving at least 1/2 an inch all
around as in my experience some fiber materials out there do shrink as the
epoxy sets)  Then when that has set start the next Fintip to fin tip and so
on until you have done them all the way around at least once, more is ok but
remember the more you add extra the heavier your rockets aft end will be.
When the last fintip to fintip has set I oven harden again for about 30
minutes.  After that I gave it a light sanding to smooth it out and add
another thin layer of epoxy, oven harden and repeat until I  had reached a
smoothness I liked.  Unless you have a bad flight there will not be much
that will phase those fins.  (unless you throw in a motor made by Mike F.
that is  LOL)

Chris Guenther
NAR L2

On Fri, Jan 29, 2010 at 5:53 PM, Julian Picard <jman13 at gmail.com> wrote:

> Hello everyone,
>
> My name's Julian Picard, and I'm new to the list. I'm here at the
> University
> of Washington, and I'm working on a building a 54mm minimum diameter, and
> I'm looking for suggestions on how to better attach the fins.
> What I did before is to make shallow fin slots and do some initial gluing,
> and then solidly glassing (or with carbon fiber) the fin can.
> I'm using a pre-glassed phenolic tube, with G10 fins.
>
> Thanks so much for you help!
> Julian
> _______________________________________________
> Rockets mailing list
> Rockets at rocketsnw.com
> http://mx1.blastzone.com/mailman/listinfo/rockets
>
>
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