Quote:
Greenlaw) writes:
>Drywall tape is a bit heavy and coarse for models. It would take a ton of
>primer or filler to make it look good.
>> I used this reinforcement method on my Laser LOC 1.5. I have not
>> flown it with any butt-kicker motors (G40 is the largest), but it has
>> held up just fine. I do not think you gain much by using this method. If
>> you are going to go to the trouble of adding reinforcement in the fin
>> fillets, I think you would be better off with some light fiberglass cloth
>> sprayed with 3M spray adhesive. This would offer the same convenience of
>> the drywall tape with a HUGE increase in strength. I would reccommend
>Absolutely NOT! First, you will need more than 3M spray to hold it on. Second,
>that spray will prevent epoxy resin or whatever from bonding to the glass. If
>you must spray, use a clear dope which is compatable with the epoxy resin.
Let me clarify. A LIGHT COAT of 3M spray adhesive will in NO WAY interfere
with the bonding of the glass and the epoxy. You are only putting enough on to
help hold the cloth in place while you wet it out. Personally, I do not use it at
all, but if you like to position things ahead of time, it can help. Unless you
have a very sharp concave radius (or sharp corner) that you are laying up, you should
not have any problems with properly wet-out cloth sticking where you put it. In
RC airplanes, we use 3M spray adhesive all the time to completely cover wings and
fuselages with NO PROBLEMS. If it really bothers you, don't use it at all--I
don't unless it is a tricky lay-up.
Quote:
>> (depending on the rocket size) 2-6 Oz/yd^2. The lighter cloth for
>> smaller rockets and the heavier cloth (possibly multiple layers) for the
>> larger rockets. Best of luck.
>6oz would be for awful big rockets. Rutan foam composite aircraft use 5oz
>cloth. For models, I'd use 3/4oz to 1.5oz cloth unless you are talking
>supersonic cloudbusters.
^^^^^^^^^^^^^^^^^^^^^^^^
I believe the Laser LOC 1.5 qualifies! :) Remember, that althought Rutan uses
5 OZ cloth, he uses MULTIPLE layers of cloth. We are usually limited by how thick we
can make our fillets. So, a single layer of 6 OZ is really not too heavy. I
would not use it for every rocket, but for medium to large high power rockets
that will see some high impulse motors, it works great. If I am going to go to
the trouble of laying FG in the fillets and having to bother with smoothing the
fillets, filling the weave, etc, etc, I am going to make it worth my while. Of
course, any additional reinforcement is better than none at all, but 3/4 oz.
cloth does not provide much increase in strength. (I didn't say NO increase)
Quote:
> Bob Kaplow NAR # 18L TRA # "Abort, Retry, Fail?"
--
Matthew Greenlaw Mechanical Engineering
http://hubcap.clemson.edu/~mgreenl