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Message-ID: <003101c90bae$90a83e90$6400a8c0@george>
From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-3102338@logan.com>
Subject: Re: [FlyRotary] Re: Composite instruction
Date: Mon, 1 Sep 2008 07:14:31 +1000
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Mike/ Randy,
I am building a Vision with composite core and although most cowls are thin 
fiberglass, they could be stiffer and lighter with a composite construction.
As the core foam is quite stiff, it will hold a shape, when heated,  shaped 
then cooled, a thin section of core about 3/16 would be sufficient, with 2 
layers of light glass (5 oz). Because the foam might distort when working on 
it in-situ, you could support it with some backing material - this would 
save making moulds. Once you have the outside glassed then take it off and 
glass the inside.
The Vision is make completely from this method.
This is how I will do my cowl.
Hope that helps.
George (down under)

> Randy,
>
> You are setting yourself up for a ton of work. I built a custom cowl for 
> my
> RV-4 out of carbon fiber (got a really good deal on the fabric). When I
> built it it was lighter than the then current RV-4 cowl and stiffer too. 
> It
> has now been hacked/patched so many times to accomodate changes to cooling
> systems, exhaust, etc.... that it has gained weight. It weighs about the
> same as the fiberglass RV-6A cowling from the airplane I'm flying.
>
> I built a plug from foam directly on the airplane. Carved to shape, 
> covered
> with fiberglass cloth and then body worked and painted to get it smooth.
> Once I was happy with it I waxed the crap out of it and shot a couple of
> coats of PVA (mold release) on it. I laid the carbon up directly on this. 
> I
> used 4 layers of 8 ounce standard weave cloth. Once cured I split it
> lengthwise and removed it from the plug. I then removed the plug from the
> fuselage.
>
> Obviously this leaves a smooth interior surface (good for cleaning) and a
> rough exterior (lots of filler and sanding). Once its all smoothed up then
> fitment to the airplane was standard Vans (combination of piano hinge and
> screws/nutplates for attachment).
>
> No idea how much time this tookbut it was definitely multiple 100s of 
> hours.
> And this is not the lightest/best way. If you really wanted the best 
> method,
> build the plug as described and then lay up a female mold on the plug. 
> Make
> your cowl pieces in the female mold. This saves the time/effort/weight of
> the filling and sanding. It also provides a means to use composite 
> sandwich
> core construction where there is some sort of core material installed
> between inner and outer layers of glass. This makes the cowl MUCH stiffer
> and allows you to use fewer layers of cloth. But the additional work of
> making a female mold was too much for me. Glad in the end that I didnt go
> this route as I would have been pissed if I'd gone to all the effort and
> then had to hack the finished cowl as I did.
>
> The guys building composite planes will probably have other ideas on how 
> to
> do this but this is what worked for me. Good Luck.
>
> Mike Wills
> RV-4 N144MW
>
>
> ----- Original Message ----- 
> From: "randy echtinaw" <rjechtinaw@toast.net>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Sunday, August 31, 2008 7:37 AM
> Subject: [FlyRotary] Composite instruction
>
>
>>I am eventually going to have to build a custom composite radiator/oil
>>cooler pod ala P-51 and possibly a cowling if I cannot get aluminum to
>>work around my RX-8 engine. I am looking for some good reference books  on
>>how to do this especially concerning making male molds - release  agents -
>>cloth to use - number of layers required - etc.??
>> My plane is wood/tube/fabric - thought I might as well use a little
>> fiberglass too :))
>> My biggest concern is making them as light as possible but still  having
>> the needed strength and stiffness.
>> Thanks
>>
>> --
>> Homepage:  http://www.flyrotary.com/
>> Archive and UnSub:
>> http://mail.lancaironline.net:81/lists/flyrotary/List.html
>>
>


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