Fred
First, I have a Rotax 914. I had a little discoloration from exhaust heat on the
cowling near the exhaust pipe exit. Probably less than an inch clearance. I
used simple aluminum backed tape on the cowling, it is usually good for 2 or 3
years before I replace it, works fine, is light, eliminates further Issues to
cowling. Keep it simple and light. You may not even have an issue with an inch
and a half clearance . Wait and see, you may have good circulation of air
and your cowls sound robust for heat.
Can't wait to see you flying over Roche!
Sent from my iPad
> On Jun 10, 2015, at 12:59 PM, Fred Klein <fklein@orcasonline.com> wrote:
>
>
> Gentlemenheres a situation and a question:
>
> I have maintained 1.50 inches clearance between the inside surface of my lower
cowl and my engine exhaust pipes. I set this up w/ the assumption that this
would be adequate considering that I have used a
> high temperature flame retardant resin (HTR250FR, by Resin Services, Inc.) for
my custom cowls. It maintains a Flexural Modulus at 350 degrees F. of 6.25 x
36,000 (whatever that means).
>
> Would anyone be willing to opine on the advisability of applying some
> aluminized,
adhesive-backed, heat barrier, to reflect radiant heat away from the cowl
surface and back towards the engine and exhaust?
>
> (This so-called heat barrier is a composite consisting of aluminum foil on a
backing material which looks like burlap to which is applied an adhesive good
for 350 degrees F.)
>
> (I have a total of 10 sq. in. of inlet and 14 sq. in. of exit area for air
> circulation
within the cowl.)
>
> (Obviously, this is not a 9xx Rotax installation.)
>
> Comments and opinions appreciated in advance,
>
> Fred
>
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