Steve Brooks wrote:

I'm looking for suggestions on exhaust wrap, i.e. what is the

best

one to use.  Has anyone used one that has held up really
good, or is there one to avoid that doesn't work well.

I'll be running a turbo, with a "J" pipe out of the turbo exiting
out of the bottom of the cowling.  I'm looking for something
to wrap that "J" pipe in.

Thanks in advance,
Steve Brooks
Cozy MKIV
13BT

Not a good idea to use exhaust wrap on a rotary. We have had at

least one

crash
partially because of exhaust wrap. Having said that I would measure

the actual

temp of the exhaust pipe out of the turbo and if it is less than say

1200 F

you might be OK.

Paul Lamar

Paul,
While we're on the subject, what's the take on ceramic coating the

exhaust

(inside and out).  My exhaust is made from the RB Wagner

bends.  While I'm

not too concerned about burnthrough, I would like to reduce the heat
transferred into the cowl as I have some aluminum radiator lines

running

nearby.  I know that exhaust wrap is a bad idea, but was

wondering what

your experience has been with ceramic coatings.

Thanks,
Mark S.

I don't have any experience with it.
Might work good on a cooler turbo down pipe. I suspect you will still
need to shield the down pipe.

How close nearby? You mainly need a visible light shield.
In other words if the plumbing can "see" the exhaust pipe
radiant heat will be transferred.

Here are some pictures of Tom Parkes turbo installation taken
at Copper State.

Paul Lamar

Ops forgot to rotate that picture. Here too are some earlier pictures
of Tom's turbo heat shielding. His down pipe is not shielded but
is quite far from anything else.

Paul Lamar

Paul,
In the second picture of Tom Parkes' plane, where the downpipe makes a turn
there is a barry mount located just behind it.  My downpipe is approx. 1/2"
from the barry mount.  I plan a small mod that will increase this to about
1".  Still, I feel that is too close for comfort and that it needs
protection from the heat.

Also, the #1 rotor (nearest front cover) exhaust runner is a couple of
inches from the water pump inlet.  My 20B pump has an extra fitting there
(I think for heater return) that I've used for my purge tank return
line.  On shut-down, after a 20 minute run at off-idle/low throttle
setting, it lost about 4 qts. of coolant that I attribute to the
overheating of this line due to heat radiating from the #1 exhaust
runner.  It wasn't overheating during the run, only after shutdown.  I
installed a temporary heat shield and it seemed to resolve the problem on
subsequent runs.  So, I will be fabricating some heat shields for sure.

My main purpose for considering the 2000 degree ceramic coating for the
exhaust would be to provide an extra margin for the 304 SS exhaust system,
and to  reduce the heat inside the cowl.  Maybe it wouldn't make that much
difference.  I know that Ed Anderson is using these same bends (uncoated)
and has over 300 hours on them, but his are straight for about 12" where
mine are only straight for about 4".  I just though it would provide a
little insurance.

Mark S.

If that is the .140 wall SS pipe bends from RB Wagner they should hold up
just fine.
Ed's are just now becoming a little discolored :)

Paul Lamar

Yes, that's what Ed reports.  So, I guess I'm just worrying over
nothing.  I'll take Tracy's suggestion and wrap the radiator tubes and
leave the exhaust as is, but inspect it on a regular basis.

Mark S.

 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2003 All world wide rights reserved.