Hi Bob,

 

I can tell from experience that even most stuff that is intended to go directly onto exhausts will quickly desintigrate in the rotary.  The stuff that is supposed to be good up to 1400 deg will start falling apart after a few hours.  That stuff you have will be done after the first flight.  Don't forget that your exhaust temps will go above 1600! 

 

I did find some exhaust wrap that was good up to 2000 deg. and it is good for about 100 hrs before becoming a little brittle and falling off.  It was worth it and made a big difference in my under cowl temps, but it was not cheap.

 

As for your fuel system....   I am sure SOMEONE has said this before (I have not been reading the list very regularly because I am in Iraq), so let me repeat for effect.  RETURN THAT FUEL ALL THE WAY TO THE TANK!   One of the great things about this high flow fuel injection system is that it is possible to essentially eliminate ANY chance of vapor lock.  Vapor lock HAPPENS even in certified planes.  It is serious. It can be fatal.  Route that fuel back to the tank and it basically can't happen.... you have a better system than a typicl lyc set-up.  Route that fuel back to the pump and you may even be making things worse than a lyc set up.

 

Sounds like you have decided to make a change, so this is just to re-enforce that decision and send the message to anyone else considering the easy way out for fuel return.... 

 

JMHO, & congratas on getting flying by the way! cant wait to see it in person some day..

 

Dave Leonard

 

On 7/25/06, Bob White <rlwhite@comcast.net> wrote:

I finished putting a layer of insulation around the exhaust system.  I
placed thermocouples in a few key locations.  One inside the
insulation, one outside, and one on the fuel rail.  OAT was 80-85F.

I ran the engine at 2200 rpm until the temps stabilized at 197 oil and
water.  I increased rpm's to 3100 and temps went up to 200 oil and 207
water. They were still increasing very slowly.  I can taxi at 3100 rpm
or less and getting a little movement should help cooling.  Also, when
I reduced power back to 2200 rpm, the temps started decreasing.  So on a
not too hot day I think the cooling will be OK for taxiing.

The insulation is a layer of reflective insulation I bough at the speed
shop that is good to 1000F.  It has a metalized layer on each side and
some kind of fibrous layer on the inside.  (The stuff itches like
fiberglass when you get it on you.)  At the end of the test, the
thermocouple on the inside layer was reading 235F and the one in the
same place on the outside of the insulation was 167F.

I still don't have the fuel return to the tank.  It's going directly
back to the fuel pump input.  So the fuel rail temps were getting
pretty high.  The fuel rail was 145F and the engine was starting to run
a little rough, presumably due to incipient vapor lock.

Next step is to open the tank and install the fuel return line.  I ran
the line from the firewall to the wing root this afternoon, so the easy
part is done.

Bob W.

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http://www.bob-white.com
N93BD - Rotary Powered BD-4 (first engine start 1/7/06)
Custom Cables for your rotary installation -
http://www.roblinphoto.com/shop/

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