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Date: Mon, 24 Jul 2006 23:30:09 -0600
From: Bob White <rlwhite@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: More cooling Tests
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Thanks Dave,

The fuel return to the tank is the next item on my todo list.  The tank
developed a leak so I have to open it up anyway.  It seemed like the
right time to fix it.

The exhaust system is a large can with a tube thru the middle that
supplies cooling air (theoretically) so the temps on the down tube
should be lower than normal for a rotary.  However, it's still too hot
for this material, whatever it is.

I hope I haven't given the impression that I'm flying yet.  This is all
taxi and static stuff. :(  I am getting pretty close though.

I hope you are doing well.  I check your blog occasionally and I'm
glad I don't have to deal with the temps shown in your July 13 photo.  I
could probably get close in Phoenix some days.  Best of luck and hope
the rest of your tour passes quickly.

Bob W.


On Tue, 25 Jul 2006 07:43:51 +0400
"David Leonard" <wdleonard@gmail.com> wrote:

> 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.
> >
> > --
> > 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/
> >
> > --
> > Homepage:  http://www.flyrotary.com/
> > Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
> >
> 
> 
> 


-- 
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/