Paul, The impossible has happened, I actually left the ground
yesterday. Flew for 3 hours. Seems my prop is too big as cannot get
over 6500 revs. Currently discussing this with Lonnie Prince. The EGT
went to over 1800 and then I assume burnt away for I now have a balmy
4-500 degrees. Is there a probe that will stand this temp?? The
alternative is to strap them to the outside of the pipe. Not ideal,
but may be an alternative. Ran most of the time at 5000 revs, and
wondered why I could only get 100 Kts, and then realised that the
prop was only turning at 1700. 5000 rpm and 21.5 MAP. Temps were a
little too cold. Water 135 and oil 145. What is the thinking on a
thermostat?? Oils pressure was 80 psi, never moved. Had over 80
litres of fuel added for the second flight of 2 hours and there is a
lot remaining, so fuel consumption was low, as is indicated by the
speed. As you can see all very scientific, but when you consider that
I was just waiting for that moment of dead silence to suddenly appear
as it did twice with my Eggenfellner monstrosity, I was not in the
mood to do many calculations.

Neil.

Congratulations.

Better to use cowl flaps as it cuts the cooling drag when they are
closed. Well worth the trouble. It is worth 3 MPH on my 182.

Here are some pictures for the new guys.

What is the diameter of that prop? It could be too big as the prop
tips are running into the transonic wall.

Is 21.5" MAP the highest you have seen? Sounds like the air filters
are clogged.

Paul Lamar


Neil,

Way to go! Three hours on your first flight is fantastic.

I too saw 1800 EGT's when running a tangential muffler on my
3-rotor. It was reasonably quiet, but didn't perform very well. I
switched to a low-tech 3-into-1 runner manifold and my EGT's dropped
into the 1500-1600 range, and I picked up 20 mph on the top end. If I
were you, I would explore that possibility. Relocating the EGT
probes won't fix the root problem. High EGT's may damage your
o-rings, and/or rotor housings.

Mark S.

Neal try this low back pressure muffler.

Paul Lamar

Mark and Paul, Seems unbelievable that you can drop that much temp by
just putting on a straight pipe. In my ignorance I would have
thought that the temp will be what it is regardless of what happens
after. Can anyone explain this?? However I cannot ignore your
experience and will have to explore the "simpler' option. What
muffler did you use without the tangential? Paul I have looked at
your muffler and am very impressed with the simplicity therein. If I
go with the straight exit pipes then it is little more to alter the
rest while I go. More mods! ARGGGG.

Neil.

Mark S has done a lot of R&D. We all owe him. He is right out there
on the bleeding edge with a 3 rotor P-port. Take off is fine with
four people in a Lancair ES with half power :)

Brian Trubee is testing the new muffler on his 2 rotor side port
RV4.

Neil, Try moving the EGT sensors down stream first. That is the
cheapest mod. My guess is about a foot.

Paul Lamar


Paul, My thanks once again. Have just inspected the engine
compartment and while all looks lovely again it is easy to see that
things have been very hot. Both EGT probes are burnt out, and the
wiring some 6 inches back from the tangential muffler are actually
fused together (The plastic covering). The electrical joiners are
actually charred. Therefore it seems that Mark is correct in
suggesting I remove that muffler , and the heat, and simplify the
whole process. Have already drawn up plans for Planexhaust to weld
up.

The real secret will be your muffler which should negate the
need for the internal muffler. The sheer simplicity appeals to me
and the lack of drag. Mine is very "draggy" so to alter as you
suggest will save a not inconsiderable amount of weight and eliminate
some of the heat in the cowl as well. With my tangential muffler I
simply cannot move the probes away without getting a reading of the
mixture of both rotors.

Therefore Paul can you give the measurements
of your muffler so I can get Planexhaust to fabricate one for me.
How would it go with a very perforated inner pipe as opposed to the
fewer and larger holes?? Suspect that I can get either from
Planexhaust. If I extend the outlet further back I also think that
this will stop a lot of noise from being able to get to the cab as
well. Currently my exit is level with the back of the pilot seat, so
another 2 feet would make a difference. Looks like I'll find out.
Heard Brian's engine running and seems quite good.

Neil.


Hear it is. Nothing really critcal about the dims.

If you don't have 321 ss go up on the wall thicknesses.
One can always trade off tube wall thickness for high temp  exotic alloys.

I am real proud of that muffler idea. It is the result of 15 years of feed
back from the news letter and thinking about the problem. :)

One of my best ideas.

I was really pleased with the sound it made.


Paul Lamar