Hi Paul.
I think you'd like an update on what's happening with my Mistral
engine, so here goes.
I've been flying the Glasair since Dec 6 of last year. engine works
fine and I'm very pleased with it.
There are still some aircraft electrical signals interfering with the
engine's sensors, so i'm getting the same warnings during flight,
all of which I've come to understand quickly, and Mistral will be
adapting the waring thresholds to suit my installation.
I'm averaging 54 liters per Hour ( about 13 USG/H ) with mogas, and
0.2 of a quart of oil. The 300 hp engine is just wonderful.
My cooling is only just satisfactory. At OAT of 30°C, i do have to
reduce immediately after gear retraction, and speed up to 140 KIAS so
get more flow. About 2 minutes into the flight, the heat wave from
the take-off reaches the sensors, and they'll set off the warning
range of the system, but i still have enough margin to the alert
threshold, and in 2 min the wave is cooled out of the system.
Longest flight so far was 2h 45 min, at FL125 where I had about 53 %
power remaining. I have yet to experience any trouble with the
engine, but the ECU's sometimes bug up when i start them up, the
remedy is simple, power down, wait a minute, and they'll do just
fine.
I have been doing aerobatics, and sustained G-turns to test the oil
flow with Mistral always checking the recorded data afterwards. Up to
4 sustained G's is all we did so far, but not a hint of any trouble.
The Mistral has a wet sump, and we did see the early signs of oil
pressure loss at values between 0 and 0.5 G, so we have chosen to
stay away from the region < 1G with this engine configuration.
I had a problem with MT propeller. they sold me what they said was
the prop, specially made for this engine, which turns at 2350 rpm at
take-off, and 2000 in the cruise. What they sold me was an off the
shelf prop for a lycoming, which turns at 2700 and 2300 resp. so when
i started doing my dive tests, the prop started overspeeding at
around 210 KIAS. I was a bit surprised, but did some test flights and
calculations, and presented them with my findings. They initially
tried to tell me i was wrong, but ended up sending me a mod that
allows the prop to go to 45° pitch, when the original setting was
35°. This clears the overspeed issue, and the prop is generally
satisfactory, but my calculations still tell me I loose 17 % because
the prop is turning at 300 rpm below which it was intended for, and
that it's working at 5° higher angle of attack than it's ideal value.
So far, MT has chosen to pretend I'm not there with regards to that
issue. Time will show that to be a mistake.
Noise....BIG problem.
Mistral gave me a long absorption muffler from Chabord in France (
the one you see in the pictures ). Chabord sells these to be put on
lycomings, and of course the result on my Glasair is catastrophic. we
measured 93 DB at take-off, and 87 DB in a cruise setting overflight
at 1000 ft AGL, but that frequency....
The extension pipe is my request. i didn't want the muffler to hang
just under the fuel bay in the wing, after all, it's an experimental
aircraft with retracts.
Chabord took about a year to build another muffler ( bet ya the
French take less time when it comes to cooking or making love ), and
it was even louder than the original. Mistral then tried a tangential
muffler from Rochhausen in Germany with a dovetail exhaust, on a 200
hp, 2-rotor engine, but no real improvement.
I displayed the aicraft at the big Friedrischafen fair for Mistral
engines ( you can say it's about like sun and fun, but mostly without
the sun ). The reactions from the public and professionals were VERY
positive. Mistral has now shifted their priority to sound reduction
as they know that they won't be able to sell any more engines like
this, and the way things stand now, we are rapidly making a bad
reputation for the product. Clients are lining up for this engine,
and there is some urgency if we don't want to loose them.
We have measured frequency ranges on my Glasair, and a theoretical
simulation will be ordered soon.
Can you tell me if there has been any significant progress on noise
surpression on your side of the Atlantic ? Mistral will provide me
with a good solution in due time, but in the mean time I'm ashamed to
fly my Glasair because it does disturb people on the ground. I
haven't built this aircraft to give aviation a bad reputation.
with kind regards,
Paul janssens
belgium
Rearrange the cooling system on the right side of the cowl. Put the
rad core next to the cowl surface and the diffuser between the core
and the hot engine to isolate the engine heat from affecting the rad
core. Put vertical louvers on the right side of the cowl to let the
hot air from the rad core escape. They can be made adjustable to
reduce the drag at cruise speed or on a cold day. This will improve
the cooling.
We have a new coaxial muffler design that works a little bit like a
ram jet, ejector or thrust augmenter so it does not add too much to
the aerodynamic drag. The tone of the rotary sound is much more
pleasant.
Peter G, I thought you might also be interested in this coaxial
muffler design speaking of turbo compound.
Paul Lamar
Paul,
Trade muffler and cooling research data with Mistral for PRSU data!
Paul Lennemann
IMHO thay are making a big mistake not using Ford mass produced gear :)
Paul Lamar
The Rotary Engine News Letter. Powered by Linux. ACRE NL web site.
http://www.rotaryeng.net. You Tube
http://tinyurl.com/beqqxas.
Copyright 1998-2013 All world wide rights reserved.