Mistral's present top priority is the G-300 which is undergoing certification.  Performance figures for this model will be released in a few weeks and ACRE will have them first.  The turbo models development is presently on hold (we can't do everything at the same time).  We have initial figures for the G-230TS but they are still far from being optimized.  I can say the following for the time being:

- 230 hp is reached at a MAP of ~43 in. Hg (I hope to get it at 41-42")
- Our turbo's critical altitude is around 20,000', it has superb performance
- Demonstrated 75% LOP cruise SFC was 0.505 lb/hp.hr at Geneva's elevation (1400').  However, we have improved efficiency much on the atmospheric engine since we got that number.  The objective is to reach 0.48.
- This engine can easily be boosted to 300 hp but that is uncomfortably close to detonation with mogas, not to mention the reduction in life expectancy.  Mistral's objective is not to offer the most power (which is child's play with a turbo engine) but a) a most reliable engine, b) 3000 hr TBO if possible also on the turbo models, and c) capability to run on mogas (i.e. safe margin from detonation).  This engine MAY end up being 240 hp but, with the constraints above, not much more.

The remaining challenge:  to make sure that the turbine wheel can survive the temperature.  We have reasons to believe that post-combustion may occur at some settings on the wheel blades' leading edge, with local temperature up to 2000°F.  We have to have the wheel made in high-temp Ni-alloy.  I hope to have this done and tested by the end of the year.

As to an all aluminum engine, I am afraid it is not anytime soon.  Al side-housings just don't last, it is confirmed by the experience of two companies which have tried.  It will be a major development effort to solve this problem.

Fly safe,

Francois



-----Message d'origine-----
De : Rotary Engine [mailto:rotaryeng@earthlink.net]
Envoyé : lundi, 31. mars 2008 22:24
À : AAA Put this in the To box
Objet : Data from Mistral


Hi Paul,


I thought you and the others might be interested to get this data in
"avant-première". We now get regularly over 200hp on our G-190. It
will be officially renamed G-200 after we prove that we can achieve the
same with the new series engines, due next June. We are still trying to
"flatten" the BSFC curves somewhat but their shape is most probably due
to the intake tuning and the "sweet spots" are rather well placed.

Initial data on the G-300 show an extremely similar pattern, just 50%
higher in horsepower.

Please note that this data was obtained using unleaded mid-grade
ethanol-free mogas (95 octane RON which is approximately 90 octane US).
  We get the same power with 100LL but 4-5% worse fuel consumption (yes,
ethanol-free mogas has higher energy density than 100LL).

BTW, I will unfortunately have to miss SNF this year, we'll have
Mistral's General Assembly the same week.


See you at AirVenture next summer.


Francois Badoux

http://www.mistral-engines.com/

http://www.youtube.com/watch?v=aLY139b65a0#GU5U2spHI_4
http://www.youtube.com/watch?v=3JQVeMoKBT0
http://www.youtube.com/watch?v=Lo1TqhQqOkg


Excellent numbers Francois! I am impressed with the LOP BSFC numbers
especially. (.44) look very good and that is right in the cruise RPM
range. Thanks for sharing with the ACRE group.
Bill Jepson

How about the turbo engine ?

Clifton.



Mistral's present top priority is the G-300 which is undergoing certification.
Performance figures for this model will be released in a few weeks and ACRE
will have them first.  The turbo models development is presently on hold
(we can't do everything at the same time).  We have initial figures for
the G-230TS but they are still far from being optimized.  I can say
the following for the time being:

- 230 hp is reached at a MAP of ~43 in. Hg (I hope to get it at 41-42")

- Our turbo's critical altitude is around 20,000', it has superb performance

- Demonstrated 75% LOP cruise SFC was 0.505 lb/hp.hr at Geneva's elevation
(1400').  However, we have improved efficiency much on the atmospheric
engine since we got that number.  The objective is to reach 0.48.

- This engine can easily be boosted to 300 hp but that is uncomfortably
close to detonation with mogas, not to mention the reduction in life
expectancy.  Mistral's objective is not to offer the most power (which
is child's play with a turbo engine) but a) a most reliable engine, b)
3000 hr TBO if possible also on the turbo models, and c) capability
to run on mogas (i.e. safe margin from detonation).  This engine
MAY end up being 240 hp but, with the constraints above, not much more.

The remaining challenge:  to make sure that the turbine wheel
can survive the temperature.  We have reasons to believe that
post-combustion may occur at some settings on the wheel blades'
leading edge, with local temperature up to 2000°F.  We have to
have the wheel made in high-temp Ni-alloy.  I hope to have this
done and tested by the end of the year.

As to an all aluminum engine, I am afraid it is not anytime soon.
Al side-housings just don't last, it is confirmed by the experience
of two companies which have tried.  It will be a major development
effort to solve this problem.

Fly safe,

Francois

You might look into having the same Japanese company, that supplies 2 mm
cast iron apex seals to Mazda, make some more durable, 3 mm cast iron apex
seals for your turbo engines Francois.

Some people are using steel 3 mm seals for that purpose but they tear up
the chrome plating on the wear surface of the rotor housings.