First our static engine RPM was only 5200 RPM.
The 82 inch prop was turning only 1730 RPM
at 5200 RPM so the prop tips are only going 415 MPH.
Normally they get closer to Mach One at static RPM.
The 82 inch diameter static prop RPM IMHO should be higher.
I suspect the exhaust manifold by pass one inch hole is too
large. Our boost was only 5 psi. IMHO that should be closer
to 20 psi. 5 psi is about the boost you get in a stock
1995, 280 HP RX7 turbo.
We have a couple of heavy duty platform scales and
if we measure the landing gear weights we can calculate
the the prop torque and hence the HP.
We can also measure the static thrust with a calibrated garage
door spring I have.
I suspect the engine was not tuned for prop load.
We know the mixture was too lean as we richened
it up and got another 1000 RPM when it was 4000 RPM.
We got it so rich there was raw fuel in the exhaust
so it caught fire after we shut it off. Fortunately no
damage to the airplane. Quick response by a
few people with fire extinguishers close by.
We also found the waste gate was beginning to open
at this modest boost level. Very very strange!!!
There are a few things we can try. IMHO make
that hole in the manifold smaller or do away
with it altogether.
Nils Castillo has been our Motec guy and he is doing
wonderful work. The Motec system is rather easy to
tune as there is a PC USB interface. Unfortunately it
needs to be tuned when the prop is not stalled.
What would be better is a manual mixture and waste
gate controls on the instrument panel complete
with LCD displays of O2, MAP and waste gate position.
Basically a cockpit PC tap into the Motec. Perhaps a tablet ap
would do the trick.
So far the water cross counter flow cooling system is working
great
except I suspect we still have steam pockets. It is labeled engine
temperature in the data log attached and never got over
106 degrees F. The sensor is in the hot pipe coming
out of the engine. Obviously we still have modest HP.
The oil temperature is a little above room temperature
and we ran the engine today six times in the space
of two hours. It takes a lot to heat 4 gallons of oil.
Paul Lamar
Paul, That sounds very much like a rotary. Sooo close and yet
troubles.
Makes me feel better at least with all the grief I had to wade
through.
Neil.
The fundamental problem is you don't know the prop load until you
get the prop on there and fly it. It is a software problem.
If the EFI measured a wide band O2 sensor and adjusted the
mixture accordingly that might work better than using a dyno
to set the mixture. I don't know if a Motec or the one you
are using will do that.
A carb measures the air flow into the engine and adjusts the
mixture accordingly.
All automotive systems use a mass airflow sensor to measure
the air flow and air temperature into the engine.
The air temperature in a turbo installation changes rapidly
as the turbo speeds up. The air is heated as it is compressed.
Check out this chart.
We do not have a mass air flow sensor on the TTC engine.
So the Motec uses intake manifold pressure and temperature
to adjust the mixture. I don't think that works as well as a mass
airflow sensor. It might be hard to find a mass airflow sensor
that could handle 650 HP.
Tracy did the same thing in the air but the feed back was too
crude
so it
could take up to a year to get it right.
I could be wrong about all this and our main problem is that
manufactured hole
in the exhaust manifold. Kyle Mohan that runs a 800HP 3 rotor
in the
in the drift competition tells me holes in the exhaust manifold is
old school :-)
Paul Lamar
19 years ago able Ibarra got 500 HP out of a turbo two rotor.
Then he got as much as 800.
NOS of course.
This was way back in 1997
Able Ibarra lives in Riverside Ca. His dad owned a muffler
shop in LA.
He was years ahead of Jim M and knows a lot more about high power
rotaries.
84 inches of Hg!!!!!! at 800 HP.
That is about 20 psi boost. (off my chart :-))
We currently only have 5 psi boost.
We should hire him.
Never the less it will be fixed.
Paul Lamar
Did RB dyno the engine on alcohol?
Dale Davies
Yes
Paul Lamar
It would be more typical to see higher revs and less thrust from a
stalled prop. Less work being done allows more revs.
Lynn E. Hanover
Every pilot knows the RPM pick's up and the acceleration increases
half way down the runway as the prop becomes un-stalled.
Paul Lamar
The Rotary Engine free News Letter. Powered by Linux. If you want off
the list PLEASE let me know and I will remove you. ACRE NL web
site.
http://www.rotaryeng.net You Tube
http://tinyurl.com/beqqxas
Copyright 1998-2016 All world wide rights reserved.