When using 2 engines together with a common power output is
there a     simple way  to assure that both engines are contributing
equal power?     I can imagine that one or the other could be doing
more work even     though they both are running at the same rpm
(obviously). I'm thinking     of using 2 of the smaller available
rotary engines on the    helicopter,  but my question could apply
more broadly to any engine  type.

     John McEverett

   "is there a simple way  to assure that both engines are contributing
  equal
  power?"

  Same problem exists in EVERY multi-cylinder engine.

  brian gochnauer

  That suggest a simple way to do it is compare EGT's.

  Paul Lamar

You would probably be much better off comparing CHT's.  EGT's are
only an imaginary number.  The EGT probe sees about nothing
interesting 3/4 of the time because the exhaust valve is closed most
of the time during the intake, compression, and power stroke.
During the other 1/4 of the time there is exhaust flow.  The
measured temperature in the exhaust manifold varies according to the
configuration of the manifold.  Same thing as the problems with
pressure variability in the intake manifold depending on several variables.

See http://www.sportaviationonline.org/sportaviation/201010#pg89 for
a nice article on the subject.

Mark LaPierre

What exhaust valves? :) We don't have no stinking
exhaust valves :) Normally people don't install
CHT's on rotaries with at least one exception but I advocate
and  maintain it is still a good idea. They just monitor coolant
temp which is common on both rotors.

Now for two engines you could monitor coolant temp but
there could be significant differences in the two separate
(if used) cooling systems.

Paul Lamar


The EGT's in a rotary will have a fairly constant temp reading as the pulse
from one side of the rotor is almost done exhausting, the apex seal is
crossing the port. The next chamber starts flowing. If the temp probe is
installed just down from where the two exhaust pipes from the ports are
joined, the "cylinder" temps are averaged. Then the two engines could be compared.

Dale Davies