This dyno chart from Able Ibarra showing 86 inches of Hg
at 800 HP on a two rotor is amazing.

Never in the history of aviation engines has it been
so easy to get 86 inches of Hg manifold pressure.

The rotary structure is such that it can tolerate this
kind of manifold pressure. Cast iron rotors and
cannon prof e-shaft.

According to Curtis Wright the exhaust valves on a R3350
dissipate 20% of the exhaust energy.

No exhaust valves on a rotary.

I am going to try to use a manual waste gate device to control
the manifold pressure on the TTC engine.

This is connected to the exhaust manifold with a 2 inch
pipe and vents the exhaust pressure. Pilot
controlled.

We are in an historical period of aircraft engine research
and development.


Paul Lamar


Paul,

Have you considered just putting a second wastegate on the pipe with the
exhaust orifice?  It looks like it is made for one.
Barry Bordes

That would work if we knew what manifold pressure was needed
from 5000 to 8000 when the prop is not stalled.

We know, (or we were told), it generated 650 HP at 8000 RPM
at sea level.
From that I can calculate the torque and guess at the manifold pressure.
That puts the manifold pressure at 70 to 80 inches of Hg from the
Ibarra dyno curves.

It is rather surprising that it can generate that much manifold pressure
with an inch and a quarter hole in the exhaust manifold.

What I don't know is how much torque or HP it takes to rotate the
82 inch dia. 66 pitch Catto prop at 2666 RPM  un-stalled of course.

There are a lots of unknowns. If we flew the airplane to 10,000
feet we would have a lot of manifold data recorded by the Motec then
maybe we could set the waste gates to suite.

It might take many test flights as we are guessing at the settings.

Paul Lamar

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