For the Cowling experts among us......
I have been flight testing my cowl flap modification over the last week or
so. The modification introduces a rotating door in the cooling duct aft of
the water and oil radiators. The door can close the duct completely,
operated by a MAC servo with a manual backup for emergency opening. On the
ground after start with the door closed, the engine warms up quickly,
solving the protracted wait for the minimum oil temperature for take-off
which was previously the norm. However, when airborne, the effect of the
door is surprisingly minimal. In the cruise at 130kts, with the flap open
the temperatures are as usual sub 100 degs - 60 to 70 degs maybe. With the
duct closed, the temperatures (water, oil, CHT) are only raised by about 10
degs. One advantage is it makes my cabin heater a little more effective.
Now, on the ground, with the door closed, the engine would overheat but, in
the air (winter temperatures remember) in the cruise over-heating is
unlikely.
Plainly, with ram air entering the upper cylinder cooling inlets, this is
where the major cooling takes place.
I must confess, the efficiency of the upper cooling surprised me!!!
Comments?
Regards,
Mike
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