X-Mozilla-Keys:                                                                                 
Terry Adams wrote:

Thank you for the reiteration of the literature on cooling drag.
When considering exhaust augmentation to the cooling outlet the velocity of
the cooling flow can approximate the flow rate in the low pressure region at
the sides of the cowl just over the leading edge of the wing.  Adding cowl
flaps to the side exits has worked to increase the flow rate of the cooling
outlet even in this area.  One may continue to dump the cooling flow under
the cowl into a high pressure region, cowl flaps or not, and attempt to
extol some margin of ejector effect from the engine exhaust velocity being
greater than the air flow velocity, but there is a turbulence penalty
whenever one mixes two flows at different velocities.
Unless you have determined a simple and functional method of regulating the
cooling inlet size to minimize drag, the cooling inlet size must still be
greater than optimum even when incorporating cowl flaps.  Lowest airframe
drag dictates smallest cooling inlet.

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