For modest air requirements like cockpit ventilation they seem to be
OK.
What is surprising to me is nobody seems to use them for what they
were designed for in the first place and that is an internal device
such as a carb inlet that is drawing air in. Apparently you get
more HP with a conventional scoop such as found on the Vans RV series,
the P38 and the Me 109 to overcome any additional drag that these type
scoops may have compared to a NACA scoop. Net result higher top speed.

BTW Tracy Crook has one of these type scoops on his rotary powered RV4
and his top speed is around 214 MPH.

Chad Robinson wrote:

Just to be clear, are these pictures of armpit scoops? For this plane, do you
have any pics of the exit air vents, or are they pretty standard?

Thanks,
Chad

I am bit confused. These are carb air intakes.

Armpit scoops are another animal. They usually take in the boundary
layer
when they should not. It is best to bypass the slow moving boundry
layer.

For rad air exit vents vary widely. Few people use cowl flaps and many
more should.
They are worth several MPH. Here is a pic of Bill Eslicks cowl flap
on a rotary powered RV6. Also some on a Ford V6 STOL.

Cowl flaps are not impossible on a pusher just difficult.

Paul Lamar
 
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