Increase in fpa as cooling drag increases on piston engines aircraft 2

[gus99]

I'm calculating the change to Cdo as a result of increasing the engine sizes on a twin piston engined aircraft. The change to basic equivalent flat plate area is simple enough using the increase in nacelle area and the appropriate factor. However there is another consideration, ie increased cooling drag for larger engines. Can anyone point me in the right direction for appropriate factors modifying crosssectional intake area to get the change in fpa for cooling drag?

Your hep appreciated,

Gus.

 

[rb1957]

i'd try Hoerner "Fluid Dynamic Drag"

 

[mohr]

Hi gus99 :

This link may help you:

http://aerade.cranfield.ac.uk/results.php?Simplequery=cooling+drag&sf=KW&st=AND&rs=NACA

Cheers

 

[gus99]

Thanks to rb1957 and mohr for the links. I havent looked at
Hoerner yet but the latter NACA link looks promising as it relates to radials which is what i have in mind. many thanks
Gus