Chris Zavatson has written a very useful article entitled "Cooling Drag" (EAA Sport Aviation, December 2007).  Well worth reading if you are greedy and want to keep the engine cool and go even faster by also reducing cooling drag.

 

Lancairians should pay extra attention because of the special place Lancairs have in aviation.  There are very few non-race piston aircraft extant that have such a low airframe flat-plate drag factor as a Lancair.  This means that any other drag inducing items have a significant affect on performance and reducing such drag has a large performance improvement payback.  One of those is cooling drag. 

 

Naysayers, stuck with rivet studded airframes, supporting fat wings with struts and built with high drag wide mouthed cowls can't seem to understand why this makes so much difference.  It does when cooling drag on our slick powered lawn darts may account for 20 or more percent of the total airplane drag.

 

Nice article Chris,

 

 Scott Krueger AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)