Chimba
I appreciate the fact the cooling air is drawn in by deck pressure differential.
And to on follow on that it is apparent that it is the outer extremities of the blade section that have the most influence on static cooling efficencies, as it is this section that is accelerating the air past the cooling air outlet. Now in a mild downwind I'm sure that the props airstream velocity has dominate influence on proceedings. But above a mild downwind component I wouldn't mind betting that the prop wash starts to suffer from the same principal problem that choppers trying to hover in ground effect have, vortex ring I think it's called. Any way you know all this and I think you probably explained it better back further.
As a side note to others, and this probaly belongs in the ground leaning thread. Those who are trying to clear fouled plugs with a hard runup should realise that if the plug is carbon fouled you can usually burn it off and clear the problem. However if you have suffered lead fouling you cannot burn it off, you need to physicaly dislodge the small bead of lead that is shorting the electrode, this is where cycling a prop at higher RPM might I say might help. Other wise it's a trip back to the tool box. Lead fouling is most likely to occour when combustion temps and plug nose temps are low and the chemical lead scavenging agents in fuel won't work. Another good reason to keep ground mixture's lean and minimise time on the ground.
Another rant
M