NJD:

With the four-strokes the 12" pitch would be a lot better, provided the engines will pull the RPM.

At 9000 RPM the 12" pitch will give you approx 90 mph in level flight, with the 8" pitch yopu'd have to crank the engines at 13500 rpm for the same speed. Simple choice, no?

I was wrong earlier saying 12x8 three blade, on a two-stroke they'd be fine. But not on a four stroke.

Servos again? When I know a standard servo wont do I'll go for a stronger servo, otherwise it gets a Futaba S148. And if it needs minimum free play the S148 gets a ball bearing cover.

Side note - I'm not saying Futaba only, I've planes with the Airtronics 94102, Hitec HS-300, FMA S300, even some Tower TS series servos. These are all "Standard" servos, and I'he had no problem with any listed. I have had problems with the FMA S301, the ball bearing version of the S300.

If, after a test flight I find the standard servo doesn't work as well as I would like I'll install a stronger one.

Two reasons for this. 1) I bought several dozen S-148 servos in a batch (got a super deal) and I still have a lot left. 2) A standard "Name Brand" servo is $15-$20, next step stronger gets into the $50 range for a "Name brand." Go "Off brand" you're still at $35. And since I'm really cheap...

Standard servo not strong enough?
. Change it, but paying might be tough.

Bill.