Thanks Av8tor.
I have an APC 18-6W, a Zinger 18-8, and a Zinger 20-6/10 in inventory..
I prefer the static thrust route, so if I have enough ground clearance,
I'l try the 20-6/10 first before deciding which Zoars to purchase. .
With the 18-6 Master Airscrew at full throttle, it sounded like the tip speed was in the 450 mph range.
But I do wear foam earplugs and ear muffs when messing with the engine, so my guess is probable way off.