Prop for Miniplane with C85/9.5:1 Lycon Pistons

[decathlondriver]

Anyone have any experience with a C85 Miniplane and know what prop diameter to use? I plan on getting the Sensenich composite/ground adjustable prop, but need to determine what diameter. The original plans call for a 68" diameter. How does one determine the prop diameter? Is it purely a ground clearance thing? What are the tradeoffs for diameter?

I've got Lycon 9.5:1 pistons and dual exhaust...airplane should end up being on the lighter side...<700 lbs..no battery/starter/alternator.

 

[Tramp]

 

[decathlondriver]

 

[Tramp]

 

[decathlondriver]