Yes, it's on the back cover of the plans - 62" max. When I built my prop, I looked through the Central States list to see what everyone was using. There are a few larger diameter, but not by much. I made mine 62" diameter because I had lowered the thrustline slightly with the ducted fan, and I'm still using the same engine mount and thrustline now, so I'm breaking the Rutan rule a bit. With RD1B I turn the engine up to 6400 and prop to 2950, 68" pitch. With a RD1C you will only get 2245 prop RPM at 6400 engine RPM. My 86 NA engine redlines at 7000. If you have the later 13B that redlines at 8000 (I think) and run it to 7500 RPM that would be 2630 prop RPM. So you will need a higher pitch with the lower prop RPM to get your cruise speed.
I didn't know you were flying EZ now Neil. How do you like it?
Perry
___
Brad,
On a standard long-ez, you shouldn’t go any longer than 62” diameter otherwise you risk a prop strike on rotation or landing (i.e., nose high attitude). Some push the envelope and use 64”.
Neil Kruiswyk
(Now a Long-EZ flyer…)
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Brad Solomon
Sent: Tuesday, April 01, 2008 3:30 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Prop selection
I'm Brad, a student at SUU in Southern Utah. we are constructing a Long EZ air craft. We have the 13b with turbo and Crooks redrive RD-1C. We want to put a two blade prop on and we are trying to find out what
length can be used. What is our limitation and what has worked best for people. If any one knows what has been used and has worked please help us out. Does 68" sound reasonable for a two blade prop? Any info would be great. Thanks. Brad