Props
 

Hey.
A friend and I are building a Guillow bipe, and we're going RC. Which should be the best engine for it? I´m thinking of a good Big mig .061, but there's also a good chance to get a .074 instead. Which would be the best one? (did I mention we're flying higher than 8000ft over sea level?. U understand we need as much power as we can get, and make the thing light).
I also need to know the prop I should use for each of them.
Suggestions anyone?

Which Bipe?
 

I built a Guillows Stearman bipe...be sure to build it strong! Try the .061 and use Cox grey 6x3 props. Don't worry that the RPM doesn't match the book estimates. Volume will be and fuel consumption will be lower, thrust will be increased and the needle will have a wider sweet spot.

Props
 

My personal preference for the .061 is an APC 6X2. For the .074 I like a 7X3.

Props
 

Hey. That's exactly the plane we're building.
What should we reinforce beside the firewall? (That's by far, the only thing we've modified).
Did u make it 3 channel? or was it only rudder elevator?
We're planning on put ailerons instead of a rudder and throttle servo. What do u think?
About the prop size, I think that the 6-3 prop might be a bit large. Won't it overheat the engine?
Thanks in advance for any input.

Stearman
 

This Guillows kit is built very light. Mine was built for control line. A .061 is more than adequite. You might even consider an .049. I'm not sure how long such a light kit will last in use. All the 1/2 A planes I fly now were designed for R/C. I reinforce my air frames so a few extra "Gs" won't hurt them. Most usually weigh in at 22-26 oz.
The large prop is to slow the engine. I have a 50" Cub with over 15 air hours on it with this setup (Cox grey 6x3 16,500 20%nitro). My 42" Citabria has about 10 air hours on it ( 5.5x4 Cox grey 17,800 35% nitro). My son has a 72" Piece -O-Cake running the 6x3. None have overheating problems. If you have overheating problems use less nitro or run more head shims. Other club members that have had problems with Norvels have asked for my help after observing several seasons of trouble-free flights.