GoeKeli, it seems the 22-10 to 23-10 sizes will be the most effective on the 55 when it comes out. . Brands and blade shape will, of course, change how well the motor pulls a plane.

Keith will be doing a bit more testing before releasing the 55, I'm sure, but there are gong to be a LOT of happy people with 80-90" planes when it hits the market.

BTW. . the exhaust is timed for tuned canister style exhaust, though it will work okay with a "muffler" You might want to check on available room for a canister inside the fuselage. Also, BME has a prototype "inside cowl" canister style muffler being designed and tested. There are also 3-d CAD generated pictures of the 55's crankcase.

http://www.bmeengine.com/html/gallery.htm is the URL for the Cad drawings and other new stuff.

Please note, also, that the listed weight of the 55 is now 1.99 lbs .. really it's 1.98, but people love sales where things are priced at $___.99 cents This weight includes prop washer and nut, as well as sparkplug. Look for UNDER 2 lbs, 7 ounces with muffler and ignition in place.