ORIGINAL: wyo69cowboy
ORIGINAL: MinnFlyer
ORIGINAL: Airplanes400
ORIGINAL: MinnFlyer
A lot depends on the specific engine, but I generally say:
40 - 46 (2-stroke) = 52 - 70 (4-stroke)
55 - 65 = 91 - 100
75 - 90 = 110 -125
Larger than that, Gasoline
I agree with the above with the exception of a .52 4-stroke engine. I'd equate them to a 25 to 32 sized two-stroke engine. I have always used .70 4-strokes in place of a .46 2-stroke.
There was a time I would have agreed with you, but I've got an OS 52 which I have used in several 40 size planes that was MORE than enough power!
Depends on how big your 40 size plane is; I had a Phoenix Decathlon with an OS46; my buddy built the same plane and used a Magnum .52. This plane calls for .46 2 stroke or .52-70 4 strokes, and weighed just over 6 lbs. I never thought the .46 was a powerhouse in this plane, but the .52 will barely do a loop with it, not for lack of trying props or anything else on the .52.
You're right about the Magnum 52. I put one on my Sig Rascal in place of a 40 2-stroke and it barely has enough power. The Rascal is even lighter than the Decathlon, I think. I did it to make the plane more "nostalgic".