I would like to meet the people who determine proper engine size on ARF's etc.....I bet they all drive 4 cylinder econo boxes and mini vans. My Super Stearman 40 calls for a 48 to 53 4 stroke. I put a Saito 72 on it and it's just right.
The Super Sportster 40 is a dream machine with a Saito 72 as well.
In my opinion; Add about 20 to the highest number they suggest and your plane will not only be more fun to fly, but, you'll also be able to get yourself out of trouble when needed.
Theres no substitute for hosrepower in a stall.
Dennis (Red Bluff,ca)
Real airplanes have 2 wings and round motors................

Hey Flatbed: I got to agree, love them cubic inches. They do come in handy in a lot of situations. I too will use power on, in a stall, or if I have altitude, I close my eyes and push the right stick forward. Happy flying Garry

What was your final weight compared to the listed(published) final weight?

Hi Bob-nj: I don't know about flatbed, but mine, a Tiger 2, came out about 4 oz. above the weight on the box. I tend to over build! I used a Saito 91 and moved the elev. and rudder servos to the back, not because the engine was so heavy, 19 + oz, an O.S. 46 fx weighs 17+ oz, both with muffler if memory serves. But because I had to move the engine so far out on the mounts because of the rear carb. Plane flew marvelous till Mr. Murphy came to visit. Also was a little on the heavy side because it had already been reincarnated once.

I like hp as well as the next person,but most planes that I have flew or owned, flew very well with the suggested engine.Now days people are trying to fly off prop instead of the wings,all planes are not for 3D. My .02.
Have a goodun,John.

My first plane had the smallest engine recomended. It flew, and I learned to fly it and learned basic aerobatics. We upgraded from a 40 to a .61 boy what a change that was.
The models will normally fly just fine with the recomended engines. You will not be able to get the wild aerobatics, or 3d flying with them. But if the kit calls out a .40 as long as you dont build heavy, a .40 should fly it.
About everyone today goes by the motto, if it calls for a 40, it gets a 60,or if its on sale it'll get the 90. People like to fly around at 1/3 throtle and be at the aircrafts N.E. speed.

Keep in mind that at scale events you must fly in a scale like manner. You lose points if your Stearman flys around like an F-15.

I have a .60 CG Super Chipmunk with a (suprise) OS .61 in it and it flys perfect

it has a realistic climb rate and plenty of power for takeoff and aerobatic.

the trend now is to cram the biggest engine into a plane that will fit. you have to remember that most planes are not ment to hover.

Also keep in mind that in a plane with an engine designation number (IE Super Sportster 40) the "40" refers to a 2-stroke. a 40 size 2-stroke has more power than a 40-4stroke. So for a 40 size plane, a 70 4-stroke is usually a good match

The rules of :thumbup: I read long ago and still live by is as follows:

1.) If the plane is built to specs (including weight), the specified engine sizes will fly the plane. However, the smallest engine listed may barely take off from a paved runway, so use mid-size, to largest size listed (if the wallet permits).

2.) If the listed engine sizes are specified in 2-stroke, and you want 4-stroke, multiply by 1.5 to get equivilant power. I.E. a .40 2-stroke is approx. equal to .60 4-stroke.

To answer Bob_NJ, I don't know what it weighs but the CG is perfect.
To answer Sport_Pilot, I only open her up to get her out of trouble when necessary.
I fly the Super Stearman / Saito 72 / 13x6, just fast enough to keep it in the air. It looks and sounds very real that way, however, if I don't like where I am , I can leave straight up from a dead stop with no problem if I choose.
Dennis (Red Bluff,ca)