I tried a Maiden flight on a 10 1/2 pound Stearman plane.On take off after the tail came up I let it build up a right bit of speed before I gave it a little elevator.It took off Ok but there was no climb out.It acted like I did not have power.The engine I am using is in Great Running shape.Before I tell you what it is I wanted to heard what engine Alot of you folks would of used.The engine is a 2 stroke So what size engine should I be using Thanks MJ

I would fit a 120 or 150 four stroke. The best fit would be a Laser 150, but failing that any of the 120 Four strokes. Best if Laser is too expensive is probably OS, but cheaper makes all work well. If you prefer a Two Stroke, it should fly on an ASP 1.08 or similar. If you want to climb vertical, try a Moki 135. ByPlanes have a lot of drag and need a lot of power to fully perform in an un-real way. Original full size plane does not climb all that well! I would recommend MDS 148, cheap and strong, but until the new carb comes out and possibly a few internal mod's, dont risk the engine stopping which is a problem to those of us using them.

Considering the performance I've been getting with a Dr1 at 9 lbs... I think you could use a O.S. .91 FS and get better performance than you have stated... I'd bet you started out using a .60. I'd also bet that you are using a propellor which is more appropriate to a single wing sport plane.

If you simply switch to the longest, lowest pitch prop your current engine would turn... you'd probably be much happier. Draggy planes (biplanes by definition are draggy) need better low speed "authority" from the prop. Getting more disk area and lower pitch gives better pull for take-off and climb.

The O.S. .91 FS on my tripe has the power for unlimited vertical... with smoke sytem active. (which drasticly cuts power) But... I'm using a long, low pitch prop. I feel that the engine is under-propped right now... and going above 75% throttle with the smoke off gives no improvement in top speed. With the O.S. recommended 12X10... I doubt it would fly worth beans. I've been using a Bolly Clubman 13.5 X 6, and I'm going to put on a MA 15 X 6 "Classic" (which is a black nylon with rounded tips) to try for torque rolls. (much heavier prop for more torque effect, and more prop blade area.. bigger disc...) If they made a 16 X 4... I'd try it.

Thanks all.The engine I tried using is a SuperTigre 75.The plane is the old Sterling kit that was heavy and time consuming.The plane came out heavy 10 1/2 pounds because I needed to make it stronger.The wing span is 65 inches and the plans called for a 56 size engine but I knew a 56 or 61 would not fly it.I was also using a 12-6 prop.I have a Super tigre 90 which I will install now.All I want is it to fly Scale.Thanks again ALL
MJ

Long ago I learnt the hard way that beefing up a kit to make it stronger, does not make a stronger plane. I built a David Boddington designed Ultimate and could not believe the small sizes of wing spars, 3/16" X 1/8" and the lack of ply doublers etc. Finished weight with MDS 148 was 9 lbs for a large Biplane. But it survived many cartwheels and withstood the most violent airobatics. A super light plane has little inertia and can fly slowly.
I agree that a 91 should fly your model with a fine pitch large prop.

First .......You are underpowered.
second.....I suggest you check your cg...........
Third......I would investigate the throws on you control surfaces.

Less power requires more movement for elevator.......take-off roll should not be so long you pucker up....

Your plane is heavy......More power is the answer...but CG will be the most important thing you change.
When you change engines.......check your cg...
Doc