I bought a set of US Aircore floats for my Midwest Aerostar. First time I tried to fly it, it was all over the sky- made a wide left hand turn- I gave it full right rudder and aileron but still couldn't control it well. Finally allowed it to land by itself. Only slight damage to the landing gear. Was it just out of balance? I thought I did a good job there. Any thoughts would help before I try it again.
Thanks!

Sounds like the floats weren't mounted straight... If the floats are on crooked, you can get all kinds of wierd control problems, and poor aileron or rudder response is very common when the floats aren't straight.

Also... some planes need the rudder and fin enlarged when you put floats on them. The added profile (what you see by looking at a side view of the aircraft) area forward of the CG requires an increase in the profile aft of the CG.

I agree with Mr. Huber about mounting the floats straight. Looking down from the top, it's important for them to be parallel to the airplane's centerline. No toe-in or toe-out, either. Looking from the side, if the top of the float is level, the wing should sit with a little up incidence.

The Aerostar has big stabilizer surfaces, and I have not seen it need more stab when floats are added. You MIGHT have the floats too far forward, tho'. THe step should be far enough back that when you put the plane on a table, it will rock forward onto the front part of the floats, and not rock back onto the transom of the floats. Generally, about a half-inch behind the balance point works. If you want to get technical, the step goes under the point that corresponds to 40% of the mean Aerodynamic chord, projected with the wing at zero incidence.

If the floats are too far forward, it hurts stability both in the air and on the water.

Thanks for the info guys! When the weather warms up, I will try it again. At this point the floats are off the plane, so I will be able to start from scratch and rebalance again. If anyone out there has used these floats I would appreciate the feedback.

Might consider adding a sub fin. The rudder might not be big enough to handle the exras hanging out in the wind. I know the cub has a sub fin on the bottom of the fuse with floats. I have flown mine with and without it, but without it, the cub does way cooler aerobatics that it won't do with it. Just a thought.

i havn't flown w/ floats bu twhen i mounted skis just a little off center they acted as a sort of unmoveable aleron and rudder, both floats a skis have large surface aereas and if out of wack will act like a warped wing, causing loss of control and often crash. make shure everything is perfectly aligned before you fly!!!