I'm thinking about building a pair of floats but the measurements seem Cinda of big
my air plane is a 40 size it is 52" long and the floats are to be 80% the fuselage length but its kind of big on the plane.[sm=confused.gif]

The floats are 41.6" long ona 52 inch plane

The floats for a fourty size should be somewhere in the 35 inch range. It will fly larger ones, but they are not needed. You could go up to about 40 inches depending on thickness, but I wouldn't go too much bigger. Depends on the plane some too.

My plane is a great planes pt-40 it only 5-6lb

would 37" be anough

Look at the pictures of full scale aircraft on floats... the floats are very large compared to the aircraft. The 80% of fuselage length formula works. Trust it.

If the floats are shrter, yes they might work. problem s, you lose some stability when on the water. It makes float placement related to CG MUCH more critical if you go with shorter floats. It is better to have them too long than too short.

You may also see that the front of the float is forward of the prop... this can seem strange, but remember the float's center of boyancy must be under the aircraft CG or the plane will not ride correctly in the water. The CG of the aircraft is generally about 25% of the fuselage lenght from the nose. The float center of boyancy is generally 40% from the front. (wider front than rear) It is OK to have the plane ride a little tail-low with empty fuel... Never OK to ride nose low with full fuel.

Rigging your first float plane... follow the numbers, they work.

and another thing what is the best building material for a beginner
(I'm not that good with fiber glass) would you use ply balsa or what?

If you have never built a set, get great planes 40 size floats. They are built up and you will learn a lot building the. There are also companies making glass floats, but they cost more and I have seen a lot of people blow them up. I didn't like the way they were built.

Mine on my stik 60 are very small, and veryshort, and they really need to be bigger for that particular plane, but it is the most stable float plane I have ever flown. The floats ride almost all the way in the water, which is bad, but hey, it works.

Mine are made of foam and glassed, it works well, but if you haven't done foam cutting and glassing, it would be a huge pain for you. Goldberg also has a set for the cub, they would work but are fairly big. I think too big for your plane, but maybe not. They sit very high in the water and are a great float.

I have seen some scratch design floats too that I would have never guessed possible, but they flew great off choppy water and smooth.

Check out the floats at tower. They are pretty good.

i have some experience at foam cutting but not glass. but is flying with floats different then flying with wheels.

I have just flown my first seaplane, a Sig Fazer on floats. It is a .40-.46 size plane, 48" span weighing in the 5 pound range. I used Falcon Trading Co floats. With their adjustable mounting system, they were very easy to install. You slide the mount ot where you want it on a ridge on top of the float and screw them in place. My plane floats very high in the water. They come with a water rudder and a pull-pull set-up, but I made my own. Here is their URL and a couple more.

http://www.falcon-trading.com/product.cfm?prodID=8

http://www.geocities.com/planefunfloats/

http://www.foamcorefloats.com/

You'll enjoy float flying, it's a lot of fun and a new experience. I found you have to be aggressive with taxiing. My plane was so high the rear end of the floats and the water rudder were out of the water. I ended up using full up elevator and a good bit of power to keep the rudder in the water to steer during taxi.

thanks guys and i finally have it its made from Styrofoam covered with balsa, ply and to mach my sceam its covered in monocoate.[;D]