I am going to biuld some floats for a cub. I was wondering how thick and long they need to be. Its a 40 size cub and need to know what wood to use and such. Any tips would be great too.

Great Planes, Goldberg, Sig, Sea Commander and others have kits for 40 size models. Check out the various websites and Tower's catalog.

Rich


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And several of RCU's contributors offer foam floats, either plain or sheeted, for very little money. For your first set, you would be far better off buying a proven design than trying to design your own.

Jim

ok thanks jim. I will look into it.

JRF, Could you PM me for more details... VERY interested

Newbtorc:

I don't have the contact info for them, but they frequently post on this forum. Do a search for "foam floats". I think one is known as "Seaplane".

Jim Casey, can you help this guy?

Jim

Seaplane is at http://www.geocities.com/planefunfloats/

Some other sources:
http://www.foamcorefloats.com/
http://www.foamfloats.com/
http://users.cwnet.com/zdgreg/index.html

Or the classic link to the site containing the Chuck Cunningham article that tells you how to make your own:
http://www.flyinglindy.homestead.com/index1~ns4.html

ok. How wide if i was to biuld my own would they need to be for a .40 cub that weighs 8 pounds? How deep must they be? I am going to biuld these and then if they hold up, they are my instructors. He just had the idea of flying off a lake so i wanted to make some instead of buying some.

Read the article. It tells you how long, how wide, where to put the step, how to rig them, etc.

Jim, I started last night! They are 36 long and 3 wide so a total water displacement of 216 square inches. Should be plenty to float a cub. Is there a tool or formula to see how many pounds that will support?-

Water weighs 62.4 pounds per cubic foot, or 0.577 ounces per cubic inch.
EACH float should displace at least the entire weight of the plane.

So, if you have a .40 size trainer that weighs 7 pounds, the floats should displace 388 cubic inches.(7 x 16 x1/.577 x 2)

32" long, 3" wide, 3" deep x.7 shape factor (they're tapered)


Cheat a little wider if U can. Tapered sides, 2 1/2" tops, 4" bottoms will pop U up faster.


Engineering is my life.

I think i will choose a new design now... lol I need more support than just foam. I will be talking to one fo the guys on here who makes them, or just buy some... what about the GWS floats?

Foam floats are great and should not be difficult to build.
There is a fellow here in Wisconsin that specializes in foam floats in all sizes that covers them with fiberglass to finish for looks and strength, and inlays a length of plywood on the top surface for mounting and strength.

They are the best floats I have ever seen....

Custom Flys and Floats
Don Eichsteadt
920-739-4728

Idea popped up, If the foam doesnt fill up with water... could i just use foam and not cover? I would like to cover with balsa, but i think i could do a Monocote covering instead.... It would be cheaper like that also....

The article in the link I sent you talks about covering styrofoam floats with packing tape. It's cheap and fast, but it just doesn't protect the floats very well. If you taxi up on a gravel beach or set the plane down on the random nut or bolt on the workbench, the floats can be marred. My best results have been with Foam cores, balsa skins, and a layer of light glass cloth. Plywood on the bottom for 2" in front of the step and at the attach points.