Finishing Foam Floats
05-16-2011, 07:30 PM
#1
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Finishing Foam Floats
Our club has a floatplane day coming up in a few weeks and I am faced with getting a model ready for this. I have a well used O/D low wing sport aerobatic model o/a length 48 " x weight about 5lbs and powered with a tired old OS .46 FX which hasn`t flown in about a year which I will dust off and intend to use.
I knew I had a set of unused foam float blanks from many years back lying around somewhere that might do the job and eventually found them. They are 36" long and have a 3/4" step mid-length but apart from that are flat on the bottom - i.e. not vee bottomed. There is a piece of paper there suggesting they were made by 'John Sullivan Model Floatplane products.'
My eye-ometer suggests these will do the trick nicely for size. I`ll intend to insert a narrow 1/4" plywood rail into the top surface to fix the mounting frame onto - I`ll bend that up from some lightweight flat Ali. bar.
For finishing, I have heard some guys just wrap the blanks with brown packing tape and go for it, but I`m looking for something a little nicer looking than that. My fiirst thouight is to brush on one coat of WBPU , sand that and then wrap them in 3/4 oz glass cloth ( I have sufficient here) and then apply another coat of WBPU through that. If that holds the glasscloth on I`ll intend to brush on two coats of regular sanding sealer and then paint with a rattle-can.
How does that sound?
What other methods are suggested?
Thanks,
Alan W
I knew I had a set of unused foam float blanks from many years back lying around somewhere that might do the job and eventually found them. They are 36" long and have a 3/4" step mid-length but apart from that are flat on the bottom - i.e. not vee bottomed. There is a piece of paper there suggesting they were made by 'John Sullivan Model Floatplane products.'
My eye-ometer suggests these will do the trick nicely for size. I`ll intend to insert a narrow 1/4" plywood rail into the top surface to fix the mounting frame onto - I`ll bend that up from some lightweight flat Ali. bar.
For finishing, I have heard some guys just wrap the blanks with brown packing tape and go for it, but I`m looking for something a little nicer looking than that. My fiirst thouight is to brush on one coat of WBPU , sand that and then wrap them in 3/4 oz glass cloth ( I have sufficient here) and then apply another coat of WBPU through that. If that holds the glasscloth on I`ll intend to brush on two coats of regular sanding sealer and then paint with a rattle-can.
How does that sound?
What other methods are suggested?
Thanks,
Alan W
05-17-2011, 05:04 AM
#2
RE: Finishing Foam Floats
Most of your plan sounds good,,
I'd just skip the first coat of poly, make the first coat the glue the 3/4 glass down coat,, just adding weight with that extra coat otherwise, IMO
Only other thing I'd suggest is adding more glass to the bottoms, if you run up on sand or rocks,, the 3/4 glass won't hold up for long. A second layer of the 3/4 should do it.
Good luck
I'd just skip the first coat of poly, make the first coat the glue the 3/4 glass down coat,, just adding weight with that extra coat otherwise, IMO
Only other thing I'd suggest is adding more glass to the bottoms, if you run up on sand or rocks,, the 3/4 glass won't hold up for long. A second layer of the 3/4 should do it.
Good luck
05-17-2011, 12:02 PM
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RE: Finishing Foam Floats
I put 1/16 balsa on the bottom of my foam floats then glassed over that. Made the bottom a lot tougher for beaching with out adding a lot of weight. I attached the balsa with the thinnest layer of epoxy I could spread on the bottom of the floats.
05-17-2011, 01:24 PM
#4
RE: Finishing Foam Floats
I usually sheet the bottom with balsa, and use a 3" strip of 1/16" aircraft plywood just in front of the step. It sits on that in transit and sometimes in storage. Scale Only is right about skipping the primer coat-use the first coat to bond the glass cloth to the foam. Add a strip of clothe to the sharp corners of the float-that's where it will be ding-prone.
