david a

I have seen several different formulas for determining the design of floats and I'm surprised at how much they differ. When I figure each one I get different lengths, heights, widths, step height. The only thing that is almost the same with each formula is the step placement. Why such disparity with float formulas?

I want to build some floats for my plane using wood, no foam, no fiberglass; just wood. I want to know what size wood to use where, where to put the center supports, what angle to make the v-hull, how wide to make the top, how much taper to put on the float from the step towards the bow and stern.

Basically, I am looking for some very detailed plans. Anyone know of a website that offers such a thing?

I was on a site and the author said that RC Modeler Magazine did a three part series on float making by Andy Lennon back in 1991. A search for this article turned up nothing.

seaplane

You might want to try to get a set of prints from a Great Planes float kit. They are built up ply and balsa. I've made a set of 60 size (42") and 40 size (34") and they work fine. They are vee bottom with a flat top........Seaplane

Geistware

My Feedback: (16)

Visit our site.
http://www.geistware.com/rcmodeling/articles/floats/

david a

Great, I'll have a look. 42" is what I need.

JimCasey

My Feedback: (1)

Or, try looking at the great planes floats on their website:
Here's a printout of the die-cutting. Scale from there.

http://www.greatplanes.com/parts/gpmq1874die.pdf

JimCasey

My Feedback: (1)

Wow, Geistware: Your site is exactly the same as http://www.armoredplanet.com/hcfc/floats.html

david a

I appreciate the sites, but I'm looking for more detailed instructions on actually building the floats. I like the program that helps to determine the size and measurements of the floats, it'll come in handy.

JimCasey

My Feedback: (1)

David A:
Perhaps in my brevity of the previous post I failed to mention that in the Great Planes' site you can download the instruction manuals. I gave you a link to the layout of all the parts, so you can print that out in any scale you want for a set of plans.

I hope that serves your needs,

david a

Had a lot of good info on that site, except for where to get the foam. How does one begin the hunt for foam?

If I knew where to obtain the size of foam needed to make a pair of floats I would start a business selling it to other modelers who want to make floats. I don't believe such a business exists now.

I can't think of many products that would require being shipped with a soild piece of foam six inches thick squared and at least 4' long.

Running all over town and dropping in on businesses to see if they have some, just doesn't work for me.

JimCasey

My Feedback: (1)

Foam: There are two types of business that supply foam. Insulation contractors and stucco contractors.
A quick check of the online yellow pages suggests that ACE supply in Montgomery would be a place to start.
What you want is probably 1# white virgin styrofoam.
You can also get 2" thick sheets at Home Depot, and glue them together with contact adhesive. Caveat: THe stuff at HD is not virgin material, and the little random lumps of regrind limit the quality of a hotwire operation.

david a

1# white virgin styrofoam; I never would had known that there different grades of styrofoam. I looked in the yellow pages under "Styrofoam" and there was nothing. I did not think of stucco or insulation.

If you glue the pieces together, how will that effect the cutting of it? I don't have hot wire capability; Can it be cut using a bandsaw with a fine tooth blade?

JimCasey

My Feedback: (1)

You can glue it together and the bandsaw will never know.

Epoxy and Poly Urethane (Pro-Bond, Gorilla Glue)are both foam-safe. Stay away from fast epoxies because of the rapid heating as they cure.

If it's hotwired, something like epoxy will make a barrier to snag the wire. Polyurethane gives off cyanide gas when heated. Contact adhesives (3m78, Dave Brown Sorghum) all work fine for hotwiring 'cause they melt at similar temps to the foam. Contact adhesives for bonding formica countertops will destroy foam (if labeled flammable) or are not worth poop(if labeled water-based)

david a

good enough

seaplane

I've made about 40 pairs of foam floats using the 2" pink styrofoam from Home Depot and gluing them together with 3M 78 spray adhesive. There is no problem with hot wire cutting.

Deadeye

David, you may find this useful, as I just built mine. Started out with a template of my own design using formulas on Giestware's website. Cut 3 1" 'Foamular' cores for each float, and glued them together with 3M Super 77. Light coats are enough, too much 77, and the foam starts to melt.

Deadeye

Now, using that long white bar sander in the first picture, I sand my angles. I just eye and measure, and it came out real good.

Deadeye

Note my centerline. I sand towards that, so it keeps things centered.

Deadeye

Once I have the foam shaped, using 3M 77 glue, I sheeted it with 3/32 balsa except for the bottom, which is 1/16 light ply. Sheet one flat spot at a time, sanding your bevels in to match the foam. This makes for a clean edge when the next sheet overlaps, sealing the foam inside the wood. Do the bottoms (light ply) last.

Deadeye

When it's all sheeted, add your end caps. On my rudder float, I used 1/4 ply and a dowel going into the foam about 6", and epoxied. Probably overkill. I sanded the edges close with a belt sander, and finished it by hand.

Deadeye

I'm going to fiberglass and paint these beauties this weekend. The mounts will be 1/4 ply with the dowel method used for the rudder. I'm making these to fit my LT-40, Super Sportster 60, and 4 Star. They will just use different mounting plates.

In hindsight, I shouldn't have made the water side angle so steep. I may have trouble planing on these. No way to know until I try it though.

Hope this helps. Cost of floats: 8 hours and about $5. Plus, I get the added bonus of admiring my handy work.

Geistware

My Feedback: (16)

You are correct.
Funny how that worked out!

david a

Those floats don't look very high. The float design program called for mine to be 4-1/4" high and 5" wide.

What grit sand paper did you use on the foam?

Deadeye

Keep in mind that heighth = drag. All you need to do is get it high enough so the prop will clear the water without a problem.

I used a very coarse grit, like maybe 80 or 100. But I finished it with 180 or so. You need aggresive grit to get the roughed angles, as it sands faster. A few swipes across the foam, and you will know what grit and pressure are required to cut.

JimCasey

My Feedback: (1)

You might get away with coarse sandpaper in pink or blue foam, but with white foam you're going to snag and rip out complete beads of the foam. I have had success using 140 grit on a good sanding bar, with light pressure. Fresh sandpaper helps.

BTW: Pink foam is twice as heavy as white, and blue is 3x as heavy as white.

AR196

David A,

foam floats have been available for many years.

How well they sell, I'm not sure.

John Sullivan was making them many moons ago (you'll find him thru Model Airplane News).

So was Len Vallie (last known contact Box 214 1113 Christie Rd, Beaver Falls BC Canada V0G 1P0).

Both these guys floats work well. Len's are completely fiberglassed, with all the materials to do the job in the kit (if he's still making them).