Photos by Walter Sidas and Thayer Syme
These simple foam floats are very easy to make in an evening and are suitable for many lightweight park flyer type models. Their design is based loosely on work done by Chuck Cunningham many years ago, and have proven quite successful on the Electrifly FlyLite that I reviewed, and recently revisited, in Fly RC.
I have not included a water rudder, simply because most park flyers will not be happy flying from the rougher water that comes with any sort of breeze and the air rudder is more than sufficient for steering while on calm water. Three-channel models like the Electrifly FlyLite are unsuitable for water flying in a breeze as their high wing, extra dihedral and light weight make them easy for the wind to upset when on the water.
That said, these light models are great float flyers when the air and water are still; perfect for those calm mornings and evenings at the lake. I am more than willing to give up rough water capabilities for the joy that comes from flying endless splash and goes from glassy water with a small, light and simple model. So, shall we make some floats? Click here to download a PDF plan, print it out and follow along.
DESIGN AND CONSTRUCTION
First, we need to size them. I stretched a tape measure along my workbench and decided that 18 inches looked about right based on the fuselage length, and the distance from the CG to the prop. Typically floats are sized to 75 to 80-percent of the fuselage length and extend a couple inches in front of the propeller. These are a bit shorter at 68 percent and reach just over an inch forward of the prop. Despite this, they have worked out well in the preferred calm flying conditions.
One float should displace at least the ready-to-fly weight of the model, thus giving a 100-precent buoyancy reserve, so my target displacement was at least 10 ounces per float. More is better, as long as the floats dont start to look too goofy or weigh too much.
Calculating the displacement of square cross section floats such as these is quite easy. Simply multiply the side area by width to get the individual float volume. Water weighs .578 ounces per cubic inch, so now multiply volume by .578 to get displacement for that one float. It should equal no less than the flying weight of the model. I made a rough sketch for the prototype floats and as drawn they measure approximately as follows.
Side Area: 23.64 sq. in.
Width: 1.625 in.
23.64 x 1.625 = 38.42 cubic inches per float
38.42 x .578 = 22.2 ounces displacement
That was more than enough capacity, yet they still didnt look too large/heavy, so I started cutting foam. Because the model was light, I made them from two pieces of foam and then joined them together. This strategy saved me the trouble of trying to cut around the step and worked out very well.
As I mentioned in the article, I cut my floats with a hot wire bow, but a band saw or long razor knife will also work. Do not use a table saw though, as foam can grab the blade and kick back violently. Extruded Styrofoam sands very easily, so even if your initial cuts are a bit rough, you can smooth them quickly with a few swipes of your sanding block.
After forming the floats halves, I joined them upside down on the workbench using a straight edge as reference. I then attached 1-inch long sections cut from Popsicle sticks using ZAP-O medium foam-safe CA as anchors for the spreader bars and rear strut.
The only finish on my prototype floats is a layer of packing tape on the underside. I first cleaned the floats as best as I could, then applied and removed a first layer of tape to remove any final residue. I then burnished on a final layer of tape that is still serving me well.
MOUNTING THE FLOATS
The stock wheels on the FlyLite are 8 inches apart, so that became my default float spacing. I used a Dremel tool to carve semicircular slots that are 3/8-inch wide, or just slightly narrower than the foam tires. By squeezing the tires into these slots and taping the rear strut under the fuselage, mounting the floats only takes a few seconds. When the holes inevitably enlarge enough to lose their tight grip, I can use a rubber band looped around the axle and spreader bar on each side to keep them secure.
The two spreader bars are bent from .032 music wire, while the rear strut is .040 wire. I bent the last 1/4-inch or so of each wire into a 90-degree bend, and drilled holes in the wood that were slightly oversized. Finally I anchored the wires in the holes with the same medium Zap CA and kicker. Make sure that your glues are foam-safe.
TAKE THE PLUNGE
Making these floats only took an hour or so, and they have greatly enhanced the fun I am having with the FlyLite. If you live anywhere near water, download this simple PDF plan, take an evening and make up a set of floats for your favorite park flyer. You wont believe how much fun you have been missing.
Click here to download the plan. It is sized to print on a single sheet of 8.5×11 letter size office paper.
Electrifly, distributed exclusively by Great Planes Model Distributors
www.electrifly.com, (800) 682-8948
ZAP is manufactured by Pacer Technology
You can make a set of simple floats for your favorite park flyer in just one evening. Click image for plans and instructions. (Download PDF Here)
|The rear float strut and spreader bar are secured to their popsicle stick mounting pads with a nice dollop of ZAP-O foam-safe CA and a squirt of ZAP Foam Safe Kicker
|The front of the struts mount to the FlyLite by pressing the foam tires into a 3/16 wide slot in the float top that I milled with my Dremel tool. Mark them with a sharpie, then work up to the proper width by checking the fit. If the pockets are a little loose, simply loop a small rubber band around the gear strut and spreader. The front spreader bar is also mounted with a popsicle stick mounting pad and ZAP-O foam-safe CA.
|The FlyLite sits patiently for your next take off
|Caught in mid transition onto the step. These floats are readily scaled for your favorite park flyer.