I decided to build a Kadet Senior in January, exclusively for Float Flying. I sent an Email to Ralph Smith at PlaneFun Floats to order a set. We communicated back and forth and agreed that a Ksr, as light as it is, should have a set of 45” Slim floats. Ralph makes conventional, traditional, proven floats with a v-bottom and sides that slope in toward a narrower top. AND he makes them with a foam core. They are light, can't sink, can't even leak! I like v-bottoms because they land a little more gently without skipping, even in choppy water, and the have a little better directional stability.
Ralph kept me posted on all stages of his construction, even though I kept telling him it was no rush, the plane would take a while since I was extensively modifying the KSr design. (I never could color inside the lines). I re-made the KSr to look like a Cub, with bolt-on flat wings with “Cub” wingtips, flaps, Ailerons, and all-new Cub tailfeathers-and electric power provided by a .60 size motor and 100A speed controller from Heads-Up RC.
Amazingly soon after I ordered the floats, a BIG box showed up on my doorstep. Courtesy of the US Postal Service, the box was undamaged in any way. Ralph and I corresponded with me letting him know they had arrived. Since the box was undamaged, I was sure the floats were safe, so I put the box aside so the floats would remain undamaged while I finished the plane.
A couple of months later, I got the plane completed to the point that I could fit landing gear struts to the floats. Ralph had packed them carefully, top-to-top, wrapped in plastic film, and had then stuffed the box with newspaper packing. I opened the box with the floats and they are GORGEOUS. Pre-sheeted, pre-sanded, with built-in hardwood spine for the strut attachment, and ply transoms to accept water rudders. Ralph even marked where the spine ends were under the sheeting, so I would know where the reinforcements were when installing the struts.
It took me a couple of weeks to work up the plan/courage to glass the floats. They were so perfect, and I struggle with fiberglass. It was important to me to do an attractive job. With recently sharpened scissors (important) I cut some ¾ oz glass cloth to shape, and applied Water Based Polyurethane (WBPU) varnish with a roller. WBPU has no solvent that will wick through the balsa sheeting to attack the foam. The roller does not drag the cloth like brushes have in my experience. Rolling on the WBPU really helped the cloth to lie flat. I glassed the bottoms first. When they were dry I flipped them over to do the tops. I added an extra strip of cloth along the keels where the floats would take punishment in transit or when beaching. When they were dry, I went over them with a sanding block and fine sandpaper to get the rough spots , then covered everything with lightweight spackling to fill the weave and the imperfections. When that was dry I sanded it back down to the cloth so the spackle coat almost disappeared, and rolled on another coat of WBPU. I wanted to show off the floats, so I left them varnished, without additional paint.
I laid out a plan on some butcher paper, and bent the landing gear legs from ¾ x 1/8 aluminum strip I got at a Home Improvement Store. The struts are bent hat-shaped so I can use #10 sheet metal screws straight down into the reinforcing spine. Not scale, but cleaner than using a nose-gear block for each strut attachment. The front struts are about 3/8” taller to get proper incidence to the floats as the Kadet fuselage tapers up from the mains toward the firewall. Then I cut spreaders from 1/16 x ¾ strip. I drilled where holes were needed, bolted the floats to the plane, and made 1/16” holes and wire x-braces from SS leader wire. My installation could be prettier, but it is light and stiff.
Flying: For the maiden flight the floats and the new plane drew favorable comments at the Florida Float Flyers' pond. The plane floated high on the floats and slightly nose-up when we placed it in the water. I have not at this time installed water rudders and may not. I found it controllable taxiing in a 10 mph breeze with only the air rudder.
With the electric, it spins a BIG 18-8 prop. I did not add spray rails to the floats and never saw a drop of spray hitting the prop. Takeoffs were without incident-the plane just accelerated in a straight line and lifted off with only a gentle breath of back-pressure on the elevator stick. Landings-well, it's a Kadet Sr.! Chop the power , the plane slows down to a walk, and after a few minutes in the pattern it arrives at your landing spot, Hold it level just above the surface and it will settle in with no splashing, skipping, or other drama. Just avoid cross-winds as the KSr is so light that wind under the wing can tip it over easily. Having a flat wing and ailerons helps. I was able to taxi in crosswinds by taxiing with full UP elevator and controlling direction with the power lever. Ailerons help level he wing. There is an article about this in my website. The v-bottom makes this technique more easily utilized.
All in all I give PlaneFun Floats a rave review.
I am glad I requested the “Slim” floats because even these seem wider than I need for the KSr.
Super excellent workmanship
Attractive scale-like proportions
No spray in the prop.
V-bottom for smooth landings and easy taxiing
Foam core-can't sink
Sheeted, with marked, reinforced hard points
Packed with great care to withstand shipping abuse
Great feedback from Ralph
I wish I had a scale to give a quantitative measure but they are light, and I daresay much lighter than equivalent fiberglass or built-up ply floats.
Update 6/25/13: EASY TO REPAIR
I was taking off from grass and hit a RR Tie (DOH!) It bounced the plane into the air and I continued with the takeoff.
I did not realize there was damage so I continued the flight, making several T&Gs, and noticing no adverse water handling. The floats certainly did not absorb massive amounts of water or change weight enough to affect flying.
One of the floats hit a little-finger-sized splinter in the railroad tie. It knocked a hole in the float about 2" long by 1/2" wide.
When I got the plane back I saw the hole in one float, and the keel of the other one was scuffed. One of the bracing wires in the LG legs was snapped. A Pretty Good impact!
I let it dry for a couple days, then cut a piece of 1/16 balsa sheet a little bigger than the hole. Trimmed the hole to the shape of the patch and picked out the balsa. The floats were cut from pink foam if you were curious. Once the hole fit the patch, I coated the cavity with gorilla glue, dropped the patch in, and put masking tape over it to keep the expanding glue from pushing the patch out as it cured. The next day, I peeled off the tape, sanded the patch smooth, and laid on some 3/4 oz cloth and WBPU to bond and seal. While I was at it I laid a strip if cloth over the scuffed keel of the other float, just for insurance.
I realigned the struts and replaced the snapped brace wire. Good as new!
Lessons learned (1) Don't take off into large solid obstacles (2) cover the patch with some waxed paper or Monokote backing, and clamp a piece of plywood over the patch, to keep the Gorilla Glue from pushing the patch up as it cures. I had to sand the patch more than I should have if it had stayed perfectly aligned. Maybe I jut used too much Gorilla Glue. I still like GG for its expanding and sealing properties and light weight.
I think these floats showed WAAY less damage and were far easier to repair than either fiberglass floats or plywood floats.