Floats and Fittings
IN MY PREVIOUS articles on off-water flying, I concentrated on identifying the basic requirements of the activity. I discussed flying sites, retrieval systems, and design parameters peculiar to water, concluding with suggestions of several models that convert nicely to seaplanes. The present article follows up with a discussion of float design, strut assembly, and hardware design and installation, and explains several modifications necessary for setting up a seaplane. Although any airplane capable of taking off and landing on water is generically defined as a seaplane, my emphasis will be on floatplane conversions with a brief nod to flying boats.
Float & Hull Design
In my efforts to design float models and seaplane hulls, I have developed several formulas based on experience. I have also drawn upon the old Langley water tank report data to complete my bag of tricks. When my bag failed me, I would just go for cut-and-try, and after two or three or more design variations I'd get it to work.
Foam Core EDO 2000 Floats
If you have access to a hot-wire setup and a bandsaw, these floats are a snap-well, almost anyway. The concept is to cut the cores down the middle before hot-wiring. Once the constant-curvature top contour is done, the floats are parted and the keel outline is drawn and cut to a bevel on the bandsaw. The halves are glued back together and finished. Begin by sizing four 3 × 6 × 32-inch one-pound-density white-foam blocks (6 × 6 blocks can be sawed in two with a bandsaw for this). If the cut isn't perfect, it won't matter, as long as the halves are marked for matching. Secure the blocks back together and fix the contour patterns on each end; I use aluminum roofing nails to accomplish this. A couple of long pins will secure the bottom. Remember not to pin where the wire will travel.
Water Flying
HISTORICALLY, water was used as a flying "field" only when land alternatives proved impractical or uneconomical. Early this century long flights over water routes were serviced by seaplanes primarily because modern airports were years away. As the network of modern airports grew along with aircraft performance, seaplanes became impractical. Today seaplanes are used mostly when "you just can't get there from here" any other way. There's a reason for recounting this bit of history. Just as landplanes displaced seaplanes when adequate land facilities (airports) became available, now our land facilities for model flying are under pressure. We can ease this pressure by going back to the water.
Water Flying
THERE ARE TWO basic floatplane design concepts: 1) the converted land model and 2) a model designed from the start for water flying. Because it's easier, most of us convert existing designs. Very little weight reduction can be achieved when building a land model for exclusive water use without redesigning the entire structure. Designing a floatplane from scratch, however, you can minimize excess weight that usually is added for crash resistance and come in at or close to the desired wing loading. The key is to select the right model to begin with and then adjust its characteristics and configuration for water operation.
