Windermere Model Waterplane Flyers
BMFA Affiliation No. 2412
Waterproofing? Most glow engine aircraft are pretty waterproof, but there are some special considerations. You should paint exposed balsa in the fuselage cavity. You need to wrap your receiver in plastic to prevent damage. Caution: Do not wrap your NiCad battery pack in any impervious material. Any watertight wrapping will cause the battery to overheat when you charge it. The battery pack, wrapped in normal latex foam vibration absorber, will be waterproof enough. Where the wing mates with the fuselage, you must take some steps to keep water out. Along the line of the wing saddle you might lay down a bead of silicone sealant on the saddle and drop the wing (covered with plastic wrap) onto the saddle, let the bead dry and remove when the sealant has cured. A third method is to simply put the wing on, sealing the gap with a bead of Vaseline. (Tech. Ed. note: some float fliers prefer to leave the receiver unpackaged and suspended mid-cabin since the package holds water in the receiver).
Rudders? In anything less than the lightest breeze, it is impossible to control the taxiing of a floatplane on water. You need rudders, and two are always better than one. The rudders should be rigged for maximum deflection left and right, as steering at low speeds requires extra bite. Rudders should swing upward out of the water so they do not have any steering effect of drag when you approach takeoff speed. Also, when you taxi back to the beach you want them to fold back to prevent strain on your steering setup. The water rudders have to work in harmony with the air rudder.
The Step? The step is that notch in the bottom of the float. You will notice that the bottom of the hull slopes upwards at about three to five degrees behind the step. This allows you to rotate the aircraft for takeoff and landing without the back of the float digging into the water. As the aircraft increases speed to takeoff, the float rides up onto the step and a huge amount of suction is eliminated. Nothing is more important than getting the step in the right place. In general terms, the step should be under the center of gravity or about a half inch to the rear of the center of gravity.
Balance? Your wheeled aircraft will normally become tail heavy when floats are added. Add balancing lead to the nose of the floats for two reasons. First, they are the farthest out and provide the greatest leverage for the least amount of lead. Second, when you take your floats off and go back to wheeled flying, you won? t have to rebalance the airplane.
Attachment gear? You have to decide whether you are going to retain the existing wheeled landing gear and adapt it to the floats or whether you are going to take off the wheeled gear and create a totally new mount. If you keep the existing landing gear, you will have to insert some hard points in the rear bottom of the fuselage at a point about half the chord width behind the trailing edge. These hard points will anchor a rear landing gear support that might be a bit lighter but similar to the front gear. If you are going to strip off the landing gear, then you will need hard points front and rear and solid support geometry to support the floats that does not twist or bend.