HP-18 Flap Aileron Gap Seal
by Bruce Patton
The sketch shows the design for a seal I have been flying for the last four years in my HP-18. It completely seals the wing/flap/fuselage junction, requires no tape or messing with at assembly, allows complete freedom of movement of the flap drive and aileron pushrod.
The secret is the "tray" that mounts above the flap crank and below the aileron pushrod. The aileron pushrod seal stays attached to the pushrod and sits in the tray at assembly. The seals on mine are made of latex glove fingers. The seal for the flap crank glues to the inside (bottom) of the tray, the aileron seal to the pushrod.
The stiff foam rubber seal is glued to the fuselage and seals to the canopy cover and wing root rib at assembly.
Looks complex, but is relatively straightforward when done. Makes a big difference in the quiet in flight. I also had to rebuild the tailcone and increase the exit size when this seal was completed. My landing gear compartment is completely sealed, the one piece canopy was designed and built with a foam seal all around. I also have sealed the misc. holes in the wing root rib with tape or dabs of silicon. Photos of the ship are available on the Schreder Sailplanes Design page, HP-18, N5596S. Great ship, tenth place in last years Sports class nationals.