Twin Fin Pusher (oz6694)
About this Plan
Twin Fin Pusher. Rubber sport model.
Quote: "A sleek-looking sport rubber job with lines similar to the famous Delanne designs. Six loops of 1/8 flat supply the power. Twin Fin Pusher, by Paul Palanek
With an eye for something different yet flyable, we decided upon a modified version of a Delanne Monoplane. The results were very encouraging.
With little need for a landing gear, we decided to eliminate it entirely. The model executes landings on its twin rudders and the lower portion of the fuselage. Using the pusher design results in an aerodynamically clean nose and, with the bubble canopy up front, we have something that can be mistaken for a hot jet from out of the blue.
The best time logged was 12:45 minutes - a thermal helped us along. In trimming the model, adhere closely to the wing and stabilizer settings given in the drawing.
Construction: Begin with the fuselage, which is box-shape in section. The longerons, diagonals and cross braces, are 1/8 in square balsa. The nose reinforcement and wing support are 1/8 in sheet balsa. Build the fuselage sides one above the other, to insure exact duplication.
The fuselage formers are shaped from 1/16 sheet balsa. The upper portion of the fuselage is covered with 1/32 sheet balsa, which adds considerable strength. The rear nose block is 1/4 in sheet balsa, keyed in place. The nose block for the forward section is soft balsa, also keyed in place. Hollow the nose block as shown to receive the rubber motor. A 1/8 in dowel holds the rubber in place.
Both the wing and stabilizer are tapered sections. For both sections a tip and root rib is shown. Build between these ribs, using 1/16 sheet balsa, and shape the required ribs. There are two ribs each required per surface and only one root rib.
The spars are 1/16 by 1/8 strip balsa and the leading edge is 1/8 square. Medium-grade 1/16 sheet balsa is used for the tips and twin rudders. Be sure the grain in the rudders runs vertically, to avoid unnecessary warpage. Use 1/8 by 1/4 in strip balsa for both trailing edges. Build 1 in tip dihedral into the wing.
All areas of the model are sanded and doped prior to covering. Tissue or light Silkspan is used. After papering, dampen with water and allow to dry. Apply two coats of clear dope to all surfaces, and trim the model as shown with colors of your choice.
The rubber motor is made up of six loops of 1/4 in flat T-56 rubber. A 1/4 in hardwood dowel holds the rubber motor in place in the nose. The other end of the rubber is held by the prop hook. Insert a hardwood plug in the rear block. Slip the hook through the plug and prop bearing, before fastening to the prop. A 10 in hardwood Paulownia prop is used.
Ordinary straight pins, bent as shown, secure the rubber that holds the wing and tail in place. With all surfaces in place, and the stabilizer set at the proper incidence, you are set for some trial runs. The model should balance where shown on the drawing. If necessary, weight the undersurface of the nose for proper balance. A few glides with minor adjustments will trim the model for power flights. At first, slight power should be used, to further study flight characteristics."
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Supplementary file notes
Article page, text and pics, thanks to davidterrell80.
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User commentsDear Steve, please find attached a few pics of a slightly enlarged Twin Fin Pusher [main pic and 003]. It has around 40in wing span and is converted to electric power and radio control. A build thread can be found on https://www.rcgroups.com/forums/showthread.php?3496099...
Ronald Lehndorff - 27/04/2020
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