Dolphin II. Radio control sport pusher model
Quote: "Popular Czechoslovakian sport model for rudder-only control, uses pusher prop on .15-size motor. Dolphin II, by Jaromir Bily.
MANY modelers like to fly R/C for fun only. Dolphin II is an answer to many of my own dreams and whims. Being a pusher configuration, it rarely breaks a prop and it stays as clean as a glider.
The basic version is a recreation flyer for hand-launching without gear. For those lucky to have a runway, a landing gear is shown. The front part is screwed in, the rear part fastened with rubber bands. The construction is very simple, the design quite straightforward, so only a few re-marks are necessary.
Using my Czechoslovakian motor, Dolphin II emerged a little tail-heavy. Using an American motor, the model should balance suitably. Nevertheless, it is advisable to save weight toward the rear, from the wings back, whereas the front can be built quite sturdy. For balance and strength, my model has a spruce nose block. Hard balsa can be substituted, if ballast is added.
The wing ribs are constructed by shaping roughly precut balsa ribs (for half the wing at a time) between the plywood root and tip ribs. Make the plywood templates from the wing center rib drawing with the notches shown on W-1, and make the tip rib from the wing tip rib drawing. Ribs W-1 have an extra deep notch for the dihedral joiner and their outlines must be reduced in the center by the thickness of the balsa sheet covering.
The next two ribs out on each panel are trimmed down to allow only for the wider leading- and trailing-edge sheeting. The center-most ribs are trimmed all around like W-1 but then are cut through at the spar notch to fit on each side of the dihedral joiner.
First step in wing construction is to make the complete spar with joiner. Assemble ail the ribs for one wing panel on the spar and pin this over the plans. Slide the trailing edge sheeting under the ribs and pin down. Now glue each rib to the spars and trailing edge sheeting, Slide the leading edge 1/8 bottom sheeting under the ribs and glue. Bevel both leading and trailing edge sheeting, following the rib curvature before adding the top sheeting. Repeat the above process for the other half of the wing. Add tips, center-most ribs, center sheeting, and the spruce leading edge center stiffener. After sanding smooth all over, cover with heavy Silkspan..."
Dolphin, American Aircraft Modeler, December 1969.
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This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.
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