Junkers Attacker (oz14557)

About this Plan

Junkers Attacker (Junkers CLS). Control line scale model for Cub .074 engine.

Note plan shows two different sets of wing ribs, for either stunt or sport flying.

Direct submission to Outerzone.

Update 14/5/2023: Added article, thanks to RFJ.

Quote: "Junkers Attacker. DURING the years 1914 to 1917, most warplanes were wire-braced affairs of wood and fabric with metal tubing used on later models until in 1918 an all-metal low-wing, full-cantilever, semi-monocoque design made its appearance at the front. Not only was it one of the first examples of all-metal construction, but also the first successful attack plane used in action. The aluminum alloy tubing structure was covered with preformed aluminum-alloy corrugated sheets which made the craft tip the scale's at 2497 lb fully loaded.

In view of the fact that the Junkers CLS, a Professor Junkers brainchild, was designed primarily to combat ground forces, it carried no forward firing machine gun. A Parabellum machine gun fired through the rear cockpit floor downward against marching troop columns and entrenched soldiers, while for defense against hostile aircraft another gun of the same make was mounted on an elevated gun mount ring. Bombs were also carried. Powered by a 180 hp Mercedes high-compression engine, the plane had a maximum speed of 76.5 mph, and at this speed the range was 153 miles.

The Junkers CLS sported no fin, the entire vertical tail surface being used as the rudder. Incidentally, the 'CL' in the designation was standard for multiplace jobs in the German Imperial Air Force just as 'D' was standard for single-seat fighters; however, the 'S' meant Schlachtflugzeug, which is equal to the designation of our attack plane. Another item of interest, which is standard equipment on modern aircraft, was the overturn pylon that prevented injury to the occupants if the craft turned over on its back while landing. This also prevented the gunner from blowing the pilot's head off with his machine gun during the excitement of aerial combat.

Our OK Cub-powered Junkers CLS is ideal for a first attempt at control-line flying scale because of the simple, economical construction and fine handling qualities. This 1/2 inch to the foot scale model will also please the experienced builder either as a sport job on 15-foot lines or as a small stunt scale job on 25-foot lines. Building time should not be more than three evenings, ready to fly.

Either the OK Cub .049 or .074 engine can be installed. Other power plants of similar range may be utilized. The Cub .049 may be in either the sport or stunt version; the more powerful Cub .074 will pull the stunt version through maneuvers without a falter. With the larger engine it is suggested that the landing gear be lengthened to allow a full 5-1/2 in prop, and the elevator area increased to make the controls sensitive on the stunt version.

The first step in construction is to cut the fuselage sides to shape. Be sure to cut the openings for the wing and stabilizer. Cement bulkheads A and B "to the fuselage sides and set aside to dry. Cut the 1/4 in sheet nose piece and cement 1/8 square vertical strips to it as the plans indicate; also cut out the nose piece for the screen and engine shaft. Bulkhead C and the tail surfaces can also be made from 1/16 sheet balsa.

Install bulkhead C and join the fuselage sides at the rear, applying liberal quantities of cement. Use pins to hold this together while the cement is drying. Now drill the engine mounting holes in the plywood bulkhead A (either for upright or pancake engine installation). Install the engine with the nuts on the rear side of the bulkhead. Apply several coats of cement to the nuts to prevent them from loosening at the bulkhead.

Sand the tail surfaces and, after the hinge and control horn have been installed, cement the stabilizer securely into the fuselage slot: Cut the bell-crank to shape and attach the .018 music wire lead-out lines. Bolt or screw the bellcrank to a piece of hard wood and cement this bellcrank mount to the fuselage in the location the plans indicate. Holes must be cut for lead-out lines. Make certain that the bell-crank moves freely. The control rod is now installed. By this time the cement on the nuts on the plywood bulkhead has dried, and the engine can be removed and the bolts replaced in the bulkhead for safekeeping. Cement the nose piece in place and install the fuel tank, either sport or stunt type. Cover the fuselage top and bottom with 1/16 sheet, noting the grain direction. Set aside to dry thoroughly.

The wing is made in three panels which are joined when all are completed. In view of the fact that the landing gear is mounted on the center section or wing root, we shall begin with the wing root..."

Supplementary file notes

Article.

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