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Chapter 8 - Baron Richthofen’s “Fokker Triplane”

While triplanes, or aircraft with three main lifting surfaces, have always intrigued model builders, it has always been most difficult to fly these craft successfully in free-flight fashion. With the advent of control-line flying, the operation of these three-winged craft was greatly simplified by the pilot's control over his craft. The sight of these craft in the air as well as on the ground is most unusual and no modeller with experience should hesitate to try a triplane. Although these craft generally possess considerable wing area for their wing span and have relatively short tail moment arms, they are not necessarily used for stunting. It will be found that the craft presented herewith contains a thin low-lift airfoil, long control horn, short bellcrank third arm, and small elevator area. As previously discussed, all of these features tend to diminish control sensitivity. To reverse these characteristics would, of course, create a highly spirited plane capable of performing numerous maneuvers of advanced calibre.

It was during World War I that the triplane became prominent. Anthony Fokker, Dutch aeronautical genius, designed this tiny craft for the German Imperial Air Service in 1917 and its immediate success caused all the leading designers of the day to follow with triplanes. One of the most unusual features of this plane was the complete absence of the brace wires which were characteristic of aircraft of that period. The wings were internally braced in what is known as "cantilever construction." Another item of interest was the engine, a seven-cylinder Oberusal rotary type of 110 horsepower. This powerplant appeared to be a conventional radial type except that the propeller was attached to the crankcase and the crankshaft was fixed to the fuselage.  Consequently, when the engine was started, the engine cylinders spun with the propeller while the crankshaft remained stationary! This whirling mass caused quite a rolling tendency in the airplane.

Aeromodeller  Photo

This "Fokker Triplane" was prepared for the English magazine "Aeromodeller" and flew very successfully. Our plans presented in this chapter illustrate a slightly smaller version of this plane. Note the sheet balsa "wing" attached to the axle between the wheels This is optional but can be made from 1/16" sheet balsa if desired. Note the straight crosses in lieu of the Maltese type shown on the plans. The Germans changed the type of cross late in 1917 winding up the war with the straight type.   Either type can be used on our triplane.

Numerous German aces flew to fame in this three-winged terror. Among these early fighters were Werner Voss, Ernst Udet, Hermann Goering, and Rittmeister Baron Manfred von Richthofen. Known as the "Red Devil", "The Baron", "The Hunter", and many other nicknames by his French and English adversaries, von Richthofen was a cool and methodical aerial duelist. With a total of eighty planes to his credit (the record for World War I), he instilled both fear and respect in his enemies as he patrolled the skies in his all-scarlet airplane. His love for hunting and his superb marksmanship are generally considered to be the major factors contributing to his numerous victories.

Baron von Richthofen was finally downed as he closed in on his intended eighty-first victim. While the Baron was stalking Royal Flying Corps flier Lieutenant Wop May, Captain Roy Brown and Australian ground machine-gunners were firing at the red triplane. His plane came to a perfect landing in no-man's-land with the dead pilot sitting erect!

Our replica of Baron von Richthofen's aerial steed is designed to accommodate engines of from .020 to .074 cubic inch displacement. It will be recognized that these power-plants fall into the "half-A" class. Should the reader desire to employ a larger engine, the plans as presented should be enlarged three times for .099" to .19" powerplants and four times for .19" to .29" engines. Obviously, the size of the wood must also be enlarged accordingly. We shall describe the "half-A" version.

Model Airplane News Photo

In view of the short tail moment arm and large elevator area the author was able to stunt his "Sopwith Triplane".   Even inverted flight and outside loops were possible with this craft.

The first item to be cut to shape is the fuselage side, of which two are required. These are joined at the rear; top and bottom cross braces are then added in the fashion described in Chapter Four. Once all of the cross braces are firmly in place, the plywood firewall is cut out with a saw and firmly cemented in place on the fuselage.

Bend the two landing-gear struts to shape and bind to the axle with soft wire similar to milk-bottle cap wire. Solder this joint well. Wrap the rear strut to the plywood brace; the forward strut is "sewed" to the firewall. Use thread for these operations and smear with cement. Firmly cement the plywood brace to the fuselage sides. Attach the wheels at this time.

Cut thirty-three rectangles measuring ¼" x ¾" from 1/16" sheet balsa. These will be the wing ribs. Each of the three wings is made   in one panel.  Pin the leading-edge stock over the plan onto the work table and follow suit with the trailing-edge stock. The above-mentioned rectangles are then inserted between the leading and trailing edges. Cement the sheet-balsa wing tip onto the ends of this structure. Apply cement to all joints. When this is thoroughly dry, the structure is removed from the work table and trimmed to the proper airfoil section. An X-Acto No. 26 knife blade is recommended for this operation. When cutting the leading and trailing edges and ribs, a very gentle slicing movement is recommended. The airfoil should resemble that shown in the side view. Sand this structure with a sanding block. These sanding strokes should be parallel to the ribs.

It will be noted that the trailing edges have a scallop on the edge. This can be made by wrapping sandpaper around a small thread spool or large dowel and sanding these into the trailing edge with gentle vertical strokes. Make certain that the bellcrank mount is installed before the wings are covered with light weight "Silkspan". Clear dope three times.

Cement the lower wing and the center wing to the fuselage. The lower wing fits into the cut-out provided in the fuselage side, while the center wing is attached directly to the fuselage top. Fillet both wings with cement.

At this time, the fuel tank can be installed. Any commercial metal tank can be used. Make certain the plastic tubing is attached before the fuselage is covered.

Roughly cut the fuselage top to shape and cement in place. Cement the sheet-balsa bottom and "cheek" blocks to the fuselage. Cut balsa rings in the manner described in Chapter Six for the cowl. These are cemented together and attached securely to the plywood firewall. When all cement is perfectly dry, the entire fuselage should receive a complete, careful sanding with 1/0 and 3/0 sandpaper. Apply "Sanding Sealer" and sand again.

Cut the tail surfaces to shape and sand smooth. Attach the commercial horn and hinge the elevator to the stabilizer.

Air Trails  Photo

As an indication of the popularity of triplanes; when the author presented this "Albatros Triplane" in Air Trails, many readers enjoyed building and flying this plane. Some even built two or three! Triplanes always attract crowds of spectators at the flying field.

Cement the stabilizer atop the fuselage and attach the rudder, offsetting as is normal practice. Apply "Sanding Sealer" and sand well.

Attach the interplane struts to the two wings, already installed, by piercing the covering at the location shown and applying plenty of cement. Each interplane strut is made in one length and runs right through the center wing. Assemble the cabin struts and attach to the fuselage by forcing the sharpened ends into the fuselage top and applying liberal quantities of cement. The accuracy of the strut installation governs the upper wing alignment. This wing is attached at this time. The struts should pierce the covering in order that they may be cemented directly to the ribs. All wings must be parallel to each other and to the fuselage centerline.  Recement all strut joint exteriors.

As mentioned previously, von Richthofen's entire airplane was colored red, as were all of the planes under his command; however, these always had another distinguishing marking, such as a contrasting colored tail or perhaps fuselage dK wing stripes, to set them apart from their leader's all-red plane. Paint the model with colored dope at this time.

All markings are made with black and white "Wondur-cal". First, the square white patches are attached and these are followed by the black crosses applied directly over the white "Wondur-cal".

The machine guns are made from standard small size ladies aluminum hair curlers. These have very realistic perforations and are available at any 5-and-10-cent store. Apply a coat of clear fuel proofer over the entire model. Screw the engine to the plywood firewall with ⅜" round-head wood screws and install the control system.

Our model is now ready for flight. Heavy carpet thread can be used for flight lines. These should be twenty-five feet long. The normal flight procedure, as described in previous chapters, should be followed for this model.

Scientific   Photo

This Fokker Triplane has the same proportions as the model described in this chapter and was extremely successful; another model designed by the author and marketed by Scientific in kit form. Note the cross insignia with white outline in lieu of white field.

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