Fokker Dr.I

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Fokker Dr.I replica at the Deutsches Museum, Munich

Fokker Dr.I replica at the ILA 2006

Fokker Dr.I triplane at an airshow

The Fokker Dr.I Dreidecker (triplane) was a World War I fighter aircraft built by the company of Anthony Fokker, and designed by Reinhold Platz. It became most famous as the plane of the Red Baron, Manfred von Richthofen.

In April 1917 the Royal Naval Air Service (RNAS) introduced the Sopwith Triplane. Their debut was sensational and they swiftly proved to be superior to the Albatros and Halberstadt scouts then in use by the German Air Service. Soon the German pilots were clamouring for a triplane of their own. The majority of the German aircraft manufacturers, including Pfalz, AEG, DFW, Schütte-Lanz, and Euler, responded with new triplane designs. Most displayed little promise, though limited production of the Pfalz Dr. I was undertaken.

Fokker responded with the V.3, a small rotary-powered triplane with a tubular steel frame fuselage and thick cantilever wings. Fokker found several deficiencies in the V.3, particularly regarding control forces. Instead of submitting the V.3 for a type test, Fokker produced a revised prototype designated V.4. The most notable changes were horn-balanced ailerons and elevators, as well as wings of increased span. The V.4 also featured interplane struts, which were not necessary from a structural standpoint, but which had the effect of minimizing wing flexing. The V.4 proved highly manueverable and much superior to the triplane prototypes submitted by other manufacturers. The rudder and elevator controls were powerful and light. Rapid turns were facilitated by the triplane's directional instability. The ailerons were also light, but not very effective.

After a type test, an immediate production order ensued. The V.4 prototype was intentionally destroyed in static structural tests. The two pre-production examples, designated F.I, were delivered in the middle of August 1917. These were the only machines to receive the F.I designation. Delivery of production machines, designated Dr.I, commenced in October of that year.

The two F.Is (103/17 and 102/17) were shipped to Werner Voss and Manfred von Richthofen on August 28th, 1917 at Marke in Belgium. Soon both were flying them in combat and racking up successes, exploiting the aircraft's remarkable climb rate and unique ability to perform flat slip-turns. Triplane 102/17 was shot down whilst being flown by Kurt Wolff on 15 September, and 103/17 flown by Werner Voss on 23 September.

The triplane also demonstrated significant drawbacks. It was considerably slower than contemporary Allied fighters in level flight and in a dive. The triplane was substantially slower than even the Albatros and Pfalz scouts it was supposed to replace. Due to the low-compression Oberursal rotary engine, performance fell off dramatically at high altitudes. As the war continued, the lack of castor oil made rotary operation more difficult. The poor quality of German ersatz lubricant resulted in many engine failures.

Furthermore, the triplane proved tricky to land, as evidenced by the wooden skids mounted on the lower wingtips. The cockpit was cramped and the close proximity of the gun butts to the cockpit, combined with poor crash padding, left the pilot vulnerable to serious head injury in the event of a crash landing.

In late October 1917 Leutnants Heinrich Gontermann and Günther Pastor were killed when their Dr.Is broke up in the air. Inspection of the crashed planes revealed extremely poor workmanship of the wings. Inspection of other triplanes revealed that moisture had caused the wing ribs to disintegrate. The triplane was immediately grounded pending an inquiry.

Improved quality control on the production line, and particularly improved waterproofing of the wing spars and ribs, largely resolved the problem. Existing triplanes were modified at Fokker's expense. However, rib failures of the upper wing continued upon the triplane's return to service, and it never fully recovered in the eyes of the pilots. In 1929, National Advisory Committee for Aeronautics (NACA) investigations found that the upper wing carried a higher wing loading than the lower wing—at high speeds it could be 2.55 times as much.

The triplane's structural problems destroyed any prospect of large scale production orders. Production eventually ended in May 1918, by which time only 320 had been manufactured. As the Fokker D.VII entered widespread service, surviving triplanes were withdrawn from frontline use and distributed to training and home defense units. Today, no genuine example of the triplane survives.

Manfred von Richthofen´s Fokker Dr.I, the last remaining, became the centrepiece of Germany's new aviation museum in Berlin, where it was destroyed in an Allied air raid during World War II in 1943, together with the famous Dornier Do X.

Variants

• V3 - Initial prototype
• V4 - First production prototype
• V5 - Fitted with a Goebel Goe.III engine
• V6 - Larger version, with a Mercedes D.II engine
• V7 - Fitted with a Siemens-Halske Sh.III engine
• V8 - Five-winged (triplane set near nose, biplane set aft of cockpit) variant of the V6
• V9 - Biplane version with an Oberursel U.0 engine
• V10 - Fitted with an Oberursel Ur.III engine

Specifications (Dr.I)

References