Fokker Dr.I

Source: Wikipedia, the free encyclopedia.
Fokker Dr.I
Fokker Dr.I
Role Fighter
Manufacturer Fokker-Flugzeugwerke
Designer Reinhold Platz
First flight July 5, 1917 (1917-07-05)
Primary user  Luftstreitkräfte
Number built 320[1]
Developed from Fokker V.4
Fokker F.I
Variants Fokker V.7

The Fokker Dr.I (Dreidecker, "triplane" in German), often known simply as the Fokker Triplane, was a World War I fighter aircraft built by Fokker-Flugzeugwerke. The Dr.I saw widespread service in the spring of 1918. It became famous as the aircraft in which Manfred von Richthofen gained his last 17 victories (plus two earlier ones in the Fokker F.I prototype in September 1917), and in which he was killed on 21 April 1918.

Design and development

Fokker V.4 prototype

In February 1917, the

elevators.[7]

Instead of submitting the V.4 for a type test, Fokker produced a revised prototype designated

interplane struts, which were not necessary from a structural standpoint, but which minimized wing flexing.[8] On 14 July 1917, Idflieg issued an order for 20 pre-production aircraft. The V.5 prototype, serial 101/17, was tested to destruction at Adlershof on 11 August 1917.[9]

Operational history

Jasta 12 flightline at Toulis
, France
Jasta 26 at Erchin
, France

The first two pre-production triplanes were designated

11
for combat evaluation, arriving at Markebeeke, Belgium on 28 August 1917.

Richthofen first flew 102/17 on 1 September 1917 and shot down two enemy aircraft in the next two days. He reported to the Kogenluft (Kommandierender General der Luftstreitkräfte) that the F.I was superior to the Sopwith Triplane.

Jasta 11, was shot down in 102/17 on 15 September, and Leutnant Werner Voss
, Staffelführer of Jasta 10, was killed in 103/17 on 23 September.

The remaining pre-production aircraft, designated Dr.I, were delivered to Jasta 11.

Jagdgeschwader
I.

Compared with the Albatros and Pfalz fighters, the Dr.I offered exceptional maneuverability. Though the ailerons were not very effective, the rudder and elevator controls were light and powerful.[15] Rapid turns, especially to the right, were facilitated by the triplane's marked directional instability.[15] Vizefeldwebel Franz Hemer of Jasta 6 said, "The triplane was my favorite fighting machine because it had such wonderful flying qualities. I could let myself stunt – looping and rolling – and could avoid an enemy by diving with perfect safety. The triplane had to be given up because although it was very maneuverable, it was no longer fast enough."[16]

Manfred von Richthofen's red Dr.I, serial 425/17

As Hemer noted, the Dr.I was considerably slower than contemporary Allied fighters in level flight and in a dive. While initial rate of climb was excellent, performance fell off dramatically at higher altitudes because of the low compression of the

ersatz lubricant resulted in many engine failures, particularly during the summer of 1918.[18]

The Dr.I suffered other deficiencies. The pilot's view was poor during takeoff and landing.[19] The cockpit was cramped and furnished with materials of inferior quality.[20] Furthermore, the proximity of the gun butts to the cockpit, combined with inadequate crash padding, left the pilot vulnerable to serious head injury in the event of a crash landing.[21]

Wing failures

Heinrich Gontermann's wrecked Dr.I

On 29 October 1917, Leutnant der Reserve

wing ribs to disintegrate and the ailerons to break away in flight.[23]

In response to the crash investigation, Fokker was forced to improve quality control on the production line, particularly varnishing of the

wing spars and ribs, to combat moisture. Fokker also strengthened the rib structures and the attachment of the auxiliary spars to the ribs.[24] Existing triplanes were repaired and modified at Fokker's expense.[25] After testing a modified wing at Adlershof, Idflieg authorized the triplane's return to service on 28 November 1917.[26] Production resumed in early December. By January 1918, Jastas 6 and 11 were fully equipped with the triplane. Only 14 squadrons used the Dr.I as their primary equipment. Most of these units were part of Jagdgeschwadern I, II, or III.[27] Frontline inventory peaked in late April 1918, with 171 aircraft in service on the Western Front.[13]

Despite corrective measures, the Dr.I continued to suffer from wing failures. On 3 February 1918, Leutnant Hans Joachim Wolff of Jasta 11 successfully landed after suffering a failure of the upper wing leading edge and ribs.

Bristol F.2Bs of No. 62 Squadron.[29]
Richthofen was seriously injured in the ensuing crash landing.

Postwar research revealed that poor workmanship was not the only cause of the triplane's structural failures. In 1929, National Advisory Committee for Aeronautics (NACA) investigations found that the upper wing carried a higher lift coefficient than the lower wing – at high speeds it could be 2.55 times as much.

The triplane's chronic structural problems destroyed any prospect of large-scale orders.[30] Production eventually ended in May 1918, by which time only 320 had been manufactured.[31] The Dr.I was withdrawn from frontline service as the Fokker D.VII entered widespread service in June and July. Jasta 19 was the last squadron to be fully equipped with the Dr.I.[32]

Surviving triplanes were distributed to training and home defense units. Several training aircraft were reengined with the 75 kW (100 hp) Goebel Goe.II.

Armistice, many remaining triplanes were assigned to fighter training schools at Nivelles, Belgium, and Valenciennes, France.[34] Allied pilots tested several of these triplanes and found their handling qualities to be impressive.[34]

One of Richthofen's Fokker Dr.Is, on display at the Zeughaus

Experimental engines

Several Dr.Is were used as testbeds for experimental engines. One aircraft, designated V.7, was fitted with the Siemens-Halske Sh.III bi-rotary engine.[35] The V.7 exhibited exceptional rate of climb and ceiling, but it proved difficult to handle.[35] Serial 108/17 was used to test the 118 kW (160 hp) Goebel Goe. III, while serial 469/17 was used to test the 108 kW (145 hp) Oberursel Ur. III.[36] None of these engines were used on production aircraft. One triplane was used as a testbed for an experimental Schwade gear-driven supercharger.

Postwar

Three triplanes are known to have survived the Armistice. Serial 528/17 was retained as a testbed by the Deutschen Versuchsanstalt für Luftfahrt (German Aviation Research Institute) at Adlershof. After being used in the filming of two movies, 528/17 is believed to have crashed sometime in the late 1930s.[37] Serial 152/17, in which Manfred von Richthofen obtained three victories, was displayed at the Zeughaus museum in Berlin.[37] This aircraft was destroyed in an Allied bombing raid during World War II.

In 1932, Fokker assembled a Dr.I from existing components. It was displayed in the Deutsche Luftfahrt-Sammlung in Berlin. In 1943, the aircraft was destroyed in an Allied bombing raid. Today, only a few original Dr.I artifacts survive in museums.

Variants

  • V.4 – Initial prototype
  • V.5 – First production prototype
  • V.6 – Enlarged prototype with Mercedes D.II engine
  • V.7 – Prototype with Siemens-Halske Sh.III engine
  • Vagel Grip SP.5 Greif - German post-war two seat copy of the Dr.I

Operators

 German Empire

Replica and reproduction aircraft

Filton Aerodrome
, United Kingdom
Dr.I replica

Large numbers of replica and reproduction aircraft have been built for both individuals and museums. Bitz Flugzeugbau GmbH built two Dr.I replicas, serial numbers 001 and 002, for use in

Twentieth Century Fox’s 1966 film The Blue Max. Replica 001 EI-APW is the oldest surviving example of the Dr.1. Because of the expense and scarcity of authentic rotary engines, most airworthy replicas are powered by a Warner Scarab or Continental R-670 radial engine.[38] A few, however, feature vintage Le Rhône 9J[39] or reproduction Oberursel Ur.II rotary engines.[40]

Specifications (Dr.I)

Official Baubeschreibung drawing

Data from Quest for Performance.[41]

General characteristics

  • Crew: 1
  • Length: 5.77 m (18 ft 11 in)
  • Upper wingspan: 7.19 m (23 ft 7 in)
  • Height: 2.95 m (9 ft 8 in)
  • Wing area: 18.7 m2 (201 sq ft)
  • Aspect ratio: 4.04
  • Empty weight: 406 kg (895 lb)
  • Gross weight: 586 kg (1,291 lb)
  • Powerplant: 1 ×
    Oberursel Ur.II
    9-cylinder air-cooled rotary piston engine, 82 kW (110 hp)
  • Propellers: 2-bladed fixed-pitch wooden propeller

Performance

  • Maximum speed: 180 km/h (110 mph, 97 kn) at 2600m
  • Stall speed: 72 km/h (45 mph, 39 kn)
  • Range: 300 km (190 mi, 160 nmi)
  • Service ceiling: 6,100 m (20,000 ft)
  • Rate of climb: 5.7 m/s (1,120 ft/min)
  • Lift-to-drag: 8:1
  • Wing loading: 31.0 kg/m2 (6.3 lb/sq ft)
  • Zero-lift drag coefficient: 0.0323
  • Frontal area at zero-lift drag coefficient: 0.62 m2 (6.7 sq ft)

Armament

  • Guns: 2 × 7.92 mm (0.312 in)
    Maschinengewehr 08
    "Spandau" machine guns

See also

Aircraft of comparable role, configuration, and era

References

  1. ^ Rimell, 1996, pp.1 & 21
  2. ^ Franks 2004, p. 9.
  3. ^ Franks 2004, p. 21.
  4. ^ Leaman 2003, pp. 30, 32.
  5. ^ Weyl 1965, p.223.
  6. ^ Leaman 2003, p. 34.
  7. ^ Weyl 1965, p. 226.
  8. ^ Weyl 1965, p. 228.
  9. ^ Weyl 1965, p. 229.
  10. ^ Weyl 1965, p. 231.
  11. ^ a b Weyl 1965, p. 232.
  12. ^ Leaman 2003, p. 53.
  13. ^ a b Franks and VanWyngarden 2001, p. 22.
  14. ^ Leaman 2003, p. 96.
  15. ^ a b Leaman 2003, p. 95.
  16. ^ VanWyngarden 2004, p. 75.
  17. ^ Nowarra 1990, p. 12.
  18. ^ Franks and VanWyngarden 2001, p. 83.
  19. ^ Weyl 1965, p. 245.
  20. ^ Weyl 1965, pp. 244–245.
  21. ^ Weyl 1965, p. 410.
  22. ^ a b Weyl 1965, p. 233.
  23. ^ a b Weyl 1965, pp. 233–234.
  24. ^ Weyl 1965, pp. 236, 239.
  25. ^ Weyl 1965, p. 235.
  26. ^ Weyl 1965, pp. 238–239.
  27. ^ Franks and VanWyngarden 2001, p. 55.
  28. ^ Franks and VanWyngarden 2001, p. 25.
  29. ^ Franks and VanWyngarden 2001, pp. 26–27.
  30. ^ Weyl 1965, p. 236.
  31. ^ Gray and Thetford 1962, p. 100.
  32. ^ Leaman 2003, p. 69.
  33. ^ Leaman 2003, p. 222.
  34. ^ a b Weyl 1965, p. 246.
  35. ^ a b Weyl 1965, p. 248.
  36. ^ Weyl 1965, pp. 249–250.
  37. ^ a b Leaman 2003, p. 181.
  38. ^ Nowarra 1990, p. 47.
  39. ^ "Cole Palen's Old Rhinebeck Aerodrome — Fokker Dr.1 Triplane". oldrhinebeck.org. Old Rhinebeck Aerodrome. 24 February 2021. Retrieved May 12, 2021.
  40. ^ "Oberursel UR.II" The Vintage Aviator. Retrieved: 6 November 2016.
  41. ^ Loftin 2004, Table I.

Sources

External links

Wikimedia Commons has media related to Fokker Dr1.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Fokker_Dr.I&oldid=1208419743"