The Fokker Dr.I, which is short for Dreidecker I, was a World War I fighter aircraft which achieved a deal of fame under the moniker Fokker Triplane. It was the preferred steed of Manfred von Richthofen, and indeed was put into production at least partly on his strong evaluation of one of the prototype F.I aircraft, serial 102/17.
In 1917, Sopwith produced one of the first combat triplanes in response to the German Albatros fighter's superior performance. These triplanes, with increased maneuverability due to their lower wing loading, began to outperform German combat aircraft. In response, Fokker-Flugzeugwerke hastily converted a fighter prototype that was in the pipeline from biplane to triplane configuration for testing. Although that particular aircraft performed poorly enough that Fokker decided not to submit it for evaluation, the concept seemed sound, and the company produced a new prototype, which it did submit to the German War Office for evaluation. That bureau ordered 20 'pre-production' aircraft for a more general evaluation. At first, two were produced, one of which was 102/17 which Richthofen tested, above.
The Dreidecker (literally, 'three-decker' or 'three-level') was thought highly of by pilots for its maneuverability. In fact, it was generally somewhat unstable, requiring constant attention to maintain it in the air. This fact, however, meant that it was noticeably more nimble in turns, dives or climbs. While the aileron control surfaces provided only middling response, perhaps due to the smaller size of each individual wing and flight surface, the rudder and elevator response was excellent - and the front-loaded airplane responded extremely quickly.
The Dr.I was put into production in September 1917. Although pilots were enthusiastic about the craft's maneuverability, it was not without its troubles. It was somewhat unforgiving on landing - modifications were eventually made to include wingtip strengthening and skids to cope with ground loops. In addition, although it was very maneuverable, it was somewhat slow in level flight compared to contemporary fighters. It used a German clone of the French Le Rhone 9J rotary engine, which had relatively low performance (low compression by design) and the excess of wing surface meant increased drag.
As time went on, deficiencies in the aircraft's design and construction became apparent. They were withdrawn from service for a time after a series of fatal crashes in October 1917. Investigation showed that the wing structures were not sufficiently weatherproofed and were failing in flight - topmost wing failures were somewhat common. After the war, investigation also turned up that the top wing on the Dr. I had over two and a half times the loading of the bottom wing, which contributed to the high rate of failures there.
In any case, these and other problems meant that production came to an end in May 1918 after only 320 or 321 aircraft had been built. The German Air Force shifted back to biplanes, as had the Allies. Despite its fame, the Dr.I reigned for a short 8 or 9 months of World War I before being relegated to rear-area duties, and very few survived the war. One example of Richthofen's survived in a Berlin museum, but was destroyed during World War II bombing raids.
There is a website where an enthusiast is attempting to ascertain the fate of every one of the 320 Dr.I's originally produced. He seems to have identified 83 aircraft so far. Regardless of his eventual total, this is an example of the passion which this airplane has produced in historians, hobbyists, and even pilots. Replica Dr.Is remain flying to this day, some even with historically-correct original engines.
Type: Single seat triplane, fighter
In Production: September 1917-May 1918
Number made: 320
Wingspans: Top - 23' 7"; Middle - 20' 5"; Lower - 18' 9"
Wing Area: 201 sq. ft
Weight: 895 lbs. dry, ~1,290 lbs wet
Power: 110 HP (84 kW)
Engine: Air-cooled rotary, Le Rhone 9J or Oberursel URII clone
Max. Speed: ~115MPH
Ceiling: ~20,000 ft (yes, 20!)
Endurance: Approx. 1.5hr
Armament: Two 7.92mm (.312) Spandau LMG (lightened machine gun), ~475 RPM air-cooled, over the cockpit, 550 rounds each
- Fokker Aircraft of World War One by Paul Leaman (Crowood, UK 2001)
- The World's Greatest Aircraft: An Illustrated history by Len Cacutt (Exeter/Bookthrift, NY 1989)
- http://www.fokkerdr1.com - hooray for enthusiasts!
Iron Noder 2010