Germany’s early ‘Flea’

Military aviation underwent extraordinarily rapid development in World War I, and a technological advantage could almost guarantee a period of air superiority.

Though these periods were often measured in only months or even weeks, they put extraordinary demands on military aircraft designers to come up with the next “new thing.” These demands, coupled with the early state of aviation, led to a huge number of exotic prototype aircraft that never saw production or service.

Of all the unusual fighter prototypes developed in World War I, probably the most extraordinary in appearance was Germany’s DFW T28 Floh (Flea), designed in late 1915 by the chief engineer of the Deutsche Flugzeugwerke GmbH of Leipzig-Lindenthal, Dipl.Ing. Hermann Dorner.

The Floh was Dorner’s attempt to give Germany a high speed, highly streamlined fighter with a performance that would sweep the Allies from the skies. The aircraft that resulted was very small — its fabric wings had a span of about 20 feet and the fuselage was less than 15 feet — and powered by a relatively large 100 horsepower Mercedes D-I water-cooled, in-line engine.

It was Dorner’s special emphasis on streamlining that led to the aircraft’s most bizarre and distinctive feature: an extraordinarily deep, wood veneer skinned fuselage. The fuselage had to be deep to completely house the Mercedes engine, its radiator and the Floh’s armament — a single 7.62 LMG 08/15 Spandau machine gun installed over the engine inside the fuselage and synchronized to fire through the propeller.

In the interest of maximum streamlining, the Floh’s top wing was flush with the distinctive teardrop fuselage shape. This did away with the need for drag-inducing centre-section struts.

Initially, the aircraft was intended to have no struts or bracing wires, but in this respect, the Floh was only partially successful. When the T28 finally reached the prototype stage, it still needed some wing struts, though it did not have the bird’s nest of rigging commonly seen on aircraft of this era.

The pilot sat high over the ground behind the wing and the undercarriage was part of the fuselage, giving it a very narrow track. Overall, it had the appearance of a short, fat insect with very short wings, thus generating the name “Floh.”

The very first flight exposed the Floh’s major problem: difficult landing characteristics. Having the wing flush with the top of the fuselage eliminated the view needed by the pilot to land the aircraft, and on its first flight the prototype had a hard landing, which resulted in damage to the wing fuel cell.

The problem was not only caused by the poor visibility but also from the shape of the fuselage, which resulted in a high center of gravity, and the narrow width of the landing gear. This caused instability on landing and compounded the pilot’s poor visibility difficulty.

Notwithstanding its appearance, the Floh’s first flights were very promising. During test flights it showed a top speed of 110 miles per hour, which was extraordinary for the time and 25 miles an hour faster than the German Fokker monoplane, which controlled the airspace over the Western Front at that time. The Floh was also considered maneuverable and easy to fly.

Dorner made several modifications to the design, notably the introduction of aerodynamically balanced elevators, and built a second prototype, but the difficulties with landing remained. In the end, the German authorities — probably fortunately for the Allies — chose not to sponsor the development of the Floh due to its difficult landing characteristics, in spite of its high speed and other good points.

Dorner attempted several other fighter designs during the war but none were nearly as exotic, and none were successful.

(Dr. Michel’s articles appear twice a month in the KA. For questions or comments, e-mail Dr. Michel at marshall.michel@spangdahlem.af.mil.)