What the Red Baron Never Knew
Computer analysis of World War I aircraft shows precisely why some were deadly and others, death traps.
- By Peter Garrison
- Air & Space magazine, January 2008
NASM (SI Neg. #85-11029)
(Page 2 of 3)
Even though Baron Manfred von Richthofen scored a number of victories in this triplane, three wings was a bad idea (see “Fokker’s Inefficient Triplane,” p. 29). No doubt it seemed to many that more wing area would mean more lift, and therefore a better rate of climb, but the rate is determined by weight, power, and wingspan.
An aerodynamicist at the Massachusetts Institute of Technology, Jerome Hunsaker, saw the fallacy of the triplane arrangement and in 1916 published a critique of it. According to Leon Bennett, whose book Three Wings for the Red Baron explores the triplane phenomenon at length, a German translation of Hunsaker’s work “did much to dampen triplane hopes.” Nevertheless, hundreds of Fokker Triplanes were built, and a reputation of high performance—especially rapid climb—grew up around them. Von Richthofen, their staunchest advocate, claimed that his triplane could “climb like a monkey and maneuver like a devil.”
Modern tests and theory agree about the devil, but not about the monkey. If the Dr.I could, in fact, outclimb the Sopwith Camel biplane that it often fought, it was not because it had an extra wing but, Bennett suggests, because its propellers were pitched to deliver maximum power at climbing rather than cruising speed. Fokker Triplanes did in fact lack in top speed what they possessed in climb.
The Fokker Triplane actually did exhibit one extremely important design innovation, but it wasn’t the three-wing arrangement. It was the thick cantilever wings. Unlike most airplanes of its era, the Dr.I needed no struts or bracing wires to hold it together, as Fokker was fond of demonstrating by having a couple dozen of his shop workers pose on
The idea of the thick cantilever wing seems to have originated not with Fokker, however, but with German Hugo Junkers, who came into his own as a manufacturer only after the war. Junkers’ all-metal monoplanes, a decade ahead of their time, had no external bracing at all.
It isn’t clear how Junkers came to the realization, around 1915, that a thick wing would not produce any more drag than a thin one. It was a counterintuitive notion; throughout the war, the British persisted in believing that thick-wing airplanes must be naturally inefficient.
Thick airfoils had a great advantage besides the structural one. Compared with thin wings, thick wings could produce more lift, by about 25 percent, because the gentle roundness of the leading edges helped air follow the curvature of the airfoil and not break away. The added lift did not affect climb rate, but it improved maneuverability, because the space within which an airplane can turn is determined by its maximum lift.
Triplanes could also fly in a very nose-high attitude, because the thick wing kept producing lift at angles at which the sharp-edged wings of Allied fighters had already given up. A U.S. pilot, James Hall, wrote of the Fokkers’ “trick of standing on their tails beneath one” with guns firing upward.