Wakes of War: Contrails and the Rise of Air Power, 1918-1945 Part I-Early Sightings and Preliminary Explanations, 1918-1938
Baucom, Donald R., Air Power History
Judging by the wakes of vapor and the lines of tracers left behind in the high, cold air, the Messerschmitts are mixing it up with Number 4 Squadron.
Francisco Tarazona, Yo Fue Piloto de Carza Rojo, September 1938. (1)
Contrail is a contraction of condensation trail, an early term applied to the thin, white clouds that appear behind aircraft when moisture in engine exhausts forms ice crystals in cold air that is already sufficiently saturated. Vapor trail was another early term applied to this phenomenon.
Although ubiquitous today, condensation trails were apparently unknown until World War I. Indeed, what may be the earliest reported observations of contrails were made in the autumn of 1918, as the Great War was drawing to a close. By the end of 1920, other sightings had been reported and several people had advanced preliminary explanations of the new phenomenon. Yet, until the opening days of the Second World War, contrails would remain an isolated phenomenon generally unknown to the public and of limited interest to military aviators.
This situation changed suddenly and dramatically during the first days of World War II. The key to this change was a revolution in aviation that took place across the decades of the twenties and thirties, as leading aviation powers, spurred on by air power enthusiasts, worked to expand the operational envelope of combat aircraft. Because of this revolution, when the Second World War opened, the world's most powerful air forces were flying warplanes with operational ceilings in excess of 25,000 and even 30,000 feet, well into the atmospheric region where conditions are often favorable to contrail formation. As a result, these aircraft routinely trailed what aviation pioneer and writer Antoine Saint-Exupery poetically called "pearly white" scarves as airmen executed their missions in the skies high over Western Europe.
Today, we associate three main types of condensation phenomena with flight. One of these is the spiraling, ribbon-like streamers that can appear in wingtip vortices under the proper atmospheric conditions. Another type is the spectacular cone-shaped Prandtl-Glauert condensation cloud that can form around the waist of high-speed aircraft. Finally, there are the long, thin, clouds spawned by aircraft engine exhausts--the common contrails that crisscross the skies over much of the world today. This last form of condensation phenomenon is the focus of this two-part paper.
Part I covers the period from the end of World War I to the eve of World War II. It begins by describing some early contrail sightings and then discusses the explanations prompted by these observations. This is followed by a review of the major developments that made high altitude flight part of routine combat operations and led to the first recorded observation of contrails in combat, this coming during the Spanish Civil War, Europe's dress rehearsal for World War II.
Part II focuses on the role of contrails in European air operations between 1939 and 1945. It also discusses British and American efforts to understand contrails so that Allied airmen could take advantage of contrails in combat operations or at least prevent enemy airmen from doing the same.
The Argonne Battle Cloud: Early Contrail Sightings
The First World War started in 1914, a little over a decade after Orville Wright coaxed his frail, primitive flying machine aloft for a twelve-second flight that covered a scant forty yards, about the length of a long pass in the National Football League. (2) Given the immaturity of aviation technology, it is not surprising that European powers opened the war with small air forces comprised of planes that were so slow that they could scarcely keep pace with today's freeway traffic. Moreover, these planes were open-cockpit machines that were generally limited to altitudes below 12,000 feet. By the end of the war, however, frontline aircraft could reach speeds of 130 mph and operate as high as 20,000 feet. …