Wakes of war: contrails and the rise of air power, 1918-1945 Part II—the air war over Europe, 1939-1945

Air Power History, Fall, 2007 by Ronald R. Baucom

Behind the engine-carrying body (fuselage or nacelle) a turbulent region or wake is formed as the airplane flies. The exhaust moisture and some of the engine heat are discharged into this wake and become diffused throughout the wake as a result of the mixing action of the turbulence. The moisture and heat do not, however, mix with the air outside the wake because there the air is "smooth.'...

It is easy to see that, if the air is so cold that it cannot hold much water as vapor, the water in the exhaust may be sufficient, when added to the moisture already in the atmosphere, to raise the humidity in the turbulent wake to or beyond the saturation value. If this condition exists, some of the water vapor will condense and a visible trail will form.

Richard V. Rhode and H. A. Pearson, Condensation Trails, NACA Wartime Report, September 1942 (1)

Introduction

As we saw in the first part of this paper, contrails were observed as early as October 1918. Yet, they remained a rare phenomelatively little interest across the 1920s and 1930s, despite developments that steadily raised the operational ceiling of military aircraft. By the time of the Spanish Civil War, state-of-the-art fighters could engage in combat in the upper regions of the troposphere where engine exhausts routinely turn into contrails. Francisco Tarazona's September 1938 report of contrails generated by dogfighting aircraft was a harbinger of things to come.

Within a year of Tarazona's report, Germany plunged Europe into a general war when she invaded Poland. In the months between the fall of Poland and the German invasion of France in May 1940, German pilots clashed in desultory combat with French and British airmen as both sides flew patrol and reconnaissance missions over Western Europe. (2) From these air operations and those that took place when Germany overran France in the spring of 1940, it was apparent that contrails were intrinsic to modern air combat and had important operational implications. These early months of the air war also spawned what may be the first published account of contrails in air combat.

The Battle for France and Saint-Exupery's Train of Frozen Stars

At the time Germany invaded France, French aviation pioneer and famed author Antoine Saint-Exupery was just short of his fortieth birthday, well past the age when men were considered fit for air combat duties. Given his age, his literary achievements, and health problems caused by earlier aircraft accidents, Saint-Exupery was not expected to volunteer for combat duty and could easily have honorably avoided it. However, he believed France was in grave danger and that all Frenchmen who could were obliged to come to her defense. (3)

True to his convictions, Saint-Exupery managed to secure an assignment flying reconnaissance planes, specifically, the Potez 63. Such an assignment was a serious challenge for a man of his age and physical condition due to the difficulties and discomforts associated with flying in the cold cockpits of high altitude aircraft. (4)

Saint-Exupery survived his combat missions against the Germans and escaped to the United States after France surrendered, settling into New York in January 1941. Here, he wrote about his wartime service and worked to build support for the war against Nazi Germany. After the United States captured North Africa, Saint-Exupery was allowed to sail aboard an American transport to Oran, Algeria. He then secured permission from French authorities to rejoin his old French reconnaissance unit, Group 2 of the 33d Reconnaissance Wing, and began flying combat missions after being retrained to fly the unit's aircraft. Shortly after he rejoined the 2/33, it was transferred to Colonel Elliott Roosevelt's 3d Photo Group, which flew the reconnaissance version of the P-38. By this time, Saint-Exupery was over forty-two years old, and regulations established thirty as the maximum age for pilots in Roosevelt's unit. Only through the intercession of a high-ranking French general with General Dwight Eisenhower's headquarters was this age requirement waived for Saint-Exupery. After being trained in the American P-38, he flew this aircraft on reconnaissance missions out of North Africa beginning in July 1943 and continuing until he was killed during a mission on July 31, 1944. (5)

In February 1942, while still living in New York, Saint-Exupery had published Flight to Arras, a memoir of his service against Nazi Germany in 1939 and 1940. Here, he described the challenges of his high altitude reconnaissance missions: the cold that could freeze the controls of his aircraft, finding and photographing enemy targets under fire, and the anxiety of knowing his plane was tailing a white streamer that pinpointed his position for enemy fighters and gunners. Regarding this last challenge, Saint-Exupery's wrote:

The German on the ground knows us by the pearly white scarf which every plane flying at high altitude trails behind like a bridal veil. The disturbance created by our meteoric flight crystallizes the watery vapor in the atmosphere. We unwind behind us a cirrus of icicles. If the atmospheric conditions are favorable to the formation of clouds, our wake will thicken bit by bit and become an evening cloud over the countryside.