ALUMINUM SHORTAGES AND WORLD WAR II: AIR FORCES EMBRACE WOOD

Despite the arguments advanced by proponents of wood, the mere threat of war did little to stimulate renewed development of wooden airplanes by potential belligerents. Germany, the main source of renewed military tensions, showed little interest in wooden airplanes. The expansion of the German air force, begun soon after the Nazi seizure of power, was also accompanied by a huge expansion of Germany’s aluminum capacity; by 1939 Germany had surpassed the United States and become the largest aluminum producer in the world. This expansion was dictated more by National Socialist Autarkiepolitik than by projected needs of the Luftwaffe, but this vast capacity no doubt dampened German interest in developing wooden airplanes.23

The raw material situation was quite different in Britain, where serious rearmament began in 1936. The expansion of the RAF occurred simultaneously with the shift to aluminum stressed-skin construction, yet British aluminum production in 1939 amount to only 15 percent of Germany’s. British strategy was to rely on Canadian and American production to supply its needs. Already in April 1939, the British Air Ministry estimated that imports would have to supply two – thirds of British requirements; these estimates proved low.24 Although the Air Ministry appeared confident of its ability to obtain the necessary aluminum supplies, this dependence apparently made the British more willing to continue the use of wood in non-combat airplanes, primarily trainers. In the late 1930s, the RAF stepped up purchases of wooden training aircraft, and by 1943 all British-made training aircraft in production used all-wood or wooden-winged construction.25

Yet Britain’s use of wood was not confined to non-combat aircraft, due largely to the efforts of a single major British aviation firm, the De Havilland Aircraft Company. This firm designed the most famous wooden airplane of the war, the de Havilland Mosquito, a twin-engine bomber, fighter-bomber, night fighter and reconnaissance airplane. The Mosquito was conceived by the de Havilland firm shortly after the Munich crisis in 1938. Geoffrey de Havilland, the company’s founder, proposed building a fast unarmed bomber, protected only by its speed and maneuverability. The de Havilland design dispensed with the anti-aircraft guns standard for bombers at the time. Without defensive armament, claimed de Havilland, his design would fly faster than the opposing fighters. He also noted the advantages of wood for production in wartime, when it would not compete for resources with the metal-using industries. The de Havilland proposal was presented to the Air Ministry in October 1938, but the unconventional design generated little interest. After the declaration of war the following September, the de Havilland firm pressed its case for the design before the Air Ministry, and in December de Havilland received an order for the Mosquito prototype. The Mosquito first flew in November 1940, a mere 11 months after serious design work began. Performance exceeded expectations, and the Air Ministry placed large production orders for the airplane.26

Production deliveries began in July 1941. The airplane soon proved itself in combat, becoming “one of the most outstandingly successful products of the British aircraft industry during the Second World War.” The Mosquito excelled in speed, range, ceiling and maneuverability, making it useful in a variety of roles. Even before the prototype flew, De Havilland began developing reconnaissance and night-fighter variants.27 With a range of over 2000 miles, the original reconnaissance version could photograph most of Europe from bases in Britain at a height and speed that made it practically immune to enemy attack. Later modifications extended the range of the reconnaissance version to over 3500 miles.28 Studies of the Allied air offensive against Germany showed the Mosquito to be far more efficient at placing bombs on target than the large all-metal bombers that formed the backbone of the bombing campaigns. Compared to the heavy bombers, the Mosquito was cheaper to build, required a much smaller crew, and suffered a much lower loss rate, only two percent for the Mosquito compared to five percent for the heavy bombers. One British study calculated that the Mosquito required less than a quarter of the investment to deliver the same weight of bombs as the Lancaster, the main British four-engine bomber.29

The Canadians also got involved in wooden aircraft production. The Canadian case is particularly instructive because of its similarity with the United States in technology and availability of materials. During the interwar period, Canada had built up a small aircraft industry, though its design capabilities remained limited. For armaments, Canada remained largely dependent on Britain, and the Canadian armed forces followed other Commonwealth countries in standardizing on British materiel. As the British rearmed in the late 1930s, they looked to Canada as a possible source of aircraft and munitions, in addition to Canada’s traditional role as a supplier of raw materials. The Canadians, however, were loathe to finance expansion of their production capacity without guaranteed orders from Britain. In November 1938, the British finally placed a significant order with the Canadian aircraft industry for 80 Hampden bombers and 40 Hurricane fighters, accepting a 25 percent higher cost as the price for creating additional aircraft capacity.30

Canada remained a reluctant ally even after joining Britain in declaring war on Germany. Nevertheless, Canada did agree to host the British Commonwealth Air Training Plan, an ambitious program that eventually provided nearly 138,000 pilots and other air personnel for the British war effort. This program would require an estimated 5,000 training airplanes. The Canadian subsidiary of De Havilland was already producing the Tiger Moth, an elementary biplane trainer of wood construction that would be used for the training program. But Britain discouraged Canadian production of the more sophisticated training airplanes, insisting instead on supplying these types from their own production or American purchases.31

This situation changed radically with the fall of France. In the bleak summer of 1940 a British defeat seemed a very real possibility. Britain cut off shipments of aircraft and parts to Canada, and no replacements seemed likely from the U. S. for quite some time. It appeared that Canada might be forced to depend on its own resources for defense.32

One key Canadian resource was timber. In a report dated May 1940, J. H. Parkin proposed a program for developing wooden military airplanes in Canada. Parkin, director of the Aeronautical Laboratories at the National Research Council (NRC), presented strong technical arguments in favor of wood structures. Parkin also stressed Canada’s large timber resources, which included large reserves of virgin Sitka spruce. Parkin proposed that “the design and construction of military aircraft fabricated of wood should be initiated in Canada immediately.”33

These proposals helped launch a major Canadian program for producing wooden airplanes. Air Vice-Marshall E. W. Stedman, the chief technical officer in the RCAF, strongly advocated the construction of wooden airplanes. In London, the Ministry of Aircraft Production sought to discourage “inexperienced Canadian designers” from developing their own airplanes. Nevertheless, the RCAF continued to urge production of a wooden combat airplane in Canada; these efforts eventually led to Canadian production of the Mosquito.34 De Havilland Canada built a plant with a mechanized assembly line for Mosquito production; this plant reached a production rate of 85 airplanes monthly by mid-1945.35

Despite British skepticism, the Canadian government strongly supported the development of innovative wooden airplanes of Canadian design. In coordination with the RCAF, the NRC launched a substantial research program to develop molded plywood construction. In July 1940 RCAF and NRC staff traveled to the U. S. to investigate the latest techniques in wooden aircraft construction. They were especially impressed with Eugene Vidal’s process. Vidal was former Director of Civil Aeronautics at the Commerce Department and an enthusiast of the “personal” airplane. Vidal had started research on molded plywood after his unsuccessful attempt to develop a $700 all-metal airplane while at the Commerce Department.36

By the fall of 1940, Vidal had become the leading American developer of plywood molding techniques, due to Clark’s failure to secure military support for Duramold.37 The Canadian government asked Vidal’s company to build an experimental fuselage for the Anson twin-engine training plane, a British design then being built in Canada. The fuselage was a success, and in 1943 a Canadian company began manufacturing the fuselages under license to Vidal. From 1943 to 1945 over 1000 of the Vidal Ansons were built in Canada. A rugged, reliable airplane, the Vidal Ansons found wide use as civil aircraft after the war. The Vidal Ansons provided one of the largest and most successful applications of molded plywood to airplane structures during the war.38

The United States also launched a major wooden airplane program during World War II, but not until severe aluminum shortages threatened to curtail aircraft production. But unlike the British and Canadians, American support for wooden airplanes remained highly ambivalent.

American rearmament did not begin in earnest until after the German invasion of the low countries in May 1940, when President Franklin Roosevelt startled Congress with his 50,000-airplane program, which called for roughly a ten-fold increase over current production. Before FDR’s dramatic announcement, military planners had repeatedly insisted that aluminum supplies were ample to meet any emergency. Although Air Corps planners had given some attention to increasing the capacity of airplane plants, they had “virtually ignored” possible shortages of aircraft materials and accessories. Conditioned by interwar parsimony, the planners had little inkling of the numbers of airplanes that the President and armed forces would demand, especially when the U. S. became involved in a shooting war.39

American aircraft manufactures began publicly reporting serious aluminum shortages in late 1940 as production accelerated to meet British as well as American needs. In early 1941, the U. S. Office of Production Management finally acknowledged that the country was facing a serious aluminum shortage, and began restricting civilian consumption of aluminum. The federal government responded by financing a massive increase in aluminum refining capacity.40 But in the meantime the military would have to find other materials if it hoped to meet the President’s production goals.

With the onset of the aluminum shortage in early 1941, the Army rushed to expand the use of wood in non-combat airplanes. Early in the year, Wright Field began asking some of the Army’s largest suppliers to establish programs for converting aluminum airplane parts to plywood or plastics, and by the mid-1941 these programs were well under way. North American Aviation had an especially active substitution program for the AT-6, the most widely used advanced trainer in the war. Three major manufacturers were developing all-wood bombing trainers for the Army; two of them, Beech and Fairchild, received production contracts before the end of the year. The Air Corps also accelerated orders for its wood primary trainers already in production; by August 1941 Fairchild was building four PT-19 trainers a day. Cessna began building a twin-engine trainer for the Army based on its commercial light transport. Wooden airplanes appeared poised to play a major role in American mobilization.41

Plans for wooden airplanes grew even more ambitious after Pearl Harbor. By March 1942, Wright Field had plans to order some 16,000 wooden airplanes,

28.0 wooden propellers and 3,000 wooden gliders. Wright Field staff estimated that the substitution program would save some 45 million pounds of aluminum in the production of existing airplanes, largely by using plywood for non-structural parts. The Army Air Forces also ordered 400 Fairchild AT-13s, a new all-wood crew trainer, a fivefold increase over the original order. In an even more ambitious project, the Army launched plans for quantity production of a large wooden transport to be developed by Curtiss-Wright, the C-76. By December 1942 Curtiss-Wright had received orders for 2600 C-76 airplanes at a total estimated cost of over $400 million, including the construction of two huge new factories.42

At first glance, the American wooden airplane program appears almost as successful as those of Britain and Canada. The Army and Navy purchased some

27.0 airplanes that used wood for a significant part of the structure, along with nearly 16,000 gliders built largely of wood. These figures imply that wood airplanes made a significant contribution to the U. S. war effort, amounting to some 9 percent of the 300,000 airplanes produced for the military from July 1, 1940 to Aug. 30, 1945 43 But a closer look reveals this contribution to be less than it seems. With one exception, none of these wooden types were for combat, and the one combat airplane never entered production. The vast majority were relatively light-weight, low-performance training airplanes, mostly based on designs from the 1930s that did not take advantage of synthetic adhesives or molding techniques. In terms of airframe weight, a more reliable index of manufacturing effort, wooden airplanes accounted for only about 2.5 percent of the total44 Furthermore, most of the models produced in quantity used wood for just a small part of the total structure, such as the wing spars.

When it came to developing new designs, the American wooden airplane program was almost a complete failure. Problems occurred in design, production and maintenance. One of the most disastrous design failures was the Curtiss-Wright C – 76, a large twin-engine transport designed to carry a 4500-pound payload. Curtiss-Wright was one of the Army’s leading suppliers, but it had no recent experience designing wooden airplanes. The project began in March 1942 with an order for 200 airplanes; the Army ordered an additional 2400 before the first prototype was completed. When the C-76 prototype was finished a mere 11 months later, it proved overweight, under strength, and difficult to control in flight. In June 1943, repeated failures in static tests led Wright Field to reduce the permissible gross weight to 26,500 pounds pending successful strengthening of the structure, leaving the airplane with a pitiful payload of 549 pounds. The project became the subject of a Congressional investigation, and in July Gen. H. H. Arnold canceled the project at a loss to the Army of $40 million 45

By the summer of 1943, aluminum had become plentiful in the United States, and Wright Field began canceling production of wood designs in favor of proven metal models. In September, J. B. Johnson reported to a NACA committee that the Army was “discouraging the use of wood construction” due to “disappointing results” with wood airplanes.46 The Army also cut off funding for wood research being conducted at the Forest Products Laboratory in Madison, Wisconsin.47 The momentum of some projects carried them forward for almost another year, but in time they too were canceled. Howard Hughes was able to continue working on his giant flying boat despite military opposition, since his funding came from the Defense Plant Corporation rather than the military. But Hughes was engaged in an act of technological hubris that was bound to fail, despite the tremendous technical skill that he brought to the project.48