Boeing Aircraft Company’s Wichita division created the X-100, X-120 and X-90 monoplanes that were state-of-the-art in their day, but whose wings were clipped by the frenetic pace of wartime combat aircraft design.
The invasion of Poland by Germany in September 1939 gave the world its first glimpse of the bludgeoning power of the Nazi Blitzkreig – “lightning war.” After only 48 hours of fighting the Luftwaffe had largely succeeded in shooting the Polish air force out of the sky, while the Wehrmacht swiftly vanquished the Polish army. Hitler’s aggression, however, was quickly met by declarations of war from England and France. World War II had officially begun.
In Wichita, Kansas, few people were concerned about the growing conflict across the vast Atlantic Ocean. America, and its leader, President Franklin D. Roosevelt, held firmly to a policy of isolationism and wanted nothing to do with Europe’s war. The only threat facing Julius Schaefer as he led Boeing Aircraft Company’s Stearman Division into the final months of 1939, was how to create more floor space to build airplanes for the United States Army Air Corps, the United States Navy and customers in Latin and South America. Only three weeks before Hitler struck Poland, the United States War Department had issued contracts worth more than $680,000 for training aircraft, along with an option for more that could drive the price upward toward $2 million.
As 1938 drew to a close, however, a special group of 58 engineers, including five from the Boeing Aircraft Company in Seattle, Washington, were hard at work completing the design and construction of a new airplane that workers dubbed “mystery ship.” Schaefer had known about the project since early 1938 when the Army Air Corps released bids for a twin-engine monoplane that could carry up to 1,200 pounds of bombs at a speed of at least 200 mph across a distance of 1,200 statute miles – the Army was on the hunt for an attack bomber.
Five airframe manufacturers responded to the Army’s request: Boeing Aircraft Company, North American Aviation in California, the Martin company in Maryland; Bell Aircraft Company in New York, and the Douglas Aircraft Company in California. After reviewing the Army’s specifications for the bomber, Bell Aircraft withdrew from the competition. The other four companies proceeded with design work. The Stearman division’s candidate was designated “X-100.” The Air Corps stipulated that a prototype airplane had to be delivered by March 17, 1939, and competitors had to build the aircraft at their own expense – Uncle Sam would not pick up the tab. In addition, companies were to design, build and present the airplane to the Air Corps for evaluation.
Boeing documents state that preliminary designs were studied by engineers in Seattle and in Wichita.
The X-100’s overall configuration was to be established by Boeing but the bomber would be built by the Stearman Division. As time progressed the X-100 became the XA-21. It was like no other airplane the Stearman Division had built up to that time, chiefly because of its all-metal, semi-monocoque fuselage. The aircraft was powered by two Pratt & Whitney 14-cylinder radial engines, featured electrically-operated retractable landing gear and Fowler-type wing flaps. Aircrew consisted of the pilot, bombardier and radio operator (who doubled as an aerial gunner). The pilot and bombardier sat in tandem beneath a large, enclosed canopy, while the gunner was stationed aft and had access to four 0.30-caliber machine guns.
The 14-cylnder, R-2180 radial engines each produced 1,150 horsepower at 2,350 RPM with 1,400 horsepower at 2,500 RPM available for takeoff, if needed. Maximum takeoff weight was 18,230 pounds. The wing spanned 65 feet and featured a total wing area of 607 square feet. The fuselage was 55 feet in length and the tip of the vertical stabilizer stood 14 feet, two inches off the ground.
The XA-21 was revealed to the public early in 1939, but because of the airplane’s military mission, only a few photographs were released by the Air Corps. Going one step further, the Army asked that the citizens of Wichita, “as a matter of patriotism, not take any pictures of the plane as it had many secret features, and newspapers are not to publish any except official pictures released by the War Department.” The prototype bomber was rolled out of the factory on January 25, 1939. After a series of thorough pre-flight inspections and systems checks, the XA-21 took to the skies above Wichita on its first flight, flown by Boeing test pilot Edmund T. “Eddie” Allen in the left seat, and Stearman Division pilot David “Deed” Levy in the bombardier’s position.
Allen and Levy continued to fly the new bomber until March 15, when it was delivered to the Air Corps at Wright Field near Dayton, Ohio. Army pilots conducted a series of flight trials that pitted Boeing’s airplane against the Martin XA-22 (Model 167 Maryland) and the North American Aviation NA-40. A fourth candidate, the Douglas Model 7B, had crashed a few weeks earlier and was out of the competition, and on April 11 the NA-40 crashed during a demonstration flight at Wright Field. As a result, neither the XA-21 nor the XA-22 were declared the winner.
In addition, the results were deemed indecisive because the Air Corps had made significant changes to its requirements for the attack bomber during the months when the four competing airplanes were being built. In January 1939, while the XA-21 was undergoing flight tests, the Army released its new proposal and awarded a contract to the Douglas Aircraft Company’s DB-7 (Army Air Corps A-20 Havoc) based solely on drawings and technical data.
Following the end of flights tests at Wright Field, the XA-21 returned to Wichita late in April 1939. During that summer, the bomber underwent modifications to convert the large, glass nose section into a more conventional configuration featuring a stepped windshield design. The Air Corps eventually purchased the airplane and it was delivered on the same day that Germany invaded Poland – Sept. 1, 1939. The Boeing bomber, along with Martin’s XA-22, were flown as experimental test platforms for more than two years before the United States entered World War II in December 1941.1
Although the XA-21 failed to win any contracts from the Army Air Corps, loss of the competition was not a major disappointment to the Boeing Aircraft Company that conceived it nor the Stearman Division that built it. Both entities were swamped with orders for primary trainers and the B-17 heavy bomber and more orders were imminent. On September 16, 1940, the Stearman Division was handed a contract worth more than
$6 million for hundreds more primary trainers, plus spare parts, for the Air Corps.
The Stearman factory, however, was not the only Wichita company to benefit from the latest tidal wave of orders for new airplanes. Dwane Wallace and the Cessna Aircraft Company received a contract from the Royal Canadian Air Force to build the Crane I – a military version of the popular commercial Model T-50 that first flew in March 1939. The Canadian order came on the heels of a contract worth more than $1 million from the U.S. War Department for 33 advanced, multi-engine training versions of the T-50 designated AT-8. One other major Wichita manufacturer, Beech Aircraft Corporation, held multiple contracts worth more than $9 million for military versions of the Model 17 cabin biplane and the Model 18 twin-engine transport. Taken all together, in September 1940 Boeing’s Stearman Division, Cessna Aircraft and Beech Aircraft were scrambling to build $40 million-worth of training, transport and liaison airplanes.
In addition to the X-100/XA-21 project, by 1939 officials at the Boeing Aircraft Company sought to preserve its reputation and leadership as a major supplier of primary training airplanes. In 1936 preliminary studies were authorized and these continued into 1937 when the decision was made to design a low-wing, tandem-seat monoplane as a potential replacement for the venerable Model 75 series biplanes. As a result, Project 18A was initiated to create an airplane that would utilize a maximum number of parts and assemblies from the PT-13 and PT-17. Boeing assigned 26 engineers to the program, and based on encouragement from the Army Air Corps, by September 1939 a prototype designated the Model X90 was to be built on speculation.2
To minimize the use of strategic materials needed for the war effort, the X90 featured a wood wing and empennage and the forward fuselage section used welded steel tubing. The aft fuselage was of all-metal, semi-monocoque construction. The conventional main landing gear was fixed and the cockpit was covered by a sliding canopy. A Lycoming R-680 radial engine rated at 225 horsepower was chosen for the prototype, although the airframe was stressed to accept engines of up to 450 horsepower.
The prototype was ready for its first flight Nov. 1, 1940, and initial flight tests were conducted that month at the Wichita municipal airport. One month later, on December 1, 1940, the Air Corps requested demonstration flights at Wright Field and “Deed” Levy delivered the ship as planned. At Wright Field the X90 underwent a series of evaluations, including replacement of the Lycoming powerplant with a 450-horsepower Pratt & Whitney R-985-AN-1 radial engine. When the Air Corps completed its work, the airplane was flown to Naval Air Station Anacostia near Washington, D.C., where it was demonstrated to the Navy. Both the Army and Navy liked the X90 and recognized its potential as a replacement for the PT-13 and PT-17.
The monoplane trainer returned to Wichita in February 1941 and the original flight test program outlined by Boeing resumed. Unfortunately, the X90 was introduced at a time when war clouds were gathering over Europe and the Stearman Division’s rough-and-ready PT-13 and PT-17 biplanes were already in mass production and providing excellent service in the field. Taking these factors into account, the War Department lost interest in the new trainer.
In May 1941, however, Boeing and the Army Air Corps opened negotiations that resulted in a contract for a basic training version designated the XBT-17. Modifications specified by the Air Corps were made to the prototype X90 and Boeing delivered the XBT-17 to the Army in January 1942. By that time, the United States was at war with the Axis Powers and once again, the War Department’s deepening concerns about a shortage of aluminum alloy and other materials, led to the Army’s decision not to place orders for the XBT-17.3
Despite failure of the XA-21 and XBT-17 programs, in 1942 the Boeing Aircraft Company responded to an Air Corps competition to select an airplane to serve as a twin-engine advanced trainer. Before America entered the war, it had become increasingly apparent to Army brass that it would be necessary to train teams of men needed to fly bombers in combat. The aircraft’s specific mission would be to teach aircrew how to work together as a team before they were assigned to an operational training unit. The Wichita Division prepared a proposal that was based on a series of studies conducted during 1939-1940, known as Project 26.
Late in 1940 the company received a request for bid and submitted its design in October, but the Army’s requirements for an aircrew trainer had changed so radically that no further action was taken until April 1941, when Boeing received another request for proposals. The Army stipulated that the airplane had to be built using as many non-strategic materials as possible. Finally, after the Air Corps made more changes to its requirements, Boeing signed a contract to build two airplanes designated Model X-120 (Army XAT-15).
Full responsibility for the design and construction of these trainers was given to 90 engineers at the Wichita Division. They developed a sub-scale model and conducted tests in a wind tunnel at Wichita University. A full-scale mockup of the twin-engine ship was completed and inspected by Army Air Corps officials in July 1941. Working 10-hour days, the engineering department generated a steady flow of drawings and blueprints to the factory, and the first prototype was completed and made its first flight in April 1942. The X-120 was conventional in many respects, with a welded steel tube fuselage structure covered with plywood and cotton fabric doped and shrunk to a tight fit. The wing panels and empennage assembly were built of wood and covered with plywood and fabric.
The first airplane was delivered to the Army in October 1942. The Air Crops liked the XAT-15 and awarded Boeing an initial contract for 75 XAT-15s that was soon increased to 325 by February 1942. To further expedite construction, contracts for 360 airplanes were given to the McConnell Aircraft Company in St. Louis, Missouri, and the Bellanca Aircraft Company in New Castle, Delaware. The Wichita Division remained responsible for all engineering data required to build the airplanes.
The XAT-15 was powered by two Pratt & Whitney R-1340-AN-1 radial engines, each rated at 550 horsepower. Wingspan was 59 feet 8 inches, length 42 feet 4 inches and height 13 feet 1 inch. Maximum weight was 14,355 pounds, maximum speed was 207 mph, cruising speed was 185 mph. The Bombay accommodated 10 100-lb. practice bombs.
As the war progressed it became clear to officers at the front lines of the United States Army Air Forces that the war was driving massive changes that needed to be incorporated into the design of new combat aircraft. In addition, there was a movement within the Air Corps toward establishing specialized schools for training aerial gunners, bombardiers, navigators and pilots instead of coordinating their training inflight. That change essentially obviated the XAT-15’s mission and the production contracts were quickly cancelled. Only the two prototypes were built. The Air Corps, however, did award contracts to Fairchild Aircraft Corporation for the all-wood AT-21 specifically to train gunners in the operation of powered turrets.
- Martin’s XA-22 eventually was placed into production as part of America’s effort to supply England and France with combat aircraft. France had ordered 115 and when war broke out in Europe, the order was increased to 215. When Germany overran France in May-June 1940, the surviving bombers were flown to England and absorbed into the Royal Air Force as the Maryland Mk. I and Mk. II. Although it was obsolete by 1940 standards, the “Maryland” performed well early in the war against the Nazi onslaught.
- Hoffman, Raymond J.B.: “History of Boeing Airplanes in Wichita,” Pages 10-11. Boeing Aircraft Company, March 10, 1946.