Page 26 - Volume 15 Number 1

IN HISTORY
24 • KING AIR MAGAZINE
JANUARY 2021
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.
Photographs of the XA-21 in flight are rare, as only one was built. The airplane had a wingspan of 65 feet, length of 55 feet and stood 14 feet tall at the tail section. It had a maximum range of 720 statute miles carrying a bomb load of 1,200 pounds at a cruising speed of 200 mph.
(Courtesy Walter House Collection)
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.