Jetrader

Aviation History: Douglas XB-19

Jetrader is bringing back its Aviation History section with Jordan Calhoun, vice president of marketing and sales at Jackson Square Aviation, at the helm. An aviation enthusiast with more than a decade of industry experience, Calhoun will explore some of the remarkable aircraft that have shaped aviation history, from celebrated icons to lesser-known designs with stories worth revisiting.

For his first installment, Calhoun turns to one of aviation’s most extraordinary experimental aircraft: the Douglas XB-19.

Douglas XB-19

Aviation history is filled with technological leaps that produce remarkable outliers in aircraft design. Many of these are remembered and celebrated; some are forgotten to time. A fascinating example is the experimental four-engine Douglas XB-19, a piston-powered leviathan with 8-foot-tall main landing gear wheels that crushed the first tarmac it ever rolled across. Its wingspan exceeded that of a Boeing 747-400, its maximum range approached that of an A330-300, and although it was designed during the Great Depression and first flew before the U.S. entered World War II, it was already considered technologically obsolete and never entered service. It was the largest plane of its day, and it would not be eclipsed until the Hughes H-4 Hercules (“Spruce Goose”) and the Convair B-36, the latter being the largest operational and conventional warplane ever built.

A Bomber Built for Global Reach

For context, Douglas designed the XB-19 aircraft around the time the U.S. had just started to take its first all-metal, enclosed cockpit, monoplane bombers. At this time, the U.S. Army Air Corps (USAAC), under “Project D,” tasked manufacturers to produce a proof-of-concept large bomber with the utmost endurance possible. As a country that is sandwiched between two of the world’s largest oceans, the U.S. Army envisioned an offensive weapons platform that could deliver ordnance to differing hemispheres and return home for supper. Douglas and Sikorsky submitted the most detailed designs, with the Douglas model advancing to prototype development for experimental evaluation in 1938. Originally designated the “XBLR-2” (Experimental Bomber Long Range 2), there would only be one XB-19 built. (A few years earlier, Boeing was awarded the XBLR-1 contract for their experimental XB-15. A topic for another piece.)

Engineering Challenges Mount

As typical with groundbreaking prototypes, the project far surpassed original timelines and was massively over budget. Delays on engine developments of the liquid-cooled Allison V-3420-11 rated at 2,600 horsepower required Douglas to utilize the less powerful air-cooled Wright Duplex Cyclone R-3350-5 at 2,000 horsepower, which, in turn, resulted in further redesigns to accommodate the new engines. (Once developed, the more powerful Allison engines were eventually installed on the aircraft, slightly changing the aircraft designation to XB-19A.)

The Wright engines were going to leave the aircraft underpowered and create excess drag due to cooling adaptations for the engines that naturally ran hot. Costs ballooned, resources spiraled and design specifications would be missed to such an extent that Donald Douglas submitted a formal cancellation request of the project to the USAAC. Fortunately, for the sake of AvGeeks worldwide, that request was declined, and the aircraft was finished.

The World’s Largest Airplane

The scale of the XB-19 cannot be overemphasized. Douglas produced the biggest airplane in the world at that time. The wingspan of 212 feet would wow any observer in today’s modern world. The length was nearly that of an A321-200 at 132 feet, with an operational range reportedly around 6,000 to 7,000 statute miles. Upon completion of manufacturing, the tires had to be deflated to drop the enormous vertical stabilizer low enough to clear the hangar doors. At an MTOW of 140,000 lbs. with only three landing gear wheels, the 8-foot-diameter main gear pulverized the concrete tarmac the aircraft initially taxied on.

The airplane was colloquially labeled as the “flying battleship,” which does not seem too far-fetched, with a planned operational crew between 13-24 airmen, of which nine were gun and turret operators. The airplane was designed for the ability to be aloft for over 24 hours, thus necessitating a flight deck that looked like a small apartment and a separate crew compartment with six bunks for the proposed relief crew of six. It even had a designated “commander” position for inflight management of the aircraft and crew in addition to the two pilots’ positions. The airplane had a tricycle landing gear configuration, exceptionally rare for USAAC aircraft at that time, to enhance directional stability on the ground. The wing roots were thick enough to house tunnels for the two flight mechanics to transition from the aircraft’s cabin to the engines to perform light maintenance and servicing in flight.

A Difficult Debut

While seemingly efficient today, the design and construction of the XB-19 took six years, ultimately rendering the aircraft obsolete in performance by the time it rolled out of its hangar in Clover Field, Santa Monica (present-day Santa Monica Airport, KSMO) and took to the skies for its maiden flight in June 1941.

The first flight was a somewhat harrowing event for the onboard crew of seven and 45,000 spectators on the ground. Perhaps due to imprecise rigging of the massive elevators or pilot error, there were notable PIOs (pilot-induced oscillations) on departure and arrival. On takeoff, Major Stanley Umstead struggled to coordinate yoke inputs to align the proper attitude for rotation and climb out. The nose noticeably bobbed up and down as the plane first took flight. On landing, pitch oscillations had the aircraft porpoising on short final through touchdown, with the aircraft dramatically bouncing three times until it finally came to a welcome stop down the runway.

Too Late for Its Mission

The behemoth cost Douglas around US$3.5 million (in 1941 dollars) and was relegated to a perennial experimental status, never seeing combat. The obsolescence in the design came down to attributes such as slow cruising speed at 135 mph and a low service ceiling at 23,000 feet, which is 10,000 feet lower than the Boeing B-17G, versus other more efficient and prolific bomber designs.

The XB-19 was relegated to large-scale and long-range experimental testing and with some domestic cargo transport for the U.S. military. Data from experimental operation of the aircraft helped to inform the designs of more successful long-range bombers, such as the Boeing B-29 and Convair B-36.

The XB-19’s Legacy

Ultimately, the XB-19 was grounded in 1946 and unfortunately scrapped in 1949. Today, only two massive main landing gear wheels weighing 2,300 lbs. survive. They are housed at the Hill Aerospace Museum in Oregon and the USAF Museum in Ohio.

Specifications

• Manufactured: 1
• First Flight: 1941
• Crew: 24 (operationally planned)
• Wingspan: 212 feet
• Length: 132 feet, 4 inches
• Height: 42 feet
• Gross Weight: 140,000 lbs.
• Max Speed: 225 mph
• Cruising Range: 5,850 miles
• Maximum Range: 7,700 miles
• Crew: 10
• Powerplant: 4x Wright R-3350-5 Duplex Cyclone (2,000 hp). Later fitted with Allison V-3420-11 (2,600 hp). 17-feet diameter propellers.
• Payload: 18 tons of bombs or 36,000 lbs.

Sources

• Aeronautics Aircraft Spotter’s Handbook, Edited by L.C Guthman, Ensign, USNR. National Aeronautics Council, INC. New York, 1943  
• Plane Encyclopedia

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