Giant B-19 proved a point

The late 1930s up to America’s entry in World War II saw a curious merge of handbuilt aircraft and mass-production techniques. The giant XB-19 experimental bomber was the crowning achievement of that prewar experimentation by Douglas Aircraft.

American aircraft manufacturers quickly embraced aluminum semi-monocoque construction methods in the 1930s that made larger airframes practical in an era when engine limitations impacted aircraft size.

As the Army Air Corps developed its identity and rationale, advocates of long-range bombardment were in ascendancy. They believed a strong bomber role was the best way for the Air Corps to prove its value, ultimately leading toward the establishment of a separate U.S. Air Force.

To answer an Air Corps proposal for a large, long-range bomber, Douglas submitted a proposal that became the Air Corps’ XBLR-2 in 1935, standing for Experimental Bomber, Long Range, Two. In that same year, Douglas was working on the DC-4E experimental prototype airliner that boasted cutting-edge tricycle landing gear, auxiliary powerplants, an onboard AC electrical system, and power boosted flight controls — all of which Douglas designers incorporated into their bigger notional bomber that became the B-19.

At the time of its rollout, the B-19 was called the largest aircraft in the world. The XB-19’s wingspan of 212 feet was more than twice that of a B-17. The XB-19’s towering fin and rudder stood 42 feet above the ground. It used a wing planform of typical style for Douglas in the 1930s, with a straight trailing edge and sharply tapering leading edge. Power initially was provided by four Wright R-3350 radial engines. 

With a range listed as greater than 5,000 miles and a ferry range of more than 7,000 miles, the XB-19 could use auxiliary bomb bay gas tanks to bring its fuel capacity to 11,000 gallons, which a Douglas publicist likened to the volume carried by a standard railroad tank car of the day.

The path from drawing board to runway was arduous, and the XB-19 did not fly until June 27, 1941. By that time, its design was not viable for a combat aircraft, based on the current state-of-the-art in the European war already raging.

But the big B-19 had a significant role to play in research and development. Douglas had instrumented its earlier DC-4E with many strain gauges to record inflight stresses and loads on parts of the airframe, and this science was also applied to the XB-19. The successful flight of the B-19 provided assurances that other large aircraft — some not as big, others like the B-36 even bigger — could be built.

Douglas’ detailed strain-gauge measurements on the B-19 provided the American aviation industry with useful statistics when it came time to envision and build newer large aircraft. It has been said the B-19 engineering data from its flight test program was still useful decades later. 

Some lessons come hard. When the XB-19 first rolled out from the Douglas Santa Monica plant, its single huge mainwheels settled into the asphalt of the ramp. Five years later, the prototype B-36 made its debut with single mainwheels, soon replaced with multi-wheel bogies to spread the load. Yet during World War II, some American aircraft like the B-29, production C-54s (vastly different from the experimental prototype DC-4E), and the B-32 all incorporated multiple-wheel maingear struts. 

The XB-19 was an early adopter of R-3350 engines, and data garnered aboard the XB-19 helped when these powerplants were selected for the B-29 Superfortress.  

The B-19 weighed 43 tons empty, and 70 tons at normal gross weight. It had a maximum allowable weight of 81 tons. Douglas counted 3 million rivets holding the XB-19 together. At its longest range of more than 7,000 miles, the XB-19 would be aloft for 55 hours. Relief crewmembers were provided ample room, including bunks in the spacious fuselage. 

Anticipating the potential for engine malfunctions while flying for days at a time, Douglas provided the XB-19 with in-flight access to the engine nacelles, to allow some maintenance and repairs to be made while aloft.

The R-3350 engines gave the XB-19 a top speed of 224 mph and a cruising speed of 135 mph. Huge flaps contributed to a landing speed of 73 mph. Some accounts say it was as low as 69 mph.

In keeping with its test bed status, the B-19 swapped its radial engines for a set of liquid-cooled Allison V-3420 engines, essentially two Allison V-12s mounted together and producing 2,600 horsepower each. This effectively added 2,400 horses to the bomber’s total output, and raised the top speed to 265 mph at 20,000 feet, and cruising speed was upped to 185 mph. With the Allisons mounted, the bomber was known as the XB-19A. First flight of this configuration came in January 1944.

When the B-19 was designed and under construction, American powered gun turrets were still gestating, and the Douglas giant used some quickly outmoded turrets that would not have fared well in combat. The nose turret mounted a huge 37mm cannon as its primary armament. Combat wisdom with other armaments during the war would validate the efficacy of .50-caliber machine guns instead. A forward dorsal turret carried another 37-millimeter gun. An aft dorsal turret and a tail turret were augmented by other hatches for gunnery in the fashion deemed adequate in the pre-war era. In later stateside test use, the guns were not carried.

By 1945, the B-19 had gone from silver prewar prototype to wartime olive drab bomber, and back to silver with the bold red and yellow accent markings of the Air Force’s All Weather Flying Center, the last assignment for this prototype.

Then it was off to Davis-Monthan Army Air Base in Tucson for storage in 1946, where the XB-19A was initially earmarked for museum preservation. But air museums were not the huge enterprises of today, and the one-off Douglas leviathan was signed over for salvage in 1949.

With steel cables thrown around the fuselage and two wrecker vehicles tugging in opposite directions, the aft fuselage was sliced through, allowing the huge tail section to fall to the desert floor. Outer wing panels were sliced off, and the characteristic forward fuselage, still sporting its unwieldy turret, was photographed in a pile of salvaged wreckage. 

One of the XB-19’s giant eight-foot main tires survives in the National Museum of the United States Air Force at Dayton, Ohio.