Douglas XB-19

Douglas XB-19

The Douglas XB‑19 was the largest bomber ever built for the United States Army Air Corps at the time of its debut in 1941, conceived as an experimental platform to explore the challenges of designing and operating very‑large, very‑long‑range bombers.

Although it never entered production or combat service, it played a crucial role as a flying laboratory that informed later heavy bomber programmes, including the XB‑35, XB‑36, and ultimately the B‑36 Peacemaker.

Origins and Development

The XB‑19 originated from Project D, initiated by the U.S. Army Air Corps on February 5, 1935, which sought an intercontinental‑range bomber capable of hemispheric defence.

Douglas won the contract under the designation XBLR‑2—”Experimental Bomber, Long Range”.

Construction proved slow and technologically challenging.

Advances in aeronautics during the late 1930s overtook the design before it was finished, yet the Army insisted on completing the aircraft to gather data on large‑aircraft aerodynamics, structures, and systems.

Competition for the next generation of heavy bombers—the XB‑35 and XB‑36—occurred two months before the XB‑19 even flew, underscoring how rapidly bomber technology was evolving.

The sole prototype, serial 38‑471, made its first flight on June 27, 1941, departing Clover Field in Santa Monica and flying to March Field.

At 55 minutes, the flight demonstrated that the enormous aircraft could be safely handled despite its unprecedented scale.

Airframe and Structural Design

The XB‑19 was designed as a giant mid‑wing, four‑engine heavy bomber with a smooth, teardrop‑shaped fuselage and a deep belly accommodating a large bomb bay.

Its dimensions were extraordinary:

Length: 132 ft 4 in

Wingspan: 212 ft

Height: 42 ft

Wing area: 4,285 sq ft

The aircraft incorporated a two‑deck fuselage, extensive internal systems, and even tunnels inside the wings, allowing flight engineers to access and service the engines during flight—an unprecedented feature for a U.S. bomber.

The cockpit featured a stepped flight deck with horizontal windows, and the nose was heavily glazed for bombardier and navigator visibility.

The tail used a single large vertical fin with low‑mounted horizontal stabilisers.

One of its most innovative features was its tricycle landing gear, a departure from the tail‑dragger configuration common in U.S. bombers of the era.

The massive main wheels were designed to support the aircraft’s enormous weight on unprepared surfaces.

Powerplant and Systems

The XB‑19 was originally powered by four Wright R‑3350‑5 Duplex‑Cyclone 18‑cylinder air‑cooled radial engines, each producing 2,000 hp.

These drove three‑bladed, constant‑speed metal propellers approximately 17–18 ft in diameter.

In 1943, the aircraft received new liquid‑cooled Allison V‑3420‑11 W‑24 engines as part of the XB‑39 programme, along with engine‑driven auxiliary powerplants to support electrical and hydraulic loads.

Fuel capacity was enormous: 10,350 gallons internally, with optional auxiliary tanks adding another 824 gallons.

Crew, Armament, and Internal Arrangement

The XB‑19 was designed for a crew of 16, with provisions for two additional flight mechanics and a six‑man relief crew, reflecting its intended long‑range endurance.

Its defensive armament evolved during development but included combinations of:

Two 37 mm Oldsmobile T9 autocannons

Five .50‑cal Browning M2 machine guns

Six .30‑cal Browning M1919 machine guns

The internal bomb bay could carry up to 36,000 lb of bombs—far more than contemporary U.S. bombers like the B‑17.

The aircraft also featured amenities unusual for its time, including a kitchen and crew rest areas, underscoring its intended intercontinental mission profile.

Performance

Despite its size, the XB‑19’s performance was modest by wartime standards:

Maximum speed: ~224 mph at 15,700 ft

Ferry range: ~7,750 miles

Operational range with heavy bomb load: ~5,200 miles

Empty weight: 86,000 lb

Gross weight: 140,000 lb

Max takeoff weight: 162,000 lb

These figures illustrate why the aircraft was quickly overtaken by newer designs: its range was impressive, but its speed and payload efficiency lagged behind emerging wartime requirements.

Operational Use and WWII Context

Although completed during World War II, the XB‑19 never entered combat.

Its slow development meant that by 1941–42, the U.S. Army Air Forces were already pursuing more advanced designs.

Instead, the XB‑19 served as a testbed at Wright Field from January to November 1942, providing critical data on large‑aircraft handling, structural loads, systems reliability, and crew ergonomics.

Its existence helped validate concepts that would be essential for the B‑29 Superfortress and the B‑36 Peacemaker, including large‑scale pressurisation systems, high‑output engines, and long‑range operational planning.

While the XB‑19 itself was obsolete, its lessons were not.

Variants

Only one airframe was built, but it existed in two major configurations:

XB‑19 (original configuration):

Equipped with Wright R‑3350 engines.

XB‑19A (converted configuration):

Retrofitted with Allison V‑3420 engines in 1943 for the XB‑39 programme.

This version was used for extended testing but never standardised.

Postwar Fate

After testing ended, the XB‑19 was slated for conversion into a cargo aircraft, but the modifications were never completed.

It made its final flight on August 17, 1946.

The aircraft was stored at Davis‑Monthan Air Force Base, where the newly formed U.S. Air Force hoped to preserve it.

However, lacking a formal museum programme, the XB‑19 was scrapped in June 1949.

Only two of its enormous main tyres were saved as artefacts.

Summary

The Douglas XB‑19 was a technological stepping stone rather than a combat aircraft—an enormous, slow‑developing prototype that arrived too late for wartime use but too early to be ignored.

Its contributions to large‑aircraft engineering, crew systems, and structural design directly influenced the next generation of American heavy bombers.

Though scrapped, its legacy lived on in the aircraft that followed.

Digital Artworks by Peter Coletti.