Staff Writer (Updated: 9/9/2009):
Walter Barling had already accumulated experience in the design of large aircraft with his involvement in the failed Tarrant Tabor, another multi-engine large bomber triplane design for Britain. The Tabor's legacy would be quickly sealed in a fatal crash on its first flight. Similarly, the Barling Bomber would still succeed this legacy but in itself become a failure on other levels - it was simply too big and overly ambitious for the time.
The Barling Bomber was designed with a cylindrical-shaped fuselage - in some ways reminiscent of the forthcoming Boeing B-29 Superfortress. The mammoth aircraft sported a triplane wing to which no fewer than six engines were affixed. Engines were of the Liberty L-12A type and developed roughly 420 horsepower a piece. The powerplants were arranged with four of them in a tractor "puller" layout and the remaining two utilized as "pusher" systems. Despite this impressive array of power, the XNBL-1 would be oft-remembered as being much underpowered. The triplane layout was thick with cabling and struts to maintain the weight of the engines and support itself along the fuselage sides. The wing system was mounted well behind the cockpit but just forward of the fuselage center. The empennage was made up of two horizontal tail surfaces joined by four vertical surfaces and the tailplane itself was adjustable from the cockpit.
The Barling could carry a crew between six and nine personnel. Two of these positions were reserved for the pilot and copilot. The remaining positions were assigned to crew members (including a dedicated flight engineer) to man the various onboard areas that included self-defense 7 x 7.62mm machine gun emplacements on flexible mounts. The undercarriage was adjustable to an extent - though not fully retractable - and sported no less than ten wheels. A set of wheels was fixed to the front underside of the nose to prevent the massive aircraft from rolling over onto itself. The rear portion of the aircraft fitted simple tail skid.
The single prototype Barling cost American tax payers the then-lofty sum of $500,000 and required its own $700,000 hangar to store it. This coupled with the underachieving performance of the aircraft earned the project the name of "Mitchell's Folly" due to Brigadier-General William "Billy" Mitchell's strong support. Construction was handled by the Witteman-Lewis Aircraft Corporation.
First flight was achieved on August 22, 1923 with Lieutenant H. R. Harris at the controls and only lasted a short while. Further trials unveiled the systems inherent inadequacies and inevitably forced the project to be grounded for several years until the sole prototype was purposely destroyed under the order of General H. H. Arnold in 1928 - no doubt in an effort to "hide all evidence" of the failed project from the American taxpayer. A second "improved" prototype was planned as the XNBL-2 but the lack of secure project funding made sure that this sequel never materialized.
Despite its legacy as a failed strategic heavy bomber attempt, the Barling Bomber was still a technological pioneer for its time. It is doubtful that even with its engine troubles resolved, the aircraft would have gone on to see much more under its name that it actually did. At any rate, several bomber advancements could eventually be attributed to this Walter Barling design including the use of the adjustable multi-wheel main landing gears, the aerodynamic shape of the fuselage and the idea of separating crew members in their stations across an enclosed fuselage.
Incidentally, the XNBL-1 designation stands for "eXperimental Night Bomber, Long range".