The End of the Road
Ultimately, the cause of technology and progression of the war itself inevitably made the B-18 an obsolete commodity. She proved underpowered for the growing USAAC requirements and her inherent defensive machine gun network left much to be desired. Her bomb load was largely outclassed by newer developments elsewhere, shortening the tactical usefulness of the B-18 in the short term. Regardless, the B-18 served as the USAAC's standard medium bomber up until 1941 for she handled herself quite well, proving adept as absorbing damage while still being flyable (a common trait of nearly all World War 2-era bombers). During the early phases of World War 2, aircraft such as the B-18 proved vastly important across their defined roles for the building American war machine. B-18s were present (unfortunately as ground targets) during the Japanese surprise attack on Pearl Harbor on December 7th, 1941 which officially involved the United States in World War 2. Nearly all B-18s at Hickam Field in the US territory of Hawaii were lost in the attack.
By early 1942, with the US war machine now ramping up to feverish pitches, antiquated designs such as the B-18 gave way to more technologically superior and modern implements. Twenty B-18 Bolos served with Canadian air forces and were known under the RCAF designation of "Digby Mk I" while being formally classified as "reconnaissance bombers" in inventory. Brazil became the only other export operator of the B-18 (under the banner of the "1st Bomber Group") and maintained three examples actively until their retirement in post-war 1946. For the Americans, the B-18 served with no fewer than 22 bomber groups from Virginia to Hawaii as well as those units deployed in Panama, the Philippines, Puerto Rico and within South America.
B-18 Bolo Walk-Around
Externally, the Bolo managed a very distinctly stout appearance thanks to its oversized fuselage bay. The cockpit and bombardier positions were held at the extreme front of the fuselage, each area identified by its use of heavy framing but both offering strong views outside of the aircraft. Ordnance loads were held in the internal bomb bay making up the center of the fuselage. Wings were monoplane in design, rounded in typical 1930s fashion, and fitted as mid-mounts along the fuselage sides. Each wing was completed with an engine nacelle along their leading edges. The midway point of the fuselage also contained vision ports for the crew within and a dorsal and ventral machine gun or observation position. An access door was noted along the fuselage side aft of the main wing assemblies. The empennage was conventional in design with a single, rounded vertical tail fin and applicable rounded horizontal planes. The B-18 undercarriage was of the "tail dragger" sort, meaning it made use of two main landing gear legs and a small tail wheel. This, along with the deep fuselage, gave Bolos their rather noticeable "nose-up" appearance when at rest. Each main landing gear leg was finished with a large wheel and the legs recessed under each engine nacelle when the aircraft was in flight. The bomb bay doors were found along the aircraft's belly aft of the cockpit floor. Two-piece doors were used to keep ordnance in check as well as complete the aerodynamic form of the B-18. Each bomb bay door opened outboard of centerline as two-piece systems that folded over on one another. The Bolo was crewed by six personnel including two pilots, a dedicated bombardier and three machine gunners. Dimensionally, the aircraft exhibited a wingspan of 89 feet, 6 inches with a running length equal to 57 feet, 10 inches. She stood at 15 feet, 2 inches in profile. Overall weight was 27,000lbs when fully laden with an internal bomb load.
B-18 Cockpit
The cockpit of the B-18 consisted of two pilot seats in a side-by-side arrangement. The instrument panel dominated the forward view and contained nearly all of the available system gauges and switches. Each position held a conventional flight yoke wheel for control from either seat. Engine controls were clustered at a center console for equal reach from either position. Should the pilot become incapacitated during flight, the copilot could therefore resume control of the aircraft without having to shift out of position. Each position also held their own foot pedals. Vision out of the cockpit was relatively good aside from the heavy use of framing consistent with other aircraft of the time. The windowed panels allowed for clear vision ahead, above and to the sides of the aircraft. Both engine nacelles were clearly visible from the pilot's positions, allowing either personnel to respond to engine fires and the like.
Armament
The B-18 was defensed by 3 x 0.30 caliber machine guns. These lacked the general firepower inherent in the more potent 0.50 caliber Browning M2 heavy machine guns so prevalent in later US aircraft, ship and vehicles throughout the war. One machine gun was fitted in the nose with another in a dorsal position. The third was mounted to a ventral position. In addition to this defensive armament, the true "bread and butter" of any bomber was naturally its ability to carry bombs. The B-18 was listed to carry up to 2,000 to 4,500lbs of internal stores for such work - be they conventional drop bombs or naval depth charges as needed.
Power
Power for the B-18 was supplied by a pair of Wright R-1820 series air-cooled radial piston engines supported within streamlined nacelles along the wings. Each engine was rated up to 1,000 horsepower of output depending on the powerplant model number (various R-1820s were used in B-18 production). This allowed for a maximum speed of 215 miles per hour (at approximately 15,000 feet) with a cruising speed of 167 miles per hour. Operational range was limited to 2,100 miles while the listed service ceiling maximized at 24,000 feet. The engines powered three-bladed metal propellers.
The B-18 Bolo Today
Today, only six examples of B-18s exist of the hundreds produced with five of these serving as static museum display pieces and one currently undergoing refurbishment. Appropriately, one of these can be found at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio - near the birthplace of the Bolo.
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