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Handley Page H.P. O/400 Heavy Bomber (1918)

Authored By Staff Writer | Last Updated: 2/2/2015

For a time, the HP O/400 was the largest aircraft ever produced for the United Kingdom.

The O/400 model series by Handley Page aircraft firm was the principle heavy bomber of the RAF by the end of the First World War. The O/400 was directly descended from the previous O/100 model series with the "100" and "400" designations assigned to each model depicting the horsepower output of the engines. Similarities aside, the O/400 not only fitted new engines to the bomber design but the system also had a newly designed bombsight that improved - if ever so slightly - the capabilities of aircraft and crew alike. The heavy bomber would be used in quantity with British forces to which more than 500 examples would be produced along with limited quantities of the type as supplied to by American forces.

The O/400 was a rudimentary design common with World War One standards, though built to an immensely large size - a 100 foot wingspan with a length of nearly 63 feet. The aircraft was crewed by a compliment of three personnel and fitted with two landing gear systems mounting two wheels a piece. The engines set the system apart from the previous O/100 design by mounting the 360hp Rolls-Royce brand Eagle VIII V-12 engines on either side of the fuselage. Wing design was of the typical heavy bomber biplane type, with struts spanning the structures. The aircraft featured a three-rudder, twin-elevator system at rear.

Armament of the mammoth Handley Page O/400 consisted of three Lewis-type machine gun systems mounted at various defensive positions about the fuselage. Ordnance capabilities were impressive with the ability to field up to 16 x 112lb bombs or up to 8 x 250lb bombs. Bombing was accomplished through a LT Commander Wimperis-designed Drift Sight Mk 1A bombsight. This system had the capability to process aerial information for the bomber to utilize in the form of drift, the aircraft's current airspeed and altitude for improved bombing capabilities over its predecessor. In all, the system was fielded in force to the end of the war, seeing full action with no fewer than eleven operational RAF squadrons throughout the English Empire.

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Specifications for the
Handley Page H.P. O/400
Heavy Bomber

Focus Model: Handley Page H.P. O/400
Country of Origin: United Kingdom
Manufacturer: Handley Page - UK
Initial Year of Service: 1918
Production: 657

Crew: 3

Length: 62.86 ft (19.16 m)
Width: 100.00 ft (30.48 m)
Height: 21.98ft (6.70 m)
Weight (Empty): 8,501 lb (3,856 kg)
Weight (MTOW): 13,360 lb (6,060 kg)

Powerplant: 2 x Rolls-Royce Eagle VIII V-12 engines developing 360 horsepower each.

Maximum Speed: 98 mph (157 kmh; 85 kts)
Maximum Range: 450 miles (724 km)
Service Ceiling: 8,497 ft (2,590 m; 1.6 miles)
Rate-of-Climb: 217 feet-per-minute (66 m/min)

Hardpoints: 8
Armament Suite:
5 x 7.7mm Lewis machine guns in nose (2x), dorsal (2x) and ventral (1x) positions.

8 x 250lb bombs OR 16 x 112lb bombs. Up to 2,000lbs of total external ordnance.

O/100 - Initial Bomber Model on which the development of the 0/400 stemmed from.

O/400 - Base Series Designation

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