Boulton Paul Overstrand

The Boulton Paul P.75 Overstrand was the last of the twin-engine biplane medium bombers of the Royal Air Force, a series that had begun during the First World War with the likes of the Vickers Vimy and Handley Page Type O. The Overstrand only saw brief service in the late 1930s and by the outbreak of the Second World War only a few surviving aircraft remained in operation with training units.

The Overstrand was essentially an upgrade of Boulton Paul's Sidestrand which had first flown in 1928 and like the Sidestrand was named for a village in Norfolk, home also of Boulton Paul's Norwich factory. The Sidestrand was similar to its First World War predecessors in that it had open cockpits and hand-operated defensive machine guns. However, unlike its predecessors, the Sidestrand could fly at 140 mph (225 km/h) making operating the exposed gun positions difficult, particularly in the aicraft's nose.

To overcome this problem, the Overstrand was fitted with an enclosed and powered nose turret mounting a single Lewis gun. As such the Overstrand was the first RAF aircraft to have a power-operated turret. Rotation was handled by pneumatic motors while elevation and depression of the gun used hydraulic rams. The pilot's cockpit was also enclosed but the dorsal and ventral gun positions remained open, though shielded.

The first Overstrand, at the time designated the "Sidestrand Mk IV", flew in 1933, powered by two 580 hp Bristol Pegasus IM.3 engines, instead of the Sidestrand's 460 hp Bristol Jupiters, and was capable of 153 mph. The bombload was also increased to 1,500 lb (680 kg).

Only 24 Overstrands were ever produced and in 1936 began replacing the Sidestrand in service. The Overstrand was operated by No. 101 Squadron RAF (which had been the sole Sidestrand squadron) and briefly by No. 144 Squadron RAF (though they were replaced by Bristol Blenheims in 1938).

At the outbreak of the Second World War only eleven Overstrands remained in service and six of these were used for gunnery training. They remained in operation until 1941 though flying was limited following the mid-air breakup of an Overstrand in 1940.

There were plans to develop a version with retractable undercarriage, dubbed the "Superstrand", but the project was abandoned.

Specifications

General Characteristics

• Crew: three or four; pilot & two/three gunners
• Length: 46 ft (14.02 m)
• Wingspan: 71 ft 11 in (21.92 m)
• Height: 15 ft 6 in (4.73 m)
• Wing area: 979 ft² (91 m²)
• Empty: 7,936 lb (3,607 kg)
• Loaded: 12,000 lb (5,455 kg)
• Maximum takeoff: lb ( kg)
• Powerplant: 2x Bristol Pegasus IM3 9-cylinder radial engines, 580 hp (433 kW) each

Performance

• Maximum speed: 150 mph (240 km/h)
• Range: 545 miles (872 km)
• Service ceiling: 22,400 ft (6,829 m)
• Rate of climb: 1,100 ft/min (335 m/min)
• Wing loading: 12.2 lb/ft² (60 kg/m²)
• Power/Mass: 0.10 hp/lb (0.16 kW/kg)

Armament

• 3 x .303 in (7.7 mm) Lewis guns in nose, dorsal and ventral gun positions
• 1,500 lb (680 kg) bombs (2 x 500 lb and 2 x 250 lb)
• four 20 lb (9 kg) bombs could be carried on fuselage racks by the cockpit and dorsal gun position

Related content

Related development: Boulton Paul Sidestrand

Comparable aircraft:

Designation sequence: P.9 - P.29 - P.75 - P.82 - P.108