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Boulton Paul P.75 Overstrand
Bomber History
In the early part of the 1930's, the RAF required modern bombers to
replace it's WW1 designed slow open cockpit bombers, such as the aged
Vickers Vimy. Boulton Paul's designer
H. A. Hughes was tasked with designing such an aircraft. As biplanes
were still the first choice for military aircraft at the time, he
modernised the existing open cockpit Sidestrand bomber design by
fitting more powerful Bristol Pegasus II.M3. engines, This was the
first step in the design of the Boulton Paul Overstrand. The new engines increased the
aircraft's top speed to nearly 150 mph, but the open cockpit and
forward gun position, which were already uncomfortable at lower
speeds, were all but unusable when exposed to the 150mph slipstream for
extended periods.
Boulton Paul Overstrand
Biplane gun
turret
Hughes relatively easily converted the open cockpit to an enclosed
glazed one, but the exposed forward gun position was not so easy.
Hughes' solution was to be a first for the RAF, he built in a fully
enclosed powered gun turret. The turret
utilised pneumatic turbine motors to rotate the turret, and twin
hydraulic rams to depress and elevate the single fitted .303 Lewis machine
gun. As the two dorsal and single ventral gun positions were
better protected from the slipstream, they
were left open. This completed the design of the Boulton Paul
Overstrand.
Boulton Paul Overstrand Bomber production
The Boulton Paul Overstrand first flew in 1933 and, as there had already
been three previous redesigns, it entered service with the RAF in 1934 as the Boulton Paul Sidestrand Mk IV. A total of twenty eight
Boulton Paul Overstrand aircraft
were produced, four of which were converted from surplus Boulton
Paul Sidestrand airframes.
Boulton Paul Overstrand
Biplane in RAF
service.
The Boulton Paul Overstrand entered service with No. 101 and 144 Squadrons,
serving in the role of a bomber for four years
before being
replaced by the RAF's new Bristol Blenheim monoplane bombers.
Boulton Paul Overstrand
Bomber during WW2
When WW2 broke out in 1939, only eleven of the RAF's Boulton Paul Overstrand
aircraft
remained operational, and these had already been de-rated to Air
Observer & Bombing and Gunnery School duties. A few others were
used as test-beds for the
Balloon Development Unit & Army Co-operation Development Units. The Boulton Paul P.75 Overstrand was finally retired in
May 1941, by
which time only a handful of aircraft remained airworthy.
Various scale
models, model kits and plans of this aircraft have
been available in the market place.
Boulton Paul Sidestrand Mk IV Biplane Specifications:
Boulton Paul Overstrand
Crew: Pilot and two or
three gunners
Boulton Paul Overstrand
Length: 46 ft 0 in (14.02 m)
Boulton Paul Overstrand
Wingspan: 72 ft 0 in (21.95 m)
Boulton Paul Overstrand
Height: 15 ft 6 in (4.73 m)
Boulton Paul Overstrand
Wing area: 980 ft² (91.1 m²)
Boulton Paul Overstrand
Empty weight: 7,936 lb (3,607 kg)
Boulton Paul Overstrand
Maximum takeoff weight: 11,923 lb (5,420 kg)
Boulton Paul Overstrand
Engines: Twin 580 hp (433 kW) Bristol Pegasus II.M3 9
cylinder radial engines
Boulton Paul Overstrand
Maximum speed: 148 mph (129 knots, 238 km/h)
Boulton Paul Overstrand
Range: 545 mi (474 nmi, 872 km)
Boulton Paul Overstrand
Service ceiling: 21,300 ft (6,490 m)
Boulton Paul Sidestrand Mk IV Biplane Armament:
Guns:
Three .303 in (7.7 mm) Lewis machine guns, one each in the nose
turret, dorsal and ventral positions
Bombs:
1,500 lb (680 kg) bombs (2 × 500 lb/227 kg and 2 × 250
lb/113 kg) and 4 × 20 lb (9 kg) bombs could be carried on fuselage
racks.
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