Boulton Paul Sidestrand

The Boulton Paul P.29 Sidestrand was a twin-engine biplane medium bomber of the Royal Air Force. Designed for daylight operations, it was manoeuvrable and provided with three defensive gun positions. Named after a village on the Norfolk coast near Boulton & Paul's factory in Norwich, the Sidestrand first flew in 1926 and entered service in 1928. It remained in service until 1936, equipping No. 101 Squadron RAF. It was an agile and relatively fast aircraft that was capable of aerobatic manoeuvres such as loops, rolls and spins.

Design and development

Boulton & Paul Ltd of Norwich built a series of twin-engined biplanes starting with the Bourges of 1918, which although not ordered into production, had demonstrated excellent performance and manoeuvrability, followed by the 'all-metal' Bolton of 1922 and the smaller Bugle of 1923. In 1924, the Air Ministry issued Specification 9/24 for an all-metal, twin-engined medium bomber, and Boulton & Paul's offering, designed by John Dudley North, led to an order for two prototypes early in 1925. The first aircraft flew in 1926, piloted by Squadron Leader Cecil Rea, the company's first full-time test pilot.

The village of Sidestrand, chosen for the aircraft name, was the home of the Secretary of State for Air, Samuel Hoare. Only 20 Sidestrands were built. The first two were similar prototypes, designated the Sidestrand Mk I. Originally intended to be powered by two Napier Lion inline engines, the Mk I was eventually fitted with 425 hp (317 kW) Bristol Jupiter VI radial engines, which also powered the first six production Sidestrands, known as the Sidestrand Mk II. The remaining twelve aircraft were powered by 460 hp (343 kW) Jupiter VIIIFs as the Sidestrand Mk III. The six Mk IIs were subsequently re-engined to bring them up to the Mk III specification. Bombs were carried internally in open bays set into the fuselage. A small compartment under the cockpit enabled the bomb-aimer to lie prone when using his sight, and also housed the radio. The undercarriage had oleo suspension legs and a tailskid. Unusually, the engine mountings were hinged for ease of maintenance, and the nose also hinged allowing access to the back of the cockpit instrument panel and to the radio compartment. Production models incorporated a prominent Servo tab on the rudder and Frise ailerons to reduce pilot control loads. The elevators horns remained unchanged in production models from the Mk I, but the vertical fin became less angular. Automatic sprung leading-edge slats were added to the top planes to reduce stalling speed. The Mk III introduced a bomb-aiming window into the nose.

The Sidestrand usually had a crew of three: pilot, nose gunner/bomb aimer and a rear gunner. Additionally, a navigator/co-pilot could be accommodated in a small cockpit immediately aft of the pilot's. There were three open gun positions; nose, dorsal and ventral. Armament for each position was a .303 in (7.7 mm) Lewis gun, the weapon being moved between the two rear positions depending on where each aircraft flew in a formation. The bomb-load was limited to , less than contemporaries such as the Tupolev TB-1.

In the early 1930s a Sidestrand Mk III was fitted with Bristol Pegasus IM3 engines. This was intended to become the Sidestrand Mk IV, but eventually became the prototype for the redeveloped Boulton Paul Overstrand which would begin replacing the Sidestrand in service in 1936. Four Sidestrands were eventually converted to Overstrand standard and are essentially considered Overstrands.

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General characteristics

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|crew=three or four (pilot, two gunners and optional navigator/co-pilot)

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|length ft=46

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|span in=11

|height ft=14

|height in=9+1/2

|height sigfig=3

|wing area sqft=979.5

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|empty weight lb=6370

|gross weight lb=10200

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Powerplant

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|eng1 number=2

|eng1 name=Bristol Jupiter VIIIF

|eng1 type=9-cylinder air-cooled radial engines

|eng1 hp=460

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Performance

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|max speed kmh=

|max speed mph=139

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|range miles=520

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|ceiling ft=20,800

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|time to altitude=6 min 42 s to

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Armament

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|guns= 2 × .303 in (7.7 mm) Lewis guns. One in nose, other in either dorsal and ventral gun positions

|bombs= 1,040 lb (473 kg) total

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References

Notes

Bibliography

Brew, Alec. Boulton Paul Aircraft since 1915. London: Putnam, 1993. .
Jarrett, Philip. "By Day and By Night: Sidestrand and Overstrand, Part 1." Aeroplane Monthly, Vol. 22, No. 11, Issue 259, November 1994, pp. 18–23. London: IPC. ISSN 0143-7240. .
Jarrett, Philip. "By Day and By Night: Sidestrand and Overstrand, Part 2." Aeroplane Monthly, Vol. 22, No. 12. Issue 260, December 1994, pp. 18–23. London: IPC. ISSN 0143-7240.
Mason, Francis K. The British Bomber since 1912. London: Putnam, 1994. .
Taylor, John W.R. "Boulton and Paul Sidestrand". Combat Aircraft of the World from 1909 to the Present. New York: G.P. Putnam's Sons, 1969. .
Taylor, Michael J.H., ed. "Boulton Paul Sidestrand".Janes's Encyclopedia of Aviation, Vol. 2. Danbury, Connecticut: Grolier Educational Corporation, 1980. .
Thetford, Owen. "By Day and By Night: Sidestrand and Overstrand, Part 3 Service History." Aeroplane Monthly, Vol. 23, No. 1, Issue 261, January 1995, pp. 32–39. ISSN 0143-7240.
Winchester, Jim. Bombers of the 20th Century. London: Airlife Publishing Ltd., 2003. .

Design and development

See also

References

Notes

Bibliography