Boulton Paul Р.75 Overstrand

Фирма "Boulton & Paul" из Норвича продала свое отделение по постройке самолетов, которое стало самостоятельной фирмой "Boulton Paul Aircraft Ltd." с заводом в Уолверхэмптоне. Самолет Boulton Paul Р.75 Overstrand был развитием машины Sidestrand. Прототип впервые ДальшеMore>>> взлетел в 1933 году. Это был переделанный восьмой экземпляр Sidestrand. Еще три переделанных машины сначала получили обозначение Sidestrand Mk V, а с марта 1934 года - Overstrand.
   Был получен заказ на 24 машины Overstrand для замены Sidestrand в 101-й эскадрилье английских ВВС. В январе 1935 года в эту часть поступил первый переделанный из Sidestrand образец. Месяц спустя она получила еще одну такую же машину. А первые, выпущенные "с нуля" Overstrand начали поступать со следующего года.
   На переделанные машины ставили звездообразные моторы Bristol Pegasus I мощностью 555 л. с. (414 кВт), на вновь построенные - двигатели Pegasus II. Кроме более мощных моторов Overstrand отличался от своего предшественника полностью застекленной носовой стрелковой установкой с моторным приводом турели. Это было впервые в Великобритании. Кроме того, Overstrand оснащался полностью закрытой кабиной пилота. Разработанные фирмой "Boulton Paul" капоты моторов и выхлопные коллекторы помогли снизить шум и уменьшить выброс пламени, что было важно для ночных полетов.
   Все бомбардировщики Overstrand собрали в Норвиче. Последний из них поставили к концу 1936 года. Четыре самолета в январе 1937-го передали 144-й эскадрилье, но вскоре их там сменили монопланы Avro Anson. 101-я эскадрилья также постепенно списала свои Overstrand, а в июне 1938-го стала перевооружаться на Bristol Blenheim Mk I. Несколько Overstrand оставили до 1941 года для обучения бортстрелков.
   Предлагался вариант Superstrand Р.80 с убирающимся шасси и более обтекаемым планером, но с появлением скоростных бомбардировщиков монопланной схемы этот проект отклонили.


ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Boulton Paul Р.75 Overstrand Mk I

   Тип: пятиместный средний бомбардировщик
   Силовая установка: два звездообразных двигателя Bristol Pegasus НМЗ мощностью по 580 л. с. (433 кВт)
   Летные характеристики: максимальная скорость 246 км/ч на высоте 1980 м; скороподъемность 338 м/мин на высоте 1525 м; практический потолок 6860 м; радиус действия 877 км
   Масса: пустого самолета 3600 кг; максимальная взлетная 5443 кг
   Размеры: размах крыла 21,95 м; длина 14,02 м; высота 4,72 м; площадь крыльев 91,04 м3
   Вооружение: по одному подвижному пулемету Lewis калибра 7,7-мм в носовой стрелковой установке, в верхней части фюзеляжа и под фюзеляжем, плюс до 726 кг бомб на внутренней и внешней подвеске

Flight, June 1934

Boulton & Paul "Overstrand"

   Developed from the well-known "Sidestrand," the new Boulton & Paul "Overstrand" is a twin-engined day bomber of 72 ft. wing span, fitted with two Bristol "Pegasus" I.M.3 555-h.p. engines. Structurally, and in its general layout, the machine follows the lines of the “Sidestrand," but noteworthy features are the transparent roof above the pilot, and the remarkable gun turret in the extreme nose of the fuselage. The "Overstrand" gun turret, shown in the photograph, is so designed that the gunner is protected from wind pressure, and gun and turret are rotated together by mechanical means.

Flight, November 1934

MODERN BRITISH AIRCRAFT REVIEWED

BOULTON AND PAUL, LTD.
This was one of the first British firms to go over to all-metal construction, and some very ingenious structural methods have been evolved by this company.

   THE Boulton and Paul "Overstrand," now in production for the British Royal Air Force, is the logical development of the "Sidestrand" twin-engined day bomber which has been in service for some years. The new machine is suitable for either day or night bombing. It is an equal-span biplane of all-metal construction fitted with two Bristol moderately supercharged "Pegasus" engines.
   In general aerodynamic and structural design, the "Overstrand" resembles closely the "Sidestrand," but a number of features have been incorporated which add materially to the all-round utility of the machine. Perhaps the most important innovation, from a military point of view, is the use of a completely enclosed, mechanically operated gun turret in the nose of the fuselage. This gun turret is so arranged that it can be rotated around a vertical axis very rapidly by the gunner, and a narrow slot in the turret enables the machine gun to be moved up or down for firing in any direction from vertically upwards to vertically downwards. The difficulty of working the gun at the very high speed at which the machine flies is thus obviated.
   An "automatic pilot" is carried in the "Overstrand," and maintains equilibrium and a steady flying speed with greater accuracy than is possible by direct manual control.
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Flight, September 1935

A REMARKABLE MEDIUM BOMBER
The New Boulton Paul Superstrand: Provision for Dive Bombing: 191 m.p.h. at 15,000 ft.: V.P. Airscrews Optional: Fully Supercharged 670 h.p. Pegasus IV Engines

   IT is amazing how far the development of a good basic design may be carried. From the time the first Sidestrand was produced, many years back, it was apparent that the Boulton and Paul Company was "on a good thing." Over a period of years various marks of Jupiter engines were, fitted to the Sidestrand, the performance being increased with each new installation, and eventually the Pegasus type was fitted. The structure was strengthened, permitting considerably greater all-up weight, performance benefited greatly, and provision was made for the crew to work in increased comfort and with greater efficiency. The Overstrand is now re-equipping No. 101 (B) Squadron which was the original - and, in fact, the sole Sidestrand squadron.

A Retractable Undercarriage

   Now the company has further developed even the Overstrand, and the new design is known as the Superstrand day and night bomber. So far as the main structural features and the majority of the detail design are concerned, nothing radically new is included, but by comparison with the Overstrand the type has increased performance, range, and bomb load, and embodies, in addition, features which improve its aerodynamic qualities, such as retractable undercarriage - the first British biplane designed with this feature - and redesigned tail unit and more protection for front and rear gunners.
   In general the design represents a twin-engined braced biplane of equal span. The main structure is of metal throughout, the more heavily stressed members (spars, longerons, the front portion of the fuselage, undercarriage members, etc.) being of high-tensile steel: duralumin is used for members carrying a secondary load, such as ribs, ailerons and certain lightly loaded struts in the rear portion of the fuselage. Those sections of the structure, the main function of which is to maintain aerodynamic form, such as cockpit decking, fuselage, engine and bomb cell fairings, are made in spruce and plywood, all external covering being doped fabric.
   The main bomb load is stowed in a recess with detachable side fairings beneath the fuselage, but auxiliary racks are provided beneath the inner portions of the lower wing. Sufficient clearance is provided in the bomb cell for the release of the projectiles in steep dives, thus enabling the machine to be used as dive bomber.
   That the type is an exceptionally steady bombing platform will be obvious to those who know the accuracy of bombing established by the Sidestrands and Overstrands.
   In the front cockpit is a Scarff gun ring equipped with a transparent dome-shaped protective covering. A window and a seat for bomb aiming are also contained in this forward cockpit. The pilot's cockpit is raised considerably above the level of that in the nose, and is provided with a transparent cover embodying sliding panels. Another Scarff ring, shielded by a folding transparent hood which merges into the fairing behind the pilot's cockpit, is situated mid-way along the fuselage aft of the main planes. There is, in addition, a prone gun position beneath the fuselage with a special gun mounting for downward firing similar to that on the Overstrand and Sidestrand.
   Cockpit heating with individual controls can be provided for all the crew stations. Wireless apparatus and a camera are accessible to the rear gunner.
   The tail plane is adjustable over a range of incidence, and the elevators and rudder, which are of the inset balance type, are provided with flap-type servo controls in their trailing edges. Frise-type ailerons are fitted to all four main planes, making for exceptional manoeuvrability.
   The engines specified are of the Mark IV Pegasus type, fully supercharged and geared, the normal output at the rated altitude of 11,500 ft. being 640 670 h.p. At maximum r.p.m. they deliver 680/710 h.p. at 15,000 ft. Fuel (440 gallons) of 87-octane number is carried partly in the fuselage and partly in the top centre plane, supply to the engines being by gravity through a common junction box. The engines are carried on quickly removable mountings on the bottom centre sections, and equipped with Boulton Paul Townend rings.
   Although four-bladed, fixed-pitch wooden airscrews are fitted as standard, three-bladed two-position C.P. metal airscrews of Hamilton type may be supplied if required. The resulting gain in performance and range can be seen at a glance from the accompanying table.
   The Superstrand is the first Boulton Paul design to embody a retractable undercarriage. This retracts mechanically into extensions of the engine nacelles. Oleo pneumatic shock-absorbers and wheel brakes are provided. The low-pressure tail wheel castors freely, and has a spring-loaded centralizing device.