A.Brew Boulton Paul Aircraft since 1915 (Putnam)

P.7 Bourges

   During 1918 John North began work on a twin-engined day-bomber to the official Specification A.2(b) which called for a twin-engined reconnaissance bomber. The design received the project number P.7. With the formation of the RAF a new list of specifications was issued, and the P.7 was aimed at three of them, No.IV, (Long-distance photographic-reconnaissance fighter), No. VI (Short-distance day bomber), and No.VIII, (Long-distance day bomber). The company referred to it as a Fighter-Bomber, however.
   Three prototypes were ordered, each of which was to differ in some details. They were each three-seat, three-bay aircraft with unstaggered wings, and a spruce frame. They were fabric covered with the standard PC10 khaki-green finish on upper and side surfaces, with clear-varnished linen on the underside. The P.7 was in competition with the Avro Type 533 Manchester, a development of the earlier Types 523 Pike and 529, and the Sopwith Cobham triplane.
   The Air Ministry had decided that all twin-engined landplanes with an all-up weight of less than 11,000 lb were to be named after inland towns of England and Wales (Seaplanes being named after coastal towns); and Boulton & Paul also still had to use the initial letters BO. For some reason the company chose a French town, Bourges, as the name for the P.7, but this was in keeping with Airco, who chose Amiens for their D.H.10, and Vickers who chose the name Vimy. The name did not find favour with the workforce who tended to call it the 'Burgess' or the 'Boanerges'.
   The crew consisted of two gunners in nose and dorsal positions, and a pilot seated in front of the wings. The pilot's position was slightly raised compared with that of the nose gunner, and he was provided with a large windscreen. The nose gunner's Scarff ring was canted forward and fitted with a trunnion device to carry two .303 in Lewis guns. There was transparent panelling in the nose and a sliding panel beneath the nose for bomb aiming. The front gunner acted as bomb-aimer, being equipped with a bombsight, and release gear. The pilot was also able to release the bombs in an emergency. The dorsal gun position was also equipped with twin guns, and the Scarff ring was recessed below the fuselage top-line.
   To fulfil the aircraft's role as a reconnaissance bomber, a large camera position was located just in front of the dorsal gunner's position, the gunner operating the camera, with provision for a case of spare plates. Provision was also made for fitting a transmitting/receiving radio.
   The first Bourges, F2903, was supposed to be fitted with ABC Dragonfly engines, and as such was designated the Mk 1A. The Dragonfly engines were late in coming, and they suffered horrendous development problems. Designed by Granville Bradshaw they were the first high-power radial engines. Unfortunately they suffered from tremendous vibration and especially cooling problems, the cylinders running a dull red after a few minutes. Their normal power was 320 hp, but this fell away considerably after a little running time. The Bourges was one of many aircraft to suffer from having been designed to take them, another being the rival Avro Manchester.
   To enable flight trials to start Bentley B.R.2 rotary engines of 230 hp were fitted to F2903, and it was redesignated Bourges Mk IIA in this form. The letter 'A' denoted the fact that the upper wing was carried straight above the fuselage on conventional struts, the letter 'B' being reserved for a different layout with the upper wing inboard of the engines being of gull configuration, sloping down to join the fuselage, to give all crew members a better all-round view, and the dorsal gunner a better field of fire.
   The fuselage was a straightforward wire-braced box-section, with slab sides. The horizontal tail was built into the upper surface of the rear fuselage, and was supported by two struts above each side, connected to the fin, which possessed pleasingly curved lines.
   The B.R.2s were set midway between the wings at the inner bay struts, and were eventually replaced by Dragonflies in a closely-cowled arrangement with large spinners and two-blade propellers. The cooling problems of the Dragonfly led to the spinners soon being discarded and the cowlings redesigned with a curved frontal section. Early flight trials had also led to the introduction of large horn balances on the four cable-connected ailerons, which increased the span from 54 ft to 57 ft 4 in.
   The undercarriage had a very wide-track, the single mainwheels being carried on V struts directly beneath the engines with a bracing strut running to the underside of the fuselage.
   The all-up weight was 6,300 lb, with a fuel capacity of 190 gallons and an internal bombload of 900 lb. The bomb-bay was between the lower spars and the shutter-opening bomb doors were operated by a system of laths and tensioned cords.
   Top speed was 124 mph at 10,000 ft, and that height could be reached in only 11 minutes. The landing speed was only 50 mph. The Bourges proved to be capable of being rolled, spun and looped with ease, and in the hands of the usual Boulton & Paul test pilot, Frank Courtney, it astonished the crowds at its first public outing at Hendon in 1919, at the reception for Commander Read and the transatlantic NC-4 flying-boat.
   The handling of the Bourges was delightful, and by shutting down one engine, Courtney was able to emulate the gyroscopic effect of the rotary in the Sopwith Camel, making up for the larger dimensions and greater inertia of the Bourges. Charlie Brown, the mechanic on the Bourges was quite happy to lean casually out of the front gunner's cockpit of the aircraft while Courtney was rolling or looping it!
   Despite the excellent performance of the Bourges no production orders were forthcoming. They were under discussion at the end of the War, but the Armistice brought an end to them, and the RAF used the D.H.10 which was just coming into service. But for the delays caused by the Dragonfly engines, the Bourges might have secured large contracts before the War's end. After the end of the War Boulton & Paul made strenuous attempts to sell the aircraft around the world, but were not helped by the attitude of the Air Ministry. The company wanted to display the Bourges at the Amsterdam Aviation Exhibition and the Paris Air Show of 1919, but were refused permission to do so by the Air Ministry. The situation must have been very frustrating for John North and the board of directors, though in truth it is unlikely that any sales would have been forthcoming.
   The rival Avro Manchester also only flew in prototype form, initially with Siddeley Pumas instead of the Dragonflies, and it was not before December 1919 that the Manchester received its Dragonflies. Because of its larger dimensions the Manchester had a slightly inferior performance to the Bourges, and was not nearly so manoeuvrable.
   The other competing aircraft the Sopwith Cobham triplane was unique in being the only Sopwith/Hawker twin-engined aircraft ever built. Like the others it was designed for the ABC engine, but it first flew with Pumas, until the Dragonflies finally arrived. Its development made leisurely progress after the end of the War and it did not even go through its trials until the spring of 1920.
   The second prototype Bourges, F2904, was the Mk 1B, and apart from differing because of the sloping inboard upper-wing sections, also had the Dragonflies installed on the lower wing, rather than at mid-gap. Work at Farnborough with a D.H.10 in which the engine positions were varied had shown, against all expectations, that placing the engines in the mid-gap position caused higher drag than if they were placed on the lower wing. Work on the first Bourges had been too advanced to change the engine arrangement, but the opportunity was taken to do so with the second prototype.
   The engines were mounted inboard of the inner wing-struts, so that the undercarriage struts had to be slightly lengthened, to give the propellers the necessary clearance. The tail also differed, the rudder being increased in area, and the fin reduced, and a large dihedral angle was given to the tailplane to match the angle of the sloping section of the wing.
   A new bomb-release system was also introduced. Stowage for three bomb supporting beams was arranged between vertical guides and supported by quick-pitch screws geared to a common horizontal shaft. When this was free to rotate each bomb came in turn to the discharge position, then left the screws and moved down laterally between oblique guides, and out of the way of the next beam and bomb. There were three bomb cells with shutter doors.
   A complete bomb-loading system was also devised for the Bourges. The bomb cell was hoisted into position by gear attached to the upper longerons and could be removed before flight.
   The third and last Bourges, F2905, was designated P.7B, and first flew in December 1920. It had the straight upper wing of the Mk 1A, but was fitted with 450 hp water-cooled Napier Lion engines on the lower wing. The mainwheels were moved slightly outboard of the engines. The engines had frontal radiators and drove four-blade propellers, giving the aircraft a top speed of 130 mph at 10,000 ft, up from 124 mph with the Dragonflies. This was a very high speed for a bomber, and coupled with the exceptional manoeuvrability of the aircraft, meant it was sometimes categorised as a fighter/bomber, and was claimed to be the fastest twin-engined aircraft in the world.
   On this aircraft revised gun mountings, designed for lightness, were fitted. They could take one or two Lewis guns and had padded stocks to help prevent the gunners receiving bruises as they pressed against them with their shoulders to help traversing.
   With a relatively short wing-span and small overall dimensions. the light wing-loading of only 8 lb/sq ft. gave the Bourges almost single-seat fighter-like agility, and yet it had an endurance of 9 1/4 hours, and could carry a significant bomb-load. A projected Mk III version of the Bourges, fitted with 290 hp Siddeley Puma engines was never built.
   F2905 was delivered to Martlesham Heath in March 1921 with 3 hr 49 min flying time. A further 5 hr were flown, most of them involving its full range of aerobatic manoeuvres, then serious failures occurred to some of the wing fittings. The top rear centre section strut was badly bent, the fitting plate attaching it to the rear spar with bolts being distorted. The front spar fittings were also deflected, but not as much. Several other fittings in adjoining bays of the top plane also showed signs of deflections. It was considered that the upper wing was moving back during a loop.
   As the aircraft was due to fly at the RAF Pageant urgent modifications were made. Oblique struts were fitted from the top longerons to the rear spar of the centre section, and further oblique struts in the bay comprising the gunner's cockpit.
   After a further 1 hr and 20 min flying which included aerobatics in practice for the Pageant and the actual display itself, further failures occurred, but not as badly as before. It was considered that the entire wing system was moving relative to the fuselage during violent manoeuvres. These failures show that the impressive aerobatic performance of the Bourges was undertaken right on the edge of the limits of the aircraft's stressing. After the second failures further strengthening was instituted to the plates, and the anti-drag wires were doubled.
   As late as 1923 F2905, by then entered on the civil register as G-EAWS, was still thrilling the crowds at the RAF Pageant at Hendon. In the hands of Frank Courtney it undertook a mock dogfight with a pair of Nieuport Nighthawk fighters performing its full repertoire of loops, rolls and spins, completed with speed and accuracy. F2903 had also entered the civil register, as G-EACE, but was scrapped in May 1920. F2904 crashed at Mousehold early in 1919, and ended upside down with severe damage. The remains were obtained from the Air Ministry by the company and were totally rebuilt as the P.8 Atlantic, for an attempt on the nonstop transatlantic flight.
   The Armistice had meant the Bourges, outstanding aircraft though it was, never went into production. The Bourges was the first twin-engined combat aircraft which was fully manoeuvrable, an outstanding advertisement for the design skills of John North and the Boulton & Paul company, but it came just too late.
   Frank Courtney later stated that of the many aircraft that he flew in his career, the Bourges was one of his four favourites. The other three were the Camel, the Bristol Fighter and the Siskin; exhalted company indeed!
   The Air Ministry and RAF were also impressed, even though they no longer had the money to place production orders, and awarded Boulton & Paul a contract to build a version of the Bourges with an all-steel airframe, the P.15 Bolton.

P.7 Bourges
   Mk 1A and 1B: two 320 hp ABC Dragonfly I; Mk IIA: two 230 hp Bentley B.R.2; P.7B: two 450 hp Napier Lion.
   Span 54 ft (57 ft 4 in with horn-balanced ailerons); length 37 ft; height 12 ft; wing area 738 sq ft.
   Mk 1A and 1B: Empty weight 3,820 lb; Mk 1: loaded weight 6,326 lb; P.7B: loaded weight 6,800 lb.
   Mk 1A and 1B: Maximum speed 123.5 mph at 6,500 ft. 121 mph at 10,000 ft. 112.5 mph at 15,000 ft; P. 7B: 130 mph at 10,000 ft. Mk 1A and 1B: Climb to 6,500 ft 7 min 40 sec, to 10,000 ft 13 min 35 sec. to 15,000 ft 25 min 25 sec; service ceiling 20,000 ft; endurance 9 1/4 hr.
   Armament: one or two Lewis machine-guns on Scarff rings in nose and dorsal positions. 900 lb bombs.

F.Manson British Bomber Since 1914 (Putnam)

Boulton & Paul P.7 Bourges

   No company toiled more persistently to secure the winner's production contracts for a D.H.10 replacement than the Norwich-based manufacturer, Boulton & Paul Ltd; nor indeed came closer to success. And once all ties with the Dragonfly engine had been broken, leaving the designer free to exploit his own choice of powerplant, the resulting aeroplane, possessing undreamed-of qualities of handling, performance and manoeuvrability, set the company on the path to building medium bombers that served the Royal Air Force until 1937. Despite the cancellation of the D.H.10 replacement requirement (after ultimate failure of the Dragonfly), Boulton Paul's experience with the Bourges and its derivatives was rewarded by contracts for the Sidestrand, and later the Overstrand medium day bombers.
   Following the design of several fighters which did not achieve production status, John North undertook the design of a twin-engine day bomber to the same Air Ministry requirement as the Manchester, Oxford and Cobham, attracted as usual by the promise held out by the ABC Dragonfly engine. Smaller and lighter than the Manchester and Oxford, but on a par with the Cobham, North's P.7 Bourges was delayed by late delivery of the ABC engines, and the company opted to commence flight trials in June 1919 with F2903 powered by 230hp Bentley B.R.2 rotary engines mounted in mid-gap, this aircraft being designated the P.7/1 Bourges Mark IIA with these engines. As originally flown, this Bourges featured plain ailerons on upper and lower wings.
   Almost immediately, unmodified Dragonfly I engines became available and with these F2903, now termed the P.7/1 Bourges Mk IA, was delivered to Martlesham Heath for preliminary trials in July, returning a maximum speed of 123 mph at 6,500 feet while carrying full fuel and half bomb load, and now fitted with horn-balanced ailerons.
   While F2903 was away at Martlesham, the second Bourges, F2904, made its maiden flight with Dragonfly engines mounted on the lower wings, but with gulled upper wings attached to the upper fuselage longerons and marked dihedral on the tailplane, resulting in a change to a new designation, the P.7/2 Bourges Mk IB (the B suffix referring to the gull wing). This aircraft, however, crashed in October and was written off. The gull wing was adopted as a means of improving the field of fire for the midships gunner (and also slightly reduced wing drag), and the dihedral tailplane was thought probably with justification to improve lateral stability while landing.
   The third Bourges, P.7/3 F2905, was also originally a Mark IB with Dragonfly engines, and was probably first flown during the winter of 1919-20, but abject frustration with these engines prompted Boulton & Paul to revert to the much less powerful but infinitely more reliable B.R.2 rotaries, the aircraft becoming the Bourges Mk IIB with gull wing. It then underwent further transformation (on the manufacturers' own initiative) with a change to 450hp Napier Lion IIB engines, becoming the Bourges Mk IIIA with straight upper wing and making its first flight early in 1921. Soon after, it was given the gull wings as the Mk IIIB, and with these it demonstrated an excellent top speed of 130 mph at 10,000 feet with full fuel and bomb load at Martlesham Heath in March that year. In this form the Bourges could be regarded as having reached a stage beyond any achieved by the other contenders for the Air Ministry's requirement for a D.H. 10 replacement. By then the requirement had lapsed, and F2905 was delivered to the RAE, Farnborough, on 9 February 1922 for prolonged flight trials and development work on the Napier Lion's radiator, and these lasted until June 1924. There is little doubt that the results of work done during this period which would have reached Boulton & Paul - were employed in formulating the Air Ministry's Specification 6/24, to which the Sidestrand was successfully tendered.
   The outstanding manoeuvrability of the Bourges, of which mention was made above, was never more dramatically demonstrated than by Frank Courtney, who publicly rolled, looped and spun F2903 at the first Hendon Air Pageant in June 1920, a feat of handling wholly unimagined in a twin-engine bomber!

   Type: Twin-engine, three-crew, three-bay biplane close-support light bomber.
   Air Ministry' Specifications: RAF Types IV, VI and VIII (later D of R Type 3).
   Manufacturer: Boulton and Paul Ltd, Riverside, Norwich, Norfolk.
   Powerplant: Mark I. Two 320hp ABC Dragonfly 1 nine-cylinder, air-cooled radial engines driving two-blade propellers. Mark II. Two 230hp Bentley BR.2 rotary engines driving two-blade propellers. Mark III. Two 450hp Napier Lion IIB twelve-cylinder, water-cooled 'broad-arrow' in-line engines driving four-blade propellers.
   Dimensions: Span (with horn-balanced ailerons), 57ft 4in; length, 37ft 0in; height, 12ft 0in; wing area, 738 sq ft.
   Weights (Mark II): Tare, 3,820 lb; all-up, 6,326 lb.
   Performance (Mark IIIB): Max speed, 130 mph at 10,000ft; climb to 10,000ft, 13 min 35 sec; service ceiling, 20,000ft; endurance, 9 1/4hr.
   Armament: Single 0.303in Lewis machine guns with Scarff ring mountings on nose and midships gunners' cockpits; provision for bomb load of up to four 230 lb bombs.
   Prototypes: Three, F2903-F2905. First recorded flight by F2903 at Norwich in June 1919; pilot believed to be Frank Courtney. No production.

P.Lewis British Bomber since 1914 (Putnam)

The company then proceeded to initiate work on its first twin-engine design, a fast reconnaissance day bomber designated the P.7 Bourges, of which three examples were ordered by the Air Ministry. Basically three-seat, three-bay, unstaggered biplanes, each differed in detail. F2903, the first prototype, was scheduled to receive a pair of the 320 h.p. Dragonfly engines in which so much hope resided. Delays with the radial Dragonfly found F2903, the P.7 Bourges Mk.IA, complete but for its engines. Rotaries, in the form of two cowled 230 h.p. Bentley B.R.2s, were therefore installed at mid-gap in the equal-span wings, the four ailerons of which were of plain type. The use of alternative engines, to enable the machine to fly in 1918, brought a revised designation of Bourges Mk.IIA for F2903, the suffix A denoting the conventional upper centre-section supported across the fuselage by struts. Eventually, F2903 received its Dragonflies, installed complete with large-diameter, bluff spinners; the four cable-connected ailerons were altered to include horn-balances, thereby increasing the span from 54 ft. to 57 ft. 4 in. Reverting to its originally intended Mk.IA designation, F2903 was not satisfactory with its spinners, which were removed, nor with its cowlings, which had to be revised.
   F2904 the second prototype - the P.7a Mk.IB - introduced several significant modifications, the most important being the incorporation of gulled upper wings inboard of the engines - sloping down to connect direct with the top longerons, the tailplane mounted at a considerable dihedral angle to match that of the gull section of the upper wings, the installation of the Dragonflies direct on the lower wings, the increase in rudder area and the reduction in the size of the fin. The lowering of the engines dictated an increase in height of the undercarriage; the object of adopting the gull portion of the top wings was to improve the field of fire for the dorsal Lewis gunner. The front Lewis gun was mounted in the extreme nose and the bomb load was carried internally.
   The third Bourges prototype, the P.7b F2905, reverted to the original straight, strut-supported, upper wings’ centre-section and received greatly increased power with its pair of water-cooled 450 h.p. Napier Lions using frontal radiators, four-blade propellers and mounted on the lower wings. Its first take-off was made in December, 1920, tests resulting in a very creditable top speed of 130 m.p.h. at 10,000 ft.
   Another version of the Bourges, the Mk.III with two 290 h.p. Siddeley Puma engines, remained a project only, but F2903, F2904 and F2905 gained a great deal of publicity through their speed and phenomenal degree of manoeuvrability. Boulton and Paul retained the services of Capt. F. T. Courtney as test pilot, and it was in his capable and skilled hands that the remarkable reputation of the Bourges in aerobatics was established. These outstanding qualities were demonstrated for the delight of the public by F2905 at the 1923 R.A.F. Pageant at Hendon when, in a mock dogfight with a pair of Nieuport Nighthawk single-seat fighters, the comparatively large Bourges showed the assembled thousands that it could loop, roll and spin with speed and ease. John North’s memorable Bourges design remains noteworthy as among the first of the twin-engine aircraft with which aerobatics could be safely performed.

J.Bruce British Aeroplanes 1914-1918 (Putnam)

Boulton & Paul P.7, the Bourges

  THE manoeuvrability of the Boulton & Paul Bourges, especially when demonstrated by Captain F. T. Courtney, is now almost legendary; and indeed its tractability was remarkable for its day, when all twin-engined aeroplanes were regarded as elephantine and unlikely to commit any indiscretion such as a loop.
  The Bourges was a sturdy, well-proportioned biplane intended for service as a fighter-bomber. Design work began in 1918 and three prototypes were ordered. The official designations of the several versions of the Bourges differ from those which have gained a certain currency; the official Mark numbers are as quoted below.
  The Bourges was designed originally to have two 320 h.p. A.B.C. Dragonfly engines. This version was officially named Bourges Mark I, and the suffix letter A was to be added to indicate a conventional straight-through upper centre-section, whilst suffix B was to indicate a dropped or gull-wing centresection.
  However, the first Bourges airframe, F.2903, was ready before engines were available. It was desired to carry out test flights as quickly as possible, so the machine was fitted with two 230 h.p. Bentley B.R.2 rotary engines in order to enable it to be flown. Plain ailerons were fitted. This version was officially designated Bourges Mk. II - or, more fully, Mk. IIA, for it had a straight-through centre-section. This designation is exactly analogous to the designations of the B.A.T. Bantam II, Avro Manchester Mk. II and Sopwith Cobham Mk. II.
  When Dragonfly engines became available they were installed in F.2903. At first they had very clean nacelles with large blunt spinners on the airscrews, but these did not prove satisfactory, aerodynamically or structurally. The spinners were removed and modified engine cowlings were fitted. In this form the Bourges had horn-balanced ailerons, and ultimately the rudder area was slightly increased. The official designation of this version was Bourges Mk. IA.
  It is in this form that the Bourges is best remembered. For a twin-engined aeroplane its manoeuvrability was phenomenal, thanks to its relatively short wing span and low wing loading: it could be looped, rolled and spun almost as easily as contemporary fighters.
  The second Bourges, F.2904, was officially designated Mark IB (though it has been popularly better known as the Mk. IA), and differed considerably from the true Mk. IA. With the object of improving the rear gunner’s field of fire, the upper mainplane was made as a gull wing: from the struts above the engines the wing sloped downwards to meet the top of the fuselage. Equally unusual was the sharp dihedral angle on the tailplane; each half was parallel to the inclined portions of the upper mainplane. The Dragonfly engines were mounted directly on to the lower mainplane and the enlarged rudder was fitted. The fin area was reduced slightly, and the vertical tail surfaces were therefore more nearly circular in outline.
  Under the designation Bourges Mk. Ill a further version was projected with two Siddeley Puma engines, most probably of the ago h.p. high-compression type which was used as an alternative to the A.B.C. Dragonfly in the contemporary Avro Manchester and Sopwith Cobham. This version was never built, but the third Bourges airframe, F.2905, was completed and flown with two Napier Lion engines of 450 h.p. each. The engines were mounted on the lower wings, and additional sloping struts were added to the centre-section bracing. The Lion-powered Bourges had the same fin and rudder as the Mk. IB. It has usually been known as the Bourges Mk. II, but that official designation had already been used for the version with B.R.2 engines.


SPECIFICATION
  Manufacturers: Boulton & Paul, Ltd., Riverside, Norwich.
  Power: Bourges Mk. I: two 320 h.p. A.B.C. Dragonfly I. Bourges Mk. II: two 230 h.p. Bentley B.R.2. Bourges Mk. Ill: projected installation of two 290 h.p. Siddeley Puma. The third airframe was fitted with two 450 h.p. Napier Lion.
  Dimensions: Span: 54 ft with plain ailerons, 57 ft 4 in. with horn-balanced ailerons. Length: 37 ft. Height: 12 ft. Chord: upper 8 ft, lower 6 ft 6 in. Gap: 6 ft 6 in. Span of tail: 16 ft. Airscrew diameter (Dragonfly): 9 ft 6in.
  Areas: Wings: 738 sq ft. Ailerons: each 27 sq ft, total 108 sq ft. Tailplane and elevators: 96 sq ft. Fin: 14 sq ft. Rudder: 21 sq ft.
  Weights and Performance (Dragonfly Engines) : No. of Trial Report: M.262. Date of Trial Report: August, 1919. Type of airscrew used on trial: A.B.8973. Weight empty: 3,820 lb. Military load: 436 lb. Crew: 540 lb. Fuel and oil: 1,530 lb. Loaded:6,326 lb. Maximum speed at 6,500 ft: 123-5 m.p.h.; at 10,000 ft: 121 m.p.h.; at 15,000 ft: 112-5 m.p.h. Climb to 6,500 ft: 7 min 40 sec; to 10,000 ft: 13 min 35 sec; to 15,000 ft: 25 min 25 sec. Service ceiling: 20,000 ft. Endurance: 9 1/4 hours. With Napier Lion Engines: Weight loaded: 6,800 lb. Maximum speed at 10,000 ft: 130 m.p.h.
  Tankage: Petrol: 1 go gallons.
  Armament: One Lewis machine-gun on Scarff ring-mounting on nose cockpit; one Lewis gun on Scarff ring-mounting on cockpit aft of wings. Bomb load.
  Production: Three prototypes were built.
  Serial Numbers: F.2903-F.2905.

H.King Armament of British Aircraft (Putnam)

Boulton & Paul (later Boulton Paul)

Bourges. The Bourges twin-engined bomber of 1918/19 was not only the progenitor of a remarkable family of generally similar 'fighting bombers', which culminated in the Overstrand, but itself displayed unusual armament features. Nose and dorsal gun positions, internal bomb-stowage, and bomb-aimer's station in the nose were features retained throughout development, but one departure, made in the interests of armament, was both structural and aerodynamic. This involved the 'gulling' of the inner sections of the top wing into the fuselage to extend the fields of fire, or, as Boulton & Paul preferred to put it, to give the pilot and gunner an unrestricted view fore and aft.
   In the original Bourges the two gun mountings were of the well-known Scarff ring type, with a trunnion device for twin Lewis guns. Fuselage width was almost exactly that of the gun-ring diameters; the nose ring was canted somewhat forward from the line of flight and the rear one was recessed below the top-line of the fuselage. There was transparent paneling in the rearward-sloping nose, for the bomb-aimer, and a sliding panel in the floor behind it. Bombs were stowed internally between the lower mainplane spars.
   In the summer of 1918 Boulton & Paul designed a scheme for shutter-like bomb doors, associated with laths and tensioned cords, and over a year later mentioned a stowage scheme involving three bomb-supporting beams mounted between vertical guides and supported by 'quick-pitch screws geared to a common horizontal shaft which, when free to rotate, allows the bombs to drop'. By this means each bomb in succession came to the discharge position, then left the screws and moved down laterally between oblique guides and out of the way of the next beam and its bomb.
   The bomb load was of the 800/900-lb order and there appear to have been three bomb cells with transverse doors or shutters.
   A special bomb-loading system was also designed for the Bourges, this taking the form of a readily attachable or detachable hoisting gear. Shafts were associated with winding drums, each shaft being carried in bearings bracketed to the upper longerons. The shafts were rotated by pawl-and-ratchet or worm gear.
   The 'gulling' of the Bourges' wings has been mentioned as a factor affecting fighting efficiency, but there was another, and a greater, factor, and that was the quite extraordinary manoeuvrability of the Bourges. This was to be reproduced in later bombers of the family.
   It remains lo mention one other development in the story of the Bourges, appearing not only in the gull-winged variant but in the Lion-engined version, officially classified as a long-distance reconnaissance three-seater, and unofficially claimed in its day to be the fastest twin-engined aircraft in the world. On the aeroplanes mentioned, the two gun mountings were sited as previously but were of a different type. The identity and true nature of these mountings has eluded the present writer for many years, but he is now able to attribute them to Major ScarrT and to show drawings. Lightness appears to have been a primary aim in this design, which was intended for two Lewis guns but was adaptable for one. As the drawings show, the two guns were sighted with the aid of a shoulder stock and it was stated:
   'The triangular frame is padded on the inner surface to prevent the operator bruising his body when pressing it against the frame to assist when turning the ring.'

A.Jackson British Civil Aircraft since 1919 vol.1 (Putnam)

BOULTON AND PAUL P.7 BOURGES IA

   Highly-manoeuvrable two-seat day bomber powered by two 320-h.p. A.B.C. Dragonfly engines, built at Norwich 1918. The first prototype became civil in its final form, as F2903/K-129/G-EACE. Looped, rolled and spun by F. T. Courtney at the first public demonstration of twin-engined aerobatics at Hendon, 6.19, scrapped 5.20. Span, 57 ft. 4 in. Length, 37 ft. Tare wt., 3,020 lb. A.U.W., 6,326 lb. Max. speed, 123-5 m.p.h.

Jane's All The World Aircraft 1919

This machine was designed late in the war as a fighter bomber. Is remarkable for its small overall dimensions. This machine combines the speed, climb, and manoeuvring qualities usually associated with a small single-seat fighter, with the fuel and load capacity expected of a large bomber. The appended specification gives the leading characteristics:
  
  
Specification.
Type of machine Twin-engined Biplane.
Name or type No. of machine Boulton & Paul P 7 "Bourges."
Purpose for which intended Bomber-fighter.
Span 54ft.
Gap, maximum and minimum 6 ft. 6 in.
Overall length 37 ft.
Maximum height 12 ft.
Chord Top plane 8 ft.;
   bottom plane, 6 ft. 6 in.
Total surface of wings 738 sq. ft.
Span of tail 16 ft.
Area of tail plane 96 sq. ft.
Area of elevators 96 sq. ft.
Area of rudder 21 sq. ft.
Area of fin 14 sq. ft.
Area of ailerons 27 sq. ft.
Maximum cross section of body 5.3 sq, ft.
Horizontal area of body 73 sq. ft.
Vertical area of body 140 sq. ft.
Engine type and h.p. 2-320 h.p. A.B.C "Dragonfly"
Airscrew, diameter and revs. 9 ft. 6 in. dia. 1650 r.p.m.
Weight of machine empty 3420 lbs.
Load per sq. ft. 8 lbs.
Tank capacity in hours 9.25 hours.
Tank capacity in gallons 190 gallons.
Performance.
   Speed at 10,000 feet 124 m.p.h.
   Speed at 15,000 feet 118 m.p.h.
   Landing speed 50 m.p.h.
   Climb.
   To 10,000 feet in minutes 11 minutes.
   To 15,000 feet in minutes 21 minutes.
Disposable load apart from fuel 1200 lbs
Total weight of machine loaded 5920 lbs.