Flight, April 1926

THE GLOSTER "GAMECOCK”
A Single-Seater Fighter With Many Novel Features

   FROM the very beginning of its existence, the Gloucestershire Aircraft Co., of Cheltenham, has concentrated on the production of high-performance aircraft, a type of which their chief designer and engineer, Mr. H. P. Folland, has had very extensive experience since - it seems ages ago now - he took a hand in the design of the S.E.5 at Farnborough during the war. When Mr. Folland joined the British Nieuport Co. a single-seater known as the "Nighthawk" was one of the first results, and although the type came too late to take an active part in the war 1914-18, a great number were built. When Mr. Folland joined the Gloucestershire Aircraft Co. he appears to have convinced Mr. D. Longden, managing director of the company, of the importance of this type, and the policy of that firm has always been one closely associated with the high-performance single-seater, although other types have been successfully produced. Some months ago we gave detailed descriptions, illustrated by sketches and photographs, as well as general arrangement drawings, of two "Gloster" machines which have proved highly successful - the "Grouse" school machine, and the "Grebe" single-seater fighter. The latter has been supplied in large numbers to the Royal Air Force, but is now about to be superseded by a more recent type, the "Gamecock." At the moment it is not possible to give a detailed description of this machine, which is not yet in quantity production, but on a recent visit to the Cheltenham works of the Gloucestershire Aircraft Co., and to their aerodrome at Brockworth, a few miles from Cheltenham, we obtained a series of flying pictures of the "Gamecock," and of a very slightly modified version of it which, being a "civilian" machine and carrying the usual registration letters, may be supplied to foreign governments. In point of fact, we believe that this latter machine is about to be sent on a tour abroad for the purpose of giving demonstration flights, presumably as a result of the Air Ministry decision to allow British aircraft constructors to demonstrate some of the latest machines abroad, and to supply them to foreign air services.
   A detailed description of the "Gamecock" may not yet be given, but the photographs show it to be, as regards outward appearance, a fairly normal single-bay biplane, fitted with Bristol "Jupiter" engine. As a matter of fact, the "Gamecock" is a good deal less orthodox than a casual inspection would indicate, partly aerodynamically, and also in the matter of constructional details. Concerning the former it may, without going into too great detail, be said that it follows the principle, first tried in the "Grouse" and later applied with great success to the "Grebe," of having a thick-section top wing and a medium-section bottom wing. Moreover, the top wing is set at a slightly greater angle of incidence than the lower, the decalage being so chosen that, in conjunction with the difference in characteristics of the two sections used, the combination provides certain very important features.
   For instance, at or near the stalling angle, the two wings contribute almost equally to the lift, and by the special arrangement of the wing tips and ailerons the lateral control is very effective, even at angles beyond the stall. The result naturally is that a low landing speed can be attained, since the lateral control does not become "sloppy" in the region of stalling speed. The wing combination is also such that at climbing speeds, or rather climbing angles, the L/D ratio is good, so that an improved climb is attained. At top speed, on the other hand the wing combination approaches in effect monoplane efficiency, since the lower plane, being set at a smaller angle of incidence than the top plane, contributes but little to the lift and has a very low drag being, of fairly small camber. A further advantage of the particular wing combination used is that travel of the centre of pressure is reduced, with consequent gain in stability, while if great controllability is desired a very short fuselage enables this to be achieved without introducing instability.
   Perhaps a few words concerning the manner in which reduced c.p. travel in obtained may be of interest. At low speeds the two wings, as already stated, contribute almost equally to the lift. In other words, the mean chord, or "equivalent plane," is roughly half-way between the upper and lower wing. At large angles the centre of pressure is, of course, fairly far forward. As the speed of the machine increases, i.e., as the angle of incidence diminishes, the upper wing contributes an increasing proportion of the lift, so that the "equivalent plane" gradually rises towards the upper wing. Meanwhile the centre of pressure moves back with decrease in incidence, but as the upper wing is staggered and the "equivalent plane" moves towards it, i.e., forwards as well as upwards, the c.p. of the whole machine does not move back as far as it otherwise would, and the overall travel is confined within fairly narrow limits.
   While on the subject of the movement of the centre of pressure in the "Gamecock," reference may be made to an impression which appears to have got about to the effect that the machine is somewhat inclined to be tail-heavy at large angles of incidence. It is considered that this is probably due wholly to extra load above specification being carried on the machine. It should be realised that on a small single-seater a variation in military load of from 400 lbs. (pilot and half fuel) to about 1,020 lbs. (pilot, full tanks and a lot of equipment) must necessarily involve a change in trim. We believe the Gloucestershire Aircraft Company has suggested to the Air Ministry that in future designs ballast would be necessary to trim a machine more satisfactorily with such a widely-varying load.
   It is not permissible at the moment to give performance figures for the Gloster "Gamecock," but by way of demonstrating some of the advantages of the particular biplane combination used in the Gloster machines it may be of interest to quote a few figures relating to two earlier types. These are the "Sparrowhawk," with 230 h.p. B.R.2 rotary engine, and the "Grouse," fitted with the same engine. The former had the normal thin-wing section in both planes (R.A.F.15) whereas the latter had thick-section H.L.B.1 in the top plane and medium section H.L.B.2 in the bottom plane. The empty weight of the "Sparrowhawk" was 1,419 lbs. and that of the "Grouse" 1,357 lbs., so that there was a saving in structure weight due to the use of thicker wings. The loaded weights for the two machines were 2,168 lbs. and 2,106 lbs., respectively, while the wing areas were 270 sq. ft. and 205 sq. ft., a not inconsiderable reduction in size. In spite of the heavier wing loading, the "Grouse" has a stalling speed of 47 m.p.h., as compared with 51 m.p.h. of the "Sparrowhawk." The figures for speed at ground level are 125 and 128, and this advantage in speed in favour of the "Grouse" is maintained at altitudes, the figures at 15,000 ft. being 111 m.p.h. and 114 m.p.h., respectively. In climb, also, the modern biplane combination scores, its time to 17,000 ft. being 37-51 minutes, as against 43 minutes. The ceiling is 400 ft. higher, i.e.,19,400 ft. instead of 19,000 ft. Both machines, it should be pointed out, carried the same military load, had the same fuel capacity, and used the same propeller.
   Returning to the Gloster "Gamecock," although little may be said at present concerning some of its more interesting features, it is possible to state that great attention has been paid to details, and that the full merits of the machine cannot be appreciated without taking these into consideration. It has already been intimated that as regards its aerodynamic features the "Gamecock" looks a normal machine, but that there is a great deal of thought and experience behind its aerodynamic design. So also with regard to construction and equipment. The machine is in a general way just a normal single-seater fighter, but the way in which details such as placing of the equipment have been thought out shows the amount of trouble that has been taken to study practical considerations. The "Gamecock" is not just a machine with high performance into which the required equipment has been crammed as best it might. Rather does it give the impression that the arrangement and placing of the equipment was the first consideration, and that around this the machine was designed.
   To give but one illustration of what is meant, it may be stated that much of the equipment carried is mounted on sliding panels which can be pulled out clear of the machine for inspection and adjustment. The machine guns are favourably placed and are accessible without the pilot having to put his hands over the side. Inspection doors are detachable in a few seconds, with nothing of the old-fashioned "meat skewers" about them. Seat and rudder bar are adjustable to suit pilots of various heights. And many other features of which no mention can be made.
   A feature of the "Grebe," and which has been retained in the "Gamecock," is the placing of the petrol tanks in the top plane, the cocks being within reach from the cockpit. The tanks themselves can be changed in a few minutes by undoing four bolts for each tank. One might go on enumerating good features incorporated in the "Gamecock," but sufficient has probably been said to show that the machine merits very close attention, and the specimen which is going abroad for demonstration purposes should help very materially in raising the prestige of British aircraft in foreign countries. A point about which nothing has been said so far is the performance of the machine at altitudes. In this respect also the particular biplane combination seems to score, as will, we think, be realised when it becomes possible to publish the certified performance figures.

Flight, June 1927

GLOSTER "GAMECOCKS" FOR FINLAND

   "THE LAND OF A THOUSAND LAKES," or "Suomi" to give Finland its native name, has comparatively recently commenced seriously to interest itself in the establishment of an Air Force. Once it did decide upon the formation of such a force, however, there were no half-measures about it. It was laid down as a governing principle that in as far as finances would permit, the best obtainable flying material was to be obtained. Finland scores over most other countries, from an air force point of view, in having at the head of its air force men who are all comparatively young, men who are not, therefore, hidebound by ancient traditions in other services, and best of all, men who are practical flying people and who thus know what to aim at, what is good, and, last but not least, what is practical instead of what is mainly of theoretical value. Knowing a little of the history of the Finnish Air Force, one is not surprised to learn that an order has recently been placed by Finland for a batch of Gloster "Gamecock II" single-seater fighters, and thus very shortly the Finnish Air Force, or rather a part of it, will be mounted on really up-to-date machines worthy of the splendid personnel of which the force is composed.
   Before commencing a description of the "Gamecock II," it may be as well to point out that in the general design of this machine one may trace quite easily an ancestry dating back through the Gloster "Grebe," and the Nieuport "Nighthawk" to the S.E.5A, with the design of which latter Mr. H. P. Folland, now Chief Engineer and Designer of the Gloster company, was concerned at the Royal Aircraft Factory (as it then was) of Farnborough. Thus Mr. Folland has had very lengthy experience of designing single-seater fighters, first at Farnborough, then with the British Nieuport Company, and during the last six or seven years with the Gloster Aircraft Company. During that period Mr. Folland has designed, and the Gloster Company produced machines of various other types, it is true, but in the main one may say that the firm has specialised in single-seater fighters or in closely related types such as racing land and seaplanes. The "Gamecock II" therefore represents the accumulated experience of Mr. Folland, his chief assistant, Mr. Preston, and the rest of the technical staff of the Gloster company, and that the Finnish Air Force is not acquiring an experiment but a well-tried type will be realised when we point out that the "Gamecock I" has been in use in the British Royal Air Force for a long time, while the "Gamecock II" as delivered to the R.A.F. is still on the "secret list." In this connection it should be pointed out that the R.A.F. "Gamecock II" differs from the type delivered to Finland mainly in that it is fitted with a British Bristol "Jupiter" Mark VI, while the Finnish machines are equipped with the Gnome-Rhone "Jupiter," which is less powerful, and thus may be expected to give a rather lower performance. Also, the Finnish machines have painted on their sides the Swastika in place of the circles of the British "Gamecocks," but it is not thought that this greatly affects the performance! The machine was demonstrated by Capt. Saint, at the Finnish Air Pageant held at Helsingfors from March 20 to 27 this winter, when it "put up a very fine show" and was greatly admired.
   As the "Gamecock I" will be familiar to many of our readers, perhaps it may be of assistance to outline briefly the main differences between it and the “Gamecock II." To begin with, the fuselages are almost identical, as are also the wings with the exception that instead of the two top plane halves meeting on the centre-line of the machine, attached to a form of cabane, a centre-section has been interposed, supported on struts from the fuselage. This has had the double effect of throwing the two halves of the top plane outwards somewhat, and of very greatly improving the view from the cockpit. As a result of the outward displacement of the top planes, the inter-plane struts have been raked outward, while yet another slight change in the wing arrangement is found in the ailerons, which are of narrower chord in the Mark II machine, and the struts separating them have been moved outward and now occur in the centre of the ailerons.
   Structurally the wings have only been changed in so far as the aileron false spars have been supplanted by spars running the whole span of the wing, giving a more rigid support for the ailerons.
   The "Gamecock II" has been "cleaned up" by altering slightly the proportions of the petrol tanks carried in the top plane. In the Mark I machine these tanks were fairly narrow from side to side, but projected below the aerofoil section considerably. The new tanks of the Mark II are somewhat wider, but lie more nearly flush with the wing surface, so that the drag of them may be assumed to have been reduced a good deal. The wind screen of the "Gamecock II" is of a different type from that of the Mark I, and has been found to disturb the air flow over the tail to a much smaller degree. The result has been that the Mark II machine has better control under all conditions.
   Of the structural features of the "Gamecock II" there is little which need be said. The methods of construction followed throughout are those employed by the Gloster company for several years. The fuselage is the usual girder type, with ash longerons and spruce struts, braced by tierods, while the wings have spruce spars, struts and ribs, and internal tierod drag bracing, with external streamline wire lift bracing. The new centre-section is, however, made of steel in view of the heavy loads imposed upon it.
   The undercarriage is of the oleo-damped type, with rubber rings absorbing landing loads in compression.
   The engine installed in the Gloster "Gamecock II," as delivered to the Finnish Air Force is, as, already mentioned, a Gnome-Rhone "Jupiter," normally developing 420 h.p., and a maximum of 454 at 1,800 r.p.m.
   The two petrol tanks, carried in the top plane and giving direct gravity feed to the engine, have a capacity of 26 gallons each, while the oil tank, housed in the deck fairing aft of the engine, has a capacity of 5 1/2 gallons.
   The load factors to which the "Gamecock II" is designed are 5 1/2 on the rear-wing truss and 7 1/2 on front-wing truss, working to a stress of 5,500 lb./sq. in. for spruce members. The fuselage has a factor of 5 1/2 for front portion, and for rear portion with landing loads. The undercarriage and tail skid have factors of 5.
   Provision is made for fitting 2 Vickers guns lying in the sides of the fuselage and firing "through" the propeller by means of the usual synchronising gear. There is space for 1,200 rounds of ammunition, and if desired racks can be fitted to carry 4 bombs weighing 20 lbs. each.
   The main dimensions of the "Gamecock II" are shown on the accompanying general arrangement drawings. The following itemised weight data may be of interest :-
Power Unit
   lb. kg.
   Gnome-Rhone "Jupiter" 800 364
   Propeller 55 25
   Oil (5 1/2 gallons) 55 25
   Petrol (52 gallons) 595 291
   Piping and exhaust pipes 40 18-2
   Gas starter, magneto, &c. 25 11-35
   Total weight of power unit 1,570 lb. 734-55 kg.

Structure Weight
   Wings, struts and wires 450 205
   Fuselage 172 78-2
   Gun mounts, &c. 25 11-35
   Fins, rudder, tail and elevator 42 19-1
   Controls 26 11-8
   Tail adjuster 6 2-73
   Undercarriage 115 52-3
   Tail skid 8 3-64
   Fairing, cockpit and seat 120 54-5
   Main petrol tanks 50 22-7
   Oil tank and cooler 18 8-2
   Miscellaneous parts 20 9-1
   Total structure weight 1,052 lb. 478-62 kg.

Military Load
   Pilot 180 82
   Electrical equipment 15 6-8
   Oxygen 21 9-55
   Instruments 26 11-8
   Guns, ammunition, sights and C.C. gear 190 86-4
   Total military load 432 lb. 196-55 kg.
   Total loaded weight of machine, 3,054 lb. (1,409 kg).
   Wing loading, 11-6 lb./sq. ft. (56-8 kg./sq. m.).
   Power loading (normal), 7-27 lb./h.p. (3-3 kg./h.p).
   The following performance figures are conservative, based upon the first machine, and have since been considerable improved upon :-
   Maximum speed at sea level 150 m.p.h. 233-7 km./h.
   10,000 ft. 140 „ 221 „
   15,000 ft. 135 „ 204-6 „
   Absolute ceiling, 22,000 ft. 6,770 m.
   Stalling speed at sea level, 50 m.p.h. 80-5 km./h.
   Climb to 10,000 ft. in 7 mins.; to 15,000 ft. in 12-23 mins.

Flight, July 1928

GLOSTER "GAMECOCK II”
One Bristol "Jupiter" Engine

   THE "Gamecock" is a high performance single-seater fighter fitted with Mark VI "Jupiter" air-cooled radial engine of 420 h.p. It forms part of the standard equipment of the Royal Air Force and is one of the fastest and most manoeuvrable machines in the service.
   In the handicap race for the Sassoon Cup in 1927, "Gamecock" machines won first, second and third places, and in the 1928 race also the fastest speed was attained by a "Gamecock" machine.
   It has recently been adopted by the Finnish Air Service and is being manufactured under licence in that country.
   The machine is supplied either in wood or metal or composite structure as required.
   It is exceedingly clean and compact in design, giving exceptional manoeuvrability. The lay-out of the equipment is a striking feature. Accessibility to the engine and all essential parts, by easily removable inspection doors, makes it a machine economical to maintain in service.
   The wings consist of a high lift section upper wing and a medium lift section lower ring of reduced span and chord. The latest version differs from the prototype in that a centre section has been introduced between the upper wings and narrow chord ailerons substituted for the earlier type, giving a much more rigid construction.
   Fuel tanks are situated in the upper wings giving a fool-proof gravity feed.
   The undercarriage is of the oleo type damper action with rubber in compression.
   The armament consists of two Vickers' guns in grooved recesses in the sides of the body firing through the propeller with synchronising gear and 1,200 rounds of ammunition. Provision is also made for fitting racks to carry 4-20 lb. (9 kg.) bombs.