M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)

P.Lewis British Aircraft 1809-1914 (Putnam)

Bristol G.E.3

   The third Gordon England biplane design to appear during 1912 was a machine of impressive appearance with a streamlined fuselage. The two seats were mounted in separate tandem cockpits, and the 80 h.p. Gnome engine was provided with a cowling over three-quarters of its circumference. Two examples were built, works numbers 112 and 113, and the type was intended for export to Turkey. However, during flying trials, the wing spars were found to be unduly flexible and this, combined with the Italian successes against the Turks in Tripoli, frustrated the sale and no further development was undertaken.
   The slim fuselage, with its circular section conferred by formers and stringers, was suspended between the pairs of two-bay wings. The undercarriage was a very strong unit on which the machine was mounted through a sturdy central pylon passing into the fuselage. Twin nose-wheels were also a part of the design, and the unusually long tailskid kept the G.E.3 in an almost horizontal position for take-off and landing. Warping of the wings was used for lateral control, and skids were fitted at the tips. In common with the earlier Gordon England biplanes there was no fixed fin.

SPECIFICATION

   Description: Two-seat tractor military biplane. Wooden structure, fabric covered.
   Manufacturers: The British and Colonial Aeroplane Co. Ltd., Filton, Bristol.
   Power Plant: 80 h.p. Gnome.
   Dimensions: Span, 40 ft. Length, 26 ft. 3 ins. Wing area, 387 sq. ft.
   Weights: Empty, 1,096 lb. Loaded, 1,996 lb.
   Performance: Maximum speed, 65 m.p.h.

Журнал Flight

Flight, November 30, 1912.

NOTES ON THE WORK OF GORDON ENGLAND, DESIGNER OF THE LATEST BRISTOL BIPLANE.

   GORDON ENGLAND has terminated his connection with the Bristol Co., but will not actually leave Filton until be has completed the tests of the two new tractor biplanes that are his latest design. When these are finished, however, he intends to widen his experience of the world of flight, which is his sole reason for leaving the Company, with which he parts on the best of terms. Gordon England, as our readers will remember, has had a varied experience already, and he commenced his acquaintance with the air long before most modern pilots knew what it was like to be aloft. He had the termrity to practise gliding in the little man-carriers made by that early pioneer, Jose Wiess, who was and still is a strong advocate of the inherent stability of the bird-like wing, with crescent shaped entry, retreated up-turned tip, and a variable camber from shoulder to tip.
   Jose Wiess made hundreds of models down in the country far removed from observation, and at last he succeeded in bringing his knowledge of the subject to a point at which he could be sure of building a model and so loading it that it could glide quite airworthily in any wind. Sometimes, when the wind was strong, he would launch his models which weighed several pounds, and they would soar upwards and backwards in the air-currents blowing up the side of the hill that served as his aerodrome. When he had reached this point, he obtained the most complete confidence in his system, and so, too, apparently, did Gordon England, for when Wiess made a machine large enough to carry a man Gordon England never hesitated about being the pilot. He just sat in the little cockpit, which would hardly hold him, and was pushed off down the steep slope. Nothing happened for a little while, and there was a precipitous drop in view straight ahead if nothing continued to happen indefinitely. Before the unpleasant alternative could occur, however, the little machine had gathered enough speed for flight, and proceeded to glide off through the air. Very soon it was some 20 or 30 feet above the ground and Gordon England had no controls of any sort to guide or control it. He could regulate the position of the centre of gravity a little by leaning forwards or backwards, but if the machine couldn't fly he could do little or nothing to make it, and if it were not inherently stable it was a sure thing that he would be tossed out sooner or later. Although he made many such glides, however, and on some occasions actually soared in strong winds he never met with any mishap. These facts are even more interesting now than they were considered to be at the time. Indeed, at the time, comparatively few people either knew about the work that was done, or appreciated its significance.
   M. Eiffel has also been making some experiments recently on surfaces of double curvature, and he has even expressed surprise at the results, for he found a tendency for the lift to drift ratio to improve with speed, and for the movements of the centre of pressure with changes of angle to be restricted to a much smaller zone than is common with wings of single curvature. The double curvature wing has long since been the subject of experimental research by Mr. W. Turnbull, in Canada, and he also drew attention to certain merits of the shape. The connection between this work and that of Wiess, and other experimenters like Etrich and Handley Page, lies in the tendency to give the so-called bird-like wings a reversal of curvature in the run. Sometimes this takes place all along the trailing edge and sometimes it is confined more particularly to the extremity, but there is no doubt that one way and another considerable interest attaches to the feature.
   Gordon England's work as a designer has, of course, necessarily been confined within the limits of the conventional, so far as general lines are concerned, and although he might doubtless like to have the opportunity of getting unfettered expression to his ideas, nevertheless the success that he had achieved with what may be described as the commercial type of machine is only all the more to his credit on that account. We publish two illustrations of his latest biplane, two of which have been built by the British and Colonial Aeroplane Co., and are at present undergoing tests.
   The wings span 12 metres, and have a chord of 1.55 metres, so that the aspect ratio is nearly 8. The gap is 2 metres, which is 1.3 times the chord, and considerably greater than usual. Recent experiments apparently tend to show that the practice of making the gap equal to the chord is equivalent to curtailing the effective area by as much as 17 per cent. On the other hand, there are difficulties about a high gap, which not only adds weight and resistance in extra strut lengths, but also to localise a centre of resistance at a considerable leverage from the pitching "pivot" that might under certain circumstances tend to disturb the longitudinal equilibrium of the machine. In these machines, however, the longitudinal equilibrium appears to be as stable as in the preceding biplanes which Gordon England designed for the Bristol Co. Although those particular machines were under-powered for the Trials conditions, and were withdrawn from official test on that account, they were frequently flown during that period, and on one occasion Gordon England flew for nearly an hour and a half with the elevator wires actually tied up so that they could not move. It is extraordinary, but nevertheless a fact, that he was unaware of the fault, which was due to an oversight on the part of a mechanic who had been making an adjustment to some other part of the machine. The circumstance of the flight might lack significance from the mere length of its duration but for the fact that it took place at the very time when Fenwick was killed, and the gust that capsized the Mersey monoplane also rocked the Bristol biplane into an excessively steep bank. During the whole of the flight, England was very busy with his warp, but he never had any occasion to use his elevator, otherwise, of course, he would have noticed that it was out of action. Even when descending, he merely switched off one half of the 100-h.p. Gnome and allowed the machine to plane down in its natural attitude. When nearing the ground, however, he wanted to use his elevator and found that it was absolutely jammed, but he alighted safely by a judicious use of the switch.
   The present machines have an overall length of 8 metres and a fixed tail plane spreading 30 sq. ft. in area. To this is attached an elevator flap spreading 15 sq. ft. and having 5.8 metres leverage over the centre of gravity of the machine. The main planes are set at 5° incidence to the line of propeller thrust, and the tail area is calculated to be sufficient to counteract the retrogression of the centre of pressure on the main planes when their incidence to the line of flight is 4 1/2°. This correction is independent of the action of the elevator, and Gordon England has found in actual practice that it is distinctly possible to feel the correcting tendency of the fixed tail when the elevator is first used on these machines for the purpose of initiating a steep descent. The elevator and the wing warping are operated by a central lever control. The rudder, which is carried at the extremity of the tapered cylindrical fuselage, has 94 sq. ft, of surface.
   The area of the wings is 387 sq. ft., the weight of the machine empty is 1,096 lbs., and it carries 900 lbs. useful load in normal flight. The 80-h.p. Gnome with which it is equipped develops 75 effective h.p. Thus, the weight per h.p., W1, is 26.6 lbs., and the weight per square foot or wing loading, is 5.15 lbs.
   Applying this wing loading to the graph of the hypothetical aeroplane developed in FLIGHT from the Military Trials, the appropriate wing-speed is given by the expression V = Sqrt(900*W2), where W2 is the loading and V is the speed in miles per hour. In this case, the wing-speed would be 68 m.p.h., and the assumption of the hypothesis is that the design of the machine is such that it experiences a resistance of 1 in 6 at that speed. A resistance of 1 in 6 with a load, W1, of 26.6 lb. per h.p. is represented by a thrust of 4.45 lb. per h.p., and this at 68 m.p.h. represents 80 per cent, efficiency, which is higher than any propeller so far tested in model form has given.
   The propeller on this machine is 8 ft. in diameter, which represents 67 sq. ft. of disc area per h.p. The thrust over the disc area is thus 6.65 lb. per sq. ft. and, so far as can be judged from the results of the Military Trials, this is a high value for the best efficiency at a speed in the order of 68 m.p.h. In fine, we should be inclined to consider that the propeller is rather small. Allowing 73 per cent, efficiency, and assuming that small variations in power produce speed changes proportional to the square rout of the power, then the speed corresponding to 73 per cent, efficiency will be 65 m.p.h. At the speed and efficiency the power will be equal to maintaining a thrust of 4.2 lbs. per h.p., but if 4.2 lbs. per h.p. is to suffice for the propulsion of 26.6 lbs. per h.p. it is clear that the inclusive resistance must not exceed an equivalent grade of 1 in 6.2. In fine, the machine has to justify itself as a low resistance biplane.
   It will be interesting to learn in due course what maximum speed this machine does attain fully leaded, but it happens that the designer expects to realise 65 m.p.h.
   The engine, an 80-h.p. Gnome, is overhung in front, and the under-carriage is very close to the lower plane which limits the propeller diameter.
   The body stands some little way above the lower plane and beneath the body project two tubular vertical struts of unequal length, one of which stands immediately above the axle, while the other stops short just under the main plane and is joined to the former by a diagonal. The axle ends are attached to the body by crutch-like diagonal struts, as can be seen by a close examination of the photographs.
   The rudder, of 9 1/2 sq. ft. area, is operated by two pedals, instead of a pivotted bar.