The progress in aeroplane design during the 1930s is well illustrated by the giant machines described in this chapter
GERMAN GIANT OF MASSIVE GRACE. With the light shining on its metal body, the G38 Junkers air liner swings round in a banked turn before leaving an airport to speed across the English Channel. The G38 is one of the biggest machines used by the German airlines, and is remarkable for its spacious and luxurious passenger accommodation.
THE astonishing progress made in aeroplane design during the 1930s is well illustrated by the Junkers “G.38,” the “Atalanta,” the “Sarafand,” and other great machines that form the subject of this chapter. These monsters, flying swiftly to far destinations across land or sea, are in striking contrast to the crude craft of wood, wire and frail linen of the early years of aviation.
As late as 1925 the belief still survived in the minds of some well-known aeronautical scientists, that the limiting size of aeroplanes was that at which the all-in weight would be about ten tons. They explained that increased span of wing demanded greater stoutness of structure, and that accordingly, the proportion of useful load which could be carried would steadily decline as size increased.
Even the biplane, with its reinforcement of strength by struts between the wings, and its smaller span for a given total load, did not solve the difficulty, according to this school of thought.
Most aeroplane designers who have worked on big aeroplanes, believe that size development may be almost unlimited, except for operational reasons or the cost of suitable aerodrome surface of sufficient extent. As to flying boats, a 56-tonner has already been built, and there appears to be no reason why we should not ere long have 100-tonners.
During the Great War, German designers were keenly interested in the evolution of big aeroplanes, and they produced several types, not all of them successful. They were developing a big monoplane class at a period when British designers very definitely preferred the biplane, which, indeed, for some classes is still the best. And the Germans were developing a new system of construction, that in which the strength of a wing depends upon its surface, and neither upon exterior bracing, nor entirely upon internal bracing on the cantilever principle.
In the year 1915, the famous firm of Junkers adopted all-metal wing construction, favoured also by some other firms. That it has certain advantages is admitted, but it must not be inferred that it is the best method tor all purposes.
The Junkers “38” is in the direct line of succession to a wartime German monoplane class, a very striking contrast to contemporary British wood and fabric biplanes, of which Handley Page bombers and air liners, and the Vickers night bomber, the “Virginia”, are the best-known examples.
Belonging to the same general class are the “Victoria” bomber transport, the “Hyderabad”, and the “Hinaidi”. The former, with other craft, has been employed extensively in the East and took a notable part in frontier troubles by the timely evacuation of threatened Europeans.
During the vogue of this class there have been many German all-metal monoplanes, and among them the Junkers “38” is a striking example, both for size and design, although it is not yet widely used on the air lines.
It is fitted either with four Junkers water-cooled, petrol engines of 650-800 h.p., or with four Junkers “Juno” heavy-oil engines. It is by no means the only four-engined monoplane type, but it is a suitable example of Junkers construction of corrugated light metal for wings and body, the corrugation giving strength possibly at the cost of some additional air-resistance.
The “38” has a span of 144 feet, and weighs all-on about 23 tons, of which about four tons may be pay load. Its cruising speed is 117 miles per hour.
Step into the long passenger cabin with its line of windows on both sides. Walk forward between the comfortable high-backed seats, and through a doorway to the commodious closed-in, glazed compartment for pilot, navigator, wireless operator and engineer.
Pilot and second officer sit side by side just above the leading edge of the wing. Behind them is a central control room, and just below them, but forward, there is accommodation for two passengers. Three others on each side, sit in glazed compartments in the leading edge. The main passengers’ room is above the body, and there are two cabins on a lower deck. In the middle are kitchen and lavatory. Altogether there is accommodation for 34 passengers. Forward in the body there are passages, left and right, through which a mechanic can walk to any of the four engines.
To overcome the monoplane’s long, shallow glide and fast-landing propensities, the wing has a trailing-edge flap extending throughout its length, giving a “slot” effect. When the pilot operates this flap, lowering it, the machine has a lower minimum speed, and can be brought down at a steeper angle. That immensely valuable adjunct to the modern aeroplane, wheel brakes, reduces the landing run, makes the machine controllable on the ground, and saves much man-handling.
The body is made on the monocoque principle, a well-knit structure, immensely strong, and without the complicated and space-filling internal bracing of most aeroplane bodies. The system, by the way, is important in war machines, since it does not depend upon long girders, called longerons, injury to which by bullets impairs the whole structure.
Compare this type with a British equivalent, the Armstrong-Whitworth “Atalanta”, fitted with four “Double Mongoose” engines of 340 h.p., an aggregate of 1,360 h.p., as against the 3,000 h.p. of the big Junkers.
The “Atalanta” is a high-wing monoplane. It has a span of 90 ft., an all-in weight of nine tons, and accommodation for 17 passengers and their luggage.
RANGER OF EMPIRE ROUTES. This four-engined monoplane is the Armstrong-Whitworth “Atalanta” air liner. Machines of this class are used by Imperial Airways on the Karachi and Singapore, and Kisumu (Kenya) and Cape Town routes The “Atalanta” is specially designed for work in tropical countries and provides exceptional comfort for passengers in hot climates, while possessing a remarkable performance. Its four “Double Mongoose” engines develop 1,360 h.p., and its loaded weight is nine tons.
In designing the “Atalanta” it was necessary to provide for Empire routes, and for landing at and taking off from aerodromes in some cases more than 6,000 ft. above sea level, in air so rarefied that a greater speed is necessary for horizontal flight, a longer run for the take-off, and a higher landing speed. In other words, unless these conditions are tolerated, and risks incurred, the machine must have light-loading in relation to its power and wing-area. Instead of its maximum of 17 passengers the “Atalanta” usually operates with eleven only.
The “Atalanta” is a proved success, and has been doing the important work of African and Indian air lines with remarkable regularity for some years, in conditions more difficult than those of European lines.
THE CAPTAIN’S COCKPIT OF THE “ATALANTA”, showing the array of instruments and dual controls.
Its wings are built up on the cantilever principle, almost entirely of metal, but with some of the surfaces of stress-taking plywood.
The passengers’ cabin is very spacious, the seating in rows of two side by side on one side of the gangway, and singly on the other. Passing forward through this cabin, you enter the steward’s pantry, then to the wireless operator’s room, and forward of that, on a higher level in the extreme bows, to the Captain and First Officer surrounded by their instruments and levers. Mails and light luggage are in forward compartments. In the “Atalanta”, designed as it is for tropical countries, there is an elaborate ventilation system.
Of a very different class from any of the foregoing is the British military flying boat, the Short “Sarafand”, truly a giant of the air, a six-engined 31-tonner, of a total of 5,580 h.p. Experience gained in the construction and flying of the “Sarafand” provides a basis for the belief of the designers that flying boats could now be built up to a gross weight of more than four times that of the “Sarafand”. They would be able to vie, in the comfort of their appointments, with surface vessels, and be capable of operating in safety over long ocean routes.
The “Sarafand” is equipped with six 930 h.p. Rolls-Royce “Buzzard” water-cooled engines, mounted tandem in three nacelles between the wings. The maximum speed, with full disposable load of more than eleven tons, is 150 m.p.h. Still-air range, carrying full military load, is 1,450 miles, which provides an ample margin for non-stop journeys between England and Gibraltar, the nearest British territory on the route to Africa and the East.
LEVIATHAN ALOFT. This huge flying boat, the Short “Sarafand”, represents the latest development in British marine aircraft. It weighs 31 tons, and with a full load flies at 150 m.p.h. Of all-metal construction, it is strong enough to weather severe storms
The “Sarafand” has been moored out tor long periods in gales. Its size enables it to take off and alight on water that is too rough for smaller craft. The metal structure has withstood the effects of saltwater corrosion and extreme heat.
From tip to tip the wing-span is 120 ft., the length is about 90 ft. The tail unit is larger than the main lifting surfaces of many aeroplanes, for it has a span of 41 feet. Each of the wing-tip floats, which stabilize the craft on the water, is more than 20 ft. Long.
The exceptional hull capacity provides ample accommodation for equipment and for the crew of ten. In the bow compartment is mounted a machine-gun, or, alternatively, a 1½-pounder quick-firer. Mooring gear is carried in this compartment, and owing to the size of the anchor a winch has to be carried.
Immediately aft of the bow compartment is the pilots’ cockpit, which is totally enclosed, and fitted with a sliding roof and windows. The second pilot’s place is not essential, because an automatic pilot is installed, this relieving the pilot of the labour of controlling the aircraft and keeping a straight course. Under the pilots’ compartment is a passage to the wardroom, in which are the navigator’s chart and table, and the engineer’s instrument boards.
A spacious compartment between the main wing spars is normally used as the officers’ quarters, and is fitted with four folding bunks and a table. Adjacent, on the starboard side, are a drying cupboard, and a hatch giving access to the centre sections of the main planes to port is the cooking and domestic equipment. Immediately aft are the crew’s quarters, and between these and the midship gun locations is a compartment for two folding bunks, stowage room for stretchers, provision for spare airscrews, tool kit, storage space tor suitcases, and a work bench with vice. In the roof of this compartment is a hatch with a bolted-down cover through which a spare engine can be lowered.
Aft of the midship gun positions is a lavatory, and additional storage space. A passage gives access to the machine-gun emplacement at the extreme end ol the hull, and the gunner is protected by a folding screen. The nine “stations” on the boat are linked by telephone.
The interior of the “Sarafand” is like that of a ship, and it seems incredible that such a monster can actually fly. It does, indeed, appear certain that marine aircraft will, ere long, take much of the first-class ocean passenger traffic and all the mails, and will supersede for many naval and military duties the destroyer and even the light cruiser.
INSIDE THE GIANT FLYING BOAT. The cabin of the “Sarafand” flying boat contains the electric light switchbaord, engine instruments and the telephone connected to various compartments.
The “Atalanta” is a proved success, and has been doing the important work of African and Indian air lines with remarkable regularity for some years, in conditions more difficult than those of European lines.
