Flight, July 1929

BRITISH AIRCRAFT AT OLYMPIA

SHORT BROTHERS, LIMITED

THREE complete machines will be exhibited on the stand of Short Brothers, of which, however, but two will be Short machines, the third being a de Havilland "Gipsy-Moth," for which Short Brothers have designed an amphibian undercarriage. The two Short machines will be the "Singapore I" on which Sir Alan Cobham made his flight to the Cape and back, and the second will be a Short "Mussel" light seaplane.

   The "Singapore I" as exhibited at Olympia will be somewhat modified as compared with the machine in its original form. To begin with, the hull has been slightly lengthened, while Rolls-Royce H.10 engines have been fitted in place of the "Condors" of the original machine. Handley Page automatic wing tip slots have also been added. The fitting of the H.10 engines will result in an improved performance both in top speed and, particularly, in getting off. At the same time, the modified "Singapore I" will get off with an overload gross weight of 27,000 lbs. as compared with the corresponding figure of 25,000 to 26,000 lbs., which was the overload gross weight of the machine in its original form.
   Constructionally, the hull of the modified "Singapore Mark I" follows usual Short practice, in which the frames are of L-section duralumin, to which the outer skin is riveted, reinforced by short fore-and-aft stringers interrupted at the frames. With this form of construction the outer skin provides all the longitudinal stiffness. In the Short system no packing is used in the riveted joints between the plates of the skin. Repairs can easily be carried out by riveting patches of duralumin over any damaged part.
   The wing structure is also entirely of duralumin, with the exception of a certain number of steel fittings. The main spars are of the box type, with duralumin flanges and webs corrugated for stiffness. The spars are produced by pressing long lengths of duralumin strip to the desired contour, instead of by rolling or drawing, as is more usually done. The ribs are girders of duralumin tube. The main spars have their flanges laminated, many thicknesses being used where the loads are heavy, thus obtaining an economic use of the spar material. "Frise" ailerons are fitted to the top plane only.
   The two Rolls-Royce type H.10 engines are housed in streamline nacelles fitted midway between top and bottom planes. The radiators, which were formerly placed in the nose of the nacelles, have been replaced by long tube radiators placed under the top plane, above the engines. Shutters are provided for varying the cooling. The nacelles themselves are of monocoque construction (metal). Oil tanks are fitted in the nacelles and are connected to external oil coolers. Hand starting gear is provided for the engines.
   A petrol supply of the direct gravity feed type is installed, the two tanks being located in the upper plane. The system is so arranged that either or both engines can be fed from either or both tanks. Should the machine be required for long reconnaissance patrol duties extra tanks can be fitted on top of the hull. The weight of these tanks and their petrol represents an overload.
   At Olympia the Short "Singapore I" will be exhibited, not with the internal arrangements used on Sir Alan Cobham's flight, but as arranged for service operations. The front gunner is situated in the bows, where is fitted a Lewis gun on a Scarff ring. This gunner, being also responsible for the bombing, is provided with bomb sight and releasing gear.
   The pilot and navigator have their cockpit between the forward cockpit and the wings. This cockpit is equipped with dual controls, and the seats, which will accommodate Irving parachutes, can be rotated about their axes to facilitate getting in or out. Inside the hull there is accommodation for the navigator and wireless operator, with a chart table fitted with drawers for the stowage of instruments, etc. Engine instruments are mounted on the front spar frame, the engineer being provided with a seat close to this instrument board. Aft of the rear spar frame are fitted two Scarff rings for Lewis guns. These gun rings are staggered on each side of the centre line to give a good angle of fire in all directions. All gun rings are so arranged as to give a field of fire vertically downwards, which improves the ability of self-defence.
   Following are the main dimensions of the modified Short "Singapore Mark I": Length o.a., 65 ft. 6 in.; wing span, 93 ft.; wing chord, 11 ft. 6 in.; wing area, 1,727 sq. ft.
   With a tare weight of 12,955 lbs. the "Singapore I" has a disposable load of 7,045 lbs., giving a normal gross weight of 20,000 lbs. The disposable load may be divided up as follows: Military load (including crew of 5), 2,115 lbs.; 610 gallons of petrol, 4,570 lbs.; 36 gallons of oil, 360 lbs. Total load, 7,045 lbs.
   The performances of the "Singapore Mark I" are: Full speed at sea level, 128 m.p.h.; minimum speed, 60 m.p.h.; initial rate of climb, 890 ft./min.; service ceiling, 15,500 ft. Time to 10,000 ft., 17 mins.; time to take-off, 16 secs. Range at most economical speed, 900 miles with normal fuel capacity.
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Flight, September 1930

SHORT "SINGAPORE" MARK II
Four Rolls-Royce F.XII M.S. Engines

   ALTHOUGH the tandem arrangement of engines has been used extensively by certain foreign designers, it has not of recent years been in favour in Britain. There are indications, however, that the system is to be given more attention in the near future, and one aircraft launched not very long ago employs this engine arrangement with, as far as the admittedly somewhat short experience of it hitherto indicates, very excellent results. The last large British aircraft to employ engines placed in tandem was the Handley Page V-1500. The latest machine to be similarly equipped in the matter of power plant installation is the new Short "Singapore" Mark II, a large all-metal flying boat designed and built for the British Air Ministry for patrol and reconnaissance duties.
   The first "Singapore" was, it may be recollected, a twin-engined flying boat fitted with two Rolls-Royce "Condor" engines. It was on this machine that, later on, Sir Alan Cobham made his flight around Africa. The latest type of "Singapore" is a development of the first machine, modified where experience with the first machine, and with the "Calcutta'' civil flying boats, has indicated that modifications were desirable.
   Due to the fact that the machine is the property of the Air Ministry, and is still classed as an experimental machine, it is not possible to refer to many of the features which make this such a very interesting flying boat. Detail alterations have been made in the hull, not only in shape, but in constructional methods and materials. Astute readers may note in the accompanying photographs that the bottom of the boat hull is of a colour different from that of the upper part, and may draw therefrom their own conclusions.
   Perhaps the greatest changes are to be noted in the super-structure. It is doubtful if any designer could have produced a "cleaner" combination of biplane wings and four engines. The placing of the four engines in two tandem pairs reduces the frontal area by half, approximately, but the designers of the "Singapore" Mark II have gone farther than that, and have simplified the wing bracing structure until it has the appearance of consisting of an irreducible number of parts. The manner in which the tandem engines are mounted on, and their fairing surrounding, the single long struts is extremely neat, and must have helped materially to reduce drag.
   Performance figures may not at the moment be published, but it is probably no exaggeration to say that the "Singapore II" is one of the world's fastest flying boats, if not indeed the fastest. The machine shown in the photographs is, of course, the service type, and at present no civil version is in existence. In view of the fact, however, that many incline to the opinion that the future Empire air route machine for passengers will be a large, multi-engined flying boat, one may hope that the not too distant future may see the introduction of a "civilianised" version with a cruising speed which will shorten the time to India and Australia to an extent which is not possible with the machines at present in use. If the four-engined arrangement of the "Singapore II" is successful - as it promises to be - the risk of forced landings should be very remote, and night-flying on certain sections of an Empire air route should not be beyond realisation. In the meantime, Short Brothers have once more produced a flying boat of service type which marks a very definite step forward in combining high performance with ease of handling.