FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1927
1927 - 0003.PDF
JANUARY 6, 1927 THE SHORT "CALCUTTA" FLYING-BOAT Three Bristol "Jupiter" Engines As first announced in FLIGHT last week, two new flying-boats are now in course of construction for Imperial Airways at the Rochester works of Short Brothers. At the moment it is not possible to give very full details of these machines, nor to state precisely where they are to be used, but we have obtained permission to publish herewith the general arrangement drawings, from which a good idea of the lines of these machines may be formed. At the same time it is possible to give a brief general description of the main features, a more detailed reference being reserved for some future occasion, when the constructional work on the new boats is somewhat more advanced. As we on FLIGHT have for very many years been firm believers in, and have made ourselves the champions of, the seaplane as a factor in Empire communications, it is naturally with very considerable satisfaction that we are now able to place on record the fact that at last Imperial Airways appear to be seriously contemplating the organisation of seaplane routes. Hitherto the only route of this kind has been that between Southampton and the Channel Islands, and a service operated once a week over a route where, in the very nature of things, there cannot be very much traffic is scarcely in keeping with the spirit of British Empire aviation. The solitary flying- boat used on this route has been spending nearly the whole of its time " sitting " on the Itchen, a familiar landmark to those who regularly use the floating bridge between Southampton and Woolston. Doubtless this use of a flying-boat may have provided data as to weathering qualities, hull soakage, etc., but it is scarcely the way to progress in Empire seaplane communications. Readers of FLIGHT will be familiar with the pioneer work on Duralumin construction which Short Brothers have been carrying out since the end of the war. Commencing with the famous " Silver Streak," exhibited at the post-war Olympia aero show, this firm has continued to develop a farm of con- struction totally different, as far as we are aware, from any used by any other firm in the world. Although detail improvements have naturally been evolved during the inter- vening years, the system remains substantially the same as that used in the " Silver Streak," and this whether the job is a flying-boat hull or an aeroplane fuselage. Without going into too great detail, it may be said that this system consists fundamentally in a stress-resisting " skin " or planking, stiffened against compression loads by longitudinal stringers, which do not, however, run through from nose to stern, as is the case with most other forms of construction, but arc interrupted at each of the " rings " or formers that give the fuselage or boat hull its cross-sectional shape. The actual " skin " is in the form of fairly short panels, riveted at each end to the flanges of the " rings " or formers, and in certain localities to the fore and aft members as well. In a fuselage of approximately streamline form this type of construction is simplicity itself, as the rings are of simple shape and the panels of the skin require no " beating." In a shape like a flying-boat hull, where the change from almost flat sides to curved chine and thence to curved planing bottom, calls for reversed curvatures, the problem is not quite so simple, but in the hull of the new " Calcutta " the lines have been sim- plified to some extent, so that the amount of panel beating required is relatively small. Thus even in a comparatively difficult shape like a flying-boat hull, the Short system of metal construction has a very great deal to recommend it from the point of view of rapid production. In the matter of wing construction, also, Short Brothers have been doing some very interesting research and experi- mental work, i-ith the result that wing spars of Duralumin, of the crinkled strip type, can now be produced rapidly and comparatively cheaply. The plant for producing these spars was described and illustrated in FLIGHT of August 26, 1926, as was also a representative spar (that of the little Short "Mussel" light seaplane). If we add that recently Short Brothers have installed at their Rochester wor^s an extensive plant for ano lie treatment of Duralumin to protect it against corrosion, and recall that this firm has its own water tank in which models of hulls, floats, etc., are tested, it vill be realised that few firms could be better equipped to tackle the not easy task of producing r,ll-met?.l flying boats for the Empire air routes. As regards the Short" Calcutta " flying-boat, two of which are now coming through the works, the general arrangement drawings will show this to be a large flying-boat of modern design in the matter of hull shape, surmounted by a fairly normal wing structure, and with a somewhat unusual arrange- ment of its engines. These will be Bristol " Jupiters," and will, it will be seen, be enclosed in streamline nacelles. The front elevation shows the " Calcutta " to be of very clean lines for a three-engined machine. The hull is of the two- step type, and has been developed from extensive work on models in the tank. Tests indicate that the new hull should be of very low resistance, very clean running, and have no tendency to " porpoise." Its constructional detail features may not be described at the moment, but the construction generally follows that of previous Short metal hulls, with such minor improvements as experience has shown to be desirable. Among the advantages of the all-metal hull perhaps one of the most important is that of freedom from water soakage, which may be a serious item in a wooden hull and may amount in some cases to several hundred pounds. Furthermore, it is claimed that the Short form of hull construction actually gives a structure which is lighter, size for size and strength for strength, than a wooden hull, quite apart from the question of water soakage. Long experi- ence with metal hulls and metal floats has shown that the corrosion problems are not as serious as was at one time thought to be the case, and the makers of the " Calcutta " are confident that with reasonable care a Duralumin hull will last for many years, if properly treated during manu- facture and subsequently during use. The passenger accommodation of the " Calcutta " will be unusually comfortable, and owing to the placing of the lower plane above the hull, and the provision of large windows, the view from the cabin will be practically unobstructed laterally and diagonally downwards. The 15 seats are arranged in three rows of 5 each, and access to the cabin will be by a hatchway that can be reached from a landing stage or from a mo tor-boat. The cabin is to be heated from the engine exhaust pipes, and a carefully considered ventilation arrangement is provided. Provision is to be made for a small bar in the cabin where light refreshments will be obtain- able, this being considered necessary in view of the fact that the machine is designed for a range of over 500 miles. Aft of the cabin is a lavatory, and behind that again a large luggage compartment, which "has a separate hatch for loading and unloading. The cockpit for the two pilots is in the nose of the hull, with two seats side by side and dual controls. There is ample room for one pilot to step down to the wireless compart- ment, which is on the starboard side, immediately aft of the pilot's cockpit. The machine is to be equipped with a parti- cularly complete wireless outfit, including transmitting and receiving apparatus, direction-finding outfit of the Bellini- Tosi type, navigation equipment, &c, The control cables to rudder, elevator, &c, run along the top of the hull in a duct so as to be entirely out of the way of the passengers. The wing structure is, as already said, of the all-metal type, with the exception of the covering, which is fabric. The spars of corrugated strip construction, and the flanges are laminated so that where local concentrated loads occur they are given an adequate thickness. In order to avoid too sudden changes of section, the laminations have their ends forked and the edges bevelled. The ribs are Duralumin tubes arranged in the form of lattices. Ailerons are fitted to the top plane only. The engine installation is shown in the general arrangement drawings. Inside the cowling of the central engine is a Bristol gas starter, which also drives the bilge pump, and, in an emergency, the general purpose generator, so that should the machine be compelled to alight on the sea it would still be able to send out wireless messages. The engines are provided with exhaust ring collectors and long tail pipes in order to reduce as much as possible the noise during flight. The petrol tanks, of which there are two, are housed in the top plane, whence the fuel is supplied by gravity feed to the three engines. Apart from the advantage \vl ich such a simple petrol system has in doing away with th^ necessity for petrol pumps, pressure gauges, etc., with liability to failure and breakdown, the placing of the tanks in the top plane, as far as possible removed from the hull, should makr it possible for the passengers to smoke with perfect safety, the more so as the hull itself is of all-metal construction. What this D
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
