de Havilland DH.66 Hercules
Устаревшие самолеты DH.10, возившие авиапочту между Каиром и Багдадом, нуждались в замене. По договору 1925 года с авиакомпанией "Imperial Airways" был создан соответствующий новым требованиям трехмоторный биплан DH.66 Hercules.
впервые поднялся в воздух 30 сентября 1926 года, вскоре после получения от "Imperial Airways" заказа на пять самолетов. Он быстро прошел испытания и был доставлен в Каир уже к середине декабря. Полет, открывший воздушное сообщение из Кройдона в Дели, стартовал в Британии 27 декабря и завершился в Индии 8 января 1927 года. Пятый самолет доставили в Каир в марте. Характеристики этих самолетов впечатлили компанию "West Australia Airways" (WAA), которая эксплуатировала машины DH.50. Она заказала четыре экземпляра Hercules. Первый из них полетел в марте 1929 года, а 2 июня машины этого типа начали обслуживать авиалинию WAA между Пертом и Аделаидой. К тому времени "Imperial Airways" заказала шестой, а затем и седьмой самолеты этого типа, поступившие заказчику в феврале 1930 года.
Шестой Hercules имел закрытую пилотскую кабину, что в дальнейшем стало стандартом на остальных машинах. Последние два Hercules потребовались авиакомпании после потери трех самолетов в летных происшествиях с сентября 1929 по апрель 1931 года, одно из которых сопровождалось человеческими жертвами.
В 1930-1931 годах "Imperial Airways" выкупила два Hercules у компании WAA. Один из них разбился в Южной Родезии в ноябре 1935-го. Остальные в декабре 1935 года были списаны и проданы в ЮАР. Их дальнейшая судьба неизвестна. Самым долгоживущим Hercules стал, вероятно, один из самолетов, ранее принадлежавших WAA - он прослужил на Новой Гвинее до 1942 года и был уничтожен японцами.
de Havilland DH.66 Hercules
Тип: транспортно-пассажирский самолет с экипажем из трех человек
Силовая установка: три звездообразных поршневых мотора Bristol Jupiter VI мощностью по 420 л.с. (313 кВт)
Летные характеристики: максимальная скорость 206 км/ч на оптимальной высоте; крейсерская скорость 177 км/ч на оптимальной высоте; начальная скороподъемность 233 м/мин; практический потолок 3960 м; дальность полета 845 км
Масса: пустого самолета 4110 кг; максимальная взлетная 7076 кг
Размеры: размах крыльев 16,92 м; длина 16,92 м; высота 5,56 м; площадь крыльев 143,72 м2
Полезная нагрузка: до 14 пассажиров и почта
Flight, June 1926
A NEW DE HAVILLAND COMMERCIAL AEROPLANE
The D.H.66 with Three Bristol "Jupiter" Engines
THE new De Havilland aeroplane, type D.H.66, which is now in course of construction at the Stag Lane works of the De Havilland Aircraft Company, marks a considerable departure in several respects from normal De Havilland practice. Thus in place of the all-wood plywood-covered fuselage, which has characterised practically all De Havilland aeroplanes for a great number of years, the new three-engined machine being built for Imperial Airways, Ltd., has a fuselage of all-steel construction as regards its main structure. The wings, on the other hand, are of normal De Havilland construction with box spars of wood and spruce ribs. It might have been thought that in a machine of this type (the estimated total loaded weight is 14,700 lbs.) a more logical combination of wood and metal construction might have been provided by making the fuselage of the normal De Havilland plywood-covered type, but using metal for the construction of the wing spars. On the subject of metal construction it has been pointed out by Mr. C. C. Walker, Chief Engineer of the De Havilland Aircraft Co., that the scarcity of wood, which is one of the reasons, if not the main one, for the Air Ministry decision gradually to change over to all-metal construction, will be particularly felt in the matter of main wing spars for large machines, as it is here the difficulty of obtaining suitable spruce in sufficient lengths will mainly make itself felt. At the moment there does not appear to be any reason to believe that there will, within the near future at any rate, be any difficulty in obtaining the necessary material for the making of high-class plywood, and so there would not appear to be any urgent necessity for insisting upon the abolition of this material for the covering of fuselages, in which form plywood has proved itself to be both economical and durable. In point of fact we believe that the De Havilland Aircraft Company would have preferred to build the D.H.66 with plywood covered fuselage, but with wings having metal spars, and that it was mainly at the desire of Imperial Airways that the wood wings and steel tubular fuselage were decided upon.
The Power Plant
Reference has already been made to the mounting of the three Bristol "Jupiter" engines, and to the illustrations showing the engine plate for the central engine and the wing structure supporting the engine plates of the wing engines. A reference to the front elevation of the machine will show that by so arranging the design that the central engine is considerably above the level of the wing engines, it has been possible to avoid overlapping of the propeller discs without placing the wing engines excessively far out from the fuselage. Experience with three-engined machines seems to show that flutter and vibration are apt to occur when the propeller discs overlap, and in the D.H.66 there should be no trouble on this score, as the slip streams should clear one another by a considerable margin.
The main petrol tanks are placed in the centre section of the top plane so as to give direct gravity feed to the engines, with consequent simplification of the petrol system. As the machine is required to have a rather large cruising radius, the petrol capacity is high, i.e., 300 gallons, and in contemplating the machine from the point of view of paying load carried, this fact should be kept in mind, as the fuel and oil to be carried account for no less than 2,500 lbs. of the disposable load.
Certain other features of the D.H.66 are worthy of a closer study, but it is preferred to defer a reference to these until a later date, when the machine is in a more advanced state of completion, and when certain other features can be illustrated by photographs and sketches, which is not possible at the present moment. No performance figures are available at present, but the following figures of weight, etc., may be of interest. The weight of the machine empty is 9,060 lbs. The weight of fuel and oil is 2,500 lbs., and of pilot and navigator 360 lbs., leaving a paying load of 2,260 lbs. As the total loaded weight of the machine is estimated at 14,700 lbs., there is an item of 520 lbs. not accounted for. This weight is believed to be represented by instruments, cabin equipment, etc., which are not included in the figure for empty weight. As the wing area is 1,536 sq. ft., the wing loading is 9-57 lbs. sq. ft.
Flight, November 1926
A NEW MACHINE FOR EMPIRE AVIATION
The D.H. 66 "Hercules," three Bristol "Jupiter VI" Engines
IN our issue of July 10, 1926, we published a detailed description, general arrangement drawings, and sketches of constructional details of the de Havilland "Hercules" designed for the Cairo-Karachi air route which is to be opened next year. The first of these machines was inspected by a number of press representatives and others yesterday at the Stag Lane Aerodrome of the de Havilland Aircraft Co. The machine looks remarkably "clean" for a large three-engined passenger carrier, and its power surplus is such that not only is it capable of flying or even climbing on any two of its three engines, but it has a high cruising speed and a very good top speed so as to be able to combat such strong head winds as must be counted with over the desert air route. As long distances will probably have to be covered without landing, the petrol capacity is high (300 gallons), which naturally means a corresponding reduction in paying load. Reliability and good performance are the features aimed at rather than extreme economy, and in any case the day has gone when it is fair to judge a machine merely upon the paying load per horse-power which it will carry. So many other factors have to be taken into account that using this basis as a criterion conveys nothing.
DH.66 был оборудован багажным отсеком объемом 4,39 м3, отсеком для авиапочты объемом 13,17м1 и салоном для семи пассажиров. Экипаж состоял из трех человек.
THE DE HAVILLAND 66 "HERCULES": Fitted with three Bristol "Jupiter VI" engines this type of machine is intended for the Cairo-Karachi air route which is to come into operation early in 1927. The Secretary of State for Air, Sir Samuel Hoare, who will be accompanied by Lady Maud Hoare, will be one of the passengers in the first machine to fly out to the East. A detailed description, with general arrangement drawings and sketches of constructional details, was published in our issue of June 10, 1926.
THE DE HAVILLAND 66 "HERCULES' : Side View. Note the three rudders and the biplane tail. The protruberance aft of the pilot's cockpit is the fresh-air intake for the cabin. Mounted next to it is the Bristol engine starter by means of which the three main Bristol "Jupiter" engines are started.
THE DE HAVILLAND 66, "HERCULES": A three-engined (Bristol "Jupiter VI") biplane used on the Middle-East route.
The de Havilland "Hercules" in flight. Five of these machines, fitted with three Bristol "Jupiters," are being built for the desert air route from Cairo to Karachi. The "Hercules" will take off fully loaded with only two engines running, and only loses height slightly flying on one engine.
THE CAIRO-KARACHI AIR ROUTE: Two aerial views of the de Havilland "Hercules," with three Bristol "Jupiter" engines, taken during a test flight in the neighbourhood of Stag Lane Aerodrome.
THE "CITY OF DELHI": These three views show the actual de Havilland "Hercules," with three Bristol "Jupiter" engines, on which Sir Samuel and Lady Maud Hoare and Air Vice-Marshal Sir Geoffrey Salmond made the flight from London to India. Upon its arrival the machine was christened "City of Delhi."
THE FIRST IMPERIAL AIR ROUTE: Out of the darkness into sunshine. The lower picture was taken in the early hours of Monday morning just before the inaugural flight to India, and shows a small crowd of enthusiasts, who braved the bitter cold, gathered at Croydon to give Sir Samuel Hoare a hearty send-off. Above, the "Hercules" taken from another machine (at 7000 ft.) a few days previously.
THE FIRST IMPERIAL AIR ROUTE: This photograph was taken at Croydon just before the start; standing beside the D.H. "Hercules" (from left to right) are Capt. F. L. Barnard (pilot), Lady Maud Hoare, Sir Samuel Hoare, Sir Eric Geddes, Sir Samuel Instone, Mr. Bullock, and Air Vice-Marshal Sir Vyell Vyvyan.
THE FLIGHT TO EGYPT: A set of pictures secured by Capt. Geoffrey de Havilland on his recent flight to the East in a "Hercules." 1 is an aerial view of Monaco, while 2 shows a glimpse of the coast of north-western Italy. A bird's eye view of the Collosseum in Rome is given in 3, and the crater of Vesuvius in 4.
THE FLIGHT TO EGYPT: A further set of pictures showing, 1, view on the east coast of Sicily; 2, lady passengers standing by the "Hercules" on Sollum aerodrome; 3, refuelling the "Hercules" at Sollum; 4, one of the Pyramids from above, and 5, the "Hercules" in front of the new hangar at Heliopolis.
THE AIR ROUTE TO INDIA: The D.H. "Hercules" (three Bristol "Jupiters"), the type which will operate the Egypt-India section.
THE CIRCUS AT THE CAPE: Six of Sir Alan Cobham's machines flying in formation, led by the D.H.66, over Cape Town.
THE CIRCUS AT THE CAPE: The D.H. 66 lands, apparently in rough ground, at the Cape Airport. Actually, the surface of the aerodrome is quite smooth.
THE CAPE AIR MAIL: Imperial Airways D.H. "Hercules," City of Karachi, arriving at Capetown on December 21 with the special Xmas air mail direct from England. The mail left Croydon on December 9.
THREE-ENGINED AEROPLANES FOR AUSTRALIA: The first "Hercules" of a batch ordered by Western Australia Airways having her Bristol "Jupiter" engines "run up." Note the tail wheel fitted instead of the usual tail skid.
De Havilland Hercules passenger carrier (three Bristol Jupiters)
THE FIRST AIR MAIL TO AUSTRALIA: The ill-fated DH "Hercules" City of Cairo, of Imperial Airways, with the mail for Australia, refuelling at Batavia. The machine, it will be remembered, crashed at Kupang shortly after.
FIRST KARACHI-DELHI AIR MAIL: Mail and freight being loaded in the Imperial Airways' "City of Delhi" D.H. "Hercules" air liner at Karachi, on the occasion of the opening of the extension of the England-India air route between Karachi and Delhi.
THE CAPE AIR MAIL: The City of Karachi being docked at Capetown at the conclusion of the first (experimental) through air mail service from England.
This view marks the arrival of Mrs. Hylton Cleaver and Capt. Donald Drew in the former's Gipsy-Moth at Rutbah Wells on April 4 last, during their tour to India. Behind Mrs. Cleaver is the Imperial Airways D.H. "Hercules" (Bristol "Jupiters") "City of Jerusalem" refuelling during the first eastbound Indian Air Mail flight.
THE D.H.66: Three-quarter front view of the fuselage in skeleton. The main structure is of steel tube, and cabin, luggage compartment, etc., are in the form of "boxes" of three-ply, slipped into the main structure.
THE D.H.66: The mounting for the central engine is extremely neat and simple. The engine plate is made of Duralumin and is very light. Details of this mounting are illustrated by sketches.
THE D.H.66: Sketch showing the triangulated structure in the lower plane, which carries one of the wing engines. The undercarriage struts are attached to the two fittings at front and rear ends of the longitudinal tube.
THE D.H.66: Some spar details. On the left, the distance-pieces separating the spar flanges in the inner bay, and on the right, the same, but in a slightly different form, in the end sections of the wing. The spars are of spruce, spindled out as indicated, and the distance-pieces are of laminated spruce, while the spar walls are of three-ply.
THE D.H.66: Some constructional details. 1, shows the fuselage joint at the point where are attached the front spar of the lower wing and the inner end of the wheel axle. 2 is another fuselage joint slightly farther aft. This sketch was made from a fuselage side lying on trestles, and the sloping strut is actually vertical, while the wiring plates visible below the longeron belong to the cross-bracing of the floor panel of the bay. The joints in the rear portion of the fuselage are of the type illustrated in 3. All the steel tube struts and longerons have Duralumin ends, forked or plain, according to local requirements. Some details of the mounting of the nose engine are shown in 4. The engine plate itself is of Duralumin and is very light. It should be pointed out that the sketch is a rear view, and shows the back of the engine plate.
D.H.66 3 Bristol "Jupiter" Engines