Ford Tri-Motor

Споры о том, действительно ли Уильям Б. Стаут является конструктором знаменитого самолета Ford Tri-Motor, продолжаются не один год. Не вызывает сомнений, что именно он сконструировал 2-AT Pullman, который компания "Stout Metal Airplane Company" выпускала в ДальшеMore>>> начале 1925 года. В августе того же года компания на правах отдельного подразделения вошла в состав компании "Ford Motor Company", после чего специалисты данного подразделения приступили к работам над трехмоторным вариантом Pullman, получившим обозначение Ford 3-AT Tri-Motor. Влияние самолета Pullman хорошо прослеживалось во внешнем виде машины: самолет представлял собой свободнонесущий высокоплан цельнометаллической конструкции, с такой же как у 2-AT гофрированной обшивкой. Однако если 2-AT, оснащенный одним двигателем Liberty, являлся достаточно изящным самолетом, то 3-AT, выпущенный в единственном экземпляре и отличавшийся тремя незакапотированными двигателями, расположенными по одному на каждой консоли крыла и в носовой части фюзеляжа, может быть легко отнесен к категории "безобразных" летательных аппаратов.
   Последовавший затем аэроплан 4-AT, совершивший первый полет 11 июня 1926 года, в целом имел схожую компоновку, с подкосным хвостовым оперением и неубирающимся шасси с хвостовым костылем, в котором главные опоры шасси были значительно усовершенствованы. Самолет пилотировал экипаж из двух человек, находившийся в открытой кабине, расположенной перед крылом, а восемь пассажиров размещались в закрытом салоне. Один из трех звездообразных двигателей Wright Whirlwind J-4 мощностью 200 л.с. (149 кВт) был установлен в носовой части фюзеляжа, а два других - в мотогондолах, размещенных на моторамах под каждой консолью крыла. Такая компоновка оставалась практически неизменной до окончания в 1933 году серийного выпуска машины. Самолет выпускался в двух основных серийных модификациях - 4-AT и 5-AT, последний появился в 1928 году и отличался большей вместимостью.
   Получивший прозвище "Tin Goose", самолет Tri-Motor выпускался также в виде целого ряда официальных и неофициальных подвариантов, с колесным, поплавковым и лыжным шасси. Данные самолеты использовались в Армии США под обозначениями XC-3, C-3, C-3A, C-4, C-4A, C-4B и C-9 (всего 13 машин), а также в ВМС и КМП США под обозначениями XJR-1, JR-2, JR-3, RR-1, RR-2, RR-3, RR-4 и RR-5 (всего 9 самолетов). Одним из доказательств высокой живучести конструкции Tri-Motor может служить такой пример: один из самолетов (5-AT-C) находился в коммерческой эксплуатации в своем первоначальном состоянии с момента его выпуска в 1929 году и вплоть до 1991 года.


Варианты

   4-AT-A: начальный серийный вариант; построено 14 самолетов
   4-AT-B: вариант 1927 года, с двигателями Whirlwind J-5 мощностью по 220 л.с. (177 кВт) и вместимостью 12 пассажиров; построены 39 самолетов
   4-AT-C: схож с 4-AT-B, но с установленным в носовой части фюзеляжа звездообразным ПД Pratt & Whitney Wasp мощностью 400 л. с. (298 кВт); построен один самолет
   4-AT-D: обозначение трех самолетов, схожих с 4-AT-B, но имевших различные силовые установки и отличавшихся индивидуальными доработками
   4-AT-E: в основном идентичен 4-AT-B, но с тремя двигателями Whirlwind J-6-9 мощностью по 300 л.с. (224 кВт); построены 24 самолета
   4-AT-F: один самолет, отличавшийся от 4-AT-E некоторыми аэродинамическими улучшениями
   5-AT-A: серийный вариант 1928 года; размах крыла был увеличен на 1,17 м; самолет рассчитан на 13 пассажиров; в составе силовой установки были применены три звездообразных двигателя Wasp мощностью 420 л.с. (313 кВт); построены три самолета
   5-AT-B: схожий с 5-AT-A, но вместимость 15 пассажиров; построен 41 самолет
   5-AT-C: схожий с 5-AT-A, но вместимость 17 пассажиров; построен 51 самолет
   5-AT-CS: морской вариант самолета 5-AT-C (с двумя поплавками Edo); построен один самолет
   5-AT-D: отличие от модели 5-AT-C заключалось в поднятом на 0,2 м крыле для увеличения высоты салона; построены 20 самолетов
   5-AT-DS: морской вариант 5-AT-D (с поплавками Edo); построен один самолет
   5-AT-E: вариант с внешними двигателями, смещенными к передней кромке крыла
   6-AT-A: эквивалент 5-AT-C, но с тремя двигателями Whirlwind J-6-9 мощностью по 300 л.с. (224 кВт); построены три самолета
   6-AT-AS: морской вариант самолета 6-AT-A (поплавковое шасси Edo); построен один самолет
   7-AT-A: новое обозначение одного самолета 6-AT-A после установки в носовой части двигателя Wasp мощностью 420 л. с. (313 кВт); позднее был модифицирован в вариант 5-AT-C
   8-AT: грузовой вариант самолета 5-AT-C (одна машина), два двигателя на крыле сняты
   9-AT: обозначение 4-AT-B после установки трех двигателей Wasp Junior мощностью по 300 л. с. (224 кВт)
   11-AT: обозначение 4-AT-E с двигателями Packard мощностью по 225 л.с. (168 кВт), позже модифицирован в вариант 4-AT-B
   13-A: обозначение самолета 5-AT-D с двигателем Wright Cyclone мощностью 575 л.с. (429 кВт) в носовой части и двумя двигателями Whirlwind J-6-9 мощностью по 300 л. с. (224 кВт) на крыле; позже переоборудован в 5-AT-D
   14-A: самолет первоначально оснащался четырьмя двигателями и имел обозначение 10-A, но затем его силовую установку модифицировали - один двигатель Hispano-Suiza мощностью 1100 л.с. (821 кВт) и два двигателя Hispano-Suiza мощностью по 715 л.с. (533 кВт); вместимость салона - 40 пассажиров; построен один самолет, но даже не облетан
   XB-906: обозначение одного 5-AT-C, переоборудованного в бомбардировщик; разбился во время заводских испытаний


ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Ford 5-AT-D Tri-Motor

   Тип: транспортный самолет с экипажем ив одного или двух человек
   Силовая установка: три звездообразных ПД Pratt SWhitney R-1340-C1 или -SC1 Wasp мощностью по 420 л. с. (313 кВт)
   Летные характеристики: макс, скорость на оптимальной высоте 241 км/ч; крейсерская скорость на оптимальной высоте 196 км/ч; начальная скороподъемность 335 м/мин; практический потолок 5640 м; дальность полета 885 км
   Масса: пустого 3556 кг; максимальная взлетная 6123 кг
   Размеры: размах крыла 23,72 м; длина 15,32 м; высота 3,86 м; площадь крыла 77,57 мг
   Полезная нагрузка: до 17 пассажиров в закрытом салоне (максимальная масса полезной нагрузки 1698 кг)

Flight, June 1929

OLYMPIA AERO SHOW 1929

The Tri-motored Ford

   The type of machine exhibited by the Ford Company at Olympia has been extensively employed in the United States by passenger-carrying air lines, and also by large business organisations desiring the advantages of private air transport facilities. After the closing of Olympia, the machine will, we learn, be flown on a demonstration tour of different European capitals, piloted by Mr. LeRoy Manning, chief of operations of the Ford Air Lines and senior test pilot of the Stout Metal Airplane Company.
   The tri-motored Ford exhibited in the new hall of Olympia is of all-metal construction, and in this case, the term does mean all-metal, not only the coverings of the wings and fuselage being metal, but even the passengers' seats. Of the internal structure but little can be seen, but we gather that the cantilever monoplane wing has three main spars, with a subsidiary structure which, in conjunction with the metal covering, maintains the aerofoil section. The wing tapers in plan and thickness from root to tips.
   The fuselage also is covered with metal, the material used being a form of metal ply, consisting of an inner layer of duralumin and two outer layers of a very pure aluminium. The material is known as "Alclad," and the advantage claimed for it is that, the outer layers which are in contact with the air being almost chemically pure aluminium, the material resists corrosion to a remarkable extent. In appearance, the "Alclad" surface is very bright, and one might readily forgive the visitor to Olympia who, on seeing the machine, exclaimed: "Here we have the real super 'Tin Lizzie'." The cabin is roomy and well lighted, and has seating accommodation for 14 passengers, the seats being arranged along the sides, under the windows.
   The two wing engines are suspended from the wing spars, and the telescopic undercarriage struts are taken, at their upper ends, to the inboard side of the engine mountings. Mudguards are fitted over the wheels, and independently operated hydraulic brakes are provided. The usual tail skid is replaced by a trailing wheel.
   The petrol capacity of the tri-motored Ford is 355 U.S.A. gallons (about 295 Imperial gallons), and 30 U.S.A. gallons of oil, 10 gallons for each engine. The engines are Pratt & Witney Wasps of 425 h.p. each.
   With a wing span of 77 ft. 10 in. and an overall length of 49 ft. 10 in., the tri-motored Ford monoplane has a tare weight of 7,500 lbs. and a gross weight of 13,500 lbs., leaving a disposable load of 6,000 lbs. The ratio of load carried to tare weight is, therefore, very good indeed.
   Very detailed performance figures are not available, but we are informed that the top speed is 135 m.p.h. and the cruising speed 115 m.p.h. These figures are exceptionally good, and would seem to indicate that the aerodynamic design of the Fokker is as efficient as is evidently the structural design.

Flight, November 1930

FORD THREE-ENGINED MONOPLANES
Two Types Described

   A FEW weeks ago we recorded the arrival in this country of two Ford three-engined monoplanes, intended for demonstration work in Great Britain and on the Continent. The machines were shipped to Ellesmere Port, there unloaded and wheeled by road the short distance to Hooton Park Aerodrome (where the Comper Aircraft Co., Ltd., had placed hangars at the disposal of the Ford Company) assembled and flown to London. It is the intention of the Ford Motor Co., if experience appears to justify so doing, to repeat the process with any machines which may be sold to European countries, and Hooton Park is ideally situated for the purpose, being within a couple of miles of Ellesmere Port on the Mersey, and within easy flying distance of any of the London aerodromes.
   The aviation department of the Ford Motor Company is of fairly recent establishment, and is presided over by Mr. G. W. Higgs, who is ably assisted by Mr. R. L. Carter, whose aviation experience was largely gained with Imperial Airways, Ltd. The aviation offices are in the new Ford House, in Regent Street. For the present it is not, we understand, the intention to start manufacture in England, but as the three-engined Ford machines have established a very good reputation in America, there is cause to believe that very considerable business will be done in Europe, and the possibility is certainly not excluded of laying down a manufacturing plant in this country. We do not know that the new Ford works at Dagenham are planned with the idea of including an aircraft section, but as they will be on a vast scale, it should not be difficult, should the need arise, to set aside a portion of them for aircraft construction.
   While the two machines were at Hooton Park, our representatives had the opportunity to examine them while they were being erected, and it was largely on the occasion of that visit that the material for the present article was collected.
   The two Ford monoplanes at present in Europe are generally similar except for their power plants, the extent of the passenger accommodation, and the wing areas. The smaller machine of the two is known as the type 4-AT-E, and the larger as the type 5-AT-C. The former is fitted with three Wright "Whirlwind" engines, while the latter has three Pratt & Whitney "Wasps." The smaller machine has seating accommodation for 11 passengers, while in the larger the number of seats can be 13 to 15, according to requirements. The manner in which, in the larger machine, the wing area is increased to carry the greater load of more passengers and more powerful engines is interesting. The Ford design includes a wing centre-section permanently attached to the fuselage, and carrying the outboard engines. To this centre-section are attached, by six bolts each, the two outer wing portions. These outer wing portions are a standard size, identical for the smaller and larger machine, and the extra area is obtained solely by increasing the span of the centre-section. While this arrangement limits the increase in area that is possible, it is actually a sound way of increasing area because it increases the span, and thus decreases the induced drag at low speeds. It does not, of course, add materially to the maximum lift coefficient, and as the increase in weight is greater than the increase in area, the stalling speed of the larger machine is greater than that of the smaller.
   Aerodynamically, the Fokker tri-motor monoplanes are of about average fineness. For example, the Everling “High-speed Figure'' is 13-6 for the "Whirlwind"-engined machine and 15-8 for the larger monoplane. Neither figure is exceptionally high, but neither is it unusually low, and the minimum drag coefficient appears to be about what one would expect.
   From the point of view of structural efficiency, the machines appear to be good, more especially, perhaps, the larger, which has a ratio of gross weight to tare weight of 1-8 which is above the average. For the smaller machine the figure is 1-56. The wing loading of the 4-AT-E is 12-9 lb./sq. ft., and the power loading 113 lb./h.p. For the type 5-AT-C the figures are 16-2 lb./sq. ft. and 11-7 lb./h.p. respectively. The speed range of both machines must be regarded as good, being 2-3:1 for the smaller machine and nearly 2-4:1 for the larger. The actual performance figures are given in the table on page 1236, from which it will be seen that the smaller machine has a top speed of 132 m.p.h. with a cruising speed of 107 m.p.h., while the larger has a top speed of 152 m.p.h., and cruises at 122 m.p.h.
   The "Wasp"-engined machine in particular should be a very useful type, with its high-cruising speed. It is becoming more and more evident that the figure of 100 m.p.h. for cruising speed which became accepted many years ago, is scarcely sufficient under modern conditions if a real saving in time is to be achieved, and a cruising speed of 100 m.p.h. would not be enough on some of the sections of British Empire routes, for example, although it should be ample for many European routes. The power expenditure per passenger is by no means excessive in the Ford machines, especially in view of the good performance, and both types should be reasonably economical to operate as regards running costs, while the type of construction adopted is such that maintenance costs should be very low.
   Structurally, the Ford monoplanes are truly all-metal, in that, in addition to the main structure, both the fuselage and wing are covered with metal. The fuselage skeleton consists of duralumin members, most of U section, to the flanges of which the metal skin is riveted. In the forward part these U section members are used for longerons as well as for vertical, horizontal and diagonal struts. Where two or more of these U section members have to be joined, this is done by simple fishplates and rivets.
   It is, perhaps, the wing structure of the Ford machines which offers the greatest interest, since it is always instructive to see how different designers tackle similar problems. A metal wing of the full cantilever type, which carries the outboard engines, has to resist considerable stresses, some distributed and some concentrated. So to design a wing that nowhere does the strength fall below a certain figure, nor at others is unnecessary material carried is an impossibility. The best the designer can do is bound to be a compromise. In the Ford machines, use is made of three main spars, of which the middle one is situated approximately at the point where the depth of the aerofoil section is a maximum, the other two being placed ahead of and behind this. In between the main spars, there are lighter stringers of U section, but these serve only to stiffen the skin, those in the centre-section and end portions of the wing not being connected together.
   The main spars are of duralumin, and have flanges of D section, built up from two strips. The top and bottom booms of the spars are joined by an N girder of plain trough section. Joining is by fishplates and riveting. The wing centre-section being of uniform profile, the spars in this are not tapered, but in the outer wing portions there is pronounced taper, and towards the wing tips, the depth of the N girders decreases to the point where the two D section flanges are joined directly together. Of wing ribs in the ordinary sense, there are none. Vertical and diagonal members, lying in a fore and aft plane, and short straight members roughly forming the wing contour, take the place of ribs, and the final aerofoil section is obtained by the metal covering of the wing. This covering is of "Alclad," a "sandwich" with sheet aluminium in the centre and a thin coating of aluminium on each side. The aluminium is, of course, subject to the effects of the air, and a thin film quickly forms, which acts as a protection for the duralumin underneath. It is said that if this thin film is scratched, the chemical action causes it to "heal," which is not, of course, the case with the anodic process surface.
   At the outer ends of the centre-section main spars, and at the inner ends of the wing piece main spars, there are steel forgings of high-grade steel and fine quality workmanship which are riveted to the D section booms of the spars. These forgings terminate at their free ends in either plain or forked ends, and connection between the centre-section spar and wing end spar is by a horizontal bolt. Six bolts secure one wing end, and the assembly and dismantling of a wing-end is an amazingly quick process, as well as one calling for no skill. In fact, the tool most frequently used is a "Brummagem screwdriver."
   The engines are mounted very much as in British machines, one in the nose and two under the wing. The wing engines are carefully faired in, and the “Wasps" in the 5-AT-C have, in addition, a development of the N.A.C.A. cowling, which looks not unlike a Townend ring, but which is, we are assured, really quite different. Drag is further reduced by enclosing the wheels, all but a small portion, in streamline casings. The wheels, by the way, are fitted with Lockheed hydraulic brakes. A tail wheel with castor action is fitted instead of a tailskid, and as the wheel brakes can be independently operated, the machines can be turned in a very small circle on the ground.
   The passenger accommodation in the Fokker monoplanes is comfortable. There is no leg room "thrown away," but the space could not be described as cramped. The seats, of the aluminium bucket type, are comfortable, the ventilation is good, and hot air can be admitted to the cabin through louvres in the floor, which draw warm air from a muff around the exhaust pipe of, the central engine.
   The pilots cockpit ahead of the wing and cabin is protected by windows, and the view obtained is very good. Dual controls are provided, and the layout of the instrument board impresses one as being particularly good. Complete navigation equipment is carried, and the wing headlights proved their worth on the very first flight to London, when the machine landed in fog and darkness at Northolt.