Dornier Do B Merkur, Do C Komet III, Do D и Do T

Последним в семействе сухопутных транспортных самолетов Komet был Do C Komet III, первый полет которого состоялся 7 декабря 1924 года. Он создавался как улучшенный и увеличенный по размерам вариант Komet II. В конечном итоге получился новый самолет, который имел такое же родство с летающей лодкой Delphin III, как Komet I и II с летающими лодками Delphin I и II. Komet III был оснащен двигателем Rolls-Royce Eagle IX мощностью 360 л.с. (268 кВт), хотя на самолеты позднего выпуска могли устанавливаться двигатели Liberty 12 мощностью 400 л.с. (298 кВт) или Napier Lion мощностью 450 л.с. (336 кВт). Самолет мог перевозить шесть пассажиров при двух членах экипажа. Komet III использовался на авиалиниях в Германии, Дании, Швейцарии и СССР (на Украине). Небольшое число этих машины строилось по лицензии в Японии фирмой "Kawasaki" с двигателями Eagle IX, Lorraine-Dietrich 12 или лицензионным вариантом BMW.
<...>

Flight, March 1921

A NEW GERMAN ALL-METAL MACHINE
The Dornier C3, 185 B.M.W. Engine

   IN our issue of December 16, 1920, we published a description of the Zeppelin Dornier machines built at Lindau. This series of "Milestones" included the latest monoplane flying boat produced at the Zeppelin works at Lindau, and it was mentioned that the products of Herr Claude Dornier, chief designer of the firm, were well worth watching. At the time we also promised to keep our readers informed of any new developments that might come along. An opportunity of keeping this promise has now occurred, the Zeppelin factory having produced a new and highly interesting monoplane to the designs of Herr Dornier. There is, we believe, quite a keen competition going on between the Zeppelin works at Lindau and those at Staaken (the chief designer at the latter factory being Herr Rohrbach) to see who can first produce a really successful commercial machine. The Zeppelin Staaken four-engined monoplane was described and illustrated in our issue of March 17, when we also reproduced the first photograph to be published in this country of a wind channel model of the new twin-engined Staaken monoplane which is now under construction. While Herr Rohrbach seems to devote his attentions to fairly large machines, Herr Dornier at Lindau now appears to specialise more in the smaller, single-engined type, the latest of his productions being the C3 monoplane illustrated herewith. For the illustrations and data relating to this machine we are indebted to the German aviation journal Illustrierte Flug-Woche.
   The Do.C3, as the new machine is styled, is an all-metal monoplane with fairly thick wing section. A peculiarity, which the Do.C3 shares with the previous monoplane flying boat, is that, although the wing is of deep section, it is tapered neither in chord nor in depth. The consequence is that it has not, apparently, been found possible to make it a true cantilever wing, it having a pair of struts on each side to support it. Aerodynamically it is an advantage to taper the wing, as a fairly high L/D ratio can then be obtained while still retaining a fairly high maximum lift. Such a tapered wing, however, is more expensive to build thin is a parallel one, and possibly it is this fact which has influenced Herr Dornier in his choice of wing form.
   Constructionally the wing of the Do.C3 is interesting on account of the fact that it is built of metal throughout. The framework of the wing is in steel, while the covering is stated to be sheet Duralumin. Although this covering does undoubtedly strengthen the wing, no account of this has been taken in stressing the machine, and the covering is merely intended to act as a means of maintaining the exact curvature of the wing, it having been found that in high-lift wings quite minute changes in curvature may sometimes have extraordinarily great influence upon the aerodynamic properties. The wing is without dihedral, and is built in one complete unit from tip to tip, the centre of the wing resting on the top of the cabin. Bracing is by means of four streamline section steel tubes, two on each side, running to the lower longerons of the fuselage. Owing to the considerable depth of the body, the angle of the bracing tubes is very good. Small ailerons are fitted near the tips, and the cranks, etc., for operating the ailerons are buried inside the wing.
   The tail plane is also of approximately rectangular plan form, and is a cantilever structure of similar construction to that of the main plane. The elevator is divided and unbalanced. The rudder, on the other hand, has a balance portion projecting forward above the fixed vertical fin. Tail planes and control surfaces are also covered with aluminium alloy.
   The fuselage is a steel structure covered with Duralumin, and is very deep in front, the engine being mounted fairly high, and the centre of thrust only slightly below the level of the wing. The cabin is aft of the engine, from which it is separated by a fireproof bulkhead. Seating accommodation is provided for six passengers, who enter the cabin through a door in the starboard side, direct from the ground, without needing any steps, the floor of the fuselage being exceptionally low over the ground. Windows are provided in each side of the cabin, and as the wing is above the cabin the passengers obtain an unobstructed view of the ground. It is pointed out that as the machine is intended to a great extent for use over the beautiful scenery of Switzerland, this is a great advantage. Great attention has been paid to the prevention of fire on board, all fuel tanks being situated in the wings, outside the body.
   The pilot is placed aft of the cabin, his cockpit being located just aft of the trailing edge of the wing. Here, it is claimed, he obtains a very good view, as he is on a level with the trailing edge, and can thus look over or under the wing at will.
   Perhaps one of the most interesting features of the Do.C3 is the undercarriage. This, it will be seen from the accompanying illustrations, is in the form of two short wing roots totally enclosing the wheel axle, with a disc wheel at each end. It would be difficult to imagine a simpler undercarriage, and although the structure is probably fairly heavy, as it almost necessarily must be in order to take the loads from the wheels at the ends of the two short cantilever wing roots, the resistance should be quite small.
   The engine fitted to this machine is a 185 h.p. B.M.W. over-dimensioned, high-compression six-cylindered motor, which is one of the best examples of modern German engine design. It is very economical in fuel, even when running throttled, while the effect of the design is to enable the engine to maintain its full power up to a height of about 10,000 ft. The normal power for cruising is 200 h.p. at 1,400 r.p.m., while for short periods, such as for getting off, the engine can be revved up to 1,500 r.p.m., when it develops about 240 h.p. As the machine is fairly lightly loaded per square foot of wing surface, she is said to get off well and to have a good climb, while requiring only a short run for getting off.
   The following are the main data relating to the Do.C3 :- Span, 55 ft. 9 ins.; length o.a., 29 ft. 10 ins.; height, 8 ft. 3 ins.; chord, 9 ft. 10 ins.; wing area, 506 sq. ft.; weight, empty, 2,420 lbs.; useful load, 1,600 lbs.; weight, fully loaded, 4,020 lbs.; load per sq. ft., 7.95 lbs.; load per h.p. (on 200 h.p. basis), 20 lbs.; maximum speed, 105 m.p.h.; cruising speed, 80 m.p.h.; ceiling, 16,500 ft.; fuel consumption, .45 lb./h.p./hour; oil consumption, .022 lb./h.p./hour; range, about 400 miles.