Miles M.4 Merlin

Пятиместный туристский моноплан M.4 Merlin представлял собой увеличенный вариант самолета M.3A Falcon. Первый полет прототип выполнил в 1935 году с мотором de Havilland Gipsy Six мощностью 200 л. с. Построено четыре самолета, два использовались в Индии, один - в Австралии.

Flight, April 1935

THE MILES "MERLIN"
New Five-seater with "Gipsy Six" Engine and Very Complete Standard Equipment: High Performance with Economical Running Indicate Fitness for Taxi Work

   NOT many months pass without rumours of yet another new machine about to be produced by Phillips and Powis at Reading. This firm has been in existence as aircraft constructors for only a little over a year, but already it has produced the "Hawk," "Hawk Major," "Hawk Racer," "Falcon," and now the "Merlin." Mr. Miles, the firm's designer, is, incidentally, probably unique in the aviation industry, as he has, in his drawing office, the help of his wife; Mrs. Miles is, with him, equally responsible for the originality and success of the machines they have designed and built.
   The "Merlin" is the outcome of collaboration between the constructors, Flt. Lt. G. Birkett (Birkett Air Service, Ltd.) and the Tata interests, who operate extensive air lines in India. The first model is being delivered to Flt. Lt. Birkett for his taxi services. It is particularly interesting as, with the exception of racing machines, it is the first standard British civil aeroplane to be designed to use a controllable-pitch airscrew, and it is also being marketed with an unusually full equipment - a commendable feature which we hope to see become general practice.
   In view of these features, let it not be thought that the "Merlin" is suitable only for the commercial operator. That is far from the case; it should prove equally attractive to the private owner who wishes to buy a machine with a high performance, and one which is ready to go anywhere at any time without the necessity for extra equipment being purchased.
   In general, the "Merlin" is a development of the "Falcon" (described in Flight of January 10) - a machine very much in the news at the present time owing to Mr. Brook's record flight in the prototype from Australia. The seating accommodation has been increased so that five persons can now be carried in perfect comfort, one beside the pilot in front and the other three on a sofa seat behind. Furthermore, the luggage locker, which lies immediately behind and slightly above this latter seat, is deep enough for a stretcher case to be carried, and a patient can be transported without removal from the stretcher.
   Structurally, the "Merlin" is a low-wing wooden-built monoplane with box plywood and spruce spars, plywood-covered wings and fuselage, and cantilever undercarriage; it differs from the earlier Miles machines in small details only, the span of wing has been increased, and this has resulted in an increase of the taper and aspect ratio. A further departure from the "Falcon" is an increase of the dihedral angle of the wings to 7 deg., which has had the effect of making the "Merlin" very stable and comfortable to fly.
   The general design of the cabin is very like that of the "Falcon"; the forward-sloping windscreen has been retained, as has the neatly hinged cabin door, while large windows on each side of and above the seats make the cabin particularly light and give a pleasantly "airy" impression.
   The engine, a D.H. "Gipsy Six,” is carried on a welded-steel-tube mounting, and the neat cowling which surrounds it is obviously responsible to no small extent for the exceptional performance of the machine.
   Like all modern P. and P. machines, the "Merlin" is fitted with the Miles wing-flap gear, which is hydraulically operated by a small quick-acting pump near the pilot's left hand.
   A short flying trial soon showed that the "Merlin" is a very considerable advance over anything which Mr. Miles has yet designed. In spite of the fact that the new Ratier controllable-pitch airscrew was not then available and that a standard wooden airscrew had to be used, the performance was quite outstanding. With five people and full tanks the take-off was below the two-hundred-yard mark, and with flaps down the landing speed was, by A.S.I., about 46 m.p.h. In the air it is at once noticeable that the increased dihedral of the wings gives that high degree of positive lateral stability which, we consider, is a desirable feature of commercial aeroplanes. The “Merlin” can be flown “hands-off” for long periods with perfect safety, even without the feet on the rudder-bar; in other words, directional as well as lateral stability is ample and definite. Furthermore, we are assured by the designer that bumps are corrected without any undue lurching, so that the machine may be considered as one which can be safely left to fly itself while maps are examined or lunch is eaten. This is a very desirable feature, particularly when it is combined with a high degree of manoeuvrability, and when, as in the "Merlin," the fin areas are so proportioned that turns can be made without touching the rudder.
   The occasion of our flight was one of fine drizzling rain, so it was possible to prove the practicability of the unusual windscreen design; it was extremely pleasing to find that there was no difficulty at all in sitting forward so as to get very near the windscreen - a great help in conditions of this kind.

Another Attractive Feature

   As can be seen from the table on p. 353, the ratio of gross weight to tare weight is unusually good for this class of aeroplane, thus there is yet another reason why the machine should prove admirable for taxi operators. That is really just what would be expected when it is known how the “Merlin" came to be conceived. Even with the high percentage payload which can be carried - in the present model the figure is about 800 lb. - the range is excellent, the tankage for forty-four gallons of fuel permitting journeys of about 800 miles without refuelling, and when the controliable-pitch airscrew is available both this and the cruising speed will probably be improved.
   The last truly commercial aeroplane - that is, one which enabled operators to make profits - to be built as the direct outcome of a designer giving an operator what he asked for was, perhaps, the D.H. "Dragon." This was designed as a result of collaboration with the late Mr. E. Hillman, and proved to be one of the most successful machines of recent times. It is interesting to note that it was built of wood just after a phase when most machines were built in metal. Now we have the "Merlin," also built in similar circumstances and also of wood , if it finds as much favour among operators abroad as has the other, it will certainly appear that the old argument that aeroplanes for abroad had to be of metal has ceased to carry any truth.
   In conclusion, the completeness of the equipment is again worth mentioning The controllable-pitch airscrew will, as soon as it is available, enhance the already outstanding performance; the electric starter, navigation lights, and landing lights built into the leading edge are what we hope to see as standard on all aeroplanes before long.