A very remarkable type of aëroplane is the giant biplane invented by the Russian aviator Sykorsky. It doubtless marks the beginning of a new era in the construction of machines on the heavier-than-air principle. Most aviators have shirked the use of a machine that could carry a large number of persons. It would seem that Russia is destined to take the lead in this class of machine, which may before long put the lighter-than-air Zeppelins entirely out of date. The machine of Sykorsky is not, indeed, a mere project, but a reality, for at Petrograd on February 25th, it flew for eighteen minutes with sixteen passengers on board. They represented a weight of 1,300 kilogrammes. The height attained in this flight was 300 metres. On February 27th the machine flew from Petrograd to Tsarskoe Selo and back again, taking nine persons, in two hours six minutes, at a height of 1,000 metres. The performance constituted a triple record of distance, height, and duration of flight with nine persons on board.

The following are the dimensions, etc.:—

Length20 metres
Span37 metres
Surface182 sq. metres
Distance between planes2.80 metres
Motive power4 Argus motors
(100 h.p. each)
Weight of motors220 kgs.
Weight of machine without
passengers		3,500 kgs.
Weight with 16 passengers4,800 kgs.

The motors are placed in groups of two on each side of the body of the machine. Each pair works a screw and each individual motor can be put into action and stopped separately. The body of the machine contains a chamber for the pilots three square metres in size, a passenger salon of five square metres, and two other chambers of three and two square metres respectively. The whole are lit by four windows on each side. The rooms can be artificially lighted by electricity and warmed by motor gas. There are, indeed, future possibilities for such a machine in war!

I have mentioned that the type of aëroplane devised by Lieutenant Dunne is characterised by a distinctive principle of its own. The claim is made that it is automatically stable. It has, however, rather a claim to “inherent stability” than “automatic stability,” if we accept the terms as Professor Bryan has defined them.

The following details appeared in the “Aëronautical Journal”:—

The salient features of the machine are the backward slope of the planes, which, in plan view, form an angle with the apex in the direction of flight, and the absence of a tail or supplementary planes of any description. The following are its chief dimensions:—Span, 46 feet; length (fore and aft), from apex to rear wing tip, 20 feet 4½ inches; length of body, 19 feet; surface, 500 square feet; weight (including pilot and six gallons of petrol), 1,700 lb.; engine, four-cylinder 50–60 h.p. Green, 1,100 r.p.m., driving twin propellers placed one on either side of the body in the rear.

The weight in flight being 1,700 lb., the aëroplane carries a load of about 3 lb. per square foot. The speed in flight averages about 40 m.p.h.

The chord of the surfaces is even throughout—6 feet; the vertical distance between the surfaces is also constant at 6 feet; at either extremity a vertical curtain is placed between the surfaces to prevent leakage of air sideways. The surfaces slope back from the apex at an angle of 58° on either side, the rear wing tips, therefore, actually being in the rear of the aft end of the body, and the entire outer extremities of the wings lying back well behind the centre of gravity.

The curve or camber of the planes is not uniform, and, briefly, it may be said that each wing may be viewed as a portion of the surface of a cone with the apex to the rear. A consequence of this is that the angle of incidence of each wing gradually decreases from the root to the tip; so much so, that while the angle at the root is positive, that at the tip is distinctly negative, the difference in the respective angles being 45°. Apart from this, an interesting feature is the extreme downward bend of the trailing edges over a short distance where the two surfaces meet in the centre; this arrangement has been adopted chiefly to enable the aëroplane to right itself naturally in the event of its having assumed a vertical position in the air. A further interesting consideration is that this machine is the only one that could safely be forced backwards. It may be added, briefly, that the loss in efficiency arising from the negative angle of the wing-tips is compensated by the backward slope and angle of the surfaces, which naturally causes the flow of air to be depleted outwardly beneath the planes, and even induces a certain amount of compression beneath the outer ends. The body is entirely covered in; the pilot’s seat is in the prow; the motor further to the rear. The centre of gravity is well forward, and about six inches above the lower plane. The propellers are carried on a transverse girder, and are chain-driven in the same direction—contra-clockwise viewed from the rear. The centre of the boss is situated 1 foot 2 inches above the lower plane, and 4 feet from the central axis of the machine. The propellers, designed by Capt. Carden, are of solid wood, 7 feet in diameter, 7 feet 6 inches pitch, each weighing 21 lb. The chassis comprises two main wheels, with a small wheel-and-skid fore and aft. The system of controls is extremely simple. The trailing edge of each extremity of the upper plane forms a hinged flap, measuring 7 feet 2 inches by 1 foot 9 inches. These are independently controlled by two levers, one on either hand of the pilot a couple of mirrors allow the pilot to ascertain the working of the steering-flaps when in flight. The throttle control is fixed to the right-hand lever.