L.Opdyke French Aeroplanes Before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing
Flight, August 23, 1913.
THE BOREL MILITARY MONOPLANE.
As the new 80 h.p. Borel monoplane has been specially designed to comply with the requirements of the military authorities, the first consideration has naturally been given to the provision of such qualities as are desirable, not to say essential, in a military machine. As these qualities include speed, weight-carrying power, stability, wide range of vision, facilities for bomb dropping, and the installation of quick-firing guns, as well as a wireless telegraph apparatus, it will be easily understood that numerous difficulties - aero-dynamic and constructional - have to be overcome in order to produce a machine embodying all of these features, and all credit is due to the Borel firm for their bold attempt to solve the problem.
From a glance at the accompanying illustrations it is at once apparent that the most noticeable departure from usual Borel practice lies in the positions of the pilot and the propeller. Whereas all previous Borel monoplanes have been of the tractor type, it will be seen that in this machine the propeller is placed behind the main planes, whilst the pilot's and passenger's seats are situated well out in front of the wings. Needless to say this position provides an excellent view in all directions for the pilot, while the passenger is also so situated that he is able to survey practically all that lies beneath the machine.
In the construction of the nacelle, which is of rectangular section, provision has been made for the mounting of a quick-firing gun, which will be worked by the passenger, whose seat, it will be observed, is placed slightly in front of the pilot's seat, thus giving both more room to enable them to operate gun and controls, respectively, without interfering with each other. The nose of the nacelle has been so designed that in flight it will deflect the air upwards over the heads of the occupants, who will fully appreciate this little attention to their comfort. In the rear end of the nacelle is the 80 h.p. Gnome engine supported between two pressed-steel frames, the front one of which serves at the same time as a support for the rear-wing spar and the rear members of the top pylon. The rear engine frame carries a ball-bearing, in which runs the propeller-shaft, or, more correctly speaking, the extension of the crank case on which the propeller is mounted.
In a monoplane of the engine-behind type, one of the constructional difficulties is that of suitably mounting the tail planes on an outrigger which will withstand torsional strains and at the same time allow of the propeller clearing all its members. In the Borel military monoplane this difficulty has been overcome by constructing the outrigger of three instead of four booms. These are in reality steel tubes, the upper one of which abuts against the boss of the propeller through the interposition of a ball-bearing. The two lower members are secured to the rear end of the chassis skids. One of our sketches shows the method of joining the struts to the tail booms, and it will be noticed that the joint is effected without piercing either boom or strut, and thereby weakening them. Another sketch shows the chassis, which impresses one as being particularly strong without affording an undue amount of head resistance. On the rear ends of the main skids will be noticed two small tusk-like extensions which are sprung in order to lessen shocks due to the tail dropping and which perform really the duties of a tail skid in the absence of a special fitting of that nature.
An interesting point in connection with the control of the machine is that the rudder and elevator cables are carried inside the two lower tubular tail booms, so that should any one of them break there is no danger of them becoming entangled in the propeller.
It has already been said that a wireless telegraph apparatus is carried. This in itself can hardly be said to be a novelty, as already messages have been sent from aeroplanes in flight, but once the machines are on the ground their utility for transmission of wireless messages is greatly decreased owing to the lack of a mast on which to secure the antennes.
The Borel machine has been so designed that it can be made to form its own mast. By standing the machine on its nose, so that it rests on the skids and on the nose of the fuselage, the tail booms are inclined upwards. Another pair of tubes of smaller diameter, which during flight are enclosed in the lower tubular tail booms, now form extensions on which the antennes may be mounted. A small auxiliary motor is provided for the production of the necessary current.
When put through its preliminary trials by M. Daucourt the machine behaved excellently, getting off easily with a passenger and three hours' fuel.