J.Herris Otto, AGO and BFW Aircraft of WWI (A Centennial Perspective on Great War Airplanes 37)

Otto Tractor Biplane

   The next original Otto B-type design was this two-bay biplane. With the Otto pusher already in production and the Prussian preference for tractor airplanes, the new B-type was designed as a tractor for acceptance by the Prussian air service. The pilot was seated in the rear cockpit that was separated from the front observer's cockpit by a significant distance, impeding in-flight communication between them. The long fuselage had large side area to stabilize the aircraft so no fin was fitted, just a movable rudder. A variety of 100-160 hp aero engines were fitted depending on availability.
   No military designation was formally given as the aircraft was not adopted by the military.

Журнал Flight

Flight, April 9, 1915.

A NEW OTTO BIPLANE.

   GENERALLY speaking, the Munich firm of Otto had confined their attention, before the war, to the production of machines of the engine-behind type. As, however, the German military authorities, unlike our own, discouraged the construction of "pusher" biplanes, nearly all the firms who had up to then been turning out engine-behind machines, concentrated on the production of tractors. A new one of these built by the Otto firm was completed and tested shortly before hostilities broke out, and as it showed excellent capabilities both in weight-lifting, speed and carrying capacity, it would appear probable that a number of these machines are being used against us, and a few notes regarding the type should therefore be of interest.
   Fundamentally, the new German Otto biplane follows fairly closely on standard lines, and such improvements as have been effected are mostly to be found in a reduction of head resistance wherever possible, a reduction which has resulted in a considerably higher speed than that usually found in German aeroplanes. The body, which is of rectangular section, is topped with a turtle back in which are the openings for the pilot's and passenger's cockpits and for the engine. The rounded nose, which is covered with aluminium sheeting, provides a very good entry for the air, thus contributing considerably towards the high speed obtained, i.e. about 87 miles per hour. The engine - a 150 h.p. Rapp - is mounted on stout ash bearers in the nose of the body, and is, as will be seen from the accompanying illustration, fitted with a long exhaust pipe running back along the side of the fuselage to a point behind the pilot's seat, so as to convey the exhaust gases out of the way of the occupants.
   In the floor of the body, ahead of the front seat, which is occupied by the observer, an opening is provided through which an unrestricted view is obtained in a downward direction for purposes of observation or for taking photographs. In addition, mica windows are fitted on each side of the body in front of the observer's seat, so that by stooping down inside the body he can be out of the draught and still obtain a fairly good view on each side.
   In plan form the main planes, of which the upper one has a slight overhang, have a pronounced taper towards the tips, that is to say, the greatest chord is in the centre, the leading edge sloping backwards and the trailing edge sloping forwards. The lower planes are attached to the sides of the body, whilst the upper planes are attached to a centre section carried on a steel tube structure coming up from the upper longitudinals of the body. Small service tanks for petrol and oil are fitted in the angle between these centre struts and the centre section of the upper plane. Two pairs of steel struts on each side of the body connect the upper and lower main planes, and cross-bracing is effected by means of stout stranded cables. The drift is taken by internal cross-bracing of the wings and by cables running from the top of the first front inter-plane strut to the nose of the body. Control is by means of the usual hand lever for longitudinal and lateral control, and a pivoted foot-bar for directional control. Large sized ailerons are fitted to the trailing edge of the upper plane only.
   A chassis of the simple V type, usually found on modern German tractors, is fitted. It is built up of stream-lined steel tubes, cross braced with thick stranded steel cables, and carrying the tubular axle which runs right across from side to side. The tail planes consist of a semicircular stabilising plane, to which is hinged the divided elevator, and of a partly balanced rudder, hinged to the stern-post of the body. Sufficient fuel is carried for a flight of five hours' duration, which gives a radius of action of approximately 220 miles. No figures are available regarding the rate of climbing, but it is said to be exceptionally good.