A SINGLE SKATER CABIN MONOPLANE The A.B.C. ” ROBIN ” with ” Conduite Interieure “
WHEN the very small, simple single-seater machine materialised in varied forms in this country some 7 years ago, the possibilities which it offered for the would-be private owner, were such as to cause considerable optimism, and enthusiasm ran high regarding what was popularly referred to as the motor-cycle of the air.” For one reason or another, however, the development of this type of machine was not proceeded with and the resources of those marmfacturers who were responsible for its inception, were later given up to the production of the two-seater light aeroplane as we know it to-day. More recently, the small inexpensive machine has been revived and an example of the type is to be found in the little A.B.C. ” Robin,” which is manufactured by the A.B.C. Motors Ltd.
While conforming to accepted principles of construction the ” Robin” is unusual as a single-seater in that is a cabin type of machine. As will be seen from the accompanying illustrations it is a high wing monoplane with V-strut bracing. The wings can be folded back so that it can be housed comfortably in a hangar of only 18 feet by 12 feet dimensions and this folding operation takes only 30 seconds.
Throughout the designing, simplicity has been aimed at and this feature is particularly noticeable in regard to the fuselage which is built up of 4 spruce longerons with light struts and formers interposed. The whole assembly is covered with ply-wood veneer and wire bracing is dispensed with. The wing is built up in two halves and like the fuselage i8 of wood. The spars are of spruce and of I section. The wing ribs are also of spruce and made up in girder fashion strengthened with three-ply gussets. Across the top of the forepart of the fuselage two metal tubes are positioned, to the extremities over which are attached swivelling duralumin blocks. These blocks
which are drilled, take a locking pin which also passes through the metal fitting on the end of the wing spars and thus the wings are attached. The locking pins incorporate a spring-loaded locking device which, while allowing very rapid and easy dis-engagement (for wing folding), makes the assembly highly secure when the machine is in flying trim.
The embodiment of cabin arrangement naturally entails unusual depth in the front fuselage and this allows the designer to fix his lift struts at a very good angle. These struts, by the way, are of steel and neatly faired.
The 35-40 A.B.C. ” Scorpion ” engine is attached to an engine plate of multiplywood, the latter being fixed to the longerons with steel plates of very neat design. The nose of the fuselage just to the rear of the engine is stiffened by diagonal steel tubes and the whole assembly is particularly rigid without having any complicated system of bracing.
An undercarriage of the ” split ” type is incorporated in the general arrangement and this has a very wide track. It is of steel tube construction and embodies the usual shock absorbing medium of rubber cord. The empennage, with the exception of the outer frame of the fin and rudder, is of wood and the tail plane itself is wire braced internally. A simple means is employed to allow of the adjustment of incidence to the tail plane. This is done by two bolts which retain the rear spar to the fuselage and by simply slackening the lock nuts and screwing the bolts one way or another the angle of setting may be altered over a considerable range.
Cables operate all the controls and the dimensions of the latter are such as to give a nicely balanced control which is so desirable on a machine of so low a weight as 680 lbs.
The petrol and oil tanks are placed in front of the cockpit and the petrol is fed by gravity. The cabin affords plenty of room for the pilot and is exceptionally well equipped. It is lined inside with veneer and well finished, and a door is fitted on the starboard side. Care has been taken to ensure a good view from the cabin, there being sliding windows at the side, a V windscreen in
lront and a hinged skyfight forms the roof of the cabin. There is a hatch in the top of the fuselage at the rear of the cabin giving access to a locker which is sufficiently roomy to carry two large suitcases, and throughout it is apparent that the machine has been produced as a serious touring machine and not merely as a joyriding toy. According to the makers the top speed of the machine is about 105 m.p.h., while 1.1 the cruising speed is in the neigh
bourhood of 85 m.p.h. and this can becomfortably maintained with the engine developing two-thirds of its normal output only, and the landing speed is about 38 m.p.h. The following are the main dimensions and data of the ” Robin” :
4ins. ; Span (folded), lift. 4ins. ; Length, 17ft. 7ins. ; Height, 5ft. 9ins. ; Chord, 4ft. 6ins. ; Area of main planes (including Ailerons), 97 sq. ft. ; Ailerons, 13 sq. ft. ; Tail plane, 9 sq. ft. ; Elevators, 6 sq. ft. ; Fin, 2.5 sq. ft. ; Rudder, 4.5 sq. ft.; Weight (empty), 415 lbs. ; Weight (loaded), 680 lbs. ; Wing loading, 7lbs. sq: ft. ; H.P. Loading, 17 lbs. h.P. ;I Climb for first minute, 750 ft. ; Climb ceiling, 21,000ft. ; Range, 340 miles.
G. G. O. M.