Журнал Flight

Flight, October 16, 1914.

THE BOLAND AIRCRAFT AND JIB CONTROL.

   As far back as 1907 - when the question of the Wright patents for aeroplane control was not such an important matter in America as it is to-day - the late Frank E. Boland started experimenting with his system of control. In 1908 he made some successful public flights on a canard-type biplane embodying his system of control. The latter was not only entirely original in form, but possessed undoubted properties as regards automatic stability. With this system of control wing-warping ailerons and vertical rudders of the orthodox type are dispensed with, and in their place are two "jibs" mounted one at each extremity of the main planes. These jibs serve to control conjointly both the lateral balance of the machine and its direction in a horizontal plane, the direction up and down being governed in the usual way by means of an elevator. In this way the control has been brought down to the simplest form possible - almost as simple as that of a motor car - for only two movements are necessary, the rotating of a wheel for steering to right or left, and a fore and aft movement of the vertical column carrying the wheel for longitudinal control. The jibs, which are somewhat pear-shaped, are mounted at the extremities of the main planes as shown in Fig. 1. They are pivoted about an oblique axis extending from the lower end of the front strut to a point about one-third from the top of the rear strut at an angle of 45° to the horizontal. The axis passes through the jib from the lower foremost corner close to the leading or forward edge, so that there is considerably more surface below and at the rear of the axis than there is above and forward of the same. Normally each jib is in a vertical plane, forming a side curtain at each end of the planes - (a), Fig. 1 - but on the rear edge of either of the jibs being pulled inwards - (b) and (c) Fig. 1 - the jib so moved presents a surface - in the direction of flight - inclining upwards both fore and aft, and outwards. This is equivalent to a surface having a negative angle of incidence, and produces a downward pressure, as well as a drag, on that side of the aeroplane at which the jib is pulled in. To make a turn, therefore, the jib on the side it is desired to turn is pulled in, with the result that a drag is caused on that side as well as a depression causing the machine to bank over the correct amount in turning. When the turn is complete the other jib is pulled in for an instant and the machine strightens out. Side-slipping on a turn is, it is claimed, impossible, as the jibs are so arranged and proportioned that they automatically provide the correct amount of bank at all times. To a large extent lateral balance is maintained by the jibs when in their normal position - as in the early Voisin machines with side curtains - but should the machine bank over owing to being caught by a side gust, &c, the jib on the high side is pulled in immediately the bank is felt, when the machine will be brought to an even keel without deviating from a straight course; if this bank is not corrected, however, the machine will merely make a turn corresponding to the amount of bank. The jibs, which move inwards and one at a time only, are connected to a control wheel by cables attached to the former near the trailing edge, whilst a spring loaded cable is attached to the leading edge of each jib and to some convenient part of the machine for the purpose of bringing the jib back into the normal position after being released.

The Boland "Tailless" Biplane.

   This system of control has been tried on several types of machines. The first was a canard-type biplane, but as the model turned out in 1913 differed only in detail improvements we will confine our remarks to the latter type, which is illustrated by Fig. 2. It will be seen that it follows somewhat the general arrangement of the English "Valkyrie" monoplanes. The main planes are double-surfaced and built up in three sections. The centre section includes the chassis, nacelle, and engine, and so forms the main unit to which the outer sections, each measuring 15 ft., are attached. The latter are built up on two main spars, the front one of which forms the leading edge, whilst the rear spar is spaced a distance of two-thirds the chord from the front one, so that there is a large amount of flexible trailing edge. The ribs are of the Wright type, consisting of top and bottom spruce battens, with solid spruce blocks in between. Top and bottom planes are separated by eight pairs of spruce struts, the balancing jibs being mounted on the two outer pairs. Mounted on the lower plane of the centre section is a coracle-like nacelle, the front portion, containing the pilot's and passenger's seats, extending well forward of the planes, whilst the rear portion carries the power plant, the propeller being situated midway between the top and bottom planes just behind the rear spars. Unlike the "Valkyrie" monoplane, there is no fixed stabilising plane in front, but a large pivoted elevator measuring 12 ft. span by 3 ft. 6 ins. chord, carried by four outriggers some 13 ft. forward of the main plains. In flight the elevator is held presenting a lifting angle, so that it supports a certain amount of load. It is double-surfaced, having a pronounced camber, and is connected by cables to a Derperdussin type rocking yoke, which also carries the wheel operating the jibs. The round-nosed extensions of the outriggers can be detached from the latter, and with them the elevator, whilst the outriggers themselves are detached in two units, each consisting of an upper and lower longeron. The latter form continuations of the chassis skids, being connected to the top ones by vertical struts. A steel axle carrying a pair of running wheels is mounted by means of rubber bands on the skids proper under the front, pilot's, seat. The engine, which is mounted in the rear of the nacelle, is a 60 h.p. 8-cyl. water-cooled Boland, weighing complete 240 lbs. The principal dimensions are as follows :- Span, 35 ft. 6 ins.; chord, 5 ft. 6 ins.; gap, 5 ft. 6 ins.; supporting area of main planes, 373 sq. ft.; overall length, 21 ft. 9 ins.; weight with fuel, 900 lbs.; speed 60 m.p.h. This machine has also been flown with success as a hydro-biplane, the wheels having been replaced by two long pontoon floats.