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Aviation History
1918
1918 - 1142.PDF
••- --_ /• OCTOBER IO, 1918. ' -welded joints under tension. In the triplane the shackles passed over the foot bar, the vertical tubes being welded to the front of the bar, thus avoiding the tension on the welded joint. The method of making the shackles is very simple, as shown in the detail sketch of Fig. 5. A short length ot tube of small diameter has its ends slotted and flattened out, holes being provided in the flat portion for the vertical bolt. Fig. 8.—The mounting of the compass on the Fokker biplane. Note the adjusting magnets mounted on a square section brass rod under the base plate. These magnets are locked in position and sealed by a lead seal. The tube is then bent and the shackle is finished. In Fig! 5 the floor boards have been omitted on the starboard side to show the controls, but under the left foot guard will be seen a segment of aluminium which serves to protect the floor against the constant rubbing of the pilot's heel. Another such guard is, needless to say, '.Jtted under the right foot. The grip in which the control column terminates at its upper end is quite different from that found on the Fokker triplane. In the present machine the grip consists of a small piece of wood, shaped to fit the fingers of the right hand, and having a slight hollow at the top for the thumb. The triggers for the machine guns are not pushed by the thumb as in the majority of other machines, but are pulled by the fingers towards the grip. On/the port side of the control lever is mounted a Bowden control for the throttle. The handle of this had been knocked off in the machine examined, so it has been impossible to ascertain its exact shape. It has there- fore been shown dotted in the sketch. This lever does not operate the throttle direct, but is connected to the proper throttle lever mounted on the port side of the body by Bowden cables. The object evidently is to enable the pilot to work the throttle from the control lever during a fight, insteadA>f having to shift his hand and possibly fumbling about for a few seconds before getting hold of the main throttle lever. It will be noticed that no provision has been made in the biplane for locking the elevators in position, the necessity for doing this having apparently been avoided by the arrangement of the gun and engine controls. Before leaving the subject of controls reference may be made to the lateral control system of the Fokker biplane, which is ssmewhat unusual. In order to facilitate an explanation of the principle on which the aileron control is based, we have prepared a diagram. Fig. 6, which shows, in purely diagram- matic form, the paths followed by the aileron cables over the various pulleys. It will be noticed that the lower plane has not been included in the diagram. This is due to the fact that nowhere do the aileron control cables pass over or through the bottom plane, as is usually the case in German machines, specially when the typically German aileron crank levers, working in slots in the top plane, are fitted. In theFokker- biplane the crank levers ar,e vertical as in British machines. So far as one is able to judge, the object which the designer had in mind whan working out this control system was to provide positive control, not only to the aileron that is being pulled down, but also to that being pulled up. The manner in which this object has been attained in the Fokker. will be understood by a reference to Fig. 6. In the explana- tion to follow we shall refer to the cable pulling down the ailerons as a positive cable, and to that pulling up the ailerons as the return cable. In the diagram the two sets of cables have been drawn differently, the positive cable being shown by a chain dotted line, while the return cables are indicated by a plain dotted line From the crank on the longitudinal rocking shaft in the fuselage the positive cable runs through a guide on the top longerons (not shown), over a pulley mounted on the top rear spar, al yag the spar, around another pulley, and hence to the lower aileron crank. The return cable from the same crank arm in the body runs through the same guide on the top longeron, to a pulley at the side of that for the positive cable, along the spar in the opposite direction to that of the positive cable, over another pulley and hence to the top crank of the aileron. The arrows in the diagram will help to make the arrangement clear. Thus, when the control lever is pulled to port, the positive cable pulls down the starboard aileron, and the return cable pulls up the port aileron. Tanks. As far as wehavebeen able to ascertain, all the tanks carried on the Fokker biplane have been incorporated in one single tank of brass. The oil tank occupies the extreme starboard side of the tank, then comes a small reserve tank, and on the port side, partitioned off from the reserve tank, the main tank, which, judging from the lines of rivets visible on the outside, is divided up into two compartments communicating Fig. 9.—-Sketch showing mounting of one of the Spandau guns on thel Fokker biplane. Inset, the clips securing'the cartridge boxes to the fuselage. with one another. From external measurements the capacity of the various tanks is approximately as follows : Oil tank, 3 gallons ; petrol, 20 gallons. These figures are only approximate. Both petrol tanks work under pressure, supplied by two pumps, one driven by the engine and the other hand operated. As shown in Fig. 7, the mounting of the tank is rather unusual, there beingf no supporting bands passing underneath the tank, which is slung from the top cross tub*s of the body by means of brackets and bolts, as shown. #' • • •
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