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Aviation History
1923
1923 - 0531.PDF
SEPTEMBER 6, 1923 light up the interior, and illumination is further provided byqjectric lights inside the engine room. An amazing number of instruments, dials, etc., are to bewatched over by the engineer, chiefly on account of the care, that has been taken in planning the installation to ensure thatthe machine shall not be forced down by engine trouble. Thus there are six separate petrol tanks, so arranged that anyone can be shut off should it become holed by shot or damaged in any way. The radiators are in six separate sections, anyor all of which can be shut off so as to reduce the amount of water lost owing to a leak or puncture to that contained in onecell. All this interconnection naturally means a considerable amount of piping, etc., and at first sight it seems impossiblethat one man could look after all the revs, counters,thermo- meters, oil-pressure gauges, taps, etc. Probably, however,an engineer who has once become familiar with the location of length is such as to fill completely the gap between fuselageand propeller shaft. In this position, therefore, the radiators are always subjected to the slip stream irom the tractorscrews, so that the engines can be run when the machine is standing on the ground or taxi-ing. As already mentioned,the radiators are divided each into three sections. These sections, or cells, are all of equal size, so that an element canbe removed from any point and inserted at any other. The consequence is that but a single small element is needed as aspare. Each element is provided with piping to a distributor box in the engine room, and taps for inlet and outlet areprovided for each element, so that both inflow and outflow can be regulated or completely shut off. From the upper and lower edges of the radiators fabric-covered streamline casings project aft, but these do not quite meet at their rear edge, leaving a space for the air to escape. THE BOULTON AND PAUL " BODMIN " : View of the engine room and transmission. the various items would have no difficulty in keeping an eyeon everything. The propellers, as already stated, are mounted some distanceout, between the wings. The two front ones are tractors, and run in opposite directions, the port being of right-hand and thestarboard of left-hand pitch. The pushers, which are four- bladers, run in opposite direction to the tractors in front ofthem, i.e., the starboard one is right-hand and the port one left-hand, and are of smaller diameter than the two-bladedtractor screws. The drive is bylong shafts and bevel gears, the whole transmission being designed and constructed byNapiers. In connection with the mounting of the propellers it is ofinterest to note that the structure carrying the shafts, gears, and propellers is entirely independent of the wing structure,although superficially it might appear to be part thereof. Each shaft runs out from the engines horizontally, and issupported at its outer end by a strut sloping up from the lower longerons of the fuselage. Cable bracing in the plane of thesloping struts completes the structure, but in order to relieve the structure of a certain amount of load a cable is run fromthe forward gear-case to the top longeron at a point in line with the rear diagonal strut. This cable transmits thepropeller thrust to the fuselage. The radiators are placed in front of, and in fact supportedfrom, the driving shafts to the front propellers, and their In the gap between these two surfaces, some little distanceahead of their trailing edge, are mounted oil radiators which cool the lubricating oil from the bevel gear casings. Placedas they are in the air stream behind the water radiators, the action of these oil coolers is automatic. The main petrol tanks, of which there are two on each side,are slung on the fore and aft members of the transmission structure. This member is in the form of a beam composed oftop and bottom tubes, separated by short tubular struts and braced by wire. The tanks are cylindrical in shape, and intheir centre is an opening slightly larger than the beam, so that the tanks can be slipped over the end of the beam. Theyare then secured in place, fore and aft, by screw-on flanges. Rubber pads are interposed between the beam and the innerwalls of the tanks. By undoing the four bolts securing the beam to the gear casings the tanks can be removed veryrapidly. Mounted above the top centre section are another two tanks,one of which is normally used as a gravity tank into which petrol can be pumped from either or all of the four main tanks.The second top tank is not normally in use, but should the gravity tank be holed by a shot the other top tank can beturned on and the gravity tank shut off, so that the loss of petrol is confined to that contained therein. A similar systemof inter-connection has been employed in the case of the other tanks, so that it is difficult to see how a complete breakdown 531
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