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Aviation History
1922
1922 - 0571.PDF
• ... gg_Mj OCTOBER 5, 1922 THE BOULTON AND PAUL " BOLTON" (P. 15) Two 450 H.P. Napier "Lion" Engines IN our issue of September 14, 1922, we published photographs of the new Boulton and Paul " Bolton " all-metal biplane (in skeleton), with two Napier " Lion " engines. On Friday of last week we paid a visit to the Boulton and Paul works at Norwich, where we had the privilege of examining the machine and of seeing it flown by Mr. Courtney. As the " Bolton " is built for the Air Ministry, but few particulars may be published, but the accompanying photographs, showing the machine after being covered will give a very good idea of the general lines. Concerning the really interesting features of the new biplane, i.e. the all-metal construction, nothing may be said, and the following notes therefore deal with the general design rather than with constructional details. Although the " Bolton " bears a certain family resemblance to the famous " Bourges," it differs from the earlier machine not only in size, but also in several other important respects. The power plant consists of two Napier " Lion " engines, vibration of the lower plane, a fact for which no doubt the special design of engine mounting is responsible. Whiie on the subject of the engines, reference may be made to the unusual starting arrangement, which is one of the neatest we have seen so far. Instead of mechanics having to climb about on the machine in order to reach and turn the starting handle, arrangements are made in the " Bolton " for starting the engines from the ground, long shafts running from the engines, inside the nacelles, down to the tail end of the nacelles, where a starting handle can be inserted and the engines turned over by a mechanic standing behind the trailing edge of the lower plane. Not only is this position very comfortable and allows of maximum effort being applied, but should the mechanic slip his foot will not go through a plane or damage some important part, as is apt to occur in machines where the mechanic lias to stand on a wing or other part. The petrol system consists of main tanks mounted in the Three views from above of the Boulton and Paul "Bolton "Lion" engines. all-metal machine, with two Napier mounted fairly high in nacelles carried on the lower plane. As the question of efficient cooling is one about which com paratively little is known, it is of interest to note that in the " Bolton " the Napier engines are left uncovered to an unusual extent, with the consequence that radiators of relatively small size can be employed. A further advantage of this arrangement is that the exhaust silencers, which are of the patented Boulton and Paul type, with aluminium manifolds terminating in steel pipes having saw-cuts in them, are very efficiently cooled. In spite of their simplicity and lightness, these silencers are certainly very effective, as we had an opportunity "of ascertaining, and it appears probable that the combination of exposed engines and small radiators offers no more resistance than enclosed engines with large radiators and complicated exhaust pipe arrange ments. Another feature noted in connection with the engines was the absence of vibration. When both engines were running all-out on the ground it was not possible to detect any fuselage, with pumps (driven by windmills) constantly de livering to a feeder tank, also mounted in the fuselage, but at sufficient height to give gravity feed to the carburettors. Thus there is no petrol in the engine nacelles, while unsightly gravity tanks, externally mounted, are avoided. The wings are of usual form as regards their external appearance, but are, like the rest of the machine, built entirely of steel, with exception of the covering, which is the usual doped fabric. It would of course, be possible to make the covering of metal also, but it is thought that the extra weight which this would entail would outweigh any advantage arising out of metal covering. The ailerons are of the type in which the hinges are placed some distance back from the leading edge, the balance being formed by the forward third of the aileron and not by a horn balance projecting forward outside the wing tip. Several interesting features are incorporated in the tail. Thus in addition to the usual trimming tail plane, a trimming fin has been employed, which works in a manner similar 571
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