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Aviation History
1947
1947 - 0233.PDF
FEBRUARY 13TH, 1947 FLIGHT UNIVERSAL POWER PLANTS ment points and a remote gear box for accessories. Details of its various structures and systems follow. A rigid triangulated engine support of welded steel tubes forms the backbone of the whole power plant. The engine is carried on four feet, of which the front two are secured by fitted bolts and the rear two by bolts which permit movement for thermal expansion. From the forward end of the mounting is slung the beam which supports the radiators. Much interesting information was brought to light dur- ing wartime investigation of engine vibration. Fractures of radiators and exhaust stubs were traced to this cause and cured, in the main by redesign of mountings. The introduction of rubber mountings for radiators has increased fll^r life tenfold. Isi America, incidentally, a civil aircraft cannot be granted a C. of A. until the whole airframe has been vibra- tion tested. There has been no similar regulation in this country. It is understood that when the Lincoln was first tested with three-bladed airscrews, excessive vibration occurred, and de-synchroniza- tion between engines and air- frame was required. Four- bladed airscrews in this case effected a cure. A slight cropping of the airscrew blades removed a similar trouble in Mosqui- toes. Recent strain- gauge measurements of the engine mount- ing have shown that the strength safety factor is consider- ably over the accepted figure. Work is now pro- ceeding on a structure of reduced weight. The main supports for the cowling are a channel-section ring at the rear and a flexible light-metal diaphragm mounted on the engine reduction gear casing in front. Top panels open like a car bonnet, and side panels hinge down to form servicing platforms. The rear cowling ring is The main tubularengine mounting and the rear bulk-head which sup- ports the cowling areshown to advantage in this photograph. 159 designed to lie forward of the main bulkhead so that air- frame designers may select the most suitable fore and aft engine position, and it is left to them to provide the 'J-P-P. top cowling panels are hinged to give access for in-spection and the large side panels can be used as maintenance platforms. The air-intake fairing and exhaust flap areshown separately. Installation drawing of the Merlin Universal Power Plant. Theengine mounting, and the cooling and air-intake systems, have been accentuated. small pressure-tight panels aft of the cowling ring. Additional sections are the radiator intake scoop which carries the air-intake fairing, and the lower panel carrying hinges for the cooling flap Side, top and bottom panels are made of 10 S.W.G. Duralumin sheet which, incidentally, is sufficient to give some protection against small arms fire and shrapnel. Full armour for military installations calls for the use of 4 mm armour plate with a weight increase of about ioolb per power plant. The main induction-air intake is placed below the spinner in a forward-facing position, taking full advantage of ram. A duct leads the air back to the supercharger intake, and embodied in the system are a hot-air intake and an air filter. A two-position forward-facing flap valve has been let into the duct at the point where it passes behind the radia- tors. With flap in the up position, hot air passing through the radiators is drawn into the engine, and with the pres- sure cowling outlet closed an intake temperature rise of 65 deg C is possible in conditions of extreme cold. Air filtration is desirable on transport aircraft, particu- larly those serving countries with dry climates, in order to avoid the need for engine changes before the established overhaul period With the increase of rated altitudes the
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