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WW1 RFC Gnome Mono Engine manual (1916)

WW1 Gnome Mono Aero Engine Manual (1916)

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A very rare original WW1 aero engine manual covering the Gnome 'Mono', the 100 h.p. 9-cylinder Monosoupape B2 engine used by the Royal Flying Corps in 1916-17 in aircraft including the Avro 504K, Sopwith Pup and Sopwith Camel. This manual would have been extremely useful for officers, N.C.O.s and airmen undergoing training or operating and maintaining the RFC's aero engines. The book is undated, but was published c.1916, and is very well illustrated with numerous photos and diagrams, plus a large fold-out schematic plan of the engine. It covers all aspects of the use and maintenance of the engine, with detailed instructions for assembling, stripping, dismantling and repair. Subjects covered include: timing, running, dismantling, cleaning and reassembling, storage and dispatch, recent alterations, and data. Full-page photographs show the various parts of the engine and stages of dismantling and reassembly.

Gnome Monosoupape was a rotary engine design first introduced in 1913 by the Gnome Engine Company. The 100 h.p. B2 version was introduced in 1916. It used a clever arrangement of internal transfer ports and a single pushrod-operated exhaust valve to replace a large number of moving parts found on more conventional rotary engines. This made the Monosoupape engines some of the most reliable of the era. The British aircraft designer Thomas Sopwith described the Monosoupape as 'one of the greatest single advances in aviation'.

The 'Mono' was produced under license in both seven and nine-cylinder versions in large numbers in most industrialized countries including Germany, Russia, Italy, Britain and the US. Two differing nine-cylinder versions were produced, the 100 h.p. B2 and the 160 h.p. 9N. 2,188 units were produced under license in Britain.

The Monosoupape had no carburetor or throttle, and since most of its air supply was taken in through the exhaust valve, it could not be controlled by adjusting the air supply to the crankcase like other rotaries. Monosoupapes therefore had a single petrol regulating control used for a limited degree of speed regulation. In early examples, engine speed could be controlled by varying the opening time and extent of the exhaust valves using levers acting on the valve tappet rollers, but this was later abandoned due to causing burning of the valves. Instead, a blip switch was used, which cut out the ignition when pressed. This was used sparingly to avoid fouling the spark plugs, since it was only safe to be used when the fuel supply was also cut. Some later Monosoupapes were fitted with a selector switch which allowed the pilot to cut out three or six cylinders instead of all nine when hitting the blip switch, so that each cylinder fired only once per three engine revolutions but the engine remained in perfect balance.

The lubrication system, as with all rotary engines, was a total-loss type in which castor oil was pumped into the fuel–air mix. Castor oil was used because it did not readily dissolve into the fuel, and because it offered lubrication qualities superior to other available oils. Over two gallons of castor oil were sprayed into the air during each hour of engine operation. This explains why most rotaries were fitted with cowls, with the lowermost quarter omitted to direct the spray of castor oil away from the pilot. Unburnt castor oil from the engine had a laxative effect on the pilot if ingested. Because the entire engine rotated, it had to be precisely balanced, requiring precision machining of all parts. As a result, Monosoupapes were extremely expensive to build, the 100 h.p. models costing $4,000 in 1916 (approx. $89,000 in 2017).



In very good condition. The boards are in very good condition, with minor signs of wear. The binding and hinges are very good and secure. The text, photographs and diagrams are in very good condition.

Published: c.1916
Illustrated with photographs and diagrams
Khaki boards, with green and black titling
Dimensions: 125mm x 200mm
Pages: 240