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Anzani 3-cylinder

Anzani 3-cylinder

72 Anzani fan engine, Shuttleworth Collection
Type	Three-cylinder air-cooled
National origin	France
Manufacturer	Anzani
Designed by
Major applications	Blériot XI

From 1905 to 1915, built a number of three-cylinder fan and radial engines, one of which powered Louis Blériot's 1909 cross-channel flight. An Anzani three-cylinder engine that powers a Blériot XI based in England is thought to be the oldest airworthy engine in the world.

Design and development

Alessandro Anzani began building motorcycle engines in France around 1905. Unusually, his motors were air- rather than water-cooled, making them light. His first designs were two-cylinder V-engines, and he rode machines powered by them to records and race success in 1905 and 1906. In the same period he had developed a three-cylinder version, more powerful than the twins. As the image shows, the engine fitted neatly into the cycle frame. Engines with cylinders arranged radially but only in the upper half-circle were termed fan type, or semi-radials; by about 1910 other manufacturers were building e.g. five-cylinder fan engines, most notably Three-cylinder fans were alternatively known as W or W-3 engines. The appeal of the fan configuration was that, because all the cylinder were above the horizontal there was little danger of the plugs being fouled by the lubricating oil. The disadvantage, particularly for an aircraft engine, was the extra weight required to counter-balance the pistons.

In response to the growing interest in aviation in France after the Wright brothers' visit in 1908, Anzani produced the first of a series of three-cylinder fan flight engines. The cylinders were each a single iron casting and the one-piece crankcase was aluminium. Pistons were steel with cast rings. In most of these the outer cylinders were at 60 to the central one, though a contemporary diagram shows one, described as the cross channel engine, with a 55° angle. They were all air-cooled side-valve engines; each exhaust valve was controlled from below by a cam in the crankcase. Each was mounted in a cell to the side of the cylinder, with the automatic, atmospheric pressure -driven spring-loaded inlet valve immediately above it, partly to minimise volume and partly to help cool the hot exhaust valve. Most contemporary and pre-1921 sources agree that the bores of these early engines were between 100 and 105 mm (3.93 and 4.13 in), but strokes between 120 and 150 mm (4.72 and 5.90 in) are quoted. Most put the output of these engines at about 18 kW (24 hp) at around 1,400–1,600 rpm.

It was an engine of this sort that famously powered Louis Blériot's Type XI monoplane across La Manche (the English Channel) on 25 July 1909. Contemporary sources differ on its bore, stroke and swept volume. The first description of the successful machine in Flight describes the engine as having dimensions of 100 × 150 mm, or a capacity of 3.53 litres. However, a few months later they printed the engineering drawing of the 55° engine, which has dimensions of 103 x 120 mm marked on it, clearly captioned as "used ... in the cross-Channel flight". If their identification was right, then Bleriot used a 3.00 litre engine. A head-on photograph of the cross-channel aircraft also shows a 55° engine.

Even before the channel flight, Anzani was selling more powerful versions with larger bores: a 120 mm bore, 4.4 litre (269 cu in) variant produced 26 kW (35 hp) and a 135 mm bore, 6.4 litre (390 cu in) engine gave 36 kW (45 hp). These fan engines remained in production until at least 1913, though there were important improvements. The exhaust valve was moved to the cylinder head and operated by rockers via push rods, and a mixing chamber was arranged in the crankcase. The 1913 three-cylinder Anzani fan engine had a cylinder separation of 72, presumably to lighten the counterbalance. By this stage it had its inlet manifold at the rear of the engine to minimise airflow cooling of the fuel air mixture.

Anzani was aware of the weight cost of the counterweight in the fan configuration and by December 1909 he had a symmetric 120 three-cylinder radial engine running. One example was a 3.1 litre (186 cu in) unit producing 22 kW (30 hp) at 1,300 rpm. Although termed the Y engine after its symmetric cylinder arrangement, it ran in an inverted Y position so that the plugs, mounted on the upper in-plane side of the two lower cylinders were only 30 from the vertical and less prone to oiling.

Applications

Survivors

The restored and flyable Blériot XI, registry number N60094 at Old Rhinebeck Aerodrome uses one of these Anzani three-cylinder "true radial" engines for its straight-line, short distance "hop" flights. Another Blériot XI, with British registry G-AANG, is allowed to fly short 'hops' at the Shuttleworth Collection, its original "fan-type" Anzani three cylinder engine is thought to be the oldest airworthy aircraft engine in the world. A 1910 Deperdussin monoplane that is also restricted to straight 'hops' uses a 'Y' type Anzani engine.

Engines on display

At the Museo Nacional de Aeronáutica Argentina there is a Three Cyl Anzani radial in working order installed on a Bleriot 11. A Y three cyl engine is on display at the Engines hall at the same Museum