Anzani 6-cylinder

Anzani
Industry	Aircraft engine manufacturing
Founded	1909
Founder	Alessandro Anzani
Products	Two-row radial aircraft engines

Adapted from the English Wikipedia article Anzani 6-cylinder, available under CC BY-SA 4.0Updated 9 August 2025

Alessandro Anzani pioneered the initial two-row radial configuration by joining two of his previous 3-cylinder Y engines on a single crankshaft with a unified crankweb.

Development

By December 1909, Anzani had successfully operated a 3-cylinder air-cooled true radial engine, which was an advancement from earlier 3-cylinder fan (semi-radial) designs that powered Bleriot during his Channel crossing. By March 1910, he finalized the first two-row radial engine: a six-cylinder assembly created by combining two sets of three cylinders arranged at a 60° angle, with one set positioned slightly aft of the other. This engine maintained characteristics from its predecessors—featuring cylinders cast as single iron units with integral valve chambers and cooling ribs; pistons made of steel fitted with cast-iron rings. Initial models employed side-valve architecture with atmospheric inlet valves and exhaust valves mechanically actuated via crankcase cams. By late 1912, exhaust valves were relocated to cylinder heads, controlled by push-rods and rocker arms, positioned at the front while the fuel inlet manifold was placed at the rear. Noticeable 150° exhaust pipes were installed, and spark plugs were arranged to reduce fouling.

The crankcase consisted of an aluminium casting; subsequent iterations incorporated a fuel mixing chamber and utilized long bolts for securing cylinders. The engine utilized a single kinked crankweb connected to wide connecting rods to limit axial displacement between cylinder rows—less than that seen in later double-row radial engines—with the rear face of the front row nearly aligned with the central plane of the rear row. This slight offset, observable from behind, means the design was not perfectly radial and is referred to as désaxé.

The earliest six-cylinder radials featured a bore of 90 mm and stroke of 120 mm, resulting in a displacement of 4.58 litres (280 cu in) and generating 34 kW (45 hp) at 1,300 rpm, weighing approximately 70 kg (154 lbs). Later variants expanded displacement to 6.23 litres (380 cu in), increasing power output to 45 kW (60 hp).

Variants

45 hp (34 kW): This initial two-row radial by Anzani produced 34 kW (45 hp) from a displacement of 4.58 L (280 cu in).
60 hp (45 kW): Featuring larger cylinder dimensions, this version delivered 45 kW (60 hp) at 1,300 rpm from a total displacement of 6.23 L (380 cu in).
TNCA Aztatl: A Mexican-produced exact replica of the 60 hp six-cylinder Anzani engine, manufactured by TNCA (Talleres Nacionales de Construcciones Aeronáuticas).