Lorraine 9N Algol


The Lorraine 9N Algol was a French 9-cylinder radial aeroengine built and used in the 1930s. It was rated at 500 hp (375 kW).

A conventionally laid out radial engine, with nine cylinders in a single row. The crankcase was a barrel-shaped aluminium alloy casting, with an internal integral diaphragm which held the front crankshaft bearing. Forward of the diaphragm there was an integrally cast cam-gear case for the double track cam-ring. The reduction gear was housed under a domed casing attached to the front of the crankcase.

Flange-mounted steel barrels were bolted to the crankcase and enclosed with cast aluminium alloy, screwed-on, cylinder head with integral cooling fins. The pistons were also made of aluminium alloy and had floating gudgeon pins. The nine pistons drove the single throw crankshaft via one channel-section master rod and eight circular section auxiliary rods. The master rod had an integral, split type big-end. The crankshaft was machined from a single forging, with bolt-on balance weights.

The Algol had a single pair of overhead inlet and exhaust valves per cylinder. The cam-ring drove roller tappets, mounted in the cam-case, which in turn operated rocker arms, fitted with ball bearings, via pushrods. The cam-ring was concentric with the crankshaft and driven via epicyclic gears.

Most Algols were conventionally aspirated via a single carburetter but at least one 1938 variant used a form of fuel injection, where fuel was blown into the induction system rather than the cylinder head.


ANF Les Mureaux 120
Bernard 161
Bloch 120
Bloch 500
FBA 290
Potez 33
Romano R.16
Weymann 66


Type: 9-cylinder single row supercharged radial
Bore: 140 mm (5.51 in)
Stroke: 150 mm (5.90 in)
Displacement: 20.78 L (1,268 cu in)
Length: 1.347 m (53.2 in)
Diameter: 1.275 m (50.2 in)
Dry weight: complete 390 kg (860 lb)
Valvetrain: one inlet and one exhaust overhead valve per cylinder, operated with rocker arms, pushrod driven via roller tappets bearing on a double track cam-ring
Fuel system: single Stromberg carburettor, heated by exhaust
Fuel type: petrol
Cooling system: air-cooled
Reduction gear: 11:17
Power output: rated 221 kW (296 hp)
Compression ratio: 6:1