The Lorraine <<Sirius>> 18-cylinder, air-cooled, type 112 air-cooled aviation engine is currently in the early stages of development. Indeed, this engine of nearly 46 liters of displacement is likely to have a greatly increased power.

The S.N.C.M. has indeed assigned for this engine a first power limit: 1,000 HP, to allow the systematic study of the various parts for their possible modification or confirmation for the evolution of the engine to a much higher power. As it currently stands, its construction features are as follows:

Oilpan. - In three pieces forged alugir. The forged metal, in addition to its higher strength, gives a greater safety coefficient than the cast metal, as a result of better homogeneity.

The bearing support webs are an integral part of the housing, which gives a perfect rigidity of the shaft line.

The AV bearing is a double roller, forming a stop for the crankshaft.

The middle bearing is a roller, as well as the AR bearing.

Cylinders. - The cylinders are composed of two assembled parts: the barrel and the cylinder head.

The barrel is made of high strength treated steel, with large cooling fins.

The cylinder head is cast aluminum, to which are attached, hot-screwed, the steel intake valve seat, the exhaust valve seat and the bronze spark plug and starter seats. The breech is likewise screwed hot and fretted on the barrel; very wide fins ensure cooling, even in the worst conditions.

Crankshaft. - The crankshaft is in 4 parts, with assembly by cone and key ensuring an absolute rigidity.

The 2-pin crankshaft at 180° is supported by three bearings. It drives to the AV the gear reducer plate and to the AR the compressor control and accessory controls.

It is equipped with a central bearing, which has the advantage of increasing the stiffness of the shaft line and eliminating any vibration, whatever the speed.

Engine coupling. - The two rows are each constituted by a master rod, with 8 links and their pistons.

The main rod is in one piece, double-T section, and journalled on the crankshaft by means of a bronze floating pad, internally and externally regulated.

The rod has a fork-shaped head, the axis being supported on the main rod by 3 eyes.

The piston is forged alugir and carries 3 pressure segments and 2 double scraper segments.

Distribution. - Each cylinder includes:

• 1 stainless steel intake valve.
• 1 hollow exhaust valve with liquid sodium cooling.
• Each valve is recalled by 2 concentric springs and is controlled by rocker arm and rod.
• 2 cam plate systems, one to the AV, the other to the AR for each respective row.

Lubrication. - The oil is circulated by 2 gear pumps.

1 high-volume pump sends the oil under pressure into the crankshaft and ensures the lubrication of the various components.

1 drain pump returns to the tank the oil recovered in the sump, through the carburetor to heat it.

Supercharger. - It is of the centrifugal type with only one speed, assuring to its turbine a multiplication of speed of 9.1, and restoring the pressure to 4.000 m. altitude.

The turbine is in electron and is supported by 2 bearings: one with rollers, the other with smooth ring.

The compressor control is of Lorraine type with epicyclic train with torsion shaft and oil control clutch by inertia valve.

Carburetor. - To facilitate resumption and starts, the carburetor is in charge on the supercharger, it is equipped with an intake limiter and an automatic gasoline corrector.

Ignition. - The ignition is of the shielded type.

Gearbox. - Lorraine type with epicyclic gear train.

Reduction ratio: 11/17.

Accessory controls. - These controls are operated via torsion shafts.

They are divided into:

• Generator control with automatic and progressive clutch;
• Vacuum pump control;
• Onboard compressor control;
• Machine gun control;
• Rev counter (tachometer?) control;
• Control of mechanical AM fuel pumps.
• Possibly train lift (lifting gear? landing gear?) pump control.