MidWest AE series

AE series
Type	Wankel aero engine
National origin	United Kingdom
Manufacturer	Mid West Engines Ltd.

The MidWest AE series are lightweight liquid-cooled single- and twin-rotor Wankel engines with dual ignition for light aircraft, formerly produced by Mid-West Engines Ltd. at Staverton Airport, Gloucestershire, UK.

This engine had its origins at the BSA Umberslade Hall research unit in Birmingham. David Garside, a BSA engineer, designed an air-cooled twin-rotor motorcycle engine that was based on the Fichtel & Sachs motor in the Hercules motorcycle. Wankel engines run very hot, so Garside gave this air-cooled motor interior cooling air that was drawn first through the rotors and into a large plenum before entering the combustion chambers via the carburetors. Only 100 air-cooled Norton Classics were produced. The later Norton Commander had liquid-cooling, but with the same air-cooling of the rotors as the Classic. These Norton engines had a total-loss oiling system, just like an oil-injected two-stroke engine.

Very closely based on the Norton engine, the MidWest engine nevertheless took things a stage further. The lubrication system became a semi-total-loss system whereby Silkolene 2-stroke oil was directly injected into the inlet tracts and onto the main roller bearings, but the oil that fed the bearings became an oil-mist within the rotor-cooling air, and around 30% of the oil was recovered and returned to the remote oil tank. Unlike the Nortons, the rotor-cooling air was forced in by a belt-driven centrifugal pump and then dumped overboard as it was considered too hot for ideal volumetric efficiency. Instead, ambient-temperature combustion air was inducted into the engine separately. Early Midwest engines had simple Tillotson carburettors, but these proved unsatisfactory, and later engines were fitted with fuel injection. This gave the advantage both of excellent fuelling, and avoided any need for carb heat.

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