The Zoche aero-diesels are a trio of radical German prototype diesel radial aero-engines intended for light aircraft, designed by Michael and Georg Zoche in the 1990s. Zoche aero-diesels are modular piston engines and are all direct-drive, air-cooled, radial two-stroke diesels with up to four cylinders per row. They all feature direct fuel-injection, two-stage charging (turbocharger and supercharger), and intercooling. In each plane (or row), all the pistons connect to a single throw on the crankshaft.
The testing and gestation period of the Zoche engines has already lasted over 25 years; and whether or when production may eventually start is unknown. However, in 2019, Georg Zoche posted this message online: "Don't worry and remain patient; we are working on it".
The range comprises three radial engines, namely: a "cross-4"; a twin-row "cross-8"; and a V-twin. As yet, there are no plans for a 3-cylinder version.
The AOPA website explains the "cross-4" ZO 01A as follows: "The radial design was chosen for its ability to be effectively air-cooled and 100% balanced at all rpm with a simple counterweight system. All four connecting rods are attached to a single crankshaft throw. This prevents any crankshaft twisting, which is hard to balance out in opposed-configuration engines. Zoche engines use a pneumatic starting system that does away with the need for a heavy-duty starter and battery system". Propeller rotation is clockwise (viewed from the cockpit). Engine mountings are attached to the cylinder heads. Engines are to be certified to JAR-E and FAR 33, and a TBO of 2,000 hours is anticipated.
The founder of the project is Michael Zoche, who claims that the ZO engines will have the following advantages:
A Zoche engine has run effectively in wind tunnel tests, but Zoche seem barely any closer to production than they were a in 2010. Experimental engine manufacturers seem to experience difficulties in proceeding beyond the prototype stage. The cited engine weights include: starter-generator, hydraulic propeller-governor, turbocharger and supercharger, and oil- and fuel-filters.
A consequence of the modular design, with all engines sharing parts (such as an intercooler), is that the larger engines have a much higher power to weight ratio than the smaller engines, as follows:
The Lambert Mission 212, a kit-built 4-seat aircraft from Belgium, was initially designed around the Zoche ZO1A engine; but, with the non-appearance of the Zoche, Lambert were obliged to select other engines, the DeltaHawkî DH200A4 (or DH180A4), or the XP-360 engine. In May 2010 the second M212 Mission (and first kit-built example) was successfully flown.
Patents: