Zoche aero-diesel
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, and intercooling. In each plane, 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".
Design and development
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. 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:
- they will be lightweight, compact and very smooth;
- low fuel consumption; high power-to-weight ratio;
- the lubrication system will allow aerobatics;
- diesel fuel injection, so no carburetor icing;
- direct-driven generator, so no drive belts;
- good reliability through a low part count and absence of poppet valves;
- pneumatic starting obviates both electric starter motor and heavy starter battery;
- complete absence of rubber hoses; cheaper parts through modularity;
- reduced fire risk compared to avgas;
- good power output, even at altitudes up to 9,000 feet.
- the engines will also have a "classic radial" appearance that is appropriate for some aircraft types.
Zoche engine variants
; ZO 01A; ZO 02A
; ZO 03A
; ZO 04A
A consequence of the modular design, with all engines sharing parts, is that the larger engines have a much higher power to weight ratio than the smaller engines, as follows:
- The 8 cylinder ZO 01A claims 2.43 bhp per kilogram;
- The 4 cylinder ZO 02A claims 1.78 bhp per kilogram;
- The 2 cylinder ZO 03A claims 1.27 bhp per kilogram.