Jabiru Aircraft Pty Ltd, I
An aircraft and engine company from Australia and their aim is to develop and sell reasonably priced aircraft and engines. There are not many companies building both aircraft and engines, but Jabiru Pty is one of them. Development started when the need came to power their in house designed aircraft when their supplier ceased production.
They started with a 60 bhp 1600cc engine to power their aircraft and after many moons this resulted in the 80 bhp four cylinder Jabiru 2200, later followed by the 120 bhp six cylinder Jabiru 3300. At one time they were also working on an eight cylinder Jabiru 5100.
They also manufacture a successful line of experimental and certified aircraft ranging from two to four seaters, all developed around and powered by their own engines. We will concentrate on the powerplants here.
The engines, if you take a look at them, are of the same basic design philosophy. The concept is simple and straight forward. The description below applies to all models. They are capable of running on Mogas or AVgas.
Jabiru engine design, Part I
The crankcase halves, cylinder, crankshaft, starter motor housings, gearbox cover (the gearbox powers the distributor rotors) and coil mounts together with many smaller components are machined using modern CNC machine tools. The sump is the only casting part.
The cylinders and crankshaft are machined from solid bar 4140 chrome molybdenum alloy steel, with the pistons running directly in the steel bores. The journals of which are precision ground prior to being Magna flux inspected. The camshaft is provided by a specialist camshaft manufacturer.
The propeller is direct crankshaft driven without a reduction gearbox. The crankshaft features a removable propeller flange which enables the easy replacement of the front crankshaft seal and provides for a propeller shaft extension to be fitted. Cylinder heads are machined from solid aluminium billet. Connecting rods are machined from 4130 alloy steel, the 45 mm big end bearings are of the automotive slipper type.
An integral alternator using rare earth magnets, provides alternating current for battery charging and electrical accessory drive. The alternator is attached to the flywheel and is driven directly by the crankshaft. The ignition system is a transistorized electronic system; two fixed coils mounted adjacent to the flywheel are energised by rare earth magnets attached to the flywheel.
The passing of the coils by the magnets creates the high voltage current which is then transported by high tension leads to the center post of two old school automotive type distributors (which are simply rotors and caps) before distribution to automotive spark plugs, two in the top of each cylinder head. The ignition system is fixed timing and, therefore, removes the need for timing adjustment. It has suppression resistors to prevent radio interference. The ignition system is fully redundant, self generating and does not depend on ships battery power. Much like a Rotax engine.
The engine is fitted with a 1 kW starter motor, which is also manufactured by Jabiru and provides very effective starting in all conditions. It has very low vibration levels, however it is also supported by four large rubber shock mounts attached to the engine mounts at the rear.
Crankshaft & Pistons
The crankshaft is designed with a double bearing at the propeller flange end and a main bearing between each big end it has no flying webs due to the opposed cylinders. 48 mm main bearings are also of the automotive slipper type. Thrust bearings are located for and aft of the front double bearing allowing either for tractor or pusher installation.
Made in Ozzie
Pistons are General Motors aftermarket made in Australia and are re-machined to include a piston pin cir clip groove. They are fitted with three rings, the top rings being cast iron to complement the chrome molybdenum cylinder bores. Valves are 7 mm (stem dia) which are purpose manufactured for the Jabiru engine in England.
Text partially from Jabiru.