My air-conditioned workshop is situated in an idyllic valley of our sub-tropical mountain hinterland. The machine tools are all of good quality and have been chosen specifically for the task. I produce almost every stage of each component. This brief description of the manufacturing processes will demonstrate the extraordinary care that is taken.

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Propellers

There are two sizes, 6x3 and 6x4, designed specifically for the pb 0.33 engine and moulded in fibreglass reinforced polyhexamethyleneodipamide resin. I made the models and patterns by hand and pantographed the moulds in the traditional manner. The plastics injection gates are central to align the glass fibre reinforcement and to avoid the weakness of weld lines. The moulds were precisely polished to give balance to the propellers. Immediately after moulding on my NESTAL machines, each propeller was carefully packed to protect the fine edges.

Engine Crankcase

I mould the aluminium crankcase using investment casting. A set of injected wax mouldings is encapsulated within a ceramic investment. Aluminium, A 356 alloy is vacuum cast into the void remaining when the wax is subsequently burnt out. The process is a craft and each crankcase bears a surface that is unique. I heat treat the castings before commencing the multitude of machining operations needed to complete the crankcase. During machining, the casting is mounted and carried upon a precise hardened steel fixture to maintain the squareness and position of each feature.

Crankcase Bushing

This is machined from bronze alloy bar and pressed into the crankcase. It is micro-honed to a fine, accurate size and finish.

Crankshaft

I machine the shaft from one piece of EN 36 A alloy steel bar. It is case hardened before I precision grind the journal and crankpin diameters and faces. The milled, rotary inlet port is integral with the crankshaft.

Thrust Washer

Machined from steel bar, this is cased hardened to run against the bushing if pusher propellers are used. It is driven by two flats on the crankshaft and has a spigot to centralise the propeller.

Propeller Washer

Made from polished aluminium, it is recessed to enclose the socket head propeller fastening bolt.

Extension Spool

This accessory is machined from aluminium bar and can be used to extend the propeller mounting further forward. It is supplied, with a longer propeller fastening bolt.

Cylinder

I machine this from steel bar. The exhaust port and three fuel transfer ports are accurately milled before the hardening process. The cylinder is then precision ground on the location flange and on the outer surface that locates within the micro-honed diameter of the crankcase. I precision grind the bore at 65,000 RPM before diamond honing to match with a specific piston.

Piston

This is machined from steel bar and hardened and tempered before being precision ground to size. I diamond hone the gudgeon bore to an accurate size and finish.

Contra Piston

This too, is from hardened and tempered steel, precision ground to an accurate fit within the cylinder.

Connecting Rod

I machine the rod from 7075 T6 high strength aluminium alloy. The big-end is micro-honed to an accurate size and finish. The hardened and ground gudgeon pin is pressed into the rod to locate it within the piston.

Head

The head is machined from aluminium bar. The cooling fins are radiused at the root to promote heat transfer. A nylon lock screw is incorporated to give added retention to the compression screw.

Compression Adjustment Screw

This is machined from brass to screw freely within the very fine thread of the aluminium head. The hard alloy steel tommy bar has domed ends.

Back Plate

Injection moulded from high temperature glass reinforced poly-phenylene sulphide plastics, this incorporates an 0 ring seal.

Single Speed Carburettor

Again, this is moulded from glass reinforced PPS plastics, with the inlet and mounting holes drilled after moulding to avoid weakening weld lines. It incorporates a surface jet spray bar and smooth venturi for good fuel atomisation. I bolt it against a machined crankcase surface with socket head cap screws.

Variable Speed Carburettor

This alternative is mounted in place of the single speed carburettor using brass studs and nuts. The body and lever are moulded from ‘glass reinforced PPS plastics. The engine speed is varied by restricting the air intake with a hardened and ground drum that can be rotated by the attached lever until stopped by the adjustment screw. Fuel mixture is firstly adjusted using the needle of the stationary spray bar and then with the air bleed screw within the body.

Needle Valve Assembly

The outer components are finely machined from brass bar while the metering needle is machined and taper ground from hardened alloy steel. This needle seals against an internal seat and can be opened to adjust the fuel flow through a cross drilled surface jet. The fuel tubing can be led either to the integral plastics tank, or to a tank within your aircraft.

Fuel Tank

I mould this from transparent, high-impact polyamide plastics. It is retained and sealed by an O ring. The capacity can be reduced by cutting the tank to the lower retention ring.

Exhaust Flap

This engine speed control is supplied with the single speed carburettor option. It is not supplied if you choose the more effective, variable speed carburettor. The stainless steel flap is rotated on the bronze bushing to restrict the exhaust. It will then decrease the engine power and speed sufficiently for many applications. There is a small outlet to allow continuous, low speed operation with the flap closed.

Exhaust Manifold

The optional, machined aluminium manifold can attach a shorter or longer length of flexible tubing to lead the exhaust from the ‘plane.

Assembly

The parts are ultrasonically cleaned before assembly. Each engine is hand started and test run just prior to dispatch.