PB Engine Australia

A quality micro diesel model aircraft engine

Model Aeroplane Engine

 

Manufacturing Process

 

Concept

I determined to make and sell the best miniature model aircraft engine that I could. A small diesel was chosen because of the functional simplicity and because it is most difficult to make well.

Design

The engine design developed from experience, from practical considerations and personal preference.

0.33 cc., or 0.02 cu.in. capacity was the smallest nominal size I could efficiently make, that could be used in free-flight, control-line and radio-control models, both outdoors and indoors.

I see beauty in form-follows-function styling. My engine was to have no unnecessary detail nor decoration. A smaller engine cannot simply be a scaled larger one, but I enjoy this difference from commonplace proportion.

Materials used had to be obtainable and able to be processed on machinery that I could acquire.

Component sizes and threads were selected to suit available tools and screws. Owners would be able to dismantle and service their engine.

Always, the aim was that it be the best. While using good, standard practice, the design would embody features and construction detail not found in any other small diesel.

With all this in mind, I made my first sketch and set the process in motion. I began to source the machines, to make the moulds, to sell our house so as to build a workshop and new house in a rural location, to sell our plastics moulding business, to make the tooling and then to develop the prototype engines.

Equipment

My machinery was chosen and bought specifically to manufacture this engine. I had definite ideas on what I wanted and it took some years to obtain the machines. Some were new; others required more or less rebuilding; several have historical significance. All are good, in good condition and ideally suited to their tasks. I shall give detail as I enlarge on the making of engine components.

Tooling

Throughout my experience, production engines have always performed better than the most carefully made prototypes. I am sure that some of this gain results from the square-ness and accuracy of precise jigs and fixtures used to locate the components during machining. The ultimate machines are those used to make machines and so I thoroughly enjoyed making the tools I use to manufacture my engine. These are often more elaborate than needed, but I prefer it that way.

Testing

The first prototypes were tested. Changes were made. Some tooling was remade. Various materials combinations were tried. Parts tolerances were established and CAD drawings finalized.

I made the first small production batch of engines and tested and checked the performance of each one.

I only then offered the engine for sale.

In some applications, the exhaust restrictor speed control did not lower the speed enough, so I later developed a variable carburettor.

There have been, and will continue to be, small refinements made.

Processes

There are many different processes needed to make engine parts and each of these processes involves other sub-processes. For instance, casting of a crankcase includes, moulding of the waxes, encapsulating of these within the investment, burnout, casting of the molten aluminium, removal after cooling and then subsequent heat-treatment before any of the multitude of machining operations can commence.

Uniquely, I carry out all these needed processes at one place and in a manner that I can describe and show.

Commercial Viability

It is unrealistic to expect that this venture could be a truly economic proposition. The engine was designed to function well rather than to be made at the lowest cost. However, I am fortunate in that I have been able to acquire the equipment, to make the specialized tooling, and to establish the manufacture and presentation. It is intended that selling the engines will now cover the on-going costs.

Outcome

I am well pleased with my pb 0.33. The product and performance are as good as I wished. The reviews have been excellent and the customers are happy.

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Peter Burford, PB Engine Australia