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5 Cylinder Rotary Engine

Nigel Taylor

The idea was to build a small 5 cylinder rotary engine that runs on compressed air. A rotary engine rotates with the propeller and the crank remains stationary.

These are my initial sketches. I will try and improve these and add some dimensions, trouble is I tend to create a drawing that allows me to get started and then the design gets developed further as I machine parts.

This shows the Unimat 3 milling attachment mounted to the cross-slide of my Hobbymat lathe. You can just make out the indexing disc attached to the rear end of the headstock.

The basic milling operations have been completed at this point and the 9.5mm holes drilled ready to accept the cylinders.

The crankcase in a more complete state with the centre machined.

This shows the holes ready for the cylinders (larger holes) and the smaller holes that will be tapped 5BA and will be the main air inlet points for each cylinder. The air will be supplied through the centre of the crankshaft with a hole drilled lining up with these holes in the crankcase.

The cylinder liners are machined from steel. They are a tight fit into the outer finned aluminium cylinder jackets. The cylinders will be held in place with 4 off 8BA bolts through the cylinder head.If I can, the plan is to drill the hole half through the cooling fins.

I'm going to use a phosphor bronze bearing and a steel crank. There is some way to go yet....

It has been some time since I have even looked at this engine as we moved house and I lost it for 2 years!!!!

So having found it I remembered why I had put it all neatly into a bag and put it away - I broken a tap in the crankcase and just could not remove it.

Part 2 - 5 Cylinder Rotary Engine

Part 3 - 5 Cylinder Rotary Engine

Part 4 - 5 Cylinder Rotary Engine

If you have made a similar engine and would like to share your experience we would love to hear from you - ed.