quorneng
Master member
This engine was made from scratch by my dad 50 years ago.
He was a serious model engineer.
An advanced design with 45 degree inclined valves, a 'hemi' head, 2 ring 'slipper' piston, with 'free flow' inlet and exhaust. The intention was to try to match the performance of a typical 'RC' 2 stoke of the period.
At that time there was no transistor ignition so it had a tiny contact breaker and used a conventional coil.
Unusual because not only was it one of the first model plane sized 4 stokes but it runs on petrol.
Even more unusual (even now!) it has a recirculating oil system with a dry sump so it uses 'pump' petrol with no oil in it.
The reason for all this was to attempt to set a new world endurance record for RC planes weighing not more than 10 lbs.
It had then just been set at 13 hours.
My Dad reckoned that a petrol 4 stoke would not only use a fuel of higher calorific value than methanol but with no oil in the fuel there would also be 5% more burnable fuel. The other 4 stoke benefit is a much better part throttle economy over a two stroke. An important consideration when the fuel would constitute 50% of the planes weight.
The intention was to fly the plane for 24 hours.
The engine was exhaustively tested and showed that on 5 pints of fuel it could have run on a decreasing throttle for something like 24 hours.
No record was ever attempted as the FAI abandoned the power endurance category on safety grounds not long after the engine was built!
It does still run although not for long due to its age!
It does not sound like it but it is turning that 9x6 at close to 9000 rpm.
That is also its original 50 year old test stand!
He was a serious model engineer.
An advanced design with 45 degree inclined valves, a 'hemi' head, 2 ring 'slipper' piston, with 'free flow' inlet and exhaust. The intention was to try to match the performance of a typical 'RC' 2 stoke of the period.
At that time there was no transistor ignition so it had a tiny contact breaker and used a conventional coil.
Unusual because not only was it one of the first model plane sized 4 stokes but it runs on petrol.
Even more unusual (even now!) it has a recirculating oil system with a dry sump so it uses 'pump' petrol with no oil in it.
The reason for all this was to attempt to set a new world endurance record for RC planes weighing not more than 10 lbs.
It had then just been set at 13 hours.
My Dad reckoned that a petrol 4 stoke would not only use a fuel of higher calorific value than methanol but with no oil in the fuel there would also be 5% more burnable fuel. The other 4 stoke benefit is a much better part throttle economy over a two stroke. An important consideration when the fuel would constitute 50% of the planes weight.
The intention was to fly the plane for 24 hours.
The engine was exhaustively tested and showed that on 5 pints of fuel it could have run on a decreasing throttle for something like 24 hours.
No record was ever attempted as the FAI abandoned the power endurance category on safety grounds not long after the engine was built!
It does still run although not for long due to its age!
It does not sound like it but it is turning that 9x6 at close to 9000 rpm.
That is also its original 50 year old test stand!
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