A little old 4 stroke!

As some of you may know my Dad was a serious model engineer and seemed to specialise in making things as small as possible.
When the world endurance record for RC planes was broken in the mid 1950s at 12(?) hrs and described in the Aero modeller it used a conventional 2 stroke glow running on 50/50 petrol/methanol mix. His comment to me was "You would get a much better fuel consumption figure with a 4 stroke running on straight petrol".
At this time the weight limit for all model planes was 10 lbs so some quick calculations suggested a 5 lbs plane carrying 5lb of fuel powered by a small 5cc (0.30) petrol 4 stroke might manage 24 hours.
At this time many small 4 strokes had been built (for example the Westbury 'Seal' 15cc 4 cylinder boat engine in 1947) but none for model aircraft.
To my surprise he was quite serious and he set about designing and building one. To him the challenge was not so much actually building a small petrol engine (he had collaborated with Westbury on some of the features of his engines) but to incorporate the best 'aircraft' technology to produce a light, powerful yet long lasting engine.

He was a pretty good draughtsman as well.
Magnesium crankcase, alloy 'hemi' head (machined from sold). inclined valves, 2 ringed piston, skew gear drive cam shaft, positive big end lubrication with a dry sump. All built from scratch with the only bought components being the 4 ball bearings and the miniature spark plug.
The completed engine on its display stand for the 1966 Model Engineer exhibition.

Wow, what a story! What became of it Q? How well did it run, does it still exist and if so, where?

that is fantastic, a level of skill most of us can only dream about.

Andy Sephton wrote: Wow, what a story! What became of it Q? How well did it run, does it still exist and if so, where?

I second those questions Q

Garry

Ah! It was getting very late so I had to stop but to continue:-
Yes it did run.
Originally it had a 'simple' carburettor with a fairly narrow venturi coupled with an insert under the head to reduce the compression ratio a touch.
Of course in those days there was no such thing as transistorised ignition so it had to use a HT coil and points.

The crankcase is set up to act as a vacuum pump so it 'sucks' the oil from the oil tank into a 'banjo' at the rear of the crankcase which feeds through to the crank pin and into the big end from where it sprays into the crankcase to be exhausted via the non return valve back to the tank. The ball bearings and valve gear only need an oil 'mist' from the crankcase.
It thus only needs 'pump' petrol and ordinary motor oil. Very cheap!

The crankcase can actually pump quite a volume of air and still have sufficient vacuum to maintain the oil flow so it raised the possibility of using simple direct acting vacuum bellows to move the control surfaces to 'nudge' a stable plane about the sky. In the days of full size servos this could have saved a significant amount of weight.

My Dad was always a believer in the "if it is designed to produce power then it should be run that way" so hour long test runs were common measuring the fuel consumption as various throttle settings right down to tick over as this sort of power level would be likely towards the end of an endurance flight.
Using the high compression and the big venturi carb the 5cc was reasonably powerful and turned the 9x6 at close to 9000 rpm and was of course fully throttle-able.
The real advantage was that the fuel consumption was largely proportional throttle position and at just under 3/4 pint/hr at full throttle a 24 hour run on 6 pints (5lbs) looked possible in conjunction with an efficient glider type airframe carrying the fuel within the wing.
Of course the big stumbling block to such a duration was powering the ignition system. A situation that was never solved so no endurance attempt was made. In any case it was not long before the 10lb rule was abolished as was the FAI absolute endurance category.
However my Dad was happy that he had achieved his goal (which was really to build a small high power 4 stroke) and it certainly seemed to encourage his peers to do the same, like Barry Hares 1/5 scale Merlin.
I still have the 5cc and have run it.

but it is quite irreplaceable and I certainly don't have the skills to replace any of the parts so it is 'retired'.
Notice at tick over it has quite an 'oily' exhaust so the intention was to make a new piston with a oil control 'scraper' ring added to clear the excess oil from the cylinder walls.

The 5cc was built entirely using his Drummond lathe (with lots of clever attachments) but his next project was going to require proper milling capabilities so he helped design the Dore/Westbury milling machine and built the prototype to demonstrate it could be made using nothing more than his 'vintage' 31/2" lathe although with his skills I am not sure how much of a test it really was.
It soon became apparent that specialist milling cutters would also be required so he designed and built the Quorn Tool and Cutter grinder, named after the village in Leicestershire where he lived. A classic case of "build the tool to make the tools to make the model".
The next project?
Bigger at 15cc but a V8. :woohoo: but that is another story.

You sound very proud of your Dad Q , and justly so in my book . What an amazing man, he was of the type that made you proud to be British. Thanks for sharing the story with us, and may I ask, is there any more , as this sort of thread fascinates me , and I am sure I am not on my own .

Garry

Garry
Proud is not quite how I would put, more like awe, particularly when I compare what I have achieved. :blush: :blush:
He did cast a long shadow which is still there more than 20 odd years after his death - as I found out at the Ashbourne scale day. :ohmy:
The photographer wanted a picture of me holding my Fairey Delta (always good for the ego ). He then asked for some details about the plane and my name which I spelled out as I usually do. His immediate reply was "I know that name, its the same as Professor Chaddock of the Quorn Tool and Cutter grinder". He seemed quite impressed he had met his son.

More stories? Well let me see.......

And i call my self an engineer,from one to another, well done that man, i am in awe :blink:

I have just found the reference I was looking for and I got the date wrong. The 5cc was entered for the 1957 Model Engineer exhibition where it won a Silver Medal.
The Gold Medal went to the 1/4 scale Gnome Monosoupape 7 cylinder Rotary entered by John Lounds.
Unusually the Gnome was actually run periodically at the exhibition - by my Dad!
Many years later he borrowed the Gnome for the Midlands exhibition and brought it home, so I can truthfully say I have started and run a Monosoupape rotary.

At about the same time (1976?) he was 'given' a OS FS-60 (10cc) as an example of the first 'production' 4 stroke for RC planes.

It is indeed a Mk1 type with the machined ally rockers.

He took it to bits and commented is was well engineered but was not very complimentary about the design of the valves and valve gear suggesting it would be pretty heavy for the power it could ever produce. Which I understand proved to be the case!

He never ran it so as far as I can tell it is still 'as new'.

Glad YOU edited that post Q, as I did blink when I saw in the email notification of the post, it had been entered in the 957 exhibition. Even I dont remember going to that one :woohoo: :woohoo: :evil: :evil: [badass]

Garry

And being a much desired mk1, with the box and papers, its got a value, unrun or mounted, in excess of £200

I thought it might be a bit unusual but unfortunately it has no box or papers of any sort.
I don't even know where or from whom it came from. My Dad said it was a 'gift' but gave no further details. It is possible it was 'donated' to him as a result of an illness or death.

Shame it has no paper etc, but i still reckon it would bring upwards of £150,