A Brief History of R/C Model Engines


The first Saito FA-30 from 1979.

Over the last 50 years the first noticeable factor is the modeller himself. No gender bending here as the point to which I will allude is purely man’s domain… Women may be allowed to coexist but man is the leading light here (at least). I’m talking about ‘THE SHED’ or, as I call it, ‘THE WORKSHOP’. Here, the only change is the style and the materials. Let me explain, briefly.

From whence we came
Man (as in mankind) dwelled in caves around the dawn of time. Safe from the elements, nasty big biting and chomping creatures and other possession hungry men. In the cave man could kindle fire, bash rocks to make weapons, bind the rock bits to long wood shafts to make spears (which he chucked into the air in the direction of edible animals), draw on the walls and snooze when the need overcame him. He was man and this was his cave. So..? 


Enjoy more RCM&E Magazine reading every month.
Click here to subscribe & save.

Well, consider current times. Man (the modeller) has his shed (man cave), wherein he makes things to chuck in the air. It is his place of solitude, a sanctum sanctorum (a private place) where he is secluded, safe from domestic trials and a quiet place wherein he can sit back, contemplate and study the inside of his eyelids. A veritable fortress in which the solitude allows man to be the absolute master, glue ‘bits’ to wood, pin plans, photos and drawings on the wall and store all manner of treasures for ‘later’ use…
As man developed better spears and weapons, he gained knowledge of better methods of lighting fires, catching and cooking animals and shared knowledge with other hunters and gatherers. In like vein so our engines and modelling equipment has changed and many of the changes have been during the last 50 years.

New engines for old
In my ‘cave’ I am blowing the dust off the engine shelf for the 1960 collection. Mind you, I definitely do not collect engines. However, I do accumulate a few (well, lots) and I fully intend to use them all again, one day (as we all do). That year was not too far from the development of digital proportional radio control and that meant more to the evolution of model engines than any other period. I had dabbled in the control of free flight models by radio as did many other modellers of my time. To me, the failures far exceeded the successes and the times the model did return undamaged were not so much a moment of enjoyment as your heart was racing every moment the model was in the air. Failures meant wrecked models, damaged engines and sputtering radio equipment that all added up to a serious pain in an already suffering money purse. Engines were (and still are) the sparkling jewels of my cave.

Along with many other modellers, free flight and control line flying was the order of the day and the engines available were designed for that purpose – no mufflers, no variable carburettors. A 10 c.c. engine was considered a large engine at the time and even at that capacity, what would you use it for? There was a 10 c.c. class for control line speed, not much interest in other control line use for such a large engine and a free flight model would have to be an absolute monster to need an engine of this capacity. Remember, I am talking about Australian modelling but there was not a great deal of difference in overseas modelling.


In the early years of R/C, 10cc was considered the upper limit.

Engine technology
The technology of the day was extremely good and several engines were outstanding in their class. A Dooling .61 ‘Yellow Jacket’ or McCoy .60 – both from the USA – to name two examples, would give you an excellent chance of good results in control line speed. The Dooling was capable of quite high RPM due to the high port timing and twin rings but the propeller to obtain such RPM was around 8 inch diameter by 12 inch pitch and, in most cases, hand starting was the norm. (Oh, the pain and bloody fingers!)
Due to the cost and rarity of such engines, the common maximum capacity was .29 c.c. and even this was considered a large engine for the time. Due to the popularity of this size capacity, there was a good variety of different engines available. In the main, engines had a cast iron piston and a steel or iron liner.

The configuration was baffle porting – a baffle incorporated on the crown of the piston, with a suitable slot in the combustion chamber of the head and the crankshaft bearing was a sleeve – bronze, cast iron or just the aluminium of the case. An engine with one or two ball races for the crankshaft was rather special and a gloating item at the field. Porting in the sleeve (liner) was a series
of small square cut-outs (typical) and, if the engine was fitted with a ring, (aluminium alloy piston) the pinning of the ring was not necessary (pinned to prevent rotation) as no port aperture was large enough to allow a ring end to catch.
As with current model engines (and all other two stroke engines), the intake port(s) in the liner was below the level of the exhaust port and this was one factor that gave me a great boost when beginning my engine servicing period. Many modellers in the early days, having moved on from de-winging flies, dismantled their model engines. The same as today, many did not bother to mark the position of the parts, resulting in reassembled engines not running correctly. Why, I don’t know, but a common problem was that the liner was fitted backwards – exhaust port to the rear.


For me it was a simple matter to rotate the liner, replace the (almost always) damaged Phillips head bolts and return the engine, capable of running as it should, to the owner. Engines and engine repairs were of great interest to me and I delved into every corner to learn more.

Radio Control Carb
In 1965 the word was spreading about the development of a new type of radio – a proportional signal radio that gave ground control of the model almost identical to the control you would have sitting in the seat of a full size aircraft. While the news was great, when it became an actuality in 1968, we weren’t prepared for engine requirements. The radio was capable of transmitting a digital proportional signal that allowed a proportional control of the moving surfaces – and the throttle of the engine. Quick as a wink the engine manufacturers started fitting variable speed carburettors to their engines, other manufacturers made after market carburettors and the race was on to design the best carby. The first engines did not throttle really well due to, in some, the port timing, the rather cold plug and, mainly, due to the carby design.

Two factors bought about the next development. One was the poor throttling characteristics and the other was noise. Rather than models being flown in distant farm paddocks (typical) or areas set aside for control line flying, the use of radio control allowed models to be flown in almost any area that had enough open ground for a take off. The engines had no mufflers and, believe me, their bark definitely was worse than their bite (even though they often did bite hard when you flick started them). The problem of throttling and reliable idle came down to the fact that the entire heat of the engine was blown straight out the short, stub exhaust. Heat is a major part of glow plug operation as residual engine heat plays a big part in keeping the glow alight – particularly at less than full RPM.


HP were a popular brand in the pre-four stroke era.

So now we had a rush of weird exhaust baffles. The most common was like a metal bow tie pivoted on a bridge in the middle of the exhaust port and controlled by a bent wire or series of wires connected to the throttle arm. Rattley, less than good and, according to radio fanatics, a source of radio noise – metal to metal induced – that could cause radio interference. Another type of baffle was a single vane that rotated within the exhaust manifold – again linked to the throttle arm – and this (almost) closed the manifold when the engine was bought back to idle.

Other ideas were tried and all had a mixed success, none really good, and then we saw the emergence of a muffler, very similar to those of today. Again there was a great flow of after-market mufflers with claims of super quietness, increased engine performance, slow and reliable idle. In the main, mufflers solved most of the variable speed and low idle problems but some were actually louder than an open exhaust. This period, in the late 60’s, through the 70’s to the 80’s, was a real boom period for modelling – particularly for engines. Manufacturers were hard at new developments (engines were big business) and we saw great improvements in carburettors and glow plugs. Accessories were also a big market item and, for the engines, we were offered a range of plug connectors, electric starters, and power panels for the field box. The old telephone battery used for heating the glow plug was losing ground as the one 12 Volt motorcycle battery in your field box powered your starter, glow plug and, later, an electric fuel pump. Some modellers still liked to hand start their engines so we had a selection of ‘chicken fingers’ – a thick rubber finger glove for your flicking finger and, later, the chicken stick – a wooden handle with a chicken finger glove on the end.

Newer, bigger and better engines
For a number of years the engine range of up to 10c.c. (.60 cu. in.) reigned supreme and, in the medium to high range, the popular engines were O.S., Enya with a sprinkling of Webra, Super Tigre, HP and other brands to a lesser degree. Engines were of very good quality, mufflers were as efficient as possible for the cost and glow plugs were very good. What else would you need?

Modelling was floating along quite nicely when O.S. upset the applecart in 1976 with the introduction of the O.S. 60 FS – a four stroke engine. Some years earlier, the Channel Island Special – a four stroke engine – was put into very limited production but it was not much more than an interest for modellers who liked something different. It was quite a good engine but, before its time. It is now highly valued by collectors. The O.S. engine was an instant success – something entirely different – and the sales caught O.S. on the hop. In my opinion they put a number on the market front to test the waters, so to speak. Many were purchased but not many were used. A great engine to put away for ‘later’ and this is evidenced by the number that crop up for sale now, NIB (New In Box).

The first large engine to gain a good support was the O.S. 90 FSR and this was a very popular engine for larger scale models. Again, I think it was an engine to test the waters for the need for larger engines. A few more manufacturers dipped their toe in the water and engine capacities were creeping up a little with 75’s and 90’s being about as large as anybody should need(?). Moki produced a 25 c.c. around this period and the only one in Australia was in a showcase in a popular model shop where it remained, as a novelty and a matter of interest, for years. Who would want or be able to use an engine of that size?…

Parts for modern engines are produced to a very high standard using CNC machines.

In 1979 the first mass produced O.S. twin – the 120 Gemini – was produced and this, unfortunately, suffered a very similar fate to the .60FS – being an engine purchased by modellers (who had the spare cash) to be stored away (yes, you guessed it!) for later use.

Mainstream engines remained pretty much the same for a few more years and other ‘novelty’ engines such as the O. S. Wankel, a 5 cylinder radial, and the Enya Vee Twin for example, appeared in the model shops every couple of years.

The four stroke engine had been very well accepted and the Saito range provided singles, twin and a radial. Enya had a number of very good four strokes starting with the very nice little .35. Webra produced several really different engines such as the T4 with an Aspin head and several overhead axial rotary valve engines. And HP produced a small range of overhead drum valve four strokes.

Rather quietly, in 1984, Neil Tidey in the UK produced his first four stroke and his engines grew in popularity due to the quality, reliability and back up service to the point where today they feature so many times in scale contests with engines from the .70 to the big 360 Vee twin.

Petrol power
Out of the blue the Quadra petrol engine was introduced. A converted hand tool engine that ran well but vibrated like a nervous jelly. A model engineer eventually offered after market service to re-balance the engine and it was then a bit more reasonable. This engine started the large craze and all manner of converted hand tool engines were modified for large model use.

Most engines were bl**dy terrible – rough, quickly produced and poorly balanced. The established manufacturers saw the appeal and larger engines of good to excellent quality were produced. Almost unbelievable advances in CNC machinery and metallurgy has given us engines of outstanding quality and the potential for the manufacturers to produce any manner of engine according to the needs of the market. Look around you. Engines have never been so good, so much so that we have been seeing clones of all the top brands of engines and even these are of recognisable quality.

The rough hand tool converts are slipping off the shelves (some as boat anchors) and being replaced by magnificent purpose manufactured large engines solely for model use. In the petrol engine category you can choose from a 14 c.c. four stroke (Saito) right up to monster 450 c.c. radials, with every size and configuration in between. On the glow engine side we have a range of sizes and configurations with, speaking of the top brand engines, a quality so high it is hard to image that it could improve.
So many gems and so few spaces on my engine shelf (Note to self – build more shelves).

The Saito production line, the engines are still assembled by hand.

Up to the minute – over and out!
For almost all the available hours of the last three days ( I did eat a couple of times) I have been running, testing and evaluating three new engines – the O.S. 55 c.c. petrol engine, the Saito 30 four stroke petrol engine and the DL 30 c.c. two stoke petrol engine. They are all now in pieces ready for further evaluation and photography and I can tell you that the inside quality is as magnificent as the running qualities of each engine. They are all superb running, extremely high quality examples of internal combustion engine technology. We have never had it so good at the pointy end of our i.c. powered models.

Article Tags:

About the Author