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Ray Tuthill

Although I had some successes with my own models including second in the class B team race at the Nationals in 1956 with Don Walker as pilot, the real successes, came when Don and I joined forces and raced as the Walker/Tuthill team. Don was every bit as much of it as I was. He was a brilliant model maker – the airframes he built were quite superb in every respect and finished to top class exhibition standards – and he was equally good as a pilot. I did the engineering bits (engines, tanks and support kit etc.) and was pit crew. We won the Davies ‘B’ Trophy at the Nationals in 1957 and 1958 and were on course to do so again in 1959 but a broken prop and ‘shaft run’ before the race affected the starting and though the engine remained very fast we only made second place. In one fantastic season around then, probably 1957, we raced 12 times, won 11, including one dead heat, and were second once!

One of the 'secrets' of our success was that I correctly analysed the key factors that were limiting team racer performance at the time and, after a lot of thought, eventually managed to develop successful solutions to them. The three principal factors were:

- Variable engine performance through each tankful gradually going from rich to right to weak which both limited average speed and wasted fuel. That was solved by the chicken hopper tank which we managed to keep to ourselves, to our considerable benefit, for about 18 months despite intense curiosity by all our rivals. It was one of the Templeman brothers who eventually worked out what we had done and asked me one day whether we were using a chicken hopper. I can't remember whether it was Mike or John but being a fairly honest type I acknowledged that he had got it right but I still did not reveal the detail of the design which was quite important. I actually got that right first time. The original prototype worked perfectly and though I subsequently tried one with a modified configuration it was not quite as good as the first so for the 'production' tanks I reverted to the original basic geometry but with improvements to the construction and the layout of external plumbing. I made some accurately sized steel formers round which to form the subsequent tanks. The first of those to the final design was made of phosphor bronze shim and soft soldered but thereafter all the ‘production’ ones were made from shim steel, silver soldered for strength and durability under racing conditions. By maximising use of the permitted fuel the tanks enabled us both to cut out a pitstop in each race and to fly at maximum speed all the time, hence our remarkable run of successes.

- Engine geometry, rigidity, detail design and accuracy of manufacture. That was where my engineering training came to the fore and paid dividends - thanks to my apprenticeship at RSAF (the Royal Small Arms Factory) and some unofficial technical help with things that were beyond the capability of my home workshop and ancient Drummond treadle lathe on which the majority of work on the engines was done.

- Reproducibility of engine performance and why some commercial engines, such as Etas, would perform exceptionally well but then become quite ordinary after being taken apart and reassembled. That was also influenced by the above factors but the most significant element was avoiding any distortion of the liner, particularly near the top of the stroke, during fitting of the cylinder head. Once I had understood the problem, the answer again lay in my engineering skills, modifications to the engine structure and dexterity in tightening the cylinder head screws uniformly.

In addition we got many other details right both on the model, engines, fuels and design of the pit stop support equipment to optimise pit stop speed and consistency. In particular with the engines I built myself, I used to tune each one individually by adjusting the compression ratio with copper head gaskets of varying thickness for optimum performance on the particular combination of engine, prop, plug and fuel mix. We found the best props were 8" X 8" Tornados, of American origin I think. They were difficult to get but we were lucky to pick up a 'job lot' and as we rarely broke them, I have still got most of them (c.3 doz.).

We started racing with some tuning of standard Eta 29s then moved on to engines I built myself incorporating some commercial components - crankcase, crankshaft, ball races and piston rings. I persuaded Ken Bedford to let us take the first one, which was proving very successful in competition, to his works to test it on his dynamometer. The peak output was .746HP at 17,600rpm. Ken was very interested as it was better than his production engines at that time and we had the first of many discussions about what I had found out and done. I then built another one which both on the dynamometer and in the model performed identically. They were both based on Eta crankcases and crankshafts and in their essential internal details and modified arrangements for the critical cylinder head fitting were identical. The first one however included more original Eta parts than the second. Later we also used a Mc Coy 29 redhead on which I think I probably did some work. Without taking it apart however I cannot now recall exactly what I did to that one but it is apparent from looking at it externally that much more of it is original McCoy than there was Eta in the first two. All three flew at 112-113 mph and would do a 5 mile heat with just one pit stop and a final with three, 1 or 2 less than anyone else could manage at the time, hence our remarkable run of successes. After a great deal of use, the first one (Eta based) eventually suffered a catastrophic fatigue failure of the crankcase casting when the cylinder parted company from the bottom half! I recently found the remains of it and also still have the other two both in good order.

We became very good friends with Ken Bedford and had many technical discussions with him which I guess he used to very good effect and built on as he eventually managed to produce engines off his production line that were better than mine. We used to test them in our model and race them for him. I recall that by about 1961 his best ones were producing just over .9HP at over 18,000rpm which was taking Don's model up to 120+ mph and enabled us to do the first ever 6 minute, 10 mile final an actual race (I think it was at Ramsgate). We understood that one of the West Essex chaps (Sid McGoun I think) had already done it in practice, with no one else in the circle to get in the way. Piloting skills become very critical at that sort of speed and Don was one of the best!

I have occasionally looked at where the Eta factory used to be on the rare occasions I have gone past on the train and it appears to be gone. I have often wondered whether Ken Bedford was still around and involved with modelling. He was into model cars himself and I remember discussing the ins and outs of making a chicken hopper tank for his 10cc (McCoy?) racing car which ran on a shorter line than we used for model aircraft and hence the effects of centrifugal force on mixture strength through the tankful were even more pronounced than in team racing. Since first writing this I have been reminded by Derek Allen’s note on the website that I subsequently gave Ken Bedford one of my ‘class B’ chicken hopper tanks for his 5cc racing car and that using it enabled him to set a new British Speed Record for 5cc cars. It was great delight to meet Ken again, together with Lyndon Bedford, on Friday 17/2/12 when in company with Malcolm Ross and our wives I visited him and took along all the old racing gear and engines etc. We had a wonderful time, reminiscing over lunch and back in his bungalow afterwards. It was the first time I had seen him since he and Dorothy came to our wedding in June 1962!

I still have the last two engines Ken gave us to race plus the two survivors of my own ones safe in the box of racing gear and all in good order. Given the nature of the fuels we used and the acidic combustion products, part of my standard routine was that no matter what time we got home after a race, the first thing I did was to partially strip the engine, give it a thorough wash out, oil it up with '3 in 1', dust it internally with molybdenum disulphide powder and reassemble it. I used to do that via the 'back door' without disturbing the cylinder head or the front crankshaft assembly. To facilitate such frequent dismantling and reassembly without stripping the 6BA threads in the alloy crankcases I used to tap them out to 1/8" Whitworth (a much more suitable thread form in light alloy) and fit studs and nuts as in full size practice rather than screws. That drill kept the engines in pristine condition and I am sure that if they were to be run up all four would still perform exactly as they did all those years ago!

3 or 4 team racers at 100+mph in the same circle is pretty spectacular and needs very agile and level headed pilots. By the time you are looking at 120mph they are lapping at just 2 seconds on 60’ lines and things are getting very hairy! Whilst we got up to 120mph I don't actually recall a race in which all the models were doing that sort of speed. In the race in which we did the 6 minute final there were only two in the circle us and one other very slow one and that proved very difficult. Staying upright, keeping out of any tangles and not having an accident was difficult enough and had to be the primary concern.

The prospect of team racing at higher speeds (I believe Gordon Yeldham did a demonstration at 135 mph) I find frankly frightening and b.... dangerous! At that sort of speed I would regard it as essential to use longer lines rather than those of our days which were originally 52’ 6” when we started in the early 1950s, then increased to 56’ in 1955 and again to 60’ in 1959. That’s what I originally wrote and I did not know whether there had ever been any further increase until I met Malcolm Ross and was amazed to learn that International class racers are still flying on the original 52’ 3” lines at speeds in excess of 130mph! I find that quite frightening – I’m obviously getting too old! I once flew my ‘49’ speed model at 132mph at a demonstration with a big crowd all round the circle using a set of class B lines as the arena was too small for the normal 65' lines with an adequate safety margin. I did NOT intend to do anywhere near that speed and had set the engine VERY rich to keep it down to about 100mph but on the short lines, even with the pressure of a pen bladder tank, it leaned out and went faster than it had ever done before and indeed the British record at the time. The speed at which I was rotating, the pull on the lines, trying to stay exactly in the centre and the thoughts of what was likely to happen if I wandered or it got away terrified me and I swore that I would never again do anything like that in front of a crowd and I never did.

Ray Tuthill (Updated 23rd Feb 2012)
Tuthill Chicken Hopper Tank
Tuthill Chicken Hopper Tank
Tuthill 29 based on ETA 29 Crankcase (113 mph)
Tuthill 29 based on ETA 29 Crankcase (113 mph)
Later Model ETA 29 (120 mph)
Later Model ETA 29 (120 mph)
Ray Tuthill's Racing Engines and Pit Gear
:: Ray Tuthill's Racing Engines and Pit Gear ::
Don Walker / Ray Tuthill Partnership in 2012
:: Don Walker / Ray Tuthill Partnership in 2012 ::
Enfield Weekly Herald 27th July 1956
Enfield Weekly Herald 27th July 1956
g4/40/424040/3/141111034.mxJgH7Pz.jpg All Herts Rally 1953
All Herts Rally 1953
Malcolm Ross, Ken Bedford, Ray Tuthill February 2012
:: Malcolm Ross, Ken Bedford, Ray Tuthill February 2012 ::
:: Shrapnel ::