Chilton Aircraft

  Post-war articles on the Chilton Monoplane
Article by Ranald Porteous Foreword by A. R. Ward
Return Of The Chilton by John Sproule Grooming the Chilton for Victory by J. Fricker
Flying the Chilton DW1 by Rob Millinship

Ranald Porteous

The following is a extract taken from the book "More Tails of the Fifties" published in 1998 by Cirrus, and reproduced here by kind permission of the publisher, Peter Campbell. This was the second in a trilogy of very entertaining books containing reminiscences from pilots who flew before and during those years. The freedom and camaraderie of that era, although constrained by post-war austerity, contrasting with our own more affluent but crowded and over regulated society. The following extract is from the chapter contributed by late Ranald Porteous and is particularly interesting coming from, as it does, one of the most accomplished pilots of his day.

I joined the de Havilland Technical School in 1934, among my student friends at de Havillands were Andrew Dalrymple and Reggie Ward. This pair of clever, witty and iconoclastic Etonians were the John Britten and Desmond Norman of their day and were determined to enter the light aircraft market, efficiently and profitably. That, had peace continued, they would have succeeded spectacularly I have never doubted. They combined the vision, the business sense and the technical ability with the resources necessary. Such Chilton DW1 light planes as still survive are a monument to these. This fabulous little machine, which took its name from Ward’s home near Hungerford where it was built, was designed by them in the Technical School under the watchful eye of Marcus Langley, as a kind of freelance exercise and I dare say that no comparable ultralight aircraft yet built has matched the Chilton for integrity and performance, both quantitative and qualitative. Dalrymple who was tragically killed on Christmas day 1945 in a captured Fieseler Storch, his first flight since before the war. He was without exception, the most intelligent pilot I have ever known. His grasp of principles was instant and complete, and enabled him to put up a stirring exhibition of low level aerobatics at an air display, with minimal experience and virtually no practice. On this occasion, shortly before the war, I had promised to do this, but was unavoidably prevented at the last moment. Determined not to allow the Chilton a "no-show", Dalrymple spent the previous evening with me, carefully mulling over all the factors involved in each manoeuvre. I read and heard later that his performance was faultless – and on this aircraft with the characteristics of a baby Spitfire.   Air racing was typified by the Kings Cup, which was big and lively news in the thirties. The same group of private owners congregated to fly at full throttle around a cross country course which was, as often as not, largely beyond the view of such spectators as may have gathered. The aircraft were lined up and flagged off one at a time in accordance with calculations made by a team of expert handicappers, whose object was to ensure that, given equal piloting skills all competitors arrived at the finish dead level. In the event the handicappers usually proved more fallible then the pilots, whose relative skills were marginally significant, as between the best and the worst, though little would have separated the best few, one from another. This being said, air racing of this nature was a marvelous sport for its participants, a splendid bunch of enthusiastic and expert people, always a tonic to be with.
I came to be hooked on it well before the war, being blooded in the little Chilton, entered in the Isle of Mann and Tynwald races in June 1938. Having left Hatfield as limit man, I recall flying my busy 32 horsepower with desperate accuracy and at almost zero height all the way to Speke (Liverpool) where I landed, still in the lead but closely followed by a gaggle of orthodox biplanes with four times the power, who were slowly but steadily catching me up. I remember also arriving at the refueling bowsers among these aircraft, whose vastly more experienced pilots were well positioned and calling loudly for "Twenty five gallons of Shell....Twenty gallons… etc. etc." My own timid request for two and three quarter gallons of National Benzole and a little Redex please" caused some amusement and rings in my ears today.

For this event the Chilton had been fitted with a new propeller, of "racing" design, i.e. of smaller diameter and courser pitch, which certainly gave one or two extra miles an hour when going flat out, despite being a trifle sluggish in acceleration and climb, this was as expected. It had been completed just before the race and there had been no time to fit the usual metal leading edge, essential to protect the wooden laminations against onslaught by rain, hail or grit. All was well at Speke, there had been no rain and the propeller was in pristine condition. The second half of the race, to Ronaldsway via St. Bees Head in Cumberland started well. The weather remained clear and dry and the little Carden Ford engine hummed contentedly as we rounded the white lighthouse on St. Bees Head, still in the lead. Ominously however, the Isle of Man was not visible and, after what seemed to be a long time flying low across the water on a compass course, spots of rain started to strike the Chilton’s tiny windscreen, increasing rapidly. To my alarm the engine revs and airspeed both fell noticeably and I began to ponder the aircraft’s ditching characteristics, the best way of inflating the old inner tube which was my sole survival kit, and the likelihood of being picked up at all. In short, I began to wish I were elsewhere.

By now the rain was quite heavy beneath the lowering cloud base but I drew a trace of comfort from the proximity of other competitors who were now looming out of the murk and passing me on either side, one with a cheery wave. At least I must be on the right track. Great was my relief when land appeared dimly, straight ahead and quite close. The little aircraft’s battered propeller was just able to lift me over the promontory before Ronaldsway and my first race ended with my being placed tenth, about halfway down the field. The propeller was a horrible sight, both leading edges looking as though bashed with a meat cleaver, so it was quickly removed in favour of a standard "touring" one, which was probably a blessing since we had entered the Chilton for the Tynwald race later in the weekend. The triangular course for this was somewhat hilly and there is little doubt that the greater diameter and finer pitch of this propeller gained more on the long uphill stretches than it may have lost downhill. Anyway despite the handicappers having reassessed the Chilton’s speed in view of its performance as far as Speke and St. Bees Head. It acquitted itself well in the Tynwald, coming third and confirming me as "hooked on racing".

One other race that remains vividly in my memory was the Folkstone Trophy in 1947. Reggie Ward had entered the Train engined Chilton, G-AFSV, for me to fly and it had been arranged that I should put in an extra lap which, with the three of the race itself, would qualify as an attempt on the International 100Km Closed Circuit Speed Record - Class A, this being for engines of two litres capacity. The little French Train engine just fell within this limit, by the skin of its piston rings. It was August, fine and warm if a trifle bumpy, 'SV ran beautifully, won its heat and was third in the final, following which I began my last "solo" lap through the now empty air. I recall a strange feeling, almost of loneliness, as we sped on. This soon changed to anxiety as flecks of oil began to appear on the windscreen and a warm smell to permeate the cockpit.  However, the lap passed quickly and I landed to find myself the possessor of an International Record and very little oil!

I had done all the original flying of the Chilton at Witney in 1937 and, in the 300 odd flying hours I had accumulated in this little craft, had suffered only one mechanical disaster, which was of our own making. We had skimmed the alloy cylinder head of the Carden excessively in preparation for some race or other. I was in transit across London, between Gatwick and Luton, at about two thousand feet on a fine, clear evening (imagine this nowadays) when their was a loud bang, with oil and steam – and a limply windmilling propeller. Luckily for me the open space which beckoned was Hurst Park racecourse and a few "S" turns bought me gently down on to firm smooth ground between various bushes in the no-mans land inside the race track itself. End of story, not a bit of it, my problem was yet to come. Off season the racecourse was closed and totally deserted. I plodded wearily around inside the various fences and barriers for what seemed an age, quite unable to find a way out or indeed to detect signs of human life. Apparently nobody had seen the Chilton land or had attached any significance to it. I recall a growing sense of panic and even visions of news headlines: "Promising young aviator starves to death in London wilderness!" But this was not to be, eventually I found an opening which led into the back garden of a suburban house, complete with owner and telephone. A replacement engine was bought in next day and the little Chilton had no difficulty in clearing the surrounding trees – so all was well.

After the war I acquired my original favourite, G-AFGH, the second Chilton and always for some reason, the nicest to handle. This was professionally reconditioned by Air Schools Ltd of Derby, where I was doing a stint as CFI of the Aero Club. The Carden engine based on a Ford 10, went simultaneously through the workshops of a local Ford agent, one Len Astle, who was a keen member of the Aero Club, which no doubt helped as ‘GH served me well until about a year later, my new position at Austers forced me sadly to say farewell to her.

After the war, when I had in effect two Chiltons, one ‘GH mine, the other the Train engined ‘SV, lent to me by Reggie Ward for safe keeping and "flag flying", I had a great tussle with the authorities over the question of reviving the pre-war ultralight permit to fly and recall passionately importuning the Minister, Lord Parkenham, at an air display. He took this in good part, seemed interested and promised to examine the matter. It apparently worked, as permits were shortly granted and the two Chiltons flew officially once more, spinners held high! I remain under the impression that these were the first post-war permits but will gladly stand correction if the record shows otherwise. 

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Foreword by A. R. Ward

The following is the foreword written by Mr. A. R. Ward co-designer of the Chilton, for Richard Riding’s book "Ultalights - The Early British Classics", published by Patrick Stephens Ltd. in 1987. The foreword is reproduced here by kind permission of the author Richard Riding.

I came to be interested in ultra-light aeroplanes at the end of 1935. My friend Andrew Dalrymple and I had been students at the de Havilland Technical School at Hatfield and we wondered to what use we could put our new aeronautical training. It occurred to us that by using all the latest know-how we could build an ultra-light that was something more like a real aeroplane, but in miniature. It would have a higher wing loading and, with a cruising speed of 100 mph, would have a better performance than existing ultra-lights. In addition we wanted to get away from the common practice of using converted motor-cycle engines, which were very rough to fly behind and were generally of questionable reliability. These engines fitted to ultra-lights provoked C. G. Grey, The Aeroplane's very outspoken editor, to label ultra-light aircraft as 'pop bottles'. Our initial choice of engine was the Ford 10 car engine which Sir John Carden had converted for aero use. It ran very smoothly, was basically reliable but was very heavy for its power. The results of our efforts was the Chilton DW1. Later we fitted a French Train engine which resulted in a more streamlined appearance and an increase in performance of nearly ten per cent more than we had calculated, though this may have been due to the highly polished cellulose finish given to the wings in place of the standard silver.

Having designed an aeroplane that did all that we asked, our next task was to encourage other people to fly it and approve of it. At first people used to look at the Chilton and admit that they were wary of flying it because it was so small. I feel the same way about today's microlight aircraft, but then I am fifty years older! I imagine that most instructors breath a sigh of relief when their pupils land safely after their first solo. Our problem was that every pilots first flight in the Chilton was a first solo, as no dual could be given in a similar aircraft. This was further complicated by the fact that the majority of club pilots, and instructors, had been trained on biplanes and still flew them, and had never before flown a monoplane equipped with flaps. Nor were they used to the slightest rotation on take-off, they tended to proceed relentlessly across the field towards the far hedge without any attempt being made to take-off. In addition with much lower drag characteristics of a monoplane, new pilots had difficulty in reducing speed sufficiently in order to use the flaps. It was also a problem judging landings, which were made some two or three feet lower than when flying a larger machine. Whilst this was not very good for one’s nerves, it was nothing compared to watching a well known Squadron Leader* who once rolled a Chilton on its final approach over trees.

We saw flying clubs as our main market for our single seater. In it, club members would be able to put in solo cross country hours towards their licences relatively cheaply and in a fully aerobatic aircraft that had a range of 500 miles cruising at 100 mph. We were in the process of negotiating a sizeable order for the Chilton when the war put a stop to everything including the planned development of the type. Then, as now, the main obstacle to the impecunious potential private pilot was the high cost of putting in the necessary number of solo hours. The Chilton would have solved that particular problem, much as accumulating hours on today’s microlights can be a cheap way of amassing hours towards achieving a Private Pilots licence. Today, I feel envious of the use of modern, double curvatures, bubble canopies, etc. But fifty years ago we too were using the most modern methods available.

Of course Dalrymple and I were not the only people building ultralight aircraft. Richard Riding’s book covers a further ninety-odd types which were built and flown during that twenty year inter-war period, an era in which British aviation was prolific in every area.

* The well known Squadron Leader, (later Group Captain) mentioned by Mr. Ward, was Edward Mole and in his very entertaining book Happy Landings (published by Airlife in 1984) he writes thus-

During the summer of 1939 I was invited to try out the Chilton, a little single seat ultralight monoplane powered by a 40hp Train engine. This was a sporty little aircraft designed and built by two bright young aeronautical students, Dalrymple and Ward, stressed for full aerobatics. It handled beautifully, just like a miniature Spitfire, and was so extremely manoeuvrable that I rather startled Ward by making a couple of flick rolls with it while on my approach to land!
I was greatly impressed with it, only four Chiltons were built before the advent of war stopped further production of this most promising little aircraft. After the war we founded the Ultra Light Aircraft Association (later to renamed The Popular Flying Association). I approached Mr. Ward to see if there was any chance of getting the Chilton into production again. He was no longer interested to do so, however, he offered to make me an extended loan of G-AFSV, the Chilton with the Train engine. This was the aircraft in which Ranald Porteous had broken the world speed record for ultra lights in August 1947. I negotiated with the Chelsea College of Aeronautical Engineering at Redhill who agreed to undertake the complete overhaul as an exercise for their students. They also decided to build an aircraft of the same design and Mr. Ward gave them whatever drawings he could locate of the original design. Unfortunately these drawings were so incomplete that although the Chelsea College did prepare a number of their own drawings, their prototype never got built.

The students at the College stripped the Chilton right down and rebuilt it completely, making up all the necessary spares as they went along. Whilst this work was in hand, I arranged for the inclusion of a number of modifications to improve its performance. They made a splendid job of the overhaul, and just before the 1950 summer break the little aircraft was proudly wheeled out ready for my flight test. It handled beautifully and I was able to demonstrate it at various air displays where it aroused great interest and helped to promote interest in the ultra light aircraft movement.

In September of that year, I entered the aircraft in the Daily Express International Air Race, which attracted 76 entries. Before the start of the race at Hurn Airport, the handicappers closely examined the aircraft and I could see they were puzzled. Then I was horrified to find that the little Chilton, which was by far the smallest aircraft in the race, had to start level with the much faster Comper Swift and I had no hope of winning. In fact although I achieved 143 mph over the course, I came in nowhere. Deeply disappointed, I took the matter up with the handicappers after the race and they told me that during their inspection they had noticed a lot of alterations had been made to the aircraft, and they could not estimate its speed. Consequently, to be on the safe side and to avoid a runaway win, they admitted I had been handicapped to severely. All the time and trouble I had taken to improve the Chilton’s performance had been completely wasted.
I was, therefore, most amused when during the following year’s Daily Express race, Hugh Kendall in another Chilton confounded the handicappers by making a runaway win, finishing some seven minutes ahead of the field. He must have souped up that Chilton very considerably, but despite their most rigorous examination of his aircraft after the race were unable to fault him.
Group Captain E.L. Mole

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Return Of The Chilton

The following is an article by the late Lt. Cdr. John Sproule, originally written in 1968, and most recently included in the book “Tail Ends of the Fifties” and is reproduced here by kind permission of his son, Sandy Sproule and the publisher Peter Campbell.

In June 1948, I became the owner and restorer of Chilton G-AFGI, this most unique little aircraft, having been found very much ‘as is’ in a dismantled condition in the old Chilton hangar-cum-barn at Savernake, near Marlborough. I bought the machine from A.R. Ward who, with the late Hon. A.W.H. Dalrymple, had designed the Chilton DW1 while they were students at the de Havilland Technical School at Hatfield. I paid the princely sum of £50 over a gin and tonic, and I bore my prize away in a truck packed with stolen hay into which we stuffed the fuselage and wings for safe transit. The truck broke down in the middle of Andover on the stroke of midnight, but that is another story. My interest in the Chilton ownership sprang from a flight I had made in one at Portsmouth in 1939, Dalrymple had telephoned me to say that he would arrive in the demonstrator at the Portsmouth Flying Club at 3.30 one afternoon and he duly arrived and I had my flight. It was a big event for me as I did not have a lot of aeroplane experience at the time. I was most impressed when, on my enquiry as to where he had arrived from, Dalrymple mentioned an airfield in Scotland! The Chilton had flown to Portsmouth non-stop using the optional overload tank and Dalrymple seemed to think that such a long flight in this very small aeroplane was hardly worth mentioning!

The restoration of G-AFGI took place in the woodworking shop at RNAS Gosport where I was Lt. Cdr. Flying at the time, and therefore fairly well fixed for such privileges. Such a restoration, working single-handed to the standards I had set myself, was quite a big job owing to the sad condition of the machine. G-AFGI must have been neglected for about seven years after Group Captain Pedley’s forced landing at Hatfield, and at Savernake a colony of healthy and very regular rats had inhabited the leading edges of the wings, while industrious insects had consumed all the soft furnishings i.e. the hammock type seat, safety belts etc. So everything had to be stripped and cleaned to the bone and secret places opened up for inspection and making good. Fortunately the casein gluing of the very lightly built structure was perfectly satisfactory, but just to make sure that the rats had not nibbled away anything vital in periods of famine, I opened up the ply skin of the wings at intervals along the spars top and bottom, so that the webs etc. could be looked at on both sides throughout their length. In addition to this, all metal fittings were removed for repainting and bolts cleaned and retreated before putting back in place with a dressing of yellow chromate. Cadmium plating turns into white powder on the best of bolts if left in wood long enough - so out they all had to come. All a considerable labour but splendid fun to do on such a miniature and elegantly designed little aeroplane. And there is a great kick to be had in cleaning up a dilapidated looking article and making it look as good or better than new, particularly when the initial outlay has been small! The 32hp water-cooled Carden Ford was obviously in need of a complete strip and overhaul, so I conveyed it in the boot of my car to the workshop of my friend Sam Youles in Waterloo Street in Hove. There I took the engine quite apart to its nuts and bolts and I handed these in several oily buckets to my old chum Dave Walden, Sam’s mechanic, with the instruction to “please, put all this together again as well as possible”.

One of the things I discovered on the engine strip, by the way, which explains Group Captain Pedley’s clouds of steam prior to his forced landing, was that the key in the water pump drive shaft had sheared. Perhaps someone had forgotten to drain the water some freezing cold winter and turned the propeller.

Dave Walden was a motor mechanic from way back and I could not have placed the engine in better hands. What he did not know about the internal combustion engine was not worth knowing and he was incapable of doing anything but the best possible work. He had, moreover, an intimate knowledge of the engineering resources of the Brighton district, i.e. where to get the best rebore and the best crankshaft regrind and so on. All good motor car stuff, you must note, but this, if carried out to Dave’s standards was fit for aeroplanes. When the major engine overhaul was finished Dave was very happy with £10 for his spare time work, and I think that, all-in, the engine expenses came to a total of £25 or so. The engine ran beautifully when it was installed, and I did over a 100 hours behind it with justified confidence, as it never missed a beat. A feature I remember with nostalgia about the Carden Ford was the very quiet and motor-car-like tick-over - you could hardly hear it. The noise at 100 mph cruise speed was like a small buzz-saw, but again this was pleasing to the ear, as it was producing satisfactory results and only using 1.8 gallons of fuel per hour! Regarding the Carden Ford engine as a prime mover, I can only say that, in spite of its weight, I found it perfectly adequate in the clean and lightly air-framed Chilton. Take-off and climb were not to be sniffed at and in my experience the water cooling system was no more bother than if it had been in a car. And it is interesting to note that in 1937 a new Carden Ford engine with twin ignition and completely converted ready to install cost £85. And how splendid to be able to go down to the village and buy spares for a few shillings over the local Ford dealer’s counter!

The Chilton propellers were all designed by Dalrymple and Ward and beautifully made in the workshops at Chilton Foliat by one Fred Luscombe. Obviously some experimentation had taken place in this field as, when I bought the aeroplane, Ward had thrown in a selection of propellers for me to try out - rather like being given a sheaf of arrows! After testing them all I settled on one with scimitar like blades which seemed to work best on all counts.

I flew G-AFGI at Gosport for the first time on the 4th September 1949 and I was very quickly at home in it. I can only sum up the aeroplane as being sensitive but quite stable and viceless. In other words a miniature Spitfire. After a while one learnt to let the machine ride the bumps with only the smallest control movements and it really was the nearest approach to the dream of flying with very small personal wings. The large split flaps made approach and landing very easy indeed and once the machine was on the ground it was down. I am sure my friend Ranald Porteous of Beagle Aircraft, the greatest living expert on Chiltons, will bear me out on all this, i.e. that the type had delightful and easy flying characteristics. And Ranald Porteous, who was and is no lightweight, was in the habit of performing all known aerobatics in the Chiltons. Proof indeed by his continued and happy presence among us, that Dalrymple and Ward had done their stressing sums correctly!

In the winter of 1949 I put G-AFGI back in the workshop again and set about designing and fitting a sliding cockpit canopy. I found that an Olympia sailplane perspex hood moulding turned back to front was readily available and an ideal shape, so I organised Wokingham Plastics to make me one with various doubling pieces in the right places! I mounted the hood on three dural rails and arranged a bungee and cable in the rear fuselage to spring load the hood rearwards. The hood was pulled forward and shut against the new windscreen by a small ratchet winding handle on the right of the cockpit. This gave a backlash-free system with an infinite variety of opening positions. A simple means for jettisoning was also incorporated. The hood mod was a great improvement to the Chilton in all respects as one did not have to dress up and you could sit about 2” higher. And it made G-AFGI look even more like a small spitfire. Getting the improvement legally permitted for the Permit to Fly was at that time another matter however, as this took far longer than the actual work and needed much more tenacity of purpose! From the ARB’s starting point of “We won’t come and look at it, and remove it forthwith” to eventually getting the mod passed as airworthy by the late A.R.Weyl, acting as consultant to the PFA, took a long time. In all fairness to everyone, I understand that things are much better these days, but after a whole winter’s careful work with only one’s personal safety at stake in the long run, the general palaver was a pest at the time. “Remove it forthwith” indeed! Not Likely!

As I said earlier on, I flew G-AFGI for about 100 hours and I eventually bought a very nice Piper Cub Coupe, G-AFSZ, early in 1951 and sold the Chilton to Hugh Kendall. Hugh was an old gliding chum of mine, but he painted my nice blue and silver G-AFGI what I thought was a rather odd mauve colour. But his most important innovations were the general gingering up of the engine and some very crafty work on the propellers. With these activities and various small cleaning up mods, he made the machine cruise at 130 mph flat out - an incredible speed for an engine nominally rated at 32 bhp. As no Carden Ford Chilton had ever done this sort of speed before, Hugh’s next most obvious task was to look around for some unsuspecting handicappers. I was therefore delighted to see him romp home first in the South Coast Air Race in September of 1951 at Shoreham. What a boost the bookies could have given to the Sproule Aeronautical Sport and Pastime Fund had I put my shirt on G-AFGI, as the odds on the Chilton winning were very long indeed!

I have always regretted selling G-AFGI, as I have always done with the various aircraft I have rebuilt in my time. There is no better and more rewarding pastime than buying them cheap and tatty, making them good and flying them. But selling your children, so to speak, is always painful and the recollection of parting with the Chilton is now much more so as this thoroughbred little English aeroplane of pre-war days is now almost extinct. The Chilton Monoplane, designed in 1937 by Dalrymple and Ward while young students, was indeed a light aeroplane classic. No doubt the de Havilland training had a great deal to do with it - and the fact that Dalrymple and Ward were both practising pilots. Even today, given the same design requirements, I doubt very much whether anyone could offer any better solutions to the various problems, the machine was simple and cheap to build and there was not an unnecessary stick of wood anywhere. And it was strong, looked and flew right. What a pity the drawings have been lost, as with the RF-4 type cowled Volkswagen engine installation, and various minor modifications such as the sliding hood, I am sure that a latter-day Chilton would still be outstanding.

Following is some background information to the above article:-

Group Captain Pedley’s forced landing in the G-AFGI he describes thus:-

In 1941 Prince Bernhard of the Netherlands, then a pilot under instruction at No.1 EFTS Hatfield, heard about a Chilton for sale at Broxbourne and he expressed an interest in buying it for his private use. Being the CFI at Hatfield at that time I undertook to go over to Broxbourne and fetch it.

When I arrived there in April 1941, I recollect my first impression of the Carden Ford engined Chilton G-AFGI was its diminutive size. I squeezed into the cockpit, started up and took off - immediately to regret it! The air speed indicator was u/s and it was equally apparent that the cooling system left a lot to be desired, for I was enveloped in a dense, blinding cloud of steam. Executing a tight and hasty half circuit I landed again, more than a little shaken.

When repairs had been made I returned again on May 15 and on that occasion got away without incident, climbing to 3,000 feet I found the Chilton to be extremely sensitive but provided one didn’t fidget about in it remained in fairly level flight. Soon Hatfield showed up ahead at which point the engine stopped abruptly. Gliding straight ahead, sweating, I just made the airfield boundary and landed in a dip on the far side of the hangars. I believe that it caused much merriment, when the CFI appeared over a rise in the ground plodding homeward trailing the Chilton behind him.

When re-engined the little Chilton Monoplane must have been a lot of fun to fly but in the trim that I knew it, this aircraft was much to unstable and mechanically unreliable to be entrusted to an inexperienced pilot. G-AFGI remained in a hangar at Hatfield until I left at the end of the year, I do not believe that HRH ever flew it - a sad story.
Group Captain M.G.F. Pedley DSO, OBE, DFC

The hangar from whence Lt. Cdr. Sproule extracted the Chilton, was that belonging to the Earl of Cardigan a large land owner thereabouts that included High Trees his private airfield on which the hangar stood. High Trees was used by Dalrymple and Ward to operate all of the Chiltons at various times. The Chilton was too small for impressment and all four eventually spent the war in storage at High Trees, where they were immobilised by the local constabulary who diligently cut through all the spark plug leads, hoping this would deter some equally diligent but probably more resourceful escaped prisoner of war intent on escape.
G-AFGI was most probably returned to High Trees by road after its sojourn at Hatfield.
Sadly, the reason for its sale at Broxbourne was because its owner, Frank Dawson-Paul who was a personal friend of both Ward & Dalrymple, had been killed during the Battle of Britain.
On July 25th 1940 Dawson-Paul was in 64 Sqn based at Kenley and was flying Spitfire L1035, and whilst trying to protect convoy CW8 that was steaming down the Channel a few miles off Dover, although heavily outnumbered, he and his comrades tried to drive off 50+ Ju 88s and 50+ Bf 109s, he was shot down at 1800hr by Bf 109s, picked up by a German E-boat and taken to a hospital near Boulogne but he died of his wounds a few days later on July 30th

Opened in 1935, High Trees airfield was just south of Marlborough, on top of the hill at the western edge of the Savernake Forest. The airfield was unusual in that it was the only airfield in Britain where one could land ‘athwart a railway line’ as a railway line emerged from a tunnel just at the northern edge of the airfield with the railway line turning eastwards around Marlborough. The airfield was also used by the RAF Central Flying School at Upavon as one of their official forced landing fields from January 1936, a maximum landing run of 1800 feet was available at that time. The airfield proved particularly useful to Wing Commander J.R. Davenport who recalled regularly flying in with a Lysander to visit his parents who lived at High Trees House, a property on the edge of the airfield owned by Cardigan.

The hanger at High Trees still exists, although now hemmed in by modern farm building and the airfield itself has been cut in half by a concrete farm track. The writer however, harbours an ambition to fly both his Chiltons back into High Trees.
R. Nerou

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Grooming the Chilton for Victory

The Aeroplane – October 1951

Hugh Kendall’s recent victory in the Daily Express Air Race in a fifteen year old aeroplane (G-AFGI) fitted with a modified motor car engine, has pointed the way to a cheap and novel form of class racing for which the need has been felt since the re-introduction of handicap events after the end of the war.  It is a common complaint that the handicap system retards, instead of encourages, efficiency in airframe and engine development, but hitherto there has seemed no way of providing a competitive event within the means of those amateurs who comprise the aeronautical racing fraternity.  The Chilton airframe and the Carden Ford engine have a common history in that only one or two of each were produced, and neither were subjected to that period of development which has proved essential in all aircraft equipment.  What Hugh Kendall has done is to bring his remarkable technical skill to bear on the still largely unexplored combination of engine and airframe, and that, coupled with his piloting ability, gave him his seven minutes lead across the finishing line.

While there are few who can combine such technical and flying ability, we have many good technicians and many equally good pilots who would be only too keen to race for worthwhile stakes, and between them there is no reason why they should not achieve similar results.  If the drawings could be made available, the Chilton airframe , which is considered almost ideal for the type of job, could be made by amateur constructors under the supervision of licensed inspectors – the Ultra Light Aircraft Association has a fully detailed home construction scheme, complete with the necessary organisation.  Labour forming the highest proportion of present day costs, an amateur-built Chilton airframe or some similar design could be put together for about £250 and on the part ownership basis on which many non-profit making flying clubs (those which do not even set out to make a profit, that is) have successfully operated for some time, no one need be a millionaire to have a £10 share.

Engines should not present too much difficulty, since with the co-operation of the A.R.B., the Carden modifications could be incorporated into the standard Ford 10 car engine.  The Carden Ford is by no means an ideal power plant at the moment – with its radiator and water, it weighs about 180 lb., and produces only 32 b.h.p. – but it is strong, smooth running, cheap, with an enormous spares organisation behind it, and as Kendall has shown, can be developed into a reliable and economical power plant.

During the Daily Express race , the Carden Ford in the Chilton, was turning over at 3,900 r.p.m., which is still well below the revs achieved  by blown Ford engines in midget racing cars, and was probably putting out about 40 b.h.p., so that its power/weight ratio is beginning to look respectable for a small engine.  Its power output will probably be limited by the fact that it is ungeared, and even now a special airscrew is needed to get the maximum performance at the present revs.  But there again is a stimulus for the design of supersonic airscrews, or rather blade tips, and such fixed-pitch wooden units need by no means to be the prerogative of the large airscrew companies.  The four feet diameter two blade airscrew on Kendall’s Chilton has slightly swept-back tips and gives a slightly advantageous pitch change through blade flexibility, for take-off and level flight conditions.

How well deserved was Kendall’s victory is shown by the hard work and hard thinking which he put into the development of the Chilton, which attracted the admiration of everybody at Shoreham.  First improvement on the airframe was actually introduced by its former owner, Lieut. Cmdr. J. S. Sproule, R.N., who added 5 m.p.h. to its former maximum speed of about 112 m.p.h. by fitting a bubble hood.  This beautifully neat modification was adapted from an Olympia sailplane cockpit cover, sliding on rails, and cable operated from a hand crank on the starboard cockpit wall. 

The major concern, however, was inevitably the engine which in its standard form has quite a few bugs.  Originally it ran too cool, and the first step by Kendall was to reduce the cooling air exit while redesigning the cowling.  Odd gaps and holes in the nose cowling were filled in, and the radiator air flow was sealed off from the engine bay.  The cooling air exit was reduced from about 5 inches in width to 1 1/2 inches and a useful decrease in drag thereby obtained.

Lubrication troubles were encountered just before the Daily Express race on its original date, and during a test flight the pistons began to seize, resulting in a forced landing.  Upon examination there were signs of lack of lubrication at the top ends, and the light alloy pistons had begun to run.  Air bubbles were present in the oil feed pipes, but fluctuating pressure was remedied by the installation of a tray filter in the sump, and ordinary Ford cast iron pistons had been fitted, with increased clearances, a more satisfactory state of affairs was achieved.

Next the former downdraught carburettor was replaced by an Amal motorcycle type, adapted to function vertically instead of horizontally.  This was not only a better unit, but increased power was gained through a cold air inlet from the radiator scoop, with the benefit of a slight ram effect.  So far, no icing has been experienced in the air, but a warm air inlet will probably be fitted for winter flying.

While practising round the Daily Express course, after this modification. The revs fell off and there were signs of fuel starvation.  Kendall tried to make Detling, but eventually had to force land in a field near Sittingbourne.  The trouble was due to the blocking of the six small petrol feed holes in the carburettor, but an increase in their diameter provided the remedy.

The forced landing itself was something of an achievement in a machine like the Chilton, the field being about 400 yards across diagonally.  An accommodating farmer, however, was good enough to cut a runway through the crops and Kendall flew out without much difficulty.

With these modifications, the Carden Ford’s achievement speaks for itself, in turning over comfortably at about 300 r.p.m. above its former limit of 3,600 r.p.m., while rubber mounting it has resulted in a great improvement in smooth running.  A thermostat from an Austin A40 holds the temperature at about 90 degrees C. during flat out running, the header tank being mounted on the engine bulkhead.  Other modifications include the provision of a normal throttle control, in place of the rather sensitive push-pull knob on the dashboard, and an aircraft boost gauge provides a useful indication of the manifold pressure.

An interesting detail modification was the incorporation into the straight exhaust stubs of three or four small vanes, to deflect the engine exhaust through 90 degrees.  These are similar to turning vanes in a wind tunnel, and they give a slight ejector effect.  The upper half of the cowling was made out of sheet dural, curving from one side to the other, and fitting flush.

So far as the airframe was concerned, it was first stripped to the wood, covered with fabric and given a Docker metallic silver finish, which itself assisted the performance.  The former wheel-barrow type wheels, each weighing 9 lbs., were replaced by braked wheels from an Olympia sailplane.  These wheels are very much smaller and weigh only 6 lbs each including the internal expanding shoe brakes.  These are operated from a lever on the control column, through a Bowden cable running over a Vickers pulley, and lateral movement of the stick gives differential action.  An industrial castor fitted with a solid rubber tyre, was mounted at the bottom of the tailskid , and through a simple yoke and bungee, became stearable to the limit of the rudder movement.  With brakes and a tail wheel the Chilton has greatly increased utility, but as the ground angle becomes equal to or greater than the stalling angle it is now less stable on the ground and needs care to keep straight when landing on runways.  For that reason it is better to make wheel landings with the modified Chilton, also because its elevator control and longitudinal stability make three pointing difficult. Click on the thumbnail below to see sketches of the mods carried out.

Mods carried out on 'FGI.

Another point is that with the very much smaller wheels, the clearance between the undercarriage fairings and the ground is limited, and some modification to the spats may be necessary. The Chilton, however, is still capable of further development and many refinements could be incorporated in the design.  An example of the detail to which Kendall has gone in his general modifications, none of which were expressly for the race, is the fitting of strips of fur at the root and tip ends of the ailerons which are designed to seal the gaps and, in consequence reduce the induced wing drag.  This has resulted in a contribution to the greatly increased rate of climb.  The modifications were achieved with a very slight increase in the tare weight to about 440 lbs. while the gross weight is about 700lbs.  A four gallon auxiliary fuel tank was fitted behind the pilots seat for the race (this was a standard Chilton mod.) which together with the 8 ½ gallon main tank gives a useful endurance on the Carden Ford’s 0.54 pints/b.h.p./hr. specific fuel consumption.  In point of fact, this tank was not necessary, as only 4.8 gallons were used during the race.  What the present maximum speed of the Chilton is, is hard to say, although it is undoubtedly in the region of 130 m.p.h., some 18 m.p.h. faster than the designed top speed.  Its further development will be watched with great interest, and there may be even more surprises.  If nothing else however, it has stimulated interest in the small racing machine, and may offer the means of progressing to closed circuit contests around areas as a small race course, where spectator accommodation already exists and the aircraft are always in sight.

What is needed is the stimulus of a large prize for the fastest speed gained by either a given combination of aircraft and engine, or perhaps at a later date, for aircraft with engine size limitation on the lines of the Goodyear Trophy races in the United States.

John Fricker

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Flying the Chilton DW1

The following article by Rob Millinship, was written as part of a larger article on the Chilton Monoplane published in Popular Flying magazine in January 2005.

Being somewhat ‘vertically challenged’ sometimes has its benefits, one benefit for me is that very occasionally I am invited to fly aeroplanes, which for the average sized pilot might prove to be something of a squeeze. A good example of this was Roy Nerou’s kind invitation to fly the prototype Chilton DW1 G-AESZ. Having taken many years to restore, the aircraft, now resplendent in its immaculate original red and silver, had been test flown by Roger Bailey – a long-time friend of Roy’s and well-known expert on pre-war sporting ultra lights, Roger had pronounced himself satisfied with the Chilton and its Carden Ford engine, but unfortunately, now living in France, was unable to commit to flying the aircraft other than on an occasional basis.

The aeroplane looks every inch a pre-war racer and in fact in later years was to have considerable success on the UK handicap racing scene. But the reason for its racer looks is slightly different, in an attempt to produce an efficient airframe around a very low horsepower converted car engine, the aeroplane needed to be exceptionally clean. Hence the reason for the ‘racer’ looks.

The initial pre-flight walk around revealed a number of features that affect the way the aeroplane flies. Firstly, and most importantly, the wing. Compared with an aircraft of a similar size, it is of quite high aspect ratio but with a noticeably sharp taper in both cord and thickness. Later versions incorporated fixed aerodynamic slots at the tip but ‘ESZ, being the prototype has no such refinements. Surely a warning to watch for a wing drop at slow speed or in low speed turns.

The next area of interest is the undercarriage. Although wide spaced for easy ground handling, each leg and wheel is enclosed in a beautiful, streamlined trouser. Excellent aerodynamically, but potentially able to trap a cushion of air beneath the aircraft on landing, causing an extended, potentially embarrassing float before touchdown – classic aerodynamic ground effect.

Great care has to be taken when climbing aboard due to the very fragile nature of the structure. Although the aeroplane appears a very solid looking machine, the actual structure is very lightly built and covered with extremely thin plywood. Roy initially gave me a very detailed brief as to where I could, and more importantly, could not pull, push, sit or stand when climbing aboard. Having sat down on the deckchair style seat I was surprised to discover that the cockpit is in fact, quite roomy and would be perfectly capable of taking a much larger pilot than me without difficulty. The seating position proving to be quite comfortable with all the controls within easy reach. The control column and rudder pedals are conventional with a push/pull type throttle control in the left-hand side of the instrument panel and a Chipmunk style three position flap lever mounted alongside the seat on the right-hand side. The instruments are vintage but entirely conventional. The only unusual feature for such a small aircraft being the coolant temperature gauge. The liquid cooled Carden Ford engine again showing its automotive ancestry. The seatbelts are classically vintage being of the Sutton harness type. Engine starting proved easy, providing the right combination choke, throttle and advance and retard are set. Once running, the most important feature is the coolant temperature gauge – the engine taking from cold, about four minutes to achieve 50°C, at which point a power check and a mag check can be carried out. Full throttle giving a maximum rpm of 3,100 on the ground, quite high as compared with most conventional aircraft engines but again entirely normal considering the engine’s automotive origins. Taxiing is easy but requires comparatively high rpm even on quite short grass. It is very easy to forget that at full power the engine is only going to deliver about 32 horsepower. Manoeuvring on the ground is achieved by increasing the power and gently easing the stick forward to unload the tail skid. This enables the comparatively powerful rudder to steer the aircraft quite satisfactorily on the ground in almost all conditions. The exception being a full or quartering tail wind which can defeat the rudder and necessitate the use of a wing walker.

Once lined up with pre-takeoff checks completed, the throttle can be advanced to maximum which will result in about 3,200 rpm, lots of noise but very little else. The initial acceleration being rather slow and requiring full forward stick to raise the tail. However, the ride is good and the wide track undercarriage helps the aircraft to remain arrow straight throughout the takeoff roll, even in comparatively strong crosswinds. Being such a low powered aeroplane the attitude for takeoff is critical, nose high or nose low and the Chilton will stay happily glued to the grass with very little inclination to take off, but by carefully adjusting with tiny amounts of forward or rearward stick, eventually take-off speed is achieved, (hopefully before arriving at the far airfield boundary) whereupon the aircraft leaves the ground and will then start to accelerate comparatively briskly. However, all things are comparative and in the case of ‘ESZ, this means accelerating from an unstick speed of about 45 mph to a safe climb speed of around 65 mph, an indicated 65 giving a rate of climb in the region of 450 feet per minute. Once settled in the climb, the power can be gently reduced from around 3,400 rpm to 3,200 rpm in deference to the age of the 1172cc Ford side valve humming away in the front. Power can be further reduced in the cruise to 3,100 rpm which in level flight gives an indicated 90 to 95 mph after about a minute’s gentle acceleration. The actual rpm being used has to be a bit of a guess due to the needle of the original tachometer becoming a blur at anything over idle speed. The blur tends to spread over about 500 rpm so the centre of the blur is adjusted for the desired rpm!

‘ESZ’ is nicely stable about all three axis and has proved to be quite pleasant as a cross-country machine. It is not particularly gust-sensitive, and is beautifully rigged so it tends to go in the direction which it is pointed without a great deal of input from the pilot. Stick forces are light, as you would expect for such a small aeroplane, with the rudder being the most powerful control and the ailerons being the weakest. The ailerons in fact, have a very soft feel around the neutral position. However the roll rate is quite adequate with good control response at higher stick deflections.

The trick with the Chilton, as with most low powered aeroplanes is to try to maintain as much energy as possible. Although quite fast for so little power, it is very easy to lose speed and energy with careless handling. Out of balance turns or worse still pulling hard into turns causes a rapid decrease in speed which then takes quite a considerable time to regain. Having now displayed the aeroplane on quite a number of occasions, I find that the key to a successful display flight is smooth low-G turns which enable the aircraft to stay over about 110 mph. At this speed the aircraft is absolutely in its element and looks every inch a 1930’s racer.

As with most aircraft of this era, the landing can be a bit of a challenge, tail-skid, no brakes, trousered undercarriage, centre section flap, and a fairly poor view all add up to potential excitement on the first few landings with the Chilton. I was fortunate in having a comprehensive brief from ‘ESZ’s test pilot, Roger Bailey who warned me about the potential for a fairly spectacular series of bounces if I were to use a conventional 3-point landing technique. His advice was to initially ‘wheel’ the aircraft on at about 55 mph. This technique works well with up to two stages of flap the aircraft settling stably on its main gear and rolling for about 200 metres on short grass, after which the speed has decayed sufficiently for the tail to settle.

The reason for avoiding a conventional 3-point landing is simple, the combination of trousered undercarriage and centre section flap combine beautifully to trap a cushion of air immediately below the centre section of the aircraft. The trapped air having very little room to escape. It feels a little like sitting on a rather squashy beach ball. Any attempt to put the tail on the ground whilst this high pressure air sits below the fuselage immediately results in the main gear leaving the ground whereupon the air escapes and the aircraft returns to the ground with a bump normally followed by an immediate return to the air then the whole process repeats itself. The three subsequent Chilton aircraft constructed all have their flap levers repositioned from the right hand side of the cockpit to the left hand side, immediately below the throttle. This simple modification would enable the pilot to immediately retract the flaps after touchdown to release the cushion of air and enable the tail to be placed immediately on the ground, thus shortening the landing roll considerably.

So did the Chilton fulfil its design and performance specification? In my opinion, yes it did but with a few reservations. It certainly had exciting performance on so little horsepower. Even in the thirties it must have been seen as a pretty exciting-looking aeroplane – definitely a sports car of the air but, the aeroplane itself is bound to be fragile, built as lightly as it is and certainly not the sort of aeroplane you could operate from a poor airstrip – neither then or now. Certainly for the more experienced and light weight pilot, (remember the maximum pilot weight is only 170 lbs) it would have been a truly exciting machine that could be operated at comparatively low cost. However I suspect that even the designers knew that for practical purposes she needed more horsepower……. which brings me to G-AFSV, Roy Nerou’s second Chilton. The last one built she was powered by a much more powerful engine, a 44 horsepower French Train 4T. ‘FSV’ is now virtually complete in Roy’s workshop and awaiting completion of the original Train inverted 4-cylinder engine. Before too long she also will take to the skies with her predecessor ‘ESZ’. I can’t wait to try a ‘big-engined’ Chilton!
R. M.

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