Flight, December 1936
RECRUITS for the LIGHT BRIGADE
New Approaches to the "Ultra-light" Problem: "Pou" Influence on One Model
The Chilton Monoplane
Under the guidance of the Hon. A. W. H. Dalrymple and Mr. A. R. Ward, the Chilton Aircraft Company of
Chilton, Hungerford, Berks, are constructing a single-seater, low-wing monoplane with a 32 h.p. Carden engine. A cruising speed of 100 m.p.h. is hoped for and the machine should land with full load at about 32 m.p.h., the latter figure being attained largely by the use of flaps, which will also increase the gliding angle. The petrol consumption should be better than 50 m.p.g.
Every effort is being made to secure a reasonable power loading to ensure a good take-off.
Plywood covering is specified for wings and fuselage; a full-scale test has been made on the latter component which withstood a factor of 10.
Data are: Span 24 ft., length 18 ft., track 6 ft., width folded 8 ft., range 400 miles. The machine should be ready for flight-testing soon after Christmas.
The use of the 45-50 h.p. Weir engine would benefit take-off considerably. Incidentally, the company feels that this power plant may provide a brighter outlook for an economical two-seater with a really practical performance.
Flight, November 1937
BRITISH CIVIL AIRCRAFT
The smaller types
NEARLY a year ago the two people behind Chilton Aircraft, Messrs. Dalrymple and Ward, started serious work on the design and construction of an ultra-light single-seater which was intended to he really outstanding both in practical performance and economy. The machine was flying early in the summer, and, once minor cooling and airscrew difficulties had been overcome, showed that both its cruising speed and general handling qualities exceeded expectations.
The construction of the Chilton, which is a low-wing monoplane, is quite orthodox, and the designers have concentrated largely on the business of making the machine as practical as possible. It is clean enough to travel at what, on 32 h.p., is quite a remarkably high speed - 112 m.p.h. - and practicability in this case obviously demanded the use of split flaps both to steepen the approach and reduce the landing speed. The engine at present fitted is a converted Ford Ten, for which Chilton Aircraft are now responsible, but the machine may be fitted with any other engine weighing less than 200 lb. – the French 44 h.p. Train four-cylinder being suggested as a useful alternative for the pilot who requires an even more exciting performance.
Chilton Aircraft, Hungerford, Berks.
Flight, December 1937
HIGH PERFORMANCE in MINIATURE
Some Comments on the Chilton Monoplane: Cruising at 100 m,p.h. on 30 b.h.p.
AFTER little more than half an hour's flying in a new type it may seem to be somewhat presumptions to make any comments on its handling and general qualities. On the other hand, initial impressions are those which really matter, since, after several hours' experience, one becomes so accustomed to a particular machine that it is difficult to remember and to analyse flying impressions as such. However, it was necessary to be content with a little plain circuit flying - which, at least, in visibility of the two-thousand-yards order, leaves one's mind free to consider a flying machine simply as a machine and not as a navigational implement.
Probably the first reaction of any person on being told of a machine which actually cruises at something rather better than 100 m.p.h. on less than 30 h.p. is that such a performance must somehow be paid for, either in a high landing speed, or in some vicious characteristic. In fact, the Chilton is perfectly normal in its habits and it lands, with the assistance of split flaps, at a good deal less than 40 m.p.h.
Its flying characteristics might be likened to those of any high-efficiency low-wing monoplane, built to a small scale. Furthermore, the machine has a rate of climb which is sufficiently good to remove any of those tree-scraping illusions from which one suffers in many of the ultra-lights; the maker's figure of 650 ft./min. is certainly not an optimistic invention. Provided that one has a properly instinctive realisation of the moment when a machine is ready to fly, the take-off, too, is quite short in distance, though moderately protracted in time. In fact, and according, as might be expected, to the purposes for which an owner requires such a machine, he can always, by a change of airscrew, obtain a superior take-off and climb at the expense of cruising speed.
The machine which I flew was fitted with a compromise in airscrews, and, although it is never possible to guarantee indicated speeds, the machine reached its 100 m.p.h. quite quickly after levelling off, and comfortably held 95 m.p.h. on very little more than 3,000 r.p.m. - 300 r.p.m. less than normal cruising. The best climbing speed appeared to be 60 m.p.h. The Ford engine is a comfortingly smooth means of propulsion, and at no time did the water temperature gauge reading exceed 85 deg. C.
In the matter of controls the Chilton is light and positive, and the machine, so to speak, demands that every turn should be a steep one. A couple of near-vertical rounds was my closest approach to aerobatics, if some flat side-slipping is discounted. This last manoeuvre the machine does well and properly, though the speed cannot be kept below about 65 m.p.h. With three-position split flaps, however, the need for such height-losing tactics is not very obvious and the best way of approaching without a motor would be to play tunes on the flap lever between the first two notches, and to apply it fully just as the boundary has been crossed at 60 m.p.h. or so. With the flaps right down the gliding angle is steep enough to suit anyone - and with the flaps up it should be possible to cover a couple of counties downwind from 2,000ft. Until the true air-brake, independent of lift flaps, appears, all split-flap controls should obviously have a series of positions for different circumstances.
Whether or not I was being too cautious with an elevator control which I knew to be very sensitive at low speeds, or whether the view of the ground as the tail goes down is an awkward one until the pilot becomes accustomed to it, the fact must be admitted that my first landing was a thoroughly bad one. It was a wheeler for a start, a slight ridge or a gust sent me flying again, and the results were made even worse by the accidental use of the engine at the wrong moment. The useful width of the undercarriage and its four inches of travel possibly saved the day (i.e., one of the wing tips) and this minor experience proved that the Chilton would take at least something of the hammering which might be provided by a thoroughly raw novice. The next two landings were irreproachable, so I am ready to take all the blame.
The accidental throttle motion was indirectly caused by a control system which works in the opposite direction to normal. This is a purely personal arrangement in a particular machine, and at no other moment did I object to the fact that the dashboard control must be pulled rather than pushed - the idea being to have the plunger out of the way when closed. The use of glider-type, or harmonium rudder pedals is another quite accidental feature which, consequently, may hardly be criticised, though paddling is thereby encouraged; full-leg rudder-bar movement certainly provides one with more definite control. Any other machine (a second one is coming along now) may have a standard throttle movement and a normal rudder-bar at the discretion of the purchaser. The next machine, too, will have the flap lever on the left side of the cockpit, where it may be moved without changing the stick hand.
It is obviously impossible to deal adequately with the characteristics of an aeroplane in a few hundred words. Let the Chilton be temporarily explained as the useful result of a real endeavour to produce an economical, and properly finished machine with normal characteristics, yet an outstanding performance.
THE CHILTON MONOPLANE
32 b.h.p. converted Ford engine with dual ignition.
Wing area 77 sq. ft.
Weight empty 398 lb.
All-up weight 640 lb. (max. 700 lb.)
Maximum speed 112 m.p.h.
Cruising speed 100 m.p.h.
Landing speed 35 m.p.h.
Rate of climb 650 ft./min.
Range 500 miles
Makers Chilton Aircraft, Hungerford, Berks.
Flight, March 1938
British light aircraft
QUITE one of the pleasantest ultralight aeroplanes from the pilot’s point of view is the little Chilton monoplane, which, in its present form, is powered with a specially modified Ford engine giving a maximum of 32 h.p. Quite apart from its exceptionally good flying qualities the facts that, on this power, its maximum speed is as much as 112 m.p.h., and its cruising speed with a standard airscrew is more than 100 m.p.h. at cruising revolutions, are worthy of note.
Nevertheless, anyone who has flown this machine will agree that its rather exceptional performance has not been obtained at the expense of difficult flying qualities or even of a particularly high landing speed, which is in the region of 40 m.p.h. with the wide-area split flaps in the appropriate position. These flaps, incidentally, make all the difference in the world to the approach, which, with such a clean machine, might otherwise require a difficult rumble technique. They are directly operated by means of a lever and have three positions, any one of which can be used with safety at speeds below 65 m.p.h. If the approach is made at 55 m.p.h. there is ample time to make an accurate hold-off and landing. The controls are light, positive, and properly harmonised, yet are not too light for the novice who has been trained on conventional aeroplanes. Nevertheless, the machine is essentially one for the reasonably expert amateur, though both its sponsors. Messrs. Dalrymple and Ward, flew it without difficulty after less than 50 hours of solo flying.
Though the machine is very much a miniature, there is ample room in the cockpit, with a tray for maps and oddments, and a reasonably large locker behind the seat for anything not wanted on the voyage. Chilton Aircraft are now responsible for the converted Ford Ten, but any other engine weighing less than 200 lb. and of appropriate power may be satisfactorily fitted.
SPECIFICATION : Span. 24ft.; length, 18ft.; all-up weight; 640 lb.; weight empty. 398 lb.; maximum speed, 112 m.p.h;; cruising speed, 100 m.p h.; landing speed, 35 m.p.h.; initial rate of climb, 650 ft./min.; range, 500 miles; price, £315. Makers: Chilton Aircraft, Hungerford, Berks.
Flight, July 1938
Out and About in the Chilton Lightweight : Cruising at 100 m.p.h. on 30 h.p. : Safe Characteristics
LATE last year I spent a short period in the air with the prototype Chilton monoplane and felt at the time that here was a machine which, though economical in first and later costs, was yet entirely fit for serious use. Unfortunately, the particular day was by no means ideal for trying out any new machine - let alone one about which, in view of its quite exceptional performance, I felt a certain, perhaps, justifiable timidity. There are ultra-lightweights and ultra-lightweights. A low cloud-ceiling effectively prevented any attempt to discover exactly what happened to the machine near the stall and, as the Chilton is intended equally for the novice and the expert, its slow speed characteristics seemed, after all, to be the very ones which would make or mar it as a flying machine.
However, a week or two ago I had an opportunity of renewing acquaintance and flew the machine for about three hours in good weather conditions. This, too, was the first of the production models, in which one or two minor improvements had been incorporated. Gradually, during the three hours, I gained more confidence, not only in the machine, but in the power unit which, as a converted car engine, might otherwise cause the prospective owner some slight misgivings. The Chilton-Ford engine continued to perform with monotonous smoothness and regularity, and, furthermore, I found, on a trip down the South Coast and back again along the line between Lympne and Tonbridge, that the Chilton's cruising speed really is 100 m.p.h.. as nearly as makes no matter.
In the course of this cross-country flying the machine was not by any means kept on a steady course or at constant altitude, yet the inclusive average over the out and home run was in the region of 88 m.p.h. On the only soberly flown section of the route I timed the machine over a distance of ten miles; the wind was almost across my track and the distance was covered in a little over six minutes - a time which gives a speed figure of about 95 m.p.h. This was at an engine speed of 3,400 r.p.m., which, with the particular airscrew in use, seemed to feel about right. Actually, the unit, at least according to the Ford people, is perfectly safe up to about 7,000 r.p.m.; not only, therefore, is there little danger of over-revving on a dive, but this high limit also permits variations in cruising engine speed to suit the slight differences in airscrew design which so often appear in the small sizes. At 3,400 r.p.m. the throttle was approximately half open, though without a manifold pressure gauge it is not possible to calculate the amount of power which is being taken out of a unit.
For those who still consider that this engine speed is somewhat high for reliability, it is worth remarking that it is merely equivalent to the normal top-gear cruising speed of the Ford Ten car Since the modified Chilton engine has a special cylinder head and a special forged crankshaft, with, of course, an airscrew thrust race, there is every reason to suppose that the unit should be adequately reliable and hard-wearing judged by aircraft standards. Practical tests with the engine have, in fact, included 100 hours at 4.000 r.p.m (full throttle), and examples fitted to Drones have done up to 250 hours without requiring anything more than routine adjustment. Naturally enough, it is possible for the radiator water to reach an unnervingly, but nevertheless perfectly safe, high temperature if the engine is badly overdriven. The Chilton has a temperature gauge on the dashboard, and in normal cruising flight in mid-summer this temperature did not exceed 95 deg. C. - which is just about right for efficiency. I have concentrated rather on the engine side of the business because this, I feel, is one which may be doubted first of all by the prospective owner, however much he may like the Chilton as a flying machine pure and simple.
Except for what is perhaps, an over-light rudder, it is impossible to make any complaints about the adequacy of the Chilton’s controls at any speed from 40 to 140 m.p.h. At the stall, with flaps up, the machine tends to drop its nose a trifle while one wing falls away very gently, and in these circumstances the rudder becomes the master control, the merest touch keeping the machine level at an indicated speed of less than 40 m.p.h. With the flaps down the actual stalling speed is lower and the machine appears to remain quite stable and under full control with the stick held right back. The Chilton flies and turns perfectly on ailerons alone.
The wing section, a modified Clark YH, is such that the machine has really typical thick wing characteristics. It must be hauled off the ground, but even at very low speeds there is absolutely no tendency for a wing to drop suddenly. There was very little wind when I flew the machine out of Gatwick, but the take-off run was measured at approximately 80 to 90 yards over a particularly hard and consequently bumpy surface. The ground angle of the Chilton is somewhat sharp and full rearward stick can be used for the landing without the risk that the machine will touch tail-skid first. In fact, at any other position of the control at the moment of touch-down the result can be a slight but harmless wheeler.
Frankly, I cannot for the life of me see why anybody should find any serious difficulties in either the flapped approach or the landing itself, though one or two pilots appear to have succeeded in breaking the unfortunate aeroplane by tactics similar to those of a badly trained first soloist; and others, upset, perhaps by their nearness to the ground at the moment of landing, have failed in their attempt to break the machine by dropping it from considerable heights. Nobody, however, has been hurt. My own reactions, as a very normally experienced amateur is that Messrs Ward, Dalrymple and others must have been singularly unlucky in their encounters with interested amateur aeroplane tasters. Both Ward and Dalrymple flew the machine safely and successfully after about 50 hours solo on other types - and neither of them would pretend for a moment that they were born birdmen or any nonsense of that sort.
Undoubtedly, on a cross-country flight, the pleasantest feature of the Chilton is the extraordinarily good view obtainable from the cockpit. This excellence, coupled with the machine's general controllability, possibly provides the only real source of danger to the person who actively enjoys flying; one is sorely tempted to fly at zero altitude, and even the best of eyes occasionally miss such obstructions as power pylons and chimneys. However, a resultant write-off could not be considered as the fault of the machine. The screen is a perfectly normal one, yet by chance or otherwise there is practically no draught and for nearly an hour I flew without goggles, which are only necessary when one’s head is popped out of one side or the other for some reason
The structure is perfectly conventional and much stronger than is actually necessary for the stresses likely to be imposed. The ply, for instance, is certainly thicker than stress considerations require. Anybody who has seen Mr. Porteous demonstrating the Chilton can have no doubts about either its controllability or its strength. Encouraged by the sight of his evolutions I even went so far as to do a couple of loops myself. The available power, though more than adequate for normal purposes, is of no particular use during such a manoeuvre and it is necessary to obtain a little more than 130 m.p.h. if one is not to risk dust and fuel discomforts resulting from a suddenly reversed load at the top of the circle.
Although the Chilton is produced in standard form with the modified Ford engine it has been stressed to take any unit with a power of 50 h.p. or less. The calculated figures for the machine fitted with, for instance, a 44 h.p. inverted Train engine, include a maximum speed of 125 m.p.h. and a cruising speed of 112 m.p.h.; the rate of climb is then 1,000ft. /min. against the standard figure of 650ft./min., and with this engine extra tankage can be arranged for a non-stop range of 2,000 miles. In normal form the Chilton has the very adequate range of 500 miles.
Flight, October 1938
British Sport and Training types
THE single-seater type of machine has always tended to have a doubtful reception amongst the prospective purchasers, but for those who require such a machine the Chilton monoplane certainly possesses a remarkable performance even when fitted, in its standard form, with a Carden-Ford engine of only 32 h.p. With this unit the maximum speed is 112 m.p.h., and a genuine cruising speed of 100 m.p.h. can comfortably be held.
Nor has this performance been obtained at the cost of safety from the point of view of the inexperienced pilot. The Chilton’s characteristics even at low speeds are very normal and, indeed, better than the average.
Naturally enough, every effort has been made to make the design a clean one, and the process of approaching and landing is simplified in these circumstances by the fitting of mechanically operated split flaps. The construction is of stressed plywood, and the wide-track undercarriage has a travel of four inches. The machine can be flown without goggles and even without a helmet, and there is ample room in two luggage compartments for light luggage.
When fitted with a rather more powerful engine the performance is even more remarkable. With a 44 h.p. Train, for instance, the maximum speed goes up to 125 m.p.h. and the rate of climb to 1,000 ft./min.; while the range is reduced only from 500 to 400 miles. In this case, however, extra tanks can be carried to increase this range to 1,000 miles. In the spring, when this engine has become available, the designers hope to fit a Cirrus Midget engine, which will convert the machine into one of relatively high performance and make it especially suitable for aerobatic training.
A somewhat larger machine is now under construction, but no details are yet available.
Chilton (Ford engine) data :- Span, 24ft.; length, 18ft.; all-up weight, 640 lb.; weight empty, 398 lb.; wing-loading, 8.3 Ib./sq. ft.; maximum speed, 112 m.p.h.; cruising speed, 100 m.p.h.; landing speed, 35 m.p.h.; rate of climb, 650 ft./min.; range, 500 miles; and price, £315.
Makers:- Chilton Aircraft, Hungerford, Berks. (Hungerford 26.)
Chilton D.W.1A G-AFSV, flown by the late Sqn Ldr "Manx” Kelly, near Booker in 1969. This aircraft was re-engined with a 62 h.p. Walter Mikron 2 in 1956.
G-AESZ, the prototype Chilton D.W.1, photographed just after completion, probably at Chilton, Hungerford, in Berkshire, 1937.
The Chilton Single-seat Light Monoplane (32 h.p. Carden engine).
The prototype Chilton was wrecked during a forced landing at Felixstowe, Suffolk, on May 24, 1953, only two years after being reconstructed.
Some idea of the machine's small size and clean lines may be gathered from this photograph. The Hon. A. W. H. Dalrymple, co-conspirator with Mr. A. R. Ward, is standing by the nose.
Another view of the prototype Chilton, location unknown.
The prototype Chilton G-AESZ, in red and silver livery.
Black Monday: Some of the racing machines (and three non-competitors) picketed out in the gale on Whit - Monday, when the Island races had to be cancelled.
QUICK CHANGE: Mr. A. R. Ward replaces the airscrew on the Chilton monoplane at the Speke control during the Isle of Man air race. Meanwhile, Mr. Green of Stanavo tops up the tanks with four gallons - after the Chilton's 160 miles at full throttle. The other personalities are no doubt helping or hindering
Possessed of a remarkably good performance for a machine with only 32 h.p., the single-seater Chilton monoplane has now been flying quite successfully for several months.
The Chilton, though a miniature, is well proportioned and looks right. Mr. R. L. Porteous posed the machine for this and the other photographs.
This frontal view of the Chilton explains where some of the speed comes from.
Coming in to land with the flaps, of notably extensive area, in the fully down position. Different flap angles can be selected for different circumstances; the operating lever is on the left side of the cockpit.
Sqn Ldr H. R. Bilborough nudges Chilton G-AFGH closer to the camera over Denham in 1949. Dr Miles Bickerton owned both the Chilton and Denham aerodrome at the time.
Chilton D.W.1 G-AFGH flying near Denham in 1949, with Sqn Ldr H. R. Bilborough at the controls.
Chilton G-AFGH was re-engined with a 55 h.p. Lycoming O-145-A2 flat four, and parts of the D.W.2 were used to restore ’GH to flying condition in the early 1950s. Note the addition of the bubble canopy.
The two photographs show Chilton G-AFGl in its original configuration, top, and re-engined with a 55 h.p. Lycoming and sporting a sliding canopy, bottom.
Chilton D.W.1A G-AFSV pulling Ranald Porteus at the time he flew the aircraft at Derby in 1948.
Another view of the Mikron-engined D.W.1A G-AFSV Barbara Ann III.
For its appearance at the First Round national air races, held at Yeadon during May, the little Chilton monoplane G-AFSV had been re-engined with a 60-h .p. Mikron engine, instead of a 44-h.p. Train.
DEBAGGED BUT CANOPIED, the single-seat Chilton D.W.la G-AFSV (c n. DW la/la/l), owned by J. E.G, Appleyard of Leeds, is seen at Yeadon, Power is a Waiter Mikron II in-line.
The Carden-Ford in the Chilton Minor
The simple panel and adequately sized cockpit of the Chilton.
DIRECTIVE CENTRE: Tidiness is the outstanding feature of the cockpit of the Chilton monoplane, some flying impressions of which are given on the next page. There are "doors" on each side and room for luggage below the headrest.
Such clean and pleasing lines as these of the Chilton monoplane are seldom found in the "ultra-light category."
The Chilton monoplane, a high-efficiency ultra-lightweight with a Carden-Ford engine.