| October 2009 |
Naval Fighter Development
The following article by (then) Sydney Camm was published in the Inter Services AIRCRAFT RECOGNITION Journal in October 1949. For ease of screen reading it has been reformatted as single columns. To give acceptable clarity, some of the figures have been expanded and the text retyped. Any typographical errors are mine, Tim Hammond, October 2009.
Introduction by Editor of Inter Services AIRCRAFT RECOGNITION Journal
Mr. Camm needs no introduction to our readers, for part of our business is knowing who designs the aeroplanes we recognise — indeed recognition of the designing hand is of some value in studying aeroplane shapes. Mr Camm joined Hawkers in 1923 and became chief designer in 1925. His long list of successful designs includes the Hawfinch, Hornet, Hart, Fury (biplane), Demon, Audax, Harrier, Hector, Henley, Hotspur, Hurricane, Typhoon, Tempest, Fury and P1040 ; and the following Naval designs Horsley, Nimrod, Osprey, Sea Fury, the Naval P1040. There are other variants and experimental types and, doubtless Mr. Camm has new designs up his sleeve which we shall see in due course. We are greatly indebted to Mr. Camm for his interest in our JOURNAL. Also to Mr. Gisbert D. S. Garrett, Editor of the Hawker Siddeley Review for the loan of diagrams and photographs for this article.
Photo Imperial War Museum
One of the earliest deck-landings ever made — in fact the first on a ship underway. The aeroplane is a Sopwith Pup, the pilot Commander Dunning, the ship HMS Furious, and the date August 1917.
NAVAL FIGHTER DEVELOPMENT
by SYDNEY CAMM C.B.E., F.R.Ae.S
IN RECENT YEARS the importance of Naval aircraft, and particularly the single-seat fighter, has received world-wide emphasis. The development of the Naval single-seater, with which this article deals, is of extreme interest and few realise that some of the earliest experiments were carried out more than 30 years ago by the Royal Naval Air Service. The first take-off from the forward deck of the aircraft carrier Vindex were made by Flt. Lt. H. F. Towler, R.N.A.S., in a Bristol "Scout" biplane in November, 1915. The first landing on a ship underway was made in August 1917 by Flt. Cmdr. Dunning, R.N.A.S., in a Sopwith "Pup" biplane on the aircraft carrier Furious. From that time development has proceeded intensively, although there have been periods when the single-seater fighter has lost its position in favour of the two seater. The table following gives a number of particulars of the main naval single-seater fighters and compares them with their contemporary R.A.F. types.
The naval fighter must, of course, embody all the desirable features of the land fighter plus special requirements associated with its work with the Fleet, as follows: —
(i) special facilities for landing.
(ii) special facilities for take-off.
(iii) longest possible duration of flight.
(iv) ability to be folded to small dimensions so that the maximum number can be carried.
(v) best possible pilot's view.
(vi) good slow flying qualities.
Before examining the implications of these requirements it would be of interest to take a glance at the development stages over the years. Although in the early '20s the flying speeds were sufficiently low to permit landing without external assistance, this state did not last for long. Maximum level speed was soon increased, bringing with it an inevitable increase in stalling speed, and it became necessary to introduce some arrangement for arresting the aeroplane on landing. This led to the introduction on board ship of arrester gear which, in its original form, consisted of a number of cables attached to sandbags. On the aeroplane the arrester gear was an "A" frame hook attached some way along the rear fuselage and lowered by the pilot in the process of landing. In those days, as will be seen with reference to Fig. 1, the all-up weight varied between 3,000 and 4,000 lb. The problem was thus comparatively easy compared to that of today, when the weight of fighters has approximately quadrupled and the landing and take-off speeds have almost doubled. Since the space for landing is limited these developments have resulted in much larger decelerating loads being applied to the aeroplane and this, together with the necessity for reducing the complexity of loads, has led to the present design of arrester hook which now takes the form of a fully articulated strut attached to the extreme rear of the fuselage.
Immediately following the early experiments in arresting came the development of the catapult for take-off. The catapult arrangement consisted of a trolley which ran along rails, the aeroplane being supported on lugs arranged two on either side of the fuselage, the average length of run being about 80 ft. from standstill to free flight. This proved much too cumbersome in operation since the aeroplane had to be lifted off the deck and mounted on the trolley. A very much simpler method had been developed which consists of pulling the aeroplane along the deck on its own wheels by the aid of a single or double towing bridle running through a slot. In operation the aeroplane is held back by a strop at its rear end which breaks at a previously pre-determined pull of the towing bridle depending upon the weight and take-off speed of the aeroplane.
Other problems met with between the years 1920 and 1935 were the necessity for providing sufficient buoyancy to enable the aircraft to float after a forced landing on the sea, and also the provision of an alternative seaplane undercarriage. While wood remained the main material of construction the buoyancy requirements were fairly easy to attain, but the change-over to metal construction in 1926 aggravated the problem, the solution being to provide containers in the wings. The requirements were embodied in most Naval aircraft up to the "Nimrod", the standard Naval fighter of the period. Another development at about this time was the inflatable dinghy. This was often installed inside the wing section and on immersion was inflated automatically from a CO2 bottle.
The War in 1939 led to a conversion of the "Hurricane" and "Spitfire" fighters for Naval use, but these aircraft did not fold their wings and the buoyancy requirement had to be abandoned in favour of the inflatable dinghy.
The post-war period has been marked by the introduction of the Hawker "Sea Fury", which was developed from the Royal Air Force fighter of the same name. In these aircraft wing folding by power operation was introduced for the first time. The wing assembly of the earlier biplane types such as the Hawker "Nimrod" was so light that manual folding was a practical proposition. With the advent of the heavier monoplane wing it soon became evident that power folding of the wing unit was essential. This is now normally achieved by an engine-driven hydraulic pump, the operation being completed in about 12 seconds.
A glance at the curve, Fig. 2, indicates vividly how performance has increased over this period of 25 years. Fig.3 shows the increase of take-off and approach speeds in the same period. From this it is interesting to observe that prior to 1930 stalling speeds were low enough to enable landing and take off operations to be carried out unassisted. Note that the approach speed of the Fairey "Flycatcher" was about 50 knots. By 1932, the year when the "Nimrod" was introduced, the approach speed had increased to 60 knots. The early war types such as the Hawker "Hurricane", Supermarine "Spitfire" and Gloster "Gladiator" had approach speeds of 68 knots, which was still fairly low due to the moderate wing loading and the use of fairly large landing flaps. The stimulus of war increased wing loadings so that the later types of Hawker "Sea Fury", Supermarine "Sea Fang" and de Havilland "Sea Hornet" have approach speeds of about 87 knots.
The introduction of jet engines has brought severe problems due to the absence of airscrew slipstream. The latter contributed greatly to the handling of the aeroplane during the approach and landing operations, as it could rapidly be turned on and off. With the jet engine the control over the variation of engine power is much less rapid, and, has no effect on lift at all. This lack of control over both speed and lift has made it necessary for jet fighters to approach at speeds corresponding to lift coefficients much lower than the maximum obtainable. The loss of lift control due to the absence of slip stream and large drag due to a windmilling propeller has made it necessary to introduce large drag-producing flaps which can be quickly controlled by the pilot. Nevertheless, in spite of this, the approach speeds have increased alarmingly, being over 100 knots for modern jet fighters.
As mentioned previously, the Naval fighter is basically a land fighter with emphasis on certain features as well as the attainment of the maximum possible performance in rate of climb, level speed and range. Unfortunately the special requirements of the Naval fighter involve a weight penalty which, in the case of a machine in the Fury class, is shown by the table in Fig. 4. It is clear, therefore, that an outstanding problem in Naval fighter design is to keep weight to the irreducible minimum. As range is vital, a further problem is that of proving sufficient volume in the aeroplane to house the equipment and also the fuel. Any increase in size over that of the basic fighter will, of course, reduce the performance and this long standing difficulty in Naval fighter design is now intensified by the introduction of the jet fighter with which maximum speeds in excess of 600 m.p.h. with one engine are now possible. \tab Unfortunately, equipment is becoming more complex and armament is certainly not lighter, so that we are forced to examine the possibilities of radical changes in future design of single-seater Naval fighter aircraft. The most obvious of these seems to be elimination of the undercarriage. In the case of a modern fighter such as the "Fury" or equivalent jet types, this will lead to a saving in weight of approximately 700 lbs; of equal if not greater importance is that it will release space for fuel and equipment.
From what has been said in the foregoing it is clear that given equal standards of design the Naval fighter will always have a performance inferior to that of its land-based counterpart. The elimination of the undercarriage, however, may well enable the position to be reversed and a naval fighter to be produced with a superior performance until the shore-based fighter is able to follow suit.
The need for the best possible Naval fighter was well expressed by Admiral M. S. Slattery when he said, at the discussion following a survey of the technical problems of the design of Naval fighter aircraft held by the Royal Aeronautical Society: "From our experience in the Mediterranean it seems that one of the things we must have is a carrier-borne fighter aircraft of the highest performance, comparable in every way to the aircraft which can be put up from the shore".
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Yugoslav lettering, as at left "B" for example, in white rather than the Sky or Medium Sea Grey expected on RAF aircraft. The aircraft is believed to have been on "A" Flight. A dark green/ocean grey upper surface camouflage. Medium sea grey underneath. No tail stripe (abandoned on British aircraft late 1944). Light/medium blue (sky blue) spinner (a Morrisons' trademark). Dummy blast plates rocket rails and rockets. What a unique sight it would make! Well here's hoping Mr Lamplough!
