Deck Landings and Catapulted Machines Enable Aircraft to Act as the Eyes of the Navy
AIRCRAFT CARRIER HMS GLORIOUS, converted from a cruiser in 1930. An aircraft carrier is more than a floating aerodrome. She is a naval unit, complete with crew for handling the ship and manning her guns. The superstructure, including funnel and bridge, is arranged at one side of the vessel to give as much clear space as possible for the flying deck.
AIRCRAFT of the Fleet Air Arm, the R.A.F. section attached to the Royal Navy, are ship-borne types. They are formed into units known as carrier-borne squadrons and catapult squadrons.
The duty of the Fleet Air Arm is to provide the Royal Navy with fighter aircraft to obtain the mastery of the air, and torpedo-spotter-reconnaissance aircraft to reconnoitre from the air, to serve as spotters for the guns, and to harry the enemy from above with bombs and torpedoes.
The kind of equipment required for work with the Fleet is somewhat different from that of the aeroplanes used by the Royal Air Force. Ship aircraft must be strong enough to withstand launching by catapult.
It is necessary to carry means for signalling when in distress at sea, and stowage is provided for special marine distress signals. The signals are generally housed near the tail of the aircraft, and sometimes in the fin, for there they are least likely to be submerged and in the event of accident are most accessible to the crew. Instruments conform to the requirements of marine practice. The air speed indicator registers in knots instead of in miles per hour. Naval codes are used for radiotelegraphy and for signalling by lamp.
The first aircraft carriers were introduced into the Navy in the early days of the war of 1914-18. All carried seaplanes. The adventures of one of them, the Ben-My-Chree, in the Mediterranean during the early part of the war read like a page from a biography of Ralegh or Drake. She sailed from Great Britain to the Dardanelles with seaplanes built by Short and Sopwith. One of the Sopwith Schneider Cup seaplanes raided the Turkish lines. It caught fire and came down on a canal between the strait and the sea, but the pilot, Maurice Wright, managed to get back to the ship. Two of her Short seaplanes made the first torpedo attacks from the Gulf of Seros. Each torpedoed a ship in the Sea of Marmara. Then the Ben-My-Chree went to the island of Imbros for reconnaissance work. After the evacuation she sailed to Port Said and thence to the Palestine coast. From Gaza her seaplanes made reconnaissance flights lasting three-and-a-half hours to points fifty miles inland over the Turkish armies. Later, from Aden, similar work was carried out. Finally, off Castelrosso (Castellorizo), the Ben-My-Chree was sunk by gunfire from the Turkish coast half a mile away.
Most of those early carriers were converted merchantmen, modified to carry the seaplanes in their holds. The seaplanes had to be slung outboard to take off from the water under their own power, and at the end of the flight they had to alight on the water and be hoisted inboard by cranes.
A great advance in the use of aircraft for purely naval purposes came with the development of the large aircraft carriers fitted with flying decks. The first of these ships was the converted cruiser Furious. Completed in 1917, she was followed by the conversions of the Argus (1918), the Eagle (1924), the Courageous (1928) and the Glorious (1930). The Hermes, laid down in 1918, was the first ship originally designed to be an aircraft carrier. The Ark Royal was launched in 1937.
Developments in the use of land-planes on aircraft carriers have proceeded steadily ever since the first flights from the Furious. The first experimental landing on her deck was made by Squadron Commander E. H. Dunning in a Sopwith Scout. His first landing was successful, but the second ended in disaster. The light little single-seater swerved over the side of the ship, dropped some 70 feet into the water and was wrecked. This accident produced a demand for means to prevent aircraft from going over the side of the ship. The flying deck of the Furious was only 80 feet across. This left all too little room once an aircraft began to swerve.
When aircraft take off and land on the flying deck the aircraft carrier steams into the wind. The wind created by her own movement added to the natural breeze passes straight along the deck from bow to stern. This flow of air enables the pilot to take off and alight relatively slowly. For example, if an aeroplane has an alighting speed of 60 and the air flow over the deck is 30 miles an hour, the aeroplane can alight at 30 miles an hour. The force of the wind quickly brings the aeroplane to a standstill, provided it runs straight along the deck. But if the aeroplane should swerve from any cause, the wind that ordinarily is the pilot’s friend becomes his enemy. Its full force, felt under the wing (or wings) on one side, tends to increase any swerve which may have been set up.
The swift tragedy that followed the second landing on the deck of a British ship caused the Navy to look about for ways and means to prevent aeroplanes from swerving or, if they swerved, to stop them from going over the side of the ship on which they alighted.
In the earliest attempts cables were laid across the flying deck with sandbags attached to their ends. When the aeroplane came down it alighted among the cables, which tangled themselves up with the tail skid and undercarriage. The aeroplane was brought quickly to a standstill by the braking effort applied by the sandbags dragging over the deck. That method, although elementary, worked and was used for a short time.
It was then replaced by an elaborate system of cables running fore and aft along the deck. Ordinarily the cables lay flat on the deck, but they could be raised to a height of some 12 to 15 inches and simultaneously tensioned by means of movable supports. The aeroplanes were then equipped with four special hooks mounted under the axles of the undercarriage, two on either side.
AN AIRCRAFT LIFT IN OPERATION. The aeroplanes in an aircraft carrier are housed in a large hangar below deck. They are transported to and from the flying deck by lifts, of which there are two. The aircraft have to be of a type with folding wings, except when they are small fighters; otherwise they would be unable to use the lifts. Workshops are provided below, where repairs and the necessary maintenance work on the aircraft may be carried out.
These hooks had strong springs which, while keeping them vertical, would give to exceptional loads and so prevent the hooks from breaking when they picked up the wires. Snap springs closed the mouth of each hook. The deck cables were spaced quite close together. When an aeroplane descended among them the hooks on the axle generally picked up some of the wires. The aeroplane was thus forced to run on a straight course along the deck, while the friction of the wires running through the hooks acted as a brake and helped to bring it to a standstill.
This method seemed satisfactory in theory, but damage occurred to many of the aeroplanes. Sometimes the aeroplane picked up the cables, struck the deck heavily, and then rebounded into the air, only to be pulled violently down to the deck by the elastic-like quality of the cable. This frequently caused broken undercarriages or tail-skids, and occasionally a broken airscrew.
To understand the following incident, it must be explained that steel nets hang outboard just below the level of the flying deck for the protection of the deck crew while machines are approaching. From the nets the handling parties can jump swiftly on to the deck to guide the landing aeroplane to the lift that lowers it to the hangar.
On one occasion a fighter came down rather heavily near the port side of the deck. It picked up only one cable in the extreme left hook. The aeroplane bounced, swerved with the offset pull of the cable, cartwheeled and leapt nose-first over the side of the ship.
In its passage over the nets, the hurtling fighter knocked off the hat of a learned doctor of science who was recording the scientific aspects of deck-landing on behalf of the Air Ministry, and tumbled him headlong into the bottom of the net. The doctor in his excitement dropped the sheaf of papers on which he had been making copious notes. As they fluttered away astern and fell into the sea, his concern was concentrated more on the loss of his data than on the loss of the aeroplane or the predicament of the pilot.
Arrester Gear Redesigned
A strangely long period seemed to elapse after the moment when the machine rushed over the side until, some two seconds later, there came the curious dull bang that accompanies the crash of a partly wrecked aeroplane into deep water.
Before the aeroplane hit the surface of the sea the attendant destroyer that always steams behind an aircraft carrier during flying operations had headed towards the spot and lowered a boat that had been manned as though by magic. Before the sailors had time or need to dip their oars in the water, the boat was alongside the wreckage.
Swiftly the pilot was helped on board, with a cut over one eye and a badly swollen lip, but otherwise little the worse for the mishap. Within five minutes of his cartwheel over the side of the aircraft carrier he was in the wardroom of the destroyer.
Comparatively few accidents of this kind have taken place. This incident did not occur on normal routine flying, but during the deck landing trials of a new fighter designed for naval use. The cause of the crash was partly due to the type of arrester gear then in use.
FAIREY SEAL IN FLIGHT ABOVE H.M.S. COURAGEOUS, in the wake of which can be seen the attendant destroyer. A destroyer is always at hand when flying is in progress, to go to the aid of any pilots who may come to grief in the water. Deck landings are the most difficult part of flying in the Fleet Air Arm, and the degree of skill required can be gauged from this picture, which emphasizes the small area on which the pilots have to land.
There followed a period when all forms of arrester gear were abolished. Pilots again landed by skilled judgment on the open deck. As a safety measure, palisades were fitted to the edges of the flying deck about one-third forward along the deck from the stem. The palisades were inclined outward at an angle of about 30 degrees to the horizontal, and interconnected by square mesh cable. If an aeroplane swerved it stood a reasonably good chance of being held up by the palisades instead of falling into the sea, but it could not run into the palisades without suffering damage.
The palisades have become a standard feature of aircraft carriers. After a number of years brakes were fitted as standard to the wheels of all aeroplanes. Aircraft carrier pilots found that brakes served a useful purpose; not only did they help to pull the aeroplane up more rapidly, but also they enabled it to be steered on the deck. Several times adroit braking played a useful part in preventing an aeroplane from going over the side.
Again, however, came the inevitable demand for arrester gear to simplify deck landing. A recent type is an elaboration of the original crude kind which used sandbags as the braking medium; in place of sandbags the transverse cables of the arrester gear of today pass through the deck and are connected to hydraulic mechanism underneath. Hinged posts enable the transverse cables to be raised about 15 inches above the deck, or dropped flush so that they do not obstruct taxying and flying off. The new gear has sufficient resiliency to avoid damaging the aeroplane, yet it has sufficient arresting power to pull the aeroplane up quickly. The pick-up gear fitted to the aeroplane is a steel member that can be lowered when landing, and raised for taking off and flying. It is provided with a hook at its lower end. When the aeroplane comes in to alight on the deck, the lowered hook trails below the after part of the fuselage and is the first part of the machine to touch the cables. The hook engages one of the cables while the aeroplane is still travelling through the air. The shock-absorbing gear allows the cable to extend, but the aeroplane is pulled to the deck and to a standstill with extreme rapidity.
There are few more beautiful sights than at sea on board an aircraft carrier when deck landing is taking place at night. The deck is floodlit - a splash of beamless light in the blue night. The salty wind blows over the deck and, 70 feet or so below, the phosphorescence displays the water rushing past the hull. Out of the darkness come the navigation lights of an aeroplane. It circles, turns into wind, then steadily descends towards the deck. At the last moment the two lights may be lost to view while passing through the oil smoke, but an instant later they can be seen again, red and green, cushioning gently down to the floodlit space.
Alighting on the deck is certainly the most difficult part of the flying of carrier-borne units. But there is a beauty in the swift surge forward of aeroplane after aeroplane when they take off. One after another, with a roar from the engines, the tails come up. The machines accelerate slowly against the blast of air coming over the ship’s deck. Then with a leap they are up and off, streaking away above the bows of the ship, outlined against the blue of the sky, or the white of the cloud ahead.
Every take-off and alighting is rigidly controlled by signal from the ship. In flight there is the need for skilful navigation over the trackless sea.
Again, there is the fascination of the ship herself, for she is much more than merely a floating aerodrome. She is a naval unit, complete with crew for handling the ship and her guns. From the wardroom to the upper flying deck is a long passage through narrow corridors, round guns, perhaps brushing the hammocks of some of the crew, up steel ladders and round corners which would bewilder the layman if he had to get there in a hurry.
A COSTLY EXPERIMENT is represented by the U.S. Navy aircraft carrier Lexington, which cost £9,090,000 to convert from a battle cruiser. With a flight deck 880 feet long and 85 to 90 feet wide, she would be a huge target in time of war. Although she has an aircraft capacity of ninety it would be impossible to operate anything approaching this number of machines simultaneously.
In the vast hangars below the flying deck there is space to carry the aeroplanes that have been lowered with their wings folded on the forward and after lifts. Only the smaller fighters have fixed wings. All the larger aeroplanes must have folding wings; otherwise they would be unable to use the lifts, and there is no other way to get them from the flying deck to the hangar and back again. The hangar, too, affords workshop facilities for repairs to be carried out to aeroplanes and engines. Spares are slung overhead. Every inch of useful space is taken up with the storage of the thousand and one things that aeroplanes require for proper maintenance for Service use.
In the capital ships and cruisers there is no room available to provide a deck for flying off and landing. In peace time the alighting problem is solved by the use of seaplanes, and the launching problem by the use of catapults. The catapult enables the seaplane to reach flying speed in a much shorter distance than is possible under its own power. On returning to the ship the seaplanes alight on the water and are hoisted inboard by crane and hoisting tackle.
Aeroplanes which are to be launched by catapult have to be strengthened to take the impetus imparted to them by the catapult, for the loads are imposed upon the aeroplane’s structure in the opposite direction to that of the loads encountered in flight.
For launching, the seaplane is mounted on the catapult carriage, whose four arms register with the four catapult points on the fuselage of the seaplane. The pilot of the machine is provided with a special headrest, against which he presses the back of his head to prevent a sudden jerk upon the neck muscles when the seaplane shoots forward on the catapult carriage.
Before the catapult carriage is released the aircraft’s engine is set at full speed by the pilot. At a signal from the pilot the catapult is “shot”. The modern British catapult is operated by cordite. In a run of between 70 and 90 feet the seaplane reaches a speed of about 65 knots, the carriage of the catapult comes into contact with the arrester gear, which brings it quickly to a stop, and the seaplane leaves the carriage and flies forward.
Punched into the Air
Some years ago an aircraft was catapulted experimentally. The catapult was of the kind actuated by an explosive cartridge. The aircraft was stressed to take the normal catapult loading with safety, but the heat of the explosion of the cartridge flashed the lubricating oil in the catapult mechanism; it acted on the moving ram like the charge in the cylinder of an oil-driven engine, causing the catapult to launch the machine with a terrific punch. The fuselage was of the old wood and wire-braced type, enclosed in a linen bag. The sudden shock broke all four main members of the fuselage and shot the aircraft into the air in a fast zoom. When the pilot landed on the deck of the aircraft carrier which was being used for the experiment the fuselage collapsed. For about fifteen minutes of flight the aircraft had been held together by the bracing wires and the linen bag.
Such things do not happen today. Catapulting has become a standardized method of launching aircraft, even of great sizes and weights.
In January 1938 there were in the Fleet Air Arm eight catapult flights and three catapult squadrons, their aircraft all manned by naval officer pilots.
The squadron is the catapult aircraft unit of the future. Three aircraft are the most usual complement in ships equipped with catapults, but this is not a rigid standard. Some of the less modem of the smaller ships may carry only one machine and at least one ship carries four. For peace time operations the aircraft used are either floatplanes or small single-engined amphibians.
AMPHIBIAN AIRCRAFT ON THE CATAPULT OF H.M.A.S. SYDNEYbefore beginning a flight. The machine is a Supermarine Seagull V. One of the advantages of an amphibian type of aircraft for catapulting purposes is that it permits air communication when required between the ship and a land aerodrome. A catapulted aircraft, when returning to the ship, alights on the water and is lifted on board by a derrick.