How emergency equipment has increased safety in flying
THE FIRST STAGE of a parachute descent is to clear the aircraft after having jumped or dived from it. The standard parachute for general service is 24 feet in diameter. It has two main parts, the harness and the pack. Complete with harness and pack, it weighs about 22 lb and has a rated descent of 16 feet a second. When the parachute is descending, a miniature parachute known as the auxiliary, or pilot, is at the top above the vent in the canopy of the main parachute. Rigging lines or shrouds from this canopy are led to four rings. These rings are connected to the harness, which is made of heavy webbing.
THE parachute is now the standard equipment for the flying personnel of the air forces of the British Commonwealth of Nations, the United States of America and other countries, and is in regular use by civilian aviators in many parts of the world.
Although balloon ascents and parachute descents were common before the aeroplane was invented, the theory of the parachute is older than that of the balloon. Early theorists do not appear to have put their ideas into practice. Their plan was to gain height by climbing a tower and then to jump off, using a sail or canopy, something like a huge umbrella, to check the force of gravity. This idea was not confined to Europe; there are legends of experimenters in the Far East who jumped from towers.
Parachute towers are now used in Russia and in France for training. By the use of such towers the Russians are making the public familiar with the parachute, although the tower is unsuitable for any purpose other than training. The canopy is fully extended and depends from a wire attached to a crane. The novice goes to the top of the tower, puts on the harness and is swung clear of the tower platform; the parachute is then released.
The Russians also use a parachute catapult for training purposes. This device, invented by Ivan Titov, an engineer, is installed in the Kirov Park of Culture and Rest, Leningrad, and can be used by seventy pupils in an hour. It is operated by a propeller-motor machine which generates a vertical current of air. The pupil stands on a grating, the fans are started, and the parachute is blown to a height of about 250 feet, before it floats out of the air-stream and descends.
The first man to descend successfully in a parachute from a balloon was Andre Garnerin, in Paris, in 1797. In 1802, this pioneer parachutist came to London and again successfully jumped from a balloon. Garnerin’s early parachutes had a vent at the apex to reduce oscillation, or swinging. The parachute which he used in London did not have a vent, nor did the parachutes of his successors until this device was rediscovered in the 1880’s.
These parachutes were attached, opened, to balloons, but in the eighties professional parachutists began to experiment with flexible parachutes. The outstanding practitioner was Major Thomas Baldwin, an American, for it was he who solved the problem of oscillation. Baldwin made a hazardous exhibition descent from a balloon, swinging wildly, like the pendulum of an erratic clock. He and the crowd were astonished that he landed alive.
This gave Baldwin the clue. He rediscovered the use of the vent, which Garnerin had embodied in his first parachutes. Until Baldwin produced his parachute, the parachutist was swung to and fro in the air like a man on a flying trapeze. The air was compressed under the apex of the canopy and could not escape; thus descent was tardy and the parachute was blown hither and thither by side-winds. The vent eased the shock when the folded parachute opened, and it enabled the parachute to descend without swaying violently in the air currents.
Parachutes were satisfactory enough until the aeroplane was invented. To make a descent from an aeroplane was found to be a somewhat hazardous adventure. Several men tried it, among them Adolphe Pegoud (1887-1915), and Leslie L. Irvin, about 1911. Irvin’s parachute was folded and was packed loosely in a sack which was made fast to the aeroplane. Irvin was attached to the parachute by a line. When he jumped from the aeroplane his falling weight pulled the parachute clear of the sack, the parachute opened and Irvin descended. He proved that a man could jump from the machines of 1911 without upsetting them.
The first parachutist to make a successful descent, from an aeroplane in England was the late William Newell, at Hendon, in May 1914.
Escaping from Captive Balloons
Other successful jumps followed. Then came the war of 1914-18. The parachute was a reliable means of escape from airships and particularly from the observation balloons used on all fronts. When a balloon was set on fire by hostile aircraft the observer jumped with his parachute. It was considered unsportsmanlike for an enemy aviator to machine-gun the parachutist; a Hague Rule specified that a parachutist should be spared during descent.
Various parachutes became well known, among them being the types produced by E. R. Calthrop. Calthrop resolutely tackled several difficult problems, especially that of escape from an aeroplane at low altitudes. As a test two parachutists jumped from Tower Bridge, London, in November 1917, and the parachutes opened and lowered them without injury into the Thames, despite the fact that the drop was only about 140 feet. In other countries the quest for reliability was keen, but despite all efforts one fact was obvious.
Men who jumped with parachutes from aeroplanes had a high rate of mortality. The parachute which was a success when used from observation balloons was not to be relied upon by aeroplane pilots and observers. The parachutes were attached to the aeroplane or were folded in a container. As the pilot jumped or was flung from the disabled aeroplane the line connecting his harness with the parachute pulled the canopy out of the container - sometimes, but not always. Often the machine was spinning, or was so badly damaged, that the line of the parachute would foul a part of the aeroplane and thus fail to operate.
AFTER HE HAS JUMPED OR DIVED from the aircraft, the parachutist’s next task is to release the parachute. Once clear of the aircraft he gives a sharp tug with his right hand; this action pulls the rip cord out, and all four flaps of the pack cover fly open. The auxiliary parachute opens immediately. The resistance of the air on the auxiliary pulls the main canopy in a long fold from the pack. The rim of the main canopy begins to open, and the air rushes up into the canopy, but cannot escape until it has forced open the upper part. The shrouds are pulled clear from the pack to the loop rings, and these pull the connecting webbing above the parachutist’s head so that the strain is taken by the harness.
Committees tried to discover a parachute that would save the lives of military aviators. They failed and when the Armistice was declared in November 1918 every Government except that of the United States shelved the problem. Americans persevered and found the parachute which fulfilled their needs.
It embodied new principles evolved by Irvin and his pilot, Floyd Smith. Irvin, who made one of the first jumps from an aeroplane, was an experienced high diver. When diving into water or nets he gained that control of mind and muscle which the diver maintains during the brief time that he is descending through the air. This, added to his experience as a parachutist, enabled him to deal with the problem in a different manner.
Irvin maintained that if a diver could control his body at will during a dive from a height of less than 100 feet, it should be possible for a parachutist to control mind and muscle while diving from a height of several thousand feet. The parachutist could dive with his parachute closed and select the moment when he would open it. It was generally thought that a man falling from a great height through the air was incapable of thought or action after he had fallen several hundred feet. Irvin decided otherwise. The United States authorities, who had accepted his parachute as the nearest to perfection, agreed to allow him to dive with it.
Piloted by Floyd Smith, the aeroplane took off on April 28, 1919. Irvin wore his harness and sat on the canvas pack containing his silk parachute. At 2,000 feet Irvin climbed from the cockpit and stood ready. He signalled to Floyd Smith and dived. As he fell he gave the ring on his harness a sharp tug and the cord operated a release device on the canvas envelope of the pack, spilling the parachute. The canopy opened in about a second and a half, the silk cords connecting it with the harness took the strain, and Irvin floated down to earth, the first man to open a parachute while falling.
The parachute is called the Irvin Air Chute. It is made by the Irving Air Chute of Great Britain, Ltd., at Letchworth, Herts. It was selected as standard equipment for the United States Air Service in 1919 and by the British Air Ministry for R.A.F. use in 1925.
More than 1,700 lives have been saved in various countries and climates by these parachutes. They have operated in all kinds of emergencies - fire in the air, wing collapse, collision, control failure at altitudes as low as 150 feet, engine failure at night, persistent spins and nose dives. Jumps have been made from aeroplanes travelling at 300 miles an hour, and descents have been made from altitudes up to 30,000 feet. Over 100,000 “live” drops have been made without failure.
The standard parachute for general service is 24 feet in diameter. Complete with harness and pack, it weighs about 22 lb, and has a rated descent of 16 feet a second. A larger parachute, 28 feet in diameter, is made for exhibition and training jumps and has a slower rate of descent. The 24-feet parachute has two main parts, the harness and the pack. There are five types of pack: the Seat, the Quick Connector, the Straight Back, the Form-Fitting Back and the Chair.
The seat pack is primarily for pilots. The quick connector is for passengers and observers who find it difficult to wear a parachute while in flight. The straight back is for use in balloons, airships and large aeroplanes; it allows freedom of movement when the wearer is walking, or climbing into the aircraft. The form-fitting back pack is for use in aircraft whose design is inconvenient for the use of other types.
THE THIRD AND FOURTH STAGES in a parachute descent are the controlling of the descent and the landing. The parachutist settles himself comfortably in the seat of his “swing”. By manipulating the suspension straps he can manoeuvre the parachute to avoid trees or buildings. To prepare for the landing he retains the sitting position, with the muscles of the body relaxed. He raises his arms to their full extent up two of the suspension straps. The moment his feet touch the ground he puffs down on the straps with his hands to help to absorb the shock of the landing.
The chair type is incorporated in the upholstery of chairs in cabin aircraft with the harness arranged so that it can be fitted in an emergency. This chair parachute has been designed to make it adaptable for women as well as for men passengers in air liners or private aircraft, and the equipment, including parachute, harness, pad and chair fittings, weighs only 16½ lb.
When the parachute is descending the miniature parachute, called the auxiliary, or pilot, is at the top, above the vent in the canopy of the main parachute. Rigging lines, or shrouds, which pass through the canopy, are led to four rings. These four rings are connected to the harness, which consists of heavy webbing with a minimum breaking strain of 4,500 lb. The harness is so designed that the parachutist sits in it as if he were in a swing and relaxes his body. No physical effort is required. He sits and floats downwards.
The design of the harness varies according to the type of parachute. When the user is equipped with quick release harness and a seat pack, the harness is connected in the following way. There are the ends of four webbing straps with lugs, and these lugs fit into a quick release box. The lower two straps form a loop over either leg; the upper two straps are the shoulder-straps. The user draws the quick release box, which is fastened to the webbing, across the left side of his body. Then he thrusts the four lugs on the ends of the four straps into the quick release box, so that the hole in each lug engages a locking plunger, locking the box.
Having risen from his seat, fully equipped, he jumps or dives from the aircraft. There are no rules for the best method of jumping from a disabled aircraft; everything depends on the circumstances. One thing is essential: “Get clear of the aircraft before you pull the rip cord”.
With an aeroplane in flames, or spinning to destruction, or diving at 300 miles an hour, the aviator must at once clear it. He acts according to his need. If the aeroplane is at a good altitude and is falling in the same line as himself he delays pulling the ring of the rip cord, because his rate of fall will be different from that of the aeroplane. When he is clear he gives a sharp tug with his right hand - which from the moment of jumping he has across his chest, with the hand gripping the rip cord ring on the left of his harness - and pulls the ring smartly.
The ring is housed in an elastic-mouthed pocket, and is attached to the rip cord, a steel cable in a flexible housing. The end of the rip cord passes through two locking cones on the pack. The sharp jerk pulls the cord out. All four flaps of the pack cover fly open under the. action of elastic, the resilience of the tightly packed silk and the spring frame of the auxiliary parachute.
The auxiliary springs out like a Jack-in-the-box and opens in a flash. The air pressure and the weight of the falling parachutist do the rest. The resistance of the air on the auxiliary pulls the main canopy, apex first, in a long fold from the pack. The rim of the main canopy begins to open, generally before the rigging lines are fully withdrawn from their pockets in the pack. The air rushes up with great velocity into the canopy but cannot escape until it has forced open the upper part.
WHEN A LANDING IS MADE the parachutist does not stand. He sinks to earth and, if necessary, rolls along the ground. If the wind is strong, immediately his feet touch the ground he strikes the dial of the quick release box. This releases him from his harness. The parachute, relieved of his weight, blows clear.
So rapid is the process of opening that it is not possible to observe it accurately with the eye. It has been filmed with a slow-motion camera, and the film shows that the air in the upper part causes the canopy to open from the apex to the periphery. The shrouds are pulled clear from the pack to the loop rings, and these pull the connecting webbing above the parachutist's head so that the strain is taken by the harness.
The user has now completed two stages of the descent: jumping or diving clear and releasing the parachute. He now begins the third stage: controlling the descent.
He settles himself comfortably in the seat of his “swing”. If he is a little too far forward he places his thumbs in the seat strap beside either leg and presses downwards, thus pushing his body upwards and back into the harness. If he is too far back, a movement in the forward direction is equally simple.
If there is any danger of his landing on buildings or among trees, he can alter the angle of gliding by side-slipping. If he wants to move to the right, he tugs the two suspension straps on his right side downwards. This action depresses the shrouds and spills some air from the left side of the canopy, causing the parachute to move to the right. The action accelerates the rate of descent. The canopy opens fully again when the rigging lines are released. A parachute naturally lands with the wind, and the parachutist therefore aims to face the direction of drift during the descent, so that he can see where he is going. If he is drifting backwards he turns the parachute. He tugs the shrouds to pull down the edge of the canopy in the direction in which he wishes to turn and then grasps the shrouds on the opposite side and, without pulling down, gives the parachute a twist, in the desired direction, turning it. He is successful, and passes on to the fourth stage of the descent, the landing.
He retains the sitting position in the harness with the muscles of his body fully relaxed. He raises his arms up two of the suspension straps to the full extent. At the instant that his feet, which are still bent with all the muscles slack, touch the ground, he pulls down on the straps with his hands to help to absorb the shock of landing. He makes no attempt to stand. He sinks to the ground and rolls, if necessary. Conditions may not be favourable. He may be making a landing in a strong wind. If this is so, when he is about 100 feet from the ground, he gives the dial of the quick release box of his harness a quarter turn, unlocking it, but not opening it. Immediately his feet touch the earth he strikes the dial smartly with his hand. This knocks all four plungers from the eyes in the harness connexion lugs, releasing the parachutist from his harness. Relieved of his weight, the parachute blows clear. The aviator retrieves the parachute as quickly as he can and rolls it up to prevent it from being carried by the wind against obstructions that will damage the silk.
If he has to alight in water, the parachutist endeavours to free himself of the parachute the moment his feet enter the water. He turns the dial just before the crucial moment, puts his feet together and stiffens his body. He punches the dial with one hand, while with the other he pinches his nostrils to prevent the water from rushing into them. At the same time he keeps his elbows pressed close to his sides to avoid injury.
INSTEAD OF JUMPING from an aeroplane, and then pulling the rip cord of the parachute when he is clear, a pupil in the Royal Air Force may follow a different procedure. With his pack in position he stands holding an outer strut and watching the pilot. When the pilot is ready he signals to the pupil, who pulls the rip cord. The pupil continues to hold the aeroplane strut until it is pulled from his grasp by the drag of the open parachute behind him.