Parachutes

     A parachute is a device used to slow the motion of an object through the atmosphere by creating drag. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon. Parachutes often take the shape of a dome, but shapes may vary including some taking the shape of an inverted dome. Depending on the situation, parachutes are used with a variety of loads, including people, food, equipment, space capsules, and bombs. Drogue chutes are used to aid horizontal deceleration of a vehicle (a fixed-wing aircraft, or a drag racer), or to provide stability (certain types of light aircraft in distress. 
     A parachute works by increasing air resistance during the objects fall. Gravity makes falling objects accelerate, but only up to a point. If you jump off a skyscraper, your body ought to speed up by 32 feet per second every second you're falling. If you were high enough off the ground, then after about a minute and a half, you'd theoretically be falling at about 2200 mph, which is about as fast as the fastest jet fighters have ever flown. In practice, that doesn't happen. 
     After about five seconds, you reach a speed where the force of air resistance increases so much that it balances the force of gravity and at that point, there is no more acceleration and you keep on falling at a steady speed called your terminal velocity. The terminal velocity for a falling person (with arms stretched out) is about 125 mph, which is fast enough to kill you upon impact. 
     Feathers fall more slowly than stones because their terminal velocity is lower. Likewise, a parachute works by dramatically lowering the terminal velocity by increasing your air resistance. Parachutes are designed to reduce your terminal velocity by about 90 percent so you hit the ground at a relatively low speed of about 12 mph. 
     Parachutes are actually three chutes in one, packed into a single backpack called the container. There's a main parachute, a reserve parachute (in case the main one fails), and a tiny little chute at the bottom of the container, called the pilot chute, that helps the main chute to open. 
     Once you're clear of the plane, you trigger the pilot chute and it opens up creating enough force to pull the main chute from the container. The main chute has to be carefully packed so the ropes that connect it to your harness open correctly and straighten out behind you. The main chute is designed to open in a delayed way so your body isn't braked and jerked too suddenly and sharply. 
     The force on a parachute is considerable, so it has to be made from really strong materials. Originally, parachutes were made from canvas or silk, but inexpensive, lightweight, synthetic materials such as nylon and Kevlar are now generally used instead.

     Parachutes were invented about a century ago, but they continue to evolve. The first known written account of a parachute concept is found in da Vinci's notebooks around 1495. The sketch he drew consisted of a cloth material pulled tightly over a rigid pyramidal structure. Although da Vinci never made the device, he is given credit for the concept. 
     Fauste Veranzio constructed a device similar to da Vinci's and jumped from a tower in Venice in 1617, but over a century would pass before further developments would be made by the famous balloonists, Joseph and Jacques Montgolfier. 
     In 1783 they succeeded in lowering animals to the ground from rooftops or balloons. During the same year Sebastian Lenormand jumped from a tower using a 14-foot diameter parachute. The first emergency use of a parachute was made by Jean Pierre Blanchard in 1785 after the hotair balloon he was in exploded. Blanchard also worked on a foldable silk parachute; until then all parachutes were constructed with a rigid frame. 
     In 1797, Andrew Garnerin made the first jump with a parachute without a rigid frame. One of Garnerin's balloon jumps from 8000 feet was observed by a French astronomer, Lalandes. As the parachute descended, severe oscillations were induced in the canopy. Lalandes suggested cutting a small hole near the apex of the canopy to inhibit the oscillations. It worked and this modification is now known as the vent. 
     During the next century, parachute use was confined to carnivals and daredevil acts. Acrobats would perform stunts on a trapeze bar suspended from a descending parachute which was released from a hot-air balloon. Public opinion became very unfavorable towards the use of parachutes when Robert Cocking fell to his death in 1837. Cocking jumped an inverted cone-shaped parachute (point down) from 5000 ft. and distinguished himself by becoming parachuting's first fatality. 
     The next major contribution to parachute systems was the development of a harness by Captain Thomas Baldwin in 1887. The concept of folding or packing the parachute in a knapsack-like container was developed by Paul Letteman and Kathchen Paulus in 1890. Paulus also demonstrated an intentional breakaway...after a first parachute inflated, it was released and pulled open a second parachute. 
     The first jump from an airplane has been claimed by both Grant Morton and Captain Albert Berry in 1911 or 1912. Morton jumped with a silk parachute folded in his arms which he threw out as he left the plane. Captain Berry had a 36 foot parachute packed into a metal case beneath the fuselage. The parachute had a trapeze bar for him to hold on to as he jumped. Also in 1911, an Italian, Pino, invented the pilot chute or drogue chute. He attached a small parachute with a rigid frame to his helmet. The pilot chute would inflate, pull the helmet off and then pull the parachute out. 
     The first free fall jump was made by Georgia "Tiny" Broadwick in 1914, but the military still did not believe that the human body could tolerate the experience of free fall for more than a few seconds before blacking out. The skeptics were convinced in 1919 by Leslie Irvin and Floyd Smith after they demonstrated free fall jumps and developed the ripcord at the parachute testing and training center at Wright Field, in Dayton, Ohio established in 1918.
     From World War I to the early 1930's, conventional round silk parachutes remained unchanged and were primarily used by military air corps in Europe, Russia, and the United States. During the 1930's a German Luftwaffe officer, Kurt Student, came up with the idea a rapid deployment strike force by parachuting men, equipment, and weapons from gliders and aircraft. Germany demonstrated the effectiveness of airborne troops delivered by parachutes during World War II. 
     The development of modern parachutes deployed at high speeds and high altitudes started in the 1930's whe tywo Germans developed a “ring slot” parachute designed to decelerate heavy, high speed payloads. This parachute was used primarily for cargo delivery and aircraft deceleration. 
     H. G. Heinrich invented the guide surface parachute used as a pilot chute or for vehicle stabilization in the supersonic (to Mach 3) deployments. The hyperflo parachute is used as a hypersonic pilot chute for Mach 1 to Mach 5 speeds. 

     The development of sport parachutes began in the early 1960's. Parachutes developed many modifications that allowed the parachutist greater maneuverability. 
     Parachutes are not always reliable as Clem Sohn discovered. Even today they are not 100 percent reliable. Navy Seal Remington Peters recently died in a parachute accident in New York City.

How the US Army's 1st Battalion, 507th Parachute Infantry Regiment trains Paratroopers...HERE