What Is a Parachute and How Does It Work?
A parachute is a device used to slow down an object that is falling towards the ground. There are two forces acting on the falling person, gravity and air resistance. Without a parachute, the gravity is more than air resistance. However, as the parachute opens, the air resistance increases. Now, air resistance is more than gravity. This slows down the parachute and the person can land safely on the ground.
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 (either by pulling on a ripcord or simply by throwing the pilot chute into the air).
It rapidly opens up behind you, creating enough force to tug the main chute from the container. The main chute has to be carefully packed so the ropes that connect it to your harness (known as suspension lines) 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. That’s safer and more comfortable for you and it also reduces the risk of the parachute ripping or tearing.
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® (a chemical relative of nylon) are now generally used instead.
Parachutes were invented about a century ago, but they continue to evolve, as inventors devise ever-better ways to improve their safety and handling. Using a parachute to bring a person safely to the ground from a plane is one thing. But what if you had to bring an entire plane to rest the same way? That was the challenge facing NASA every time the Space Shuttle (the reusable space plane, now-retired) came back to Earth.
During its launch phase, the Shuttle had a powerful main engine and rocket boosters to power it into space. But when it came back again, it was nothing but a glider, drifting through the air and counting on its stubby wings to carry it home.
Once it was safely back inside Earth’s atmosphere, the Shuttle hit its 4.5km (2.8mile) long landing strip at about 350km/h (220mph)—rather faster than a typical jet airplane (which lands at speeds more like 240km/h or 150mph). When the wheels were on the ground, the crew applied the brakes to bring the craft safely to a halt, but they also used a horizontal parachute called a drag chute to help. It was about 12m (40ft) across and helped to cut the Shuttle’s speed by about 75 percent before it was jettisoned.