A Brief History:

The idea for a parachute can be credited to the ancient Greeks

And Leonardo da Vinci however it was the French who made

And used the first parachutes in the eighteenth century.

The first drop from an aircraft was made in 1797 by Frenchman

Andre Jacques Garnerin, using a basket underneath an open

. Parachute. The parachute was made of silk and stiffened with

Poles.

The first limp parachute jump, similar to the ones used today,

Was made in 1897 by American Tom Baldwin. It was also an

American who made the first intentional freefall in 1919.

Freefalling was officially recognised as a sport by the AFI-the

Worlds Air Sports Federation in the 1950’s.

How:

There are three ways to experience the sport of parachuting.

One is to do a tandem jump, in which a beginner falls out of an

Aeroplane at roughly 14000ft with an instructor attached to

Their back who does everything necessary for it to be safe.

Another way is to do a RAPS (Ram Air Progression System)

Course. This is a six hour training programme followed by the

Beginners first solo static line jump. A static line jump is one

In which the parachute is attached to the plane and all the

Skydiver needs to do is exit the plane in a stable position. The

Third way to begin the sport is through an AFF (Accelerated Free

-Fall) course. In which the soon to be skydiver partakes in an

Intense course allowing the beginners first jump to be from a

Height of 12000ft with to instructors to help maintain the

Correct body position.

The Physics:

There are two main forces acting on a skydiver as they are falling

Towards the earth, gravity and air resistance. Gravity acts on the

Skydivers mass creating a force which pulls the jumper closer to

Earth, and causes them to accelerate. The equation for this is:

Where W is weight, m is the mass of the sky diver and g is gravity

Usually taken as 9.81ms.

Using this equation we can work out what force is acting on an

Average skydiver who’s mass is 75kg.

However this equation does not take air resistance into account

The equation for air resistance is:

In which Cd is the drag coefficient ρ is the density of the air v is

The velocity and A is the surface area of the skydiver.

From this equation we can see that the forces acting on the sky

Diver are dependant on the skydivers body position. This is why it

Is important to have a stable body position. The drag coefficient

In this equation includes form drag, skin friction drag, wave drag

And induced drag components. The drag coefficient is usually

Worked out using a wind tunnel simulating the forces on a body in

Freefall.

When both these forces are equal there is no net force,

When

At this point the free faller reaches terminal velocity, the fastest

Speed they can reach with their current body positions, in a given

Density of air with a given drag coefficient. The equation for terminal

Velocity is:

At an altitude of between 6000ft and 4000ft the skydiver opens their

Parachute. This increases the surface area and therefore the air

Resistance acting on the skydiver. Similar to how the body position of

The skydiver effects the air resistance the shape and size of the

Parachute also effects the force of the air resistance acting on the

Skydiver and the parachute.

From the equation for terminal velocity it is possible to see that if the

Area is increased the terminal velocity decreases and so the skydiver

Is decelerating. The two forces balance out once more and a new lower

Terminal velocity is reached.

Here are some other websites on skydiving and the physics of sky diving:

NASA

Skydiving page

The black nights parachute centre