The Science behind Parasailing

Parasailing is a bit like a plane’s flight, it deals with the same forces:

-     Thrust is a reaction force described by Newton's 2nd and 3rd laws. When a system expels or accelerates mass in one direction, the accelerated mass will cause a proportional but opposite force on that system.

ExaExamples of this are:

A bird achieving thrust by flapping its wings.

The propeller blades of a plane (not the engine) or the turbine engine of a plane forcing air behind the plane.

A boat's propeller producing thrust by forcing water in the opposite direction the boat is travelling in.                                          

Click HERE for great clip explaining THRUST  (see below...sorry, we're still writing and uploading this)

Well...whilst we work out how to attach a podcast to a link...just go here:http://www.grc.nasa.gov/WWW/K-12/airplane/thrust1.html   scroll down till you get to 'short movie on Orville and Wilbur Wright'. Slow to start, but IS very good explanation.     

-       Drag

-          Lift

-          Weight

-          Acceleration

In a plane, lift is achieved by the wing’s shape and surface, which is curved, shaped like a teardrop. The plane’s engines create thrust, which creates the plane’s velocity. The air flowing over the top of the wing moves faster than the air underneath, due to its surface.

It also happens because the air flowing over the top has to move further to reach the ‘trailing edge’ (or the back edge), than the air under the wing. This reduces the air pressure above the wing and creates a higher air pressure under it, causing an upwards force that causes the wing to get ‘sucked up’ into the lower pressure area, away from the lower air pressure above the wing. This is ‘Bernoulli’s Theorem’, and it shows ‘lift’.

However, when this lift is affected by what is known as ‘drag’. This is created when an object collides with air molecules while moving through the air. This collision creates a frictional force, which is ‘drag’. This slows it down as it is a backwards force. Drag is also affected by the surface area of the object, the more surface area, the more drag. And the faster something moves, the more drag it creates.

Parasailing is very similar to this, but as it uses a parachute’s canopy rather than wings, which has a larger surface area, it creates more drag. When the boat towing the parachute accelerates, creating it’s ‘velocity’, the parachute streams behind and creates ‘drag’, using the canopy of the parachute. When the canopy moves through the air, the air flows into the canopy, and the pressure in it becomes greater than the pressure above it, therefore creating lift, like with the plane’s wings. As long as the lift is greater than the weight (of the rider + parachute), the parachute will climb, and as long as the thrust is greater than drag, the boat will accelerate, which also causes the parasailer to climb.

In order for the parasailer to land, the boat slows down, decreasing its acceleration and velocity, until the lift no longer counters the gravity, so it is pulled back down.

Click here to go to our story on parasailing with Sammy Duvall in Orlando!