Shuttlecocks

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The format of the original posting has been altered.   

In this edited Internet extract, we focus on the engineering within such an everyday object.

The science of the shuttlecock

By Sunny Dhondkar

People need to understand that shuttlecocks are awesome.

Contents:

1     A lot of drag 

2    Aerodynamics of a shuttlecock

3    Spin

4    Why does a shuttlecock need to spin?

5      The Gyroscopic Effect

            Figure 1

1

          A lot of drag 

1. A tiny little shuttlecock is made up of 16 feathers.
2. 
   
3. Arranging these feathers in the manner you see in real has got a lot of engineering while designing it.
4. 
   
5. When you hit a shuttlecock with your racquet, it travels with a certain velocity. 
6. 
   
7. Its movement through air welcomes a lot of drag (viscous force of air that opposes the motion of a body). 
8. 
   
9. That’s why a shuttlecock has feathers on it, pointed outwards (giving it a conical shape).

2 

Aerodynamics of a shuttlecock

 

                                                                      Figure 2

1. These feathers give a large surface area prone to face the drag due to air and decelerate the motion of the shuttlecock. 
2. 
   
3. This way, we increase the time for the players to react and hit the shuttlecock. 
4. 
   
5. Otherwise, doing the same with a spherical ball would have been difficult (since it gains greater velocity when it’s hit and it also travels larger trajectories).
6. 
   
7. Now, coming to the interesting part…
8. 
   
9. You must have noticed that these feathers aren’t oriented in a straight manner, but they are tilted a bit (each one of them), about their axis.
10. 
    
11. There’s a reason for this.
12. 
    
13. This diagram will explain it well:

3  

 Spin

                Fig 3 -  View of a shuttlecock when it’s pointed against you after you hit it

1. Basically, when a shuttlecock moves through the air medium, air molecules (or you can say, air as an entire fluid) exert a normal force on each of the tilted feathers.
2. 
   
3. This normal force on each feather provides a torque about the main axis (longitudinal axis) of the shuttlecock. This is the axis that’s perpendicular to the cork.
4. 
   
5. The resultant torque on each feather adds up and gives a spin to the shuttlecock about its longitudinal axis.
6. 
   
7. Hence, the shuttlecock spins through the duration it stays in the air, like in Item 4.
9. Torque is the rotational equivalent of force.
10. 
    
11.  ..to get something to spin, or to alter the rotation of a spinning object, apply a torque. [Source of 3.11 here.]

4

Why does a shuttlecock need to spin?

1. Now, you might ask, “Why does a shuttlecock need to spin?”
2. 
   
3. Well, good question.
4. 
   
5. A shuttlecock has to spin to remain stable.
6. 
   
7. It should keep its cork pointed forwards all the time, and it should cover a path that is planned and aimed by the player, who hits it. For this to happen, the shuttlecock should remain stable in the air.
8. 
   
9. Now, you might ask, “Why does spinning provide stability?”
10. 
    
11. See, I know every question that you’d ask. Ain’t I cool?

5   

The Gyroscopic Effect.

1. Well, it happens due to the Gyroscopic Effect.
2. 
   
3. The gyroscopic effect is the tendency of a spinning body to maintain a steady axis of rotation.
4. 
   
5.  That is, a rotating body will maintain its motion and will oppose a change in its motion.
6. 
   
7.  It is the same reason a spinning top doesn't fall, while a stationary top does.
8. 
   
9. This wheel being stable in its position and not falling off the rope lies in the same category of the gyroscopic effect:
10. 
    
11. 
    
12. 
13. 
    
14. You can try straightening out the feathers and watch how miserable your play of badminton gets.
15. 
    
16. Well… that was the engineering behind the design of a shuttlecock.
17. 
    
18. And, yeah, people shall understand how interesting those tiny feathery punks are.

The original webpage goes on to look at bullet spin.

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