The Physics of Sports Racket Tension

[Jimmy87]

Hi,

I am interested to find out the answer to whether high tension or low tension strings on badminton/squash rackets give more power/force. There are so many conflicting sources on the internet I wanted to see if it can be answered in a concrete way by physics. So, some sources are saying that a lower string tension will create more of a trampoline effect and lead to more power. Some reliable sources such as racket stringing services generally say this. Other sources (including an international badminton coach) say that higher string tension leads to greater power. However, they say that a higher tension does make the sweet spot much smaller so a bad hit on a higher tension racket will have much less power than the same bad hit on a lower tension racket but if both were hit in the sweet spot the higher tension will have much more power.

Is there any modelling of physics that could provide a concrete answer as to which tension would give more power assuming all other variables are held constant such as racket head speed at contact, centre strike etc. Or even just peoples ideas and general thoughts would be great.

Thanks for any insights.

 

[Vanadium 50]

The only source of power/force is your arm, not the strings. That doesn't mean rackets don't differ, but it does mean you need a different language to discuss the differences.

 

[A.T.]

I am interested to find out the answer to whether high tension or low tension strings on badminton/squash rackets give more power/force.

Are you asking how to maximize the elasticity of the collision (minimize dissipated energy)?

 

[Jimmy87]

Are you asking how to maximize the elasticity of the collision (minimize dissipated energy)?

Yeh I think so. I am basically asking that if you had two rackets which made contact with the ball/shuttle with the same racket head speed but one racket had strings with a higher tension than the other which racket would cause the ball/shuttle to leave the racket head with a higher velocity. There is so much inconsistency with sources - some saying higher tension strings gives more power, some saying looser strings. From my own experience of playing badminton I definitely have experienced more power (faster shuttle speed) with higher tension rackets but the sweet spot definitely gets smaller so any off center hits either break the strings or have much less power/shuttle speed. I just wanted some physics to be applied to this to confirm whether higher or lower string tension gives a higher shuttle speed.

 

[Jimmy87]

Are you asking how to maximize the elasticity of the collision (minimize dissipated energy)?

For example, this forum on the subject produces about a 50/50 split in terms of who thinks tighter strings produce more power.

http://www.badmintoncentral.com/for...-smash-from-tighter-or-looser-strings.108492/

 

[PeroK]

For example, this forum on the subject produces about a 50/50 split in terms of who thinks tighter strings produce more power.

http://www.badmintoncentral.com/for...-smash-from-tighter-or-looser-strings.108492/

Most of the analysis on that forum is muddled, to say the least. First, the underlying physics is clear: all the energy comes from the initial energy of the shuttle and the player. Nothing else in the system can actually generate energy. So, it's really a more complex question of how the equipment can a) maximise energy transfer from the player's muscles and b) minimise energy lost during the collision.

Now, consider the following:

You have a cricket bat, a tennis racket and a badminton racket. And, you have a cricket ball, a tennis ball and a shuttle. That gives you nine combinations of racket and object to be hit.

In each case, the solution goes beyond the basic physics, and illustrates that, unfortunately, you can't just do some energy-momentum equations and get the answer.

The simple fact is that you need a more specific and experimentally-based analysis of the effect of tighter strings: it may critically depend on the mass of the shuttle, for example. It may also depend on the player and the way they swing the racket: someone with perfect technique may find, say, tighter strings better; whereas, someone with less snap in their wrist may benefit from looser strings. In other words, racket-head speed could be another major factor.

 

[A.T.]

I just wanted some physics to be applied to this to confirm whether higher or lower string tension gives a higher shuttle speed.

I would rather look for experimental results done by some racket company. This is not easy to compute.

I definitely have experienced more power (faster shuttle speed) with higher tension rackets but the sweet spot definitely gets smaller so any off center hits either break the strings or have much less power/shuttle speed.

This makes sense to me intuitively. There should be an optimal string tension for any combination of:
- impact speed
- impact location
- impact angle
- shuttle mass
- material properties of the strings
- material properties of the head
- elasticity of the racket frame
So there is no general rule saying that more tension is better or worse.

 

[Andy Resnick]

Hi,

I am interested to find out the answer to whether high tension or low tension strings on badminton/squash rackets give more power/force.

As pointed out, there's not really a clear answer to this question. However, there is a clear answer to a related question, which is that lower tension strings increase the amount of time the ball is in contact with the racquet, which provides the player an increased sense of control:

http://www.tennisindustrymag.com/articles/2005/01/does_higher_string_tension_giv.html

 

[A.T.]

However, there is a clear answer to a related question, which is that lower tension strings increase the amount of time the ball is in contact with the racquet, which provides the player an increased sense of control:

I can imagine that for non-perpendicular impacts, less tension makes final ball/shuttlecock movement direction closer the to the racket movement direction.