Trampoline effect

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mandrin

mandrin

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The trampoline effect is present in sports where striking with an implement occurs such as for instance badminton, tennis, hockey, baseball and golf. It is not really that there is a spring effect, but rather that it allows a somewhat better transfer of kinetic energy.

It is particularly important in baseball and golf where there is a premium on the distance obtained. In baseball the trampoline effect is quite complicated to analyze due to the complex vibrations occurring in a baseball bat. In golf however it is a bit easier to analyze.

The trampoline effect is a real phenomenon and has increased the average driving distance on the PGA Tour by 10 yards or more in just three years. Nothing has had so great an effect in such a short period of time. However for the average golfer the difference seems to be rather minor.

Enter here, [size=+1] The Trampoline Effect [/size], and enjoy.

mandrin
 
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diggerdog

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Need graph help:

I too have conducted some trampoline research, and while the conclusion is taking shape, I don't know how to put the results to graphical form. Help would be appreciated;

Enjoy-http:my.break.com/media/view.aspx?ContentID=156978
 
rwh

rwh

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mandrin said:
The trampoline effect is a real phenomenon and has increased the average driving distance on the PGA Tour by 10 yards or more in just three years. Nothing has had so great an effect in such a short period of time. However for the average golfer the difference seems to be rather minor.

mandrin
Click to expand...

Very interesting. Why do you think the average golfer can't take advantage of the trampoline effect?
 
mandrin

mandrin

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rwh said:
Very interesting. Why do you think the average golfer can't take advantage of the trampoline effect?
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rwh,
The amateur shooting around 90 to100 is not regularly connecting with the sweet spot. Moreover, as Jim points out, the trampoline effect is more pronounced at higher swing speeds. This results in the average amateur not really being able to gain much from the trampoline effect. :(
 
mandrin

mandrin

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Trampoline effect, #2

The very few reactions re to the ‘trampoline effect’ post surprised me a bit. I expected there to be a fairly big crowd enticed with drivers and buying them almost compulsively. ;) Yet barely any reaction with the exception of some light hearted humorous reactions.

I will try again with another post still expecting that there must be some interest in this subject. So for those who have exhausted the interesting You Tube knowledge base, concerning trampoline effects, :D , are very welcome to delve into another post on the [size=+1] trampoline effect [/size].
 
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shootin4par

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but mandrin why are you suprised, you of all people should now the truth about most anything in life gets very little attention

I have a question, is it possible with the tramploine effect that if you have too much that the ball stays on the face too long and the point in which it releases the off of the clubhead, theclubhead is going slower so the ball speed is lower
 
mandrin

mandrin

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shootin4par said:
but mandrin why are you suprised, you of all people should now the truth about most anything in life gets very little attention

I have a question, is it possible with the tramploine effect that if you have too much that the ball stays on the face too long and the point in which it releases the off of the clubhead, theclubhead is going slower so the ball speed is lower
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shootin4par,

If the club face is made flexible we have two mass spring systems working in series and their combined effect is to decrease the resonance frequency of the ensemble, hence causing an increase in duration of impact. Hence there is no escape trampoline effect only existing for increased impact duration.

If we take it in a very broad sense one can say that for the club and ball to work towards greater ball speed they have to be roughly working on the same ‘wave length’. In other words have about the same resonance frequency for the respective mass spring systems.

If the clubface is completely rigid it does not able to help very much. If it could be made very flexible, it, again, can’t help very much. Think of two strings close together having about the same resonance frequency. Striking one will readily excite the other, resonating in sympathy.

For pure resonance systems such as tight strings they interact only, and then very vigorously, when their resonance frequencies are close. In our case this interaction is not very critical but the interaction between clubhead and ball is nevertheless rather similar in nature.

Notice in Fig1 a peak. This corresponds to maximum contribution of the clubhead to an increase in ball speed. Making the clubface either softer or stiffer reduces its contribution to creating additional ball speed. One could say they are tuned.

However, due to inherent material constraints it is difficult to make a clubhead having a clubface so flexible that your argument becomes a factor to consider, hence your question whilst interesting is purely academic. :D

Don’t forget that the clubhead is only helping towards greater ball speed by giving up kinetic energy, hence, slowing down, so that the ball can attain more speed. Your question is a bit ambiguous. ;)
 
J

Jim Kobylinski

Super Moderator
Expanding on shootn's post mandrin:

Since COR. was maxed out at .830, the new testing that club manufacturers are trying to "max out" is the CT test which is the "characteristic of time" test. Meaning how long the ball is sticking to the clubface through the impact interval.

How does the CT time effect ball speed?
 
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shootin4par

New
thank you mandrin
while I do not understand all of the post, some lines confuse me, but I am able to fully understand your answer in relation to my question. I will shoot another at you soon;) but it is nice to finally feel like I am in the know rather then the dark :)
 
mandrin

mandrin

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CT - characteristic time

Jim Kobylinski said:
Expanding on shootn's post mandrin:

Since COR. was maxed out at .830, the new testing that club manufacturers are trying to "max out" is the CT test which is the "characteristic of time" test. Meaning how long the ball is sticking to the clubface through the impact interval.

How does the CT time effect ball speed?
Click to expand...
Jim,

The measurement of the characteristic time CT is done with a small apparatus consisting of a steel weight suspended from a pendulum. The weight is released from various heights to strike the clubface. The characteristic time CT is simply the time that the weight and clubface remain in contact with each other.

Both the pendulum weight and the clubface are conductive and are readily made to form a closing electrical contact during impact duration. A digital storage scope can be used conveniently for measuring and direct readout of this impact duration – the characteristic time CT. Indeed, a very simple and elegant test procedure. It is only meant to be used for testing drivers.

The characteristic time CT is a direct measure for the spring stiffness k for the clubface. The limit has been set at 239 microseconds, plus a test tolerance of 18 microseconds, for a maximum of 257 microseconds. The spring stiffness k as a function of CT can be derived as:

k = Pi^2 (m1+m2+m3)/CT^2

m1=pendulum mass, m2=clubface mass, m3=clubhead mass, k=stiffness of clubface and CT=characteristic time.

As such the pendulum test is a direct measurement for the springiness of the clubhead. A larger characteristic time means a softer spring and as result a more efficient transfer of the kinetic energy from clubhead to ball during impact, hence a greater coefficient of restitution, COR, and a greater ball separation speed.

In contrast to the coefficient of restitution, which is related to both, clubhead and ball interacting, and impact speed, the characteristic time CT is only a function of the clubhead and very easily measured anywhere with a small apparatus.
 
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