Originally Posted by Lihu
According to some quick calculations based upon a reasonably reliable paper published: http://www.eng.yale.edu/physicsofgolf/Coefficient%20of%20Restitution.pdf
The 48gm of lead should have only yielded a ball velocity increase of 3.5mph which translates to only about 5.5 yards carry distance increase. So, this means that the 10-15 yard gain I observed must have been caused by an increase in the swing speed with additional weight or that the COR is not constant when weight is added to the club head.
The momentum equations will yield a 25% increase in ball velocity, but the COR will be based upon the kinetic energy which will increase the delta KE loss by also 25%.
The other issue is if adding weight to the club head changes the COR? I wonder if the equipment is deemed non-conforming? I would guess that it is still conforming because they use a steel ball test on the face and measure that the time the ball is in contact with the face is less than 257 microseconds (239 limit + 18 tolerance). Mass seems to have nothing to do with the results of the USGA test.
Need to do some more detailed calculations and model this thing over the next few weeks to figure out what happened in the experiments. Possibly measurement error as well? I checked them with the laser, but it could have been only a delta of 5.5 yards that cause the balls to hit the fence or fall short of it?
In any case, I am going to re-do the measurements again in a more controlled fashion.
Here is an easier one to work with.
Ball Speed = Smash Factor x Club Head Speed
Smash Factor = (1 + COR) x cos(Spin Loft) / (1 + Ball Mass / Club Head Mass)
Basically the only thing changing weight does is change the smash factor. Basically if you keep everything the same, then if you just add 20 grams to the clubhead, lets say going from 180 to 200. You should gain 2.5-3.6 mph ball speed depending on your clubhead speed.
Here's the thing, for every 1 mph you loose in clubhead speed due to adding weight, you loose around 2.8 mph ball speed. Again keeping everything constant except the clubhead mass.
At least that is what those equations are telling me in excel. I could be wrong, or the equations could be overly simplified, but you get the idea as to why golf club makers keep clubhead weight around 180-210 grams. It is a good zone were golfers can feel the club to get decent contact, also have enough mass to get a good smash factor, and light enough to keep club head speed up.
To me though, I would also take into consideration that maybe you like a heavier feeling golf club (swing weight). Maybe you are gaining better contact. I doubt you are gaining clubhead speed from adding weight.