Increase Swing speed? Heavy or Light Driver

[Jay-Bird]

I guess I'll answer that myself. Torque = Polar MOI * Angular Acceleration

Sorry, watching hockey...

[zeg]

Swing speed alone doesn't make the ball go far. It's total power put into the ball.

No. Well... this is sort of misleading. There's no reason to bring torque into it because the golf ball is not going to be set into a rotational motion. Even though the club is moving on a rotating path, there's not much benefit to thinking about the collision in these terms. In the moment of impact, the club head is essentially moving on a straight line, and the golf ball will leave on a straight line, so it's really better to consider it in terms of linear velocity and energy.

The simplest model that sort of gets this right is to consider an elastic collision between two masses in a linear collision with no external forces. I've written this up on a post somewhere in this forum, but the net result is that for the same swing speed, a heavier club head will hit the golf ball faster. (It will also transfer a smaller fraction of club head energy to the ball, but there'll be more energy to start with so it's still more total energy in the ball.) The key result, though, is that for a fixed club head mass, the ball launch velocity scales with the club head velocity in direct proportion. The argument that kinetic energy scales with velocity and therefore gives more ball speed is simply incorrect. However, even this model is not particularly good, because it neglects a lot of important effects. For example, energy due to linear motion is actually not conserved because the ball picks up spin, is not perfectly elastic, etc. But it's the best place I know to start.

[Shanks A Million]

No. Well... this is sort of misleading. There's no reason to bring torque into it because the golf ball is not going to be set into a rotational motion. Even though the club is moving on a rotating path, there's not much benefit to thinking about the collision in these terms. In the moment of impact, the club head is essentially moving on a straight line, and the golf ball will leave on a straight line, so it's really better to consider it in terms of linear velocity and energy.

Ding ding ding, we have a winner!

[jamo]

The simplest model that sort of gets this right is to consider an elastic collision between two masses in a linear collision with no external forces. I've written this up on a post somewhere in this forum, but the net result is that for the same swing speed, a heavier club head will hit the golf ball faster. (It will also transfer a smaller fraction of club head energy to the ball, but there'll be more energy to start with so it's still more total energy in the ball.) The key result, though, is that for a fixed club head mass, the ball launch velocity scales with the club head velocity in direct proportion. The argument that kinetic energy scales with velocity and therefore gives more ball speed is simply incorrect.

Thank you. That's what i was trying to say.

However, even this model is not particularly good, because it neglects a lot of important effects. For example, energy due to linear motion is actually not conserved because the ball picks up spin, is not perfectly elastic, etc. But it's the best place I know to start.

The maximum allowed COR allowed by the USGA is .83, with 1 being perfect elasticity.

[zeg]

The maximum allowed COR allowed by the USGA is .83, with 1 being perfect elasticity.

Good point---thus there is definitely significant energy lost to heat by rule. I'm not sure how to quickly estimate what impact this has on the collision, but I'd guess it's a small adjustment and doesn't affect the relative importance of velocity vs club head mass.

By the way, in last sentence my post that you quoted, I meant to say "kinetic energy scales with velocity squared," of course.

[Mike Boatright]

I think the best set up for the average guy is to get a 1 inch longer shaft that is probably 10 grams heavier than your used to and lower loft this will maximize roll and give you an extra 12 yards. Even if you maaged to somehow gain 5 mph swing speed the standar 10.5 driver would give you 6 yards of carry in ideal conditons roll is more consistent.

[Mike Boatright]

I think the best set up for the average guy is to get a 1 inch longer shaft that is probably 10 grams heavier than your used to and lower loft this will maximize roll and give you an extra 12 yards. Even if you managed to somehow gain 5 mph swing speed the standard 10.5 driver would give you maybe 6 yards of carry in ideal conditons roll is more consistent you would need a good 18 mph of swing speed to see 20 yards of extra carry and thats never going to happen.