School me on static driver loft and actual loft at impact

Comparing two driver heads of the same model, where the stated loft of one head is 9 degrees and the other is 10 degrees. Assuming the same swing, delivery, and a slightly high-toe impact location (robot arm?), what differences could we expect?

IME, the 10 degree driver head would generate less ball speed, >1 degree increase in initial launch angle, and more spin than the 9 degree head. I can't explain why technically. I'm guessing bulge and roll has a part to play in this, but would really like to hear a better explanation of the physics. Thanks!

If you assume center face contact in both instances, the bulge and roll are irrelevant - they only come into play for off-center hits.

In theory the ball speed on the higher lofted head would be slower - but that's because a little bit more energy is going into spin so a little less goes into the linear energy of the ball. In actuality, the difference in ball speed will be trivial - a reduction on the order of 0.2%.

Yes, launch will be about 7/10ths of a degree higher and maybe a couple hundred rpm of spin added.

> @pitchinwedge said:

> Comparing two driver heads of the same model, where the stated loft of one head is 9 degrees and the other is 10 degrees. Assuming the same swing, delivery, and a slightly high-toe impact location (robot arm?), what differences could we expect?

>

> IME, the 10 degree driver head would generate less ball speed, >1 degree increase in initial launch angle, and more spin than the 9 degree head. I can't explain why technically. I'm guessing bulge and roll has a part to play in this, but would really like to hear a better explanation of the physics. Thanks!

Same impact position, 1* of loft difference is average 0.85 as launch angle on a driver, a high club speed player around 0.8, a low club speed player around 0.9

Spin values change from 208 rmps at 80 mph to 290 rpms at 110 mph

Ball speed is the same if you compare them on a Trackman, we only see a difference on the paper .

You may want to check out[ Tom's Article](http://www.golfwrx.com/201777/dynamic-loft-angle-of-attack-and-your-launch-angle/ " Tom's Article") here on GoflWRX

Thanks Howard!