Angle of Attack – Its Role in Optimizing Launch Parameters
by Tom Wishon
Anyone that pays attention to those golf professionals who never tire of discussing new techniques, methods and machinations to squeeze every ounce of power (and therefore distance) out of their drive has most likely heard about angle of attack. They have heard how almost every long-drive competitor hits the ball with a “positive angle of attack,” and they have heard how positive angle of attack accents these player’s extreme swing speeds to further maximize distance. But how does angle of attack help the average golfer and how can clubmakers incorporate that knowledge into fitting their customers?
Increasing launch angle to optimize carry distance can primarily be accomplished in two ways — through an increase in the clubhead’s loft or from hitting the ball on the upswing. Hitting the ball on the upswing is also known as generating a positive angle of attack with the swing, and golfers that strike the ball on the upswing know firsthand how a positive angle of attack maximizes the already tremendous energy generated from extreme swing speeds.
When launch angle is increased by adding loft, the efficiency of the clubhead-to-ball energy transfer is not as great as when (or if) the same launch angle is created through a positive angle of attack. For example, if the TWGT Trajectory and Ball Flight Software indicates that a golfer would benefit from a higher launch angle as induced by more driver loft, that change should be made because more carry distance can be achieved. But the golfer who can increase their launch angle with a positive angle of attack will always optimize their launch parameters to a greater extent. However, clubmakers should not take this as an edict to immediately change a golfer’s swing, unless the golfer wishes to experiment on their own. Achieving a more optimal launch angle through a change in loft produces better distance results for most golfers.
When the ball is hit on the upswing, the shot’s launch angle is greater than the driver’s measured loft because the head’s loft is tilted upward by the swing. A golfer with a level or downward angle of attack always needs greater clubhead loft to achieve the same launch angle as a golfer with a positive angle of attack (See Illustration). When the same launch angle is generated with a lower loft angle on the clubhead, there is greater clubhead-to-ball energy transfer, resulting in more distance. This result occurs because the upswing, or positive angle of attack, has a significant effect on a physical phenomenon known as the force vector of the head.
The force vector is the direction of movement of the force generated by the clubhead’s mass from the golfer’s swing speed toward the ball and it is always perpendicular to the clubhead’s loft. With a positive angle of attack, the force vector also travels in an upward direction to the ball. When a high launch angle is generated by a positive angle of attack using a lower-lofted driver head, the ball slides up the face less, thus creating less spin and losing less energy at impact because the force vector is perpendicular to that lower loft. Yet, the ball takes off at a higher launch angle and with a greater amount of velocity for any given swing speed because of the upward or positive angle of attack.
It is not uncommon for national long drive competitors to generate launch angles of 12 to 15 degrees with driver heads featuring real loft angles of five to six degrees. In these extreme cases, long-drive hitters are accomplishing a high launch angle-to-head loft ratio with changes in their swing, ball position and tee height which allow the driver to contact the ball on the upswing, well after it passes the low point in the swing arc. (While this is not a product of clubfitting, TWGT asked our in-house teaching professional, David March, to offer some tips in this month’s E-TECHreport where clubmakers may advise golfers who are interested in maximizing their distance off the tee through swing modification.)
Clubmakers should also realize that most golfers will not have the physical
ability to make such swing changes. In those players, optimizing launch
parameters with the best increase in clubhead loft will always produce
positive results, particularly if the golfer has a swing speed under 100mph
and has been previously using a driver with traditional lofts between
9 and 10 degrees. Again, the TWGT Trajectory and Ball Flight Software
is the preferred fitting tool to advise golfers on how to best optimize
their launch parameters.
For example, if the golfer hits the 11-degree driver and has an average
launch angle of 13.5 degrees, their angle of attack is +4.0 degrees. If
the golfer hits the 11-degree driver and has an average launch angle of
7.5 degrees, their angle of attack is -2.0 degrees. The TWGT Trajectory
and Ball Flight Software is designed in its Manual Mode to accept input
for Angle of Attack, and with this, optimizing extremely accurate launch
parameters for the golfer.
©2003 Tom Wishon Golf Technology