Launch Monitor Experts

[mikpga]

Importance of Backspin

Attended a seminar yesterday and heard something which caught my attention...

The speaker mentioned that through his experiences he believes backspin isn't as important as we have made it out to be if you can't produce ball speed under 150mph...

He said that backspin becomes an important number to look at only once the ball becomes 'ballistic', which simply means over the 150mph ball speed...

He mentioned that all other golfers who cannot create this kind of ball speed need not worry about their backspin #'s, simply identify what hits the ball the furthest...

I tend to agree initially, but haven't given it much thought yet...

Opinion and thoughts?

[hoganfan924]

The slower the ballspeed and/or lower the launch angle, the more spin is required to create sufficient lift to keep the ball airborne for maximum carry. That relationship does not have a discontinuity in the data, so to establish an arbitrary ball speed where spin "doesn't matter," is just that, arbitrary, and has no basis in science. There is an optimal spin rate for each combination of ballspeed and launch angle. I believe that ballspeed is of primary importance, launch angle is secondary and spin rate tertiary, because launch angle and spin rate can be dramatically altered with equipment, but clubhead speed cannot.

[Jim_0068]

I'd have to see the data and what his conclusions are, however PRECISE backspin numbers aren't as important think they are. As long as you are in a 500rpm range of where your "theoretically" ideal spin number is i'd say you are ok.

The difference of an optimum condition with Xrpm of swing and another with Xrpm of spin + 500rpm spin is not going to be dramatic

[BILL12x]

[quote name='hoganfan924' post='817560' date='Dec 9 2007, 08:06 AM']The slower the ballspeed and/or lower the launch angle, the more spin is required to create sufficient lift to keep the ball airborne for maximum carry. That relationship does not have a discontinuity in the data, so to establish an arbitrary ball speed where spin "doesn't matter," is just that, arbitrary, and has no basis in science. There is an optimal spin rate for each combination of ballspeed and launch angle. I believe that ballspeed is of primary importance, launch angle is secondary and spin rate tertiary, because launch angle and spin rate can be dramatically altered with equipment, but clubhead speed cannot.[/quote]
I agree with everything you said above except that clubhead speed cannot be altered by equipment.

It most certainly can! By using a lighter shaft, or longer shaft, or both, you can significantly alter clubhead speed.

[pocketfulladoubles]

The argument of spin vs. 150mph doesn't make much physical sense. Things in nature do not adhere to such an on/off switch. Of course, it may not be a linear relationship meaning that you wouldn't expect to see an even increase in spin importance with ball speed. Nonetheless, you would expect to see some exponential relationship. I'd ask the lecturer to back up this statement with a mathematical model and ask what the coefficient and exponent is on the relationship. I bet he can't and I bet you could ignore such nonsense.

Here's a couple of references:

Lieberman, B.B. (1990) "Estimating lift and drag coefficients from golf ball trajectories". Science and Golf, (ed. A.J. Cochran), E. & F.N. Spon, London, 187-192.

Smits, A.J. and Smith, D.R. (1994) "A new aerodynamic model of a golf ball in flight".

Zagarola, M.V., Lieberman, B. and Smits, A.J. (1994) "An indoor testing range to measure the aerodynamic performance of golf balls".

DRAG FORCE ON A GOLF BALL IN FLIGHT AND ITS PRACTICAL SIGNIFICANCE, D. WILLIAMS ( (Royal Aircraft Establishment, Farnborough) )