Homer Kelley (geek) teaches golf to Paul Runyan (PGA Champion)

[Garland Bayley]

Kelley covered practical applications of Newton's laws of motion.

"If you are on a par 3 hitting into a crosswind," Kelley proposed, "the ball will change direction, but not lose distance."

"Ha!" chirped Runyan. "Got you there. Every time I hit into a crosswind it falls short."

"According to Newton's laws," Kelley replied, "the ball will change direction in the same direction as the force imposed upon it, in this case the wind, but it will not lose distance because the force is across and not against the ball."

"Don't give me that," chided Runyan. I have never reached a par three in a crosswind using the same .club I use when it is calm. The ball drops short every single time."

Runyan was giddy at having tripped up Kelley -- and then the light came on.

"if you are on a par three shooting into a left to right crosswind," Kelley said, "do you aim a little bit to the left?"

"Only if I want to reach the green!" Runyan answered to a chorus of chuckles.

"Well then you are no longer shooting straight into a crosswind, are you?"

"How's that?" asked Runyan in a voice that sensed the tables were about to turn.

"Once you move your aim a little bit left, you are not only shooting straight into a crosswind but also into a quartering wind." explained Kelley. "the force imposed upon the ball is both across and now ever so slightly asainst the ball, which causes the loss of distance."

This passage is from GCA member Scott Gummer's new book Homer Kelley's Golfing Machine.

http://golfclubatlas.com/forum/index.php/topic,39982.0/

[astavrides]

Interesting, but I think the situation is more complicated than the passage suggests.  There are issues of lift and drag etc.  I think it would take me a long time to figure it out, if indeed I could.  Hopefully someone else will chime in.  Anyway, is Runyan's perception correct in the first place?

[Ben Sims]

It's the same principles as flying into a crosswind.  Say I want to maintain a course of 010.  I have a wind out of a heading of 280 at 10 knots.  That means I have a 10 knots direct crosswind.  Using the 60/1 rule--just trust me okay--I must put in about 2-3 degrees left drift correction to account for this if I want to maintain a course of 010.  My heading becomes 007, 008.  I am now ever so slightly aligned into the wind.  Now looking at my fuel flow in lbs/hr, I see that the auto-throttle has indeed added a slight amount of thrust to counteract for the heading into the wind. 

Now take this to the next level.  When flying across the North Atlantic, we routinely see crosswinds of 80 knots or more.  Heading changes become more like, say, 15-20 degrees into the wind.  Fuel flow rates increase significantly. 

Same applies to golf ball.  You need more thrust--ball speed--when into a cross.  And now we can add the concept of true airspeed vs. groundspeed.  So you lose, say, 2 mph GROUNDSPEED based on heading slightly into the cross.  Even though your ball speed remains the same. 

[astavrides]

It's the same principles as flying into a crosswind.  Say I want to maintain a course of 010.  I have a wind out of a heading of 280 at 10 knots.  That means I have a 10 knots direct crosswind.  Using the 60/1 rule--just trust me okay--I must put in about 2-3 degrees left drift correction to account for this if I want to maintain a course of 010.  My heading becomes 007, 008.  I am now ever so slightly aligned into the wind.  Now looking at my fuel flow in lbs/hr, I see that the auto-throttle has indeed added a slight amount of thrust to counteract for the heading into the wind. 

Now take this to the next level.  When flying across the North Atlantic, we routinely see crosswinds of 80 knots or more.  Heading changes become more like, say, 15-20 degrees into the wind.  Fuel flow rates increase significantly. 

Same applies to golf ball.  You need more thrust--ball speed--when into a cross.  And now we can add the concept of true airspeed vs. groundspeed.  So you lose, say, 2 mph GROUNDSPEED based on heading slightly into the cross.  Even though your ball speed remains the same. 

10 knots =~11mph.

If you just have to aim 2-3 degrees left for a 10 knot wind, that translates to aiming 6-10 yards left of target for a 200 yard shot which seems reasonable.  But I have a hard time thinking that the small component of the force opposite to the forward direction of the ball is enough to make much of a difference in club selection.  Maybe Runyan was talking about a 20-30 mph crosswind?  I would be interested to hear other people's experience in this regard.  (or to see more calculations).  (Often though, we will want to cut the ball to get help from the wind or draw the ball to work it into the wind which of course complicates matters.)

[Rich Goodale]

My brain hurts....

[Bill_McBride]

My brain hurts....

Vector analysis is a painful subject.