Here is something i posted on another site showing the differences of a longer versus shorter driver and the effects. What i have below is assuming that you will hit the shorter driver flush more often, hence the higher efficiency rating i used:
What is that 7mph of ball speed worth in carry distance?
120mph x 2.5 (max efficiency) = 300 yard carry
115mph x 2.5 (max efficiency) = 288 yard carry
So what is that worth per yard per mph of ball speed?
12 yards (difference in carry) / 7 (difference in ball speed) = roughly 1.71 yard per mph of ball speed you lose.
Here's the check:
7mph of ball speed x 1.71 ~ 11.97yards
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Hmm....so this poster for that one inch he lost he gave up about 12 yards of carry distance. However this is taking into account he is hitting the center of the face on both drivers.
So we have to change a variable....basically change the efficiency rating by decreasing it.
120mph x 2.3 = 276 yard carry
115mph x 2.5 (max efficiency) = 288 yard carry
hmmm....which is looking better now
also just for giggles 115mph x 2.3 = 265 yard carry
Basically with your 45" driver you are going to be much further on flush hits but your AVERAGE driving distance should theoretically be LESS than the shorter driver because you should be able to hit it flush more often.
But conversely if you mishit the short driver you are much shorter than you would've been with the mishited 45" driver.
DECISIONS? DECISIONS?
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I'm not a TGM or PGA certified Pro, but I did stay at a Holiday Inn Express last night