My last post identified a number of disadvantages of single length irons, primarily, hitting the wedges to 8 iron to long (because the shafts are longer than conventional) and hitting the 6-3 irons to short (as the shafts are shorter than conventional clubs).
Apart from hitting the ball squarely, that is without the club face being overly open or closed to the target line and club path, the two factors that most influence distance are swing speed and effective loft.
Effective loft is the actual loft of your club head at impact as opposed to the stated loft on the club you are hitting. If your hands are ahead of your club head at impact you have a good chance of matching the effective loft to the actual loft of the club. If the club head passes your hands at impact (flipping) the club will be de-lofted and the ball will fly a shorter distance.
Club Head Speed and Ball Carry
A couple of issues come into play. With the driver each MPH of club head speed generates approximately 2.4 yards of carry if the swing speed is in the 110 MPH range. Just as a point of reference the average swing speed on the PGA Tour is 112 MPH, which translates into an average carry of 269 yards.
At lower swing speeds, around 90 miles per hour, each MPH of club head speed generates approximately 2.3 yards of carry. Again as a point of reference, the average swing speed on the LPGA is 94 miles per hour which works out to an average carry distance of 220 yards.
As the swing speed decreases with the shorter clubs the carry distance per MPH is also reduced. A typical 7 iron swung at 78 MPH (the average on the LPGA) results in a carry of 141 yards, a distance of 1.8 yards of carry per MPH of club head speed.
With single length irons, the 7 iron is the unofficial standard in terms of overall club length, in the range of 37 inches, and good male amateur players will swing a club of that length around 78 MPH.
The question is what happens when you take a 6 iron and reduce the length by one half-inch. Based on averages a one half-inch reduction in overall club length will result in the loss of 1.5 to 2 MPH of swing speed which means your 6 iron will carry 2.7 to 3.6 yards shorter at a length of 37 inches than it would at 37.5 inches. By the same token, an 8 iron which would normally play at 36.5 inches when extended to 37 inches will fly 2.7 to 3.6 yards further.
In the next post I will look at the effect of loft on ball carry distance.