-----Original Message-----
[mailto:[EMAIL PROTECTED] Behalf Of Alan Brooks Sent: Tuesday, January 04, 2005 7:46 PM
Since it was easy to do I just ran Max Dupilka's Trajectory program for an 80-mph, 250-g club head at various lofts. The distances I got are as follows:
Loft Distance (yards) 12 175 24 178 36 138 48 100
Reasonable numbers for lofts above 24*...
Actually, not very surprising. If you look at a different graph in my Club Design Notes (the one on driver distance), the optimum loft for an 80mph clubhead speed is about 16*, and the falloff on either side is such that 12* and 24* go fairly similar distances.
At 08:21 AM 1/5/05 -0500, Childers, Tedd A wrote:
Alan, I think that the concept for single length would apply separately for irons and woods. Can you re-run the numbers using say a 42" club length for woods with a 100 MPH swingspeed (I guess head weight would be around 220 grams).
Wrong numbers. The guy who swings a 7i at 80mph needs over 46" of shaft length (assuming roughly the same swing) to get 100mph. The 42" club length (which is probably a good one for a single-length game improvement wood set) would swing under 91mph.
220g is probably not a bad weight to use.
I think the target weight is closer to 266 grams for these heads, with the length at 36.6-37.5", depending on the golfer and the shaft used.
I agree. It's more like a 7-iron. So my numbers below will use 266g 7-iron.
Can Max's program predict how much difference in swingspeed and/or distance one would get between a 38" club with a 253g head and a 37" club with a 266g head, assuming the same loft?
No, but you can use simple geometry if you make the right assumptions. There aren't too many assumptions you have to make:
(1) The clubs are well enough heft-matched that the golfer makes the same swing with the same effort and tempo for all the clubs.
(2) [I couldn't think of any more I had to make]
I used the Wishon trajectory program instead of Max's. But I have found them to give pretty similar results. The biggest differences between the programs tend to come when you have much too little head speed for the loft (that is, way down on the low-loft side of the curve); that was not the case with any of these clubs.
I centered the two sets (one "normal", the other constant-length) around the same 7-iron: 36* loft, 266g, 80mph clubhead speed. I assumed that the swing was the same, so that geometry determined the clubhead speed in all cases. I used my favorite loft progression, a straight 4* progression from the 2-iron to the PW.
Here were the results.
Iron Loft Prog Const
Length Length
==== ==== ==== ====
2 16 194 184
3 20 190 183
4 24 182 177
5 28 172 169
6 32 161 159
7 36 149 149
8 40 137 139
9 44 126 128
PW 48 114 117Observations:
* There is "compression" of the distances at the ends. You wouldn't want a 2-iron in the progressive-length set, and you wouldn't want a 2- or 3-iron in the constant-length set; they are too close to the next club in distance.
* If you look just at 4-iron to PW, there is not a lot of range advantage to the conventional set. The ranges are 68 yards vs 60 yards.
* If I were designing such a set (as Tim is) I'd make the loft spacing a little more. A spacing of about 5* would give better club-to-club spread.
That's where I am for now. Back to the salt mines.
DaveT
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