Joined: 09 Apr 2007
Location: New Jersey, USA
|I'm trying to encourage y'all to post your questions to the forum, rather than sending them to me by private message or email. That way everybody can get the benefit of the discussion -- and someone else might have a better answer than I would.
Anyway, Anthony sent me the following question in a private message. I'm reposting it to the forum, and answering it here...
|I had a gentleman on my launch monitor today. He's 62 years old. He's not a big swinger but gets decent yardage on his drives. He swings at 81 mph and uses a 9.5 degree driver. I've golfed with him personally in the past and always felt that he hit his drives pretty high, especially since he had a 9.5 degree driver. I was always curious to see what his AoA was.
Well, as they say "One test is worth 1000 expert opinions" and here's the data .
My question to you is this: According to my Zelocity info he is pretty much right on -- 81 mph club speed, 117 mph ball speed, 17 degree launch angle. (they suggest a 16.9 deg launch angle for this ball speed).
I now use Trajectoware all the time, but could not get my numbers to come anywhere close. I started with a ballspeed of 81, added his average AoA of 2.7 degrees and was not able to come anywhere near a launch angle of 17 with a 9.5 degree driver. I added some impact tape to the clubface and he was hitting them high on the face for some additional loft (1-2 degrees) but still not near 17 degrees.
The way I see it, using Trajectowareand based on an 81 mph clubhead speed I'd have him in a 13.5 degree driver with a 14.4 deg launch angle,, carrying 177 with an AoD of 32.6 deg. One last note, I would say his on the course driver carry is about 200 yards.
Any insight you could provide would be appreciated. (I would hope that the AOA info is not that far off on the launch monitor-especially since we hit a decent amount of shots for an average).
Before we worry about impact parameters, let's first look at the launch parameters. I tried a few points from your data, and TrajectoWare Drive gives carry distances 8-10 yards shorter than your Zelocity. Do you have actual measured carry distances, or just the Zelocity calculation? The discrepancy is mildly disturbing, though too small to consider a real problem.
Looking at the data you cite (the average of the MacTek data), I see that the Zelocity reports an AoA of 2.7*. TrajectoWare Drive computes impact conditions for the measured launch conditions. It deduces AoA of 3.5* (fairly close to the Zelocity) and a dynamic loft of 16*. I agree with you that's a far cry from the nominal 9.5* stamped on the sole of the driver.
This guy seems to be the poster child for the case I discussed in my posting earlier today in response to Richard Kempton's question. See http://forum.trajectoware.com/viewtopic.php?t=37. It talks about why dynamic loft could be very different from the manufacturer's rated loft.