Dave Tutelman -- August 19, 2007
Wade asked my opinion of constant-length iron sets. I realized my study
on this is more than ten years old now, and needs to be revisited.
Here's my new take on the issue.
article compares the carry distance and trajectory of two sets of irons
-- conventional and single-length. The study was motivated by the
recent introduction of iron heads with the same weight across the set.
Such clubs have been made available to the public by 1 Iron Golf, and components to custom clubmakers by My Ostrich Golf.
This is a little different from my years-ago study described in the "Length" chapter of my Design Notes;
that study assumed a golfer skilled enough to swing a club properly
over a wide range of swingweights -- as would have been required with
the clubheads available at the time.
The table shows the carry distances for several different sets of irons:
Parameters of the study:
- A conventional set, with length increments of 1/2" per club.
- A constant-length set, with the same lofts as the conventional set.
- A constant-length set made with iMatch irons from My Ostrich Golf, which have a different set makeup. I will discuss the iMatch irons below.
- Used the Dupilka trajectory software. (TrajectoWare Drive does not yet do irons.)
- Used the 4-degree loft spacing common in the mid-1990s, to keep things coherent.
- Assumed 80mph clubhead speed for a 5-iron.
gold row in the table shows that the 7-iron is the "pivot club". That
is, both constant-length sets have a 7-iron identical to that of the
- Following from the previous point: all the single-length irons
have the same head weight, shaft weight, length, and therefore they are
all the same as the 7-iron.
- Corollary: they all have the same swingweight and moment of inertia as the 7-iron.
- Therefore, they all have the same clubhead speed as the 7-iron, 78mph.
Pictures of the trajectories:
Over the 3i-PW sets, the constant-length set show a "range
of 10 yards compared to a conventional set. That is, the range covered
by the constant-length set is about 10 yards less than the conventional
set. About a third of the range
loss is in the gap between the 3-iron and 4-iron. This is probably
because a low-lofted iron needs the extra clubhead speed, in order to apply the spin to keep the ball in the air.
study was done using an 80mph clubhead speed for the 5-iron, which is
probably fairly realistic (perhaps even high) for most mid-handicap
golfers. A higher clubhead speed might counter the extra range
compression in the longest irons. But it is probably not realistic for
the less-skilled player most likely to be attracted to constant-length
last two columns show the performance of the iMatch irons. Tim Hewitt
designed these with bigger loft gaps between the longer irons, in order
to counteract the loss of range there. It appears to have worked.
Conclusion: The constant-length irons
are generally recommended for people who have trouble with the longer
irons. Such clubs will probably be a help for them, down to the 5-iron
and likely even the 4-iron, at the cost of a small compression in
range. That compression is:
range compression gets more severe with lower loft. So constant length
is not a good solution for clubs as long as a 3-iron, which should
still be candidates for replacement by hybrids or lofted fairway woods.
- 5 yards, PW to 5-iron.
- 7 yards, PW to 4-iron.
while we are looking at the edges of the set, let's consider the
shorter irons. (That is, clubs with more loft than the "pivot club".)
Most golfers do not have a problem with those clubs. In fact, many
golfers (including yours truly) are more accurate hitting the shorter
clubs. For such golfers, both range compression
and accuracy could be made more favorable if the higher-lofted clubs
were those of a conventional set.
Bottom line: I
feel that a 4- or 5- through 7-iron with the length and mass of a
7-iron could be a big help for some golfers. But longer clubs than that should be
replaced by hybrids or metalwoods, and shorter clubs are more
advantageous in a conventional design.
Last modified -- 11/18/2011