The Pro Shop

Gear Talk: Hunter Hines, Part One

Wednesday, October 17, 2012 /by

This week, Dunlop launched three new racquet series: the 3.0, 6.0, and 8.0. The racquets build on previous Biomimetic technologies, with some key improvements. To understand more about the new sticks, I sat down with Hunter Hines, Dunlop’s Director of Marketing and Product Development. We spoke about the frames’ new beam designs, as well as some of the ways the company has modified its grommet system. (For Part Two, click here.)

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Justin diFeliciantonio: There are a number of new sticks out this fall by Dunlop. Let’s start with the F3.0 Tour, M3.0, and S3.0 Lite, all three of which build on the company’s well-respected 300 line. I’ve read that the head shapes of these racquets have been completely redesigned. Is this true? Why the change?

Hunter Hines: Yeah, we’re calling the new head shape True Oval. It’s designed to be a rounder head shape, which gives a larger and wider sweet spot compared to our old 300 and 300 Tour molds. The old 300 and 300 Tour were and are fantastic racquets. But they lack a bit in terms of pop and spin. Through our research, we’ve found that a rounder head shape lends itself to added power and spin more so than the traditional, oblong head shape of Dunlop’s past.

JD: Really? How does rounding out the head shape increase power and spin?

HH: Well specifically, it increases spin by allowing the ball more string area to roll on. I’m not going to tell you the frame’s shaped like a lollipop. But an increase in diameter, even a small one, from 3 to 9 o’clock up through 10 to 2 o’clock can make a tremendous difference in terms of how much time the ball spends on the strings. And power-wise, in redesigning the head shape we didn’t just make it rounder. We also altered the frame’s cross section. The beam, in general, is far sharper and less boxy than the old 300 and 300 Tour models. This type of beam shape is much more aerodynamic, which allows for greater racquet-head speed and thus more power than previous versions.

JD: So this change in head shape: You’re saying it’s more about expanding dwell time than increasing a player’s margin of error when spinning the ball? Or is it both?

HH: Really, it’s both. The new design isn’t strictly trying to cut down on players framing shots. But as grips become more and more Western, framing does become more of a concern. Have you ever seen a topspin forehand or backhand at a thousand frames per second? It’s really quite interesting. In slow motion, you can see that, when the ball first strikes the stringbed near the upper portion of the frame, it doesn’t just bounce off the strings; the ball actually rolls across the stringbed. So greater distance from 3 to 9, as well as up into 10 to 2 [o’clock] provides more stringbed for the ball to slide across. And as more and more players continue to use monofilament strings, the extra head space is also going to give even more opportunity for the strings to grip the ball, and in turn for the ball to spin faster.

JD: You just said that the 3.0 series’ beams have been made sharper and more aerodynamic. Could you explain this more in detail?

HH: Well, if you look at the 3.0 series, we’ve got several aerodynamic features. As I said, the beam itself has more edge to it, whereas the 300s and 300 Tours of years past have been very traditional, with a classic box beam. The other improvement to the 3.0 is what we’re calling Cx grommets. With this new grommet system, the string actually sits pocketed flush with the frame; it’s not raised above the frame, like on a traditional grommet strip. This equates to less wind resistance. Again, it seems like a very small change, but it actually makes a big difference in terms of how the frame moves through the air.

JD: Do you actually test these racquets in a wind tunnel? How does Dunlop back up its claims that these new frames are more aerodynamic?

HH: They all are tested in a wind tunnel, absolutely, at a sporting institute in the U.K. We test multiple parameters in the tunnel. One is frame shape alone, minus any technology—just to make sure that the frame itself is much more aerodynamic than what it’s supplanting in the line. And what we’ve found in that, with the 3.0’s new True Oval head shape and hybrid cross section [read: the sharper frame geometry], we’ve been able to reduce the drag coefficient by eight percent. That’s just the geometry of the frame alone, with no other further enhancements and technology.

JD: And that number arises from, what, putting the frame parallel and perpendicular to the incoming wind? What are the experimental orientations of the frame?

HH: It’s an average of several orientations in static positions. The racquets are tested straight on, sideways, and at a number of other angles. We don’t test the racquets backwards, obviously, because you don’t have as much [meaningful] backwards movement in the game. When it counts, you’re accelerating the racquet toward the ball.

JD: So there haven’t been any measurements of aerodynamics taken from moving racquets? Like mimicking the path of a swing?

HH: No, there haven’t. You know, even if we did have the technology to do such a test, it’d be very difficult to mimic everyone’s swing, because each player operates on a different swing plane. So all we can really do is an apples-to-apples comparison, from various angles in a static position.

JD: Let’s go back to the grommets. I’ve read in your promotional materials that the grommets aren’t just designed differently; they’re also made from a different material called MoS2. Could you explain what this is?

HH: Right, the Cx is the style of grommet; MoS2 is the material that the grommet’s made of. [Note: The Cx grommets can only be found in the 3.0 racquet series; MoS2 is included in the 3.0, 6.0, and 8.0 series.] MoS2 is Dunlop’s shorthand for a material called molybdenite. It’s actually a mineral, which has a very low coefficient of friction. Meaning, if you take molybdenite and rub it against itself, it has a friction coefficient similar to that of wet ice on wet ice. As such, when you fabricate grommets with molybdenite, it minimizes friction between the string and the grommet hole, allowing the strings to move more freely upon impact with the ball. And when you let the strings move and snap-back farther, this amplifies power.

JD: So in short, less grommet friction and more string movement equates to more power and spin.

HH: Correct. Especially if it’s a softer multifilament string, the less energy that’s occupied overcoming friction from the grommets, the more elasticity there is rebounding the ball.

JD: Could you give an example?

HH: Say you hit, for example, cross strings 12, 13, and 14, but not cross strings 11 or 15—12 through 14 are going to be pulling tension on 11 and 15, basically. And the further you can pull that tension, because of less string–grommet friction, the deeper the ball pockets, the more energy the stringbed returns to the ball, and the more power that results from the shot.

JD: Okay.

HH: And going back to the spin component: The further polyester-type strings are allowed to stretch and move out of place on impact, the harder they theoretically snap back as the ball leaves the stringbed. [Note: Research has shown the extra spin production seen with monofilament strings, like Luxilon, is due to greater string movement and “snap-back.”] So that’s, again, another power- and, in particular, spin-enhancing result from the MoS2 grommets.

JD: So you think it’s not just the string pattern and material that affects snap-back, but also the nature of the grommets?

HH: I believe that, absolutely. If you have less resistance to the string moving, then you have less resistance to the string snapping back.

JD: This molybdenite, what are its other industrial applications?

HH: It’s used in a lot of different industries—in aerospace, industrial lubricants, microchips, and even ski wax. The idea here was, really, we wanted to make something that was similar to the self-lubricating properties of a snakeskin. If you touch a snake, it feels very dry. But when it moves, it secretes a lipid mixture that allows it very, very low frictional resistance against the ground. That’s the idea behind using molybdenite in our grommets; it's technology informed and inspired by nature.

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