New EquipmentNovember 13, 2018

Callaway Big Bertha irons aim to create new distance potential with shape-shifting design

The Callaway Big Bertha irons newest iteration essentially reflects one fairly simple goal of its design team: “What if we float the mass?”

That’s how Callaway lead iron designer Scott Manwaring put it recently. The mass he’s talking about is a substantial brick of tungsten that for all intents and purposes floats low in the cavity of the Big Bertha, the company’s latest super-game improvement iron. The Big Bertha also is designed to launch iron shots higher with the boost of extra ball speed from a face that flexes at the USGA limit for spring-like effect.

The Big Bertha reflects an accumulation of Callaway’s iron design technology over the last half-dozen years. That includes first the face-cup construction where the face extends around the perimeter and is welded to the back and hosel portion of the club. The new Big Bertha iron features the thinnest face-cup construction in company history to create higher ball speeds.

From there, Callaway’s iron designs moved toward improving the feel of these irons by filling the cavity portion with air-infused urethane microspheres that allow the face to deflect but controls the vibration to give impact more of a one-piece feel. It's a technology the company launched early this year with its Rogue family of irons.

The one final piece of that iron ideal is what Manwaring sees in the Big Bertha iron, which features that floating mass, or what the company is calling the “suspended energy core.” This complex technology involves a piece of metal injection molding tungsten, which features more than twice the density of steel to make it especially effective in lowering the center of gravity to help iron shots launch higher. That tungsten piece is wrapped in a thermoplastic urethane jacket and suspended in a layer of the urethane microspheres material.

“We’ve taken the gloves off now and we can position the CG where we feel it’s best through the set,” Manwaring said. “This construction basically eliminates some of the constraints we had in the past and improves all the characteristics we want.”

Unlike its predecessor (Big Bertha OS), the new Big Bertha irons are not a hollow construction, but rather a three-piece construction involving face, hosel and back, and the tungsten. Callaway’s team improved the design idea of having mass positioned low within the undercut portion of the sole, largely because the back part of the iron that in the past enclosed the shape and made it hollow has been removed, said Alan Hocknell, Callaway’s senior vice president for research and development.

“We took that away to really get access into the low part of the cavity,” he said. “We’re using metal injection molding to get the tungsten into the size and shape we want it exactly for each iron; they’re essentially custom fitted pieces of tungsten for each iron in the set that allows us to put the center of gravity wherever we want it for the different purposes of each iron.”

The whole construction idea of essentially having the heavy mass hang freely and low in the head also improves feel through the idea of mass damping. In this technique, often seen in the construction of tall buildings, heavy mass in one end helps control unwanted vibrations. That’s essentially one of the roles played by the dense tungsten pieces in the new Big Bertha irons. Previously, Callaway irons featured an internal “standing wave,” where the structure of the iron’s sole curved back on itself in one flowing piece of steel kept mass low.

“The standing wave is still there,” Manwaring said. “It’s just that now it’s an independent piece and a higher density. We’re getting a higher percentage of the body weight in to the wave.”

That new multi-piece structure results in irons with a lower CG, and because of the lower CG’s naturally higher launch, the lofts on the new Big Bertha irons are a degree stronger. That allows for more ball speed, but because of the lower CG, there isn’t a decrease in launch angle. The result are shots that launch both higher and faster.

Higher and faster is also the mantra for the new Big Bertha hybrids, which become the company’s first hybrid to feature both an adjustable hosel and Callaway’s “Jailbreak” design structure. That feature uses two vertical bars that join the crown and sole near the face to concentrate more flexing across a wider area of the face, and was first launched in 2017's Epic driver and followed up with the company's Rogue driver, fairway woods and (fixed hosel) hybrids.

The Big Bertha hybrids feature a redesigned adjustable hosel that’s shorter and lighter to save 12 grams. That weight savings allows for both the Jailbreak structure up front and a more optimized CG. Also optimized are the head shapes in the Big Bertha hybrids, which get progressively smaller as lofts increase all the way up to an 8-iron loft of 33 degrees.

The Big Bertha irons are offered with KBS Max 90 steel shafts and UST Mamiya Recoil ESX and ZT9 graphite shafts. The hybrids are offered in six lofts (3H at 18 degrees to 8H at 33 degrees) with Recoil ESX and ZT9 graphite shafts. Both the irons and hybrids will be in stores Jan. 18 (Irons, 4-iron through gap wedge: $1,200 in steel, $1,300 in graphite; Hybrids: $270 each).