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Blizzard's Flip Core Rocker: Understanding the Construction and Benefits

This post is sponsored by SkiEssentials.com

Understanding Blizzard's Flip Core Rocker

Without a doubt, one of the key elements to Blizzard's recent success is their highly acclaimed Flip Core technology. The odd thing is, despite the technology's popularity, it remains somewhat hard to distinguish what exactly "Flip Core" means. Now in its third year of production (first introduced in the 2011-2012 lineup), Flip Core remains as popular as ever, and only slightly less mysterious. After skiing Blizzard's line of Flip Core skis for the past few years, we can certainly can attest to their stability and ease of use. Still, the details of Flip Core's unique construction process remain murky for most. As a result, we figured we should take the time and do our best to explain what exactly Flip Core is, as well as how it improves the performance of the ski.

What is Blizzard Flip Core Rocker Ski Technology?

Flip Core all started as an idea back in 2010 when the late Arne Backstrom (former Blizzard athlete) was skiing with Blizzard rep Clem Smith out in California. On a whim, Arne mentioned to Clem that he thought they were building their rockered skis the wrong way. He suggested that rather than profile a ski's core and bend it in the mold, Blizzard should try profiling the core of the ski, and then flip it into the mold, giving it a pre-formed rocker profile. In short, the idea was presented to the engineers at Blizzard, and the result was Flip Core.(Read about Flip Core and more in our interview with Jed Duke).

So how does Flip Core work exactly? Well typically when a ski is made, it's core material is profiled into a subtle arch shape. This profiled core is then placed on top of the base materials, in a mold that's in the shape of the camber profile of the ski. Other materials such as metal, fiberglass, and the top sheet are then added on top of the profiled core. At this point, the mold compresses and the ski is subjected to intense pressure as all of it's materials become bonded together.

How Rocker is Made: Blizzard Flip Core

The difference with Flip Core lies in that very first step, when the core profile is constructed. At this point Blizzard creates the camber profile of the ski, on the top side. The core is then flipped into the mold which matches the camber profile that Blizzard has already given the ski. From here on out, the construction process is the same as most other skis. The top layers are placed on top of the core, and pressure is added.

With all of that said, it still might be unclear what the actual advantage of Flip Core is. Ultimately, the key to the technology's success is the fact that the wood in the core of the skis, isn't stressed in the construction process. As a result, the end product has a much more natural flex, as the rocker profile of the ski is the actual shape of the wood, and not the result of bent wood.

The on snow translation of the Flip Core process is clear. If you've ever skied on a Flip Core ski, you've undoubtedly noticed the stability of the rocker. Even on a ski like the Blizzard Bushwacker, which has no metal in its core, the rocker profile is exceptionally stable on firm snow. Of course when you do add metal to the ski, such as the Blizzard Brahma or Blizzard Bonafide, the result is an unbeatably versatile ski. With Flip Core, you're able to lock into fast, firm carves while still being able to stop on a dime. Flip Core rocker gives your skis more stability than other rocker profiles, allowing you to take your skis from 60 - 0 in a split second. This kind of stability induced "speed bleeding" is helpful not only on the groomers, but in the powder too. When Arne initially brought up the concept of Flip Core, one the things he envisioned was a ski that could scrub speed like no other. He wanted to be able to ski big mountain lines, and safely drop his speed as quickly as possible when he found himself in sketchy situations. As Arne expected, the stability of Flip Core helped greatly in these situations.

Speaking of backcountry lines, Flip Core also improves a ski's ability to float in powder. Due to the fact that Flip Core maintains the natural shape of the core, without bending it, the flex of the skis have an incredibly smooth, even flex. Skis like the Blizzard Gunsmoke or Blizzard Cochise have no problem staying afloat in the powder with Flip Core. With the natural rocker shape, your skis simply have no reason to sink.

2014 Flip Core Lineup

In short, Flip Core is a superior rocker technology, because it gives the ski a natural, stable flex that simply can't be matched by traditional ski construction. By avoiding the need to bend the wood core of the ski, Blizzard has allowed the wood to maintain it's natural shape without additional stress. The result of Flip Core, is a complete lineup of skis that have a remarkably smooth, consistent flex that'll be sure to impress even the most skeptical skiers. If you haven't been on a pair of Blizzard skis in the last few years, then you've been holding yourself back for too long. Make this season count with a pair of Blizzard Flip Core Skis!

Posted by Matt on 8/15/13

Comments (13)

Very interesting article. Thanks!
As an aside, are there any differences b/t the Bushwhacker & Black Pearl other than top sheet?
HI reddirt, the only difference between the Black Pearl and Bushwacker is the top sheet and size availability.
Interesting article... some more info can be found here http://blistergearreview.com/features/what-is-flipcore if you would like to read more about!
Interesting article. I have one question remaining. When building the core profile does Blizzard cut/mill the profile from a solid wood core or is does the shape come from layering?
“It still might be unclear what the actual advantage of Flip Core is”. I can think of a good one.

When a flat core is cambered in the press, the belly will be in compression and the back in tension. When the ski comes out of the press it’s going to decamber a bit. In the free state, the glass layer of the belly will be in tension and the back in compression. If the ski’s been in the press long enough for the resins to completely cure (which takes a long time and hurts production rates), no problem:you shouldn't see any difference between flat and precambered cores. If not, then there will likely be some creep and no two skis will creep the same way. You’d likely see increased ski-to-ski variation in camber, stiffness, and damping.

A precambered core will be unstressed in the press and when removed will not rebound, eliminating stress in the glass layers and resulting in much less part-to-part variation. Plus you have the potential for increased production rates because you might be able to remove them from the press in less time than ever before. Everyone wins.
I'm still missing something (and for the record, I'm on one of these skis and love it)...
The first step does not describe HOW the core "shaping" takes place in the two processes. Nor does any of this tell me why tension-free/"natural"-rocker is better. Perhaps being under tension is a good thing? Also, I don't see how this process "doesn't stress" the wood used in the construction unless the entire shape is 100% planed (or however the shaping happens assuming it's a process of cutting shape from a block-- AKA losing more material than a pressed shape) into the final shape, and the pressing does zero to add shape.
As it is, this is almost 100% marketing-speak to me. After all, it says the Cochise is a floaty powder ski... and yet at 108 underfoot it's actually not very floaty compared to other skis of that width.
Given that, I'm not convinced the stability of these skis doesn't come from something altogether more simple: high quality materials, subtle shapes ("early rise" compared to the more aggressive rocker on other brands), and a lot of metal in the models that seem to collectively get the highest accolades... Bonafide and Cochise.
mfa81- Definitely another great article, with a lot of in depth information. Did you guys ever get around to doing the comparison test with the Caylor's like Rowen proposed in the comments? I'd be interested to hear the outcome of what adding bamboo to Flip Core would do...

FlashGordon- That's an excellent question. I suspect that like most cores, flip core combines strips of wood that have been adhered horizontally, but that the actual core profile comes from one piece vs. several stacked layers. If you're exta interested in finding out the answer to this, I'll see if one of our Blizzard reps knows and I can get you a definite answer.

Chilehed- Another great point. I would absolutely include that in the article if I could say it more definitively. While there haven't been any tests (that I'm aware of) that compare the sort of "rebound" that you're referring to, it would only make sense that that's the case. I think the lack of having the rebound as a result of the stressed core is also what gives Flip Core that added stability. It's almost a case of inertia where if the core is happy how it is, it's going to resist change. On the flip side, if the core already feels a little stressed and wants to rebound, I could easily see it being more willing to "change states" and therefore be slightly less stable all around.

Thanks to everyone for the comments, we love having discussions like these!
I don't know what Blizzard does but traditional torsion box core construction involves small strips of wood (sometimes different types of wood) usually glued together vertically with pieces glued on top and bottom to form a box. The strongest type of construction is a double torsion box whereby they build a box around the first core box.
If one of the advantages to Flip-Core is not needing to bend the ski during the construction process then I would assume that Blizzard (and maybe others) shape the core with a band saw and sanding rather than bending.
skiessentials - I have no doubt that there will be some degree of rebound when a flat core comes out of the press. The amount will be dependent on the relative stiffness between the core and the fiberglass; it might not be obvious to the naked eye but it absolutely will be there. (This assumes that the wood doesn’t get stress-relieved during the process).
Thinking about this some more: A ski is really just a composite spring, and the vibration response of a spring is dictated by (among other things) the modulus of elasticity. If the core material has a constant modulus below the yield stress, exhibits no creep below the yield stress and never reaches the yield point during use, then the response of the ski should have nothing to do with the amount of retained stress (either tensile or compressive). You’d see this with, for example, a metal core.
I believe that most woods have a fairly constant modulus below yield, however they do tend to creep at stresses below yield. So over time I’d expect to see relaxation in the core, which would translate to changes in the shape of the ski. How the wood relaxes is strongly influenced by the orientation and structure of the grain and fiber of the wood, which is never exactly the same from core to core, so once again as the core relaxes over time the skis will change shape and no two will do so in exactly the same way.
Note that these changes are due to creep within the core itself, and have a different cause than the changes I described earlier which are due to creep in the glass resins prior to full cure.
So now we have two reasons why a shaped core, one which in the free state has the shape of the finished ski, might reduce part-to-part variation.
Another reason might have to do with the damping coefficient of the wood. If the relaxation of the fibers (which causes the creep) also causes changes in the damping coefficient, then the ski will lose liveliness and again it won’t be the same from ski to ski, or even from stringer to stringer within the core. So you could have subtle changes in damping from side to side, or along the length of the ski, and that will cause odd resonances that might be detectable underfoot.
Another thing: fatigue failures are accelerated when the material undergoes stress reversals, when the surface goes from tension to compression and back again. Suppose the core of a traditionally cambered ski in the free state has residual compressive stresses at the lower surface (the belly) as I originally described. When you stand on it on a flat groomer, it flattens out and the stress goes to zero because that’s the shape the core was when you made it. When you bend it in a turn you get tensile stresses. So as you work the ski you always get stress reversals.
But with a shaped core, the core isn’t pre-stressed. When you bend it in the turns the bottom of the core goes into tension, but when you release it there’s less tendency to go into compression because the fiberglass layers aren’t forcing it do that. So rather than the stress alternating from, for example, -50 psi to +100 psi, maybe it’s going from -20 to +130. Such a change in the amount of stress reversal might have a positive impact on core life.
Just thinking out loud. Great article, thanks to you and tylrwnzl for writing it.
Well interesting. Why in the diagrams is the core in the first illustration upside down? It's flipped for the molding process. But just for the picture. There's no "up/down" in making it until it's in a ski. If that's where the name comes from, so be it, but it would more accurately be described as "pre shaped core".
If it's just pre-shaped, Blizzard is not nearly the first to do this. Maybe for rocker, don't know. Volkl used to send to some shops the poplar wood core of their racing skis in the 90's. Shops would hang it on the wall as it really was a thing of beauty. Pre- shaped with camber, and had hundreds of holes drilled through for polyester resin absorption or through bonding I guess.
They also used to say that the wood was taken from special trees in the Black Forest, etc.
One of those skis, the P20, listed for $735 in 1996.
So, the description above is still a little fuzzy, as per usual in the ski industry.
More interestingly, a couple years ago at Squaw we were skiing with someone who's pretty in touch with the ski industry. The flip core thing was pretty new then and the Bonafide was the ski people could just not go on living without. We asked him about it. He told us one engineer had said they really didn't know exactly why the skis were so good. It could just be the combination of everything and have nothing to do with flip core.
But the ski industry loves catch phrase technology issues. It makes it easier for store employees to say what differentiates the ski. Even if they don't understand it. Anyone ever get Head to adequately explain "Liquid Metal"? Nope. Sure sounds good though. Even store salesmen just used to laugh at it with the customer, sort of as a plus, and just say it was a really good ski.
Don't laugh. Liquidmetal is just a trademark owned by a company that produces amorphous metal alloys. They really do have useful engineering properties; among them are improved yield strength, fatigue strength, elastic limit, corrosion resistance, and wear resistance. One downside is that they also tend to be more brittle, but an application that doesn't have much impact loading (like a snow ski) might well benefit from their use.
EpicSki › Gear Articles › Blizzards Flip Core Rocker Understanding The Construction And Benefits