From all of is here at Flyboy Wakesurf, we wish you and yours a great Labor Day weekend! We’re sure everyone can use the extra time off. We’ll be observing the 3 day weekend also, and so won’t post again until Tuesday! Before we take off for the holiday we wanted to review the fabrication of the Honeycomb Carbon wakesurf test panel and then also the limited results of that test panel.
You may remember in the last post that we talked about how other sports tend to develop equipment that is shorter, lighter and stiffer. It makes sense in something like slalom skis that shorter would be better than say a pair of skis that was 10 feet long! Shorter arcs or shorter radiuses in turning would equate to faster runs down the course. We’d also venture a guess that at some point there is that point of diminishing returns. Possibly in a slalom ski it could get too short, causing erratic turns or crashes. If you’re a loyal reader you’ll remember that we threw James Walker out on those 2′ sections of plywood. They were wildly out-of-control, but seemed to define the requisite wetted surface area. Now we also tested that carbon fiber hollow wakesurf board and the dynamic bottom on that wake surf board astonished us in the sense that it was so much faster. Not all that predicatble, but certainly faster.
The point being that the change in the shape of the bottom of the board created a faster board. Much faster than we needed, so it would be possible, at least in theory, to develop a board that was smaller and still had the requisite speed for wakesurfing. It could be that we are already at the smallest and lightest for serious wakesurfing, but perhaps not?
So, we’re toying with that concept of lighter, stiffer and shorter or LSS. Towards that end we are trying to test a few panels, including this honeycomb carbon wakesurf test panel that “might” allow us to develop something along those lines of LSS.
To make this honeycomb carbon wakesurf test panel, which will be two carbon fiber skins on the outside – top and bottom – of the aluminum honeycomb, we wet out both of the pieces of the carbon fiber with epoxy.
Now the next picture needs a little explanation. We are creating two pieces and THEN we will combine those two pieces in a secondary bonding step. The reason for this is that we don’t want the excess epoxy in teh top layer to drain into the underlying honeycomb, creating extra weight in the honeycomb and possibly weak spots where the resin drain off. So what we will do is glue the honeycomb on TOP of one of the strips. The other strip is laid down on top of a peel ply that will leave a texture surface which will aid in the secondary bonding step.
The peel ply we used in this test panel is white and doesn’t show up all that well. but under the strip of carbon fiber that is further away is that peel ply.
On top of the peel ply we’ve laid a section of breather cloth which will absorb excess resin and also prevent the aluminum honeycomb from puncturing the vacuum bag during pump down!
Once all of that is in place we pump down a vacuum and allow the two separate parts to cure over night while under a vacuum. When we pull the parts out, we have one piece of carbon fiber in an epoxy matrix and the other piece is that same carbon fiber and epoxy, plus we’ve glue the aluminum honeycomb to it.
You can see in the picture above that the honeycomb added piece is much stiffer than the carbon fiber and epoxy only piece. We certainly can imagine there would be flex in the carbon fiber alone piece! The point being that carbon fiber all by it’s lonesome isn’t an adequate predictor of wakesurf board flex.
A few things that we’d like to point out. One is the misnomer that carbon fiber is crazy stiff. It certainly is stiffer than fiberglass in an epoxy matrix, but it bends under it’s own weight. In terms of stiffness to weight, carboard is stiffer for the equivalent amount of weight. Also epoxy is relatvely strong, but it is nowhere near as stiff as polyester resin. Things to remember as we continue with out LSS quest!
In the next post, sometime early next week, we show some of the interesting results of testing the final honeycomb carbon wakesurf panel and we’ll also show the secondary bonding step to create the final test panel.
Thanks so much for following along, we appreciate it! Again, we hope you all have a great Labor Day weekend!