this thread is touching on some basic solutions but very effective. I worked in the U.S. Space Program for a few years as a designer and structural engineer. The generation of debris at Max-Q and Max-Buffet (trans-sonic) is
a grim reality. Drilling holes is viable.
The vehicle we built was a cryogenic bird and literally leaked continuously on purpose. On the 4th mission, the liquid hydrogen was gassing normally through the skin up near the nose cone. On this particular mission the gas remained in the boundary layer. The Vehicle became completely enveloped in about an inch of hydrogen gas. When the gas reached down to the tail- L.O.M. (loss of mission). Looked like a giant firework.
That single payload/vehicle was in the neighborhood of $1.2B (a “Hubble-like” telescope, but made to point someplace else).
Moral of the story- it pays to get rid of your gas properly!
You know, we worry here about how to put together something as simple as a surfboard, but dealing with stuff like liquid hydrogen and other exotic fuels and materials, boundary layers at multiple mach numbers, structures and components of the sort you need to make something like that work…
Hi doc, yeah I miss it, mostly the paycheck. The whole time I worked on the Titan IV project, I would come home and shape. I subbed my glassing since I had so little time. When the opportunity came and I could choose more of what I wanted to do, I built surfboards and taught school. Then the opportunity came again, and I wanted to build boards full time. I must be crazy, but I’m super stoked!!!
So, Ben, I am wondering if he was part of the range safety interrogation committee after that Titan exploded? There was a tall surfer-type there. I had to fly to Colorodo for that lashing. (It wasn’t my fault, I SWEAR!!! ha ha). As an engineer, I was surprised that there were a few surfers/sailboarders tossed into the egghead mix. I interviewed with Lawrence-Livermore in the 80’s which was connected with Sandia, I didn’t take the position but could have ended up working with those guys. Surfers in the lab, imagine it!
I think my Dad may have given that lashing. He was a director at MM on Titan IV and I have clear memories of his reaction to that explosion… I’m sorry on his behalf. Given the SD location, I assume you were a GD guy.
My current lab (MEs, EEs, and chemists) is full of surfers, and lots of them are looking for ways to engineer less and surf more or twist what we do for a surf tie in. The trouble is we do primarily micro-fluidics work that is tough to scale up by a factor of a million to the size of a board and very expensive to play with on any scale. I have seen rocker profiles and breaking waves being modeled on workstations with our internal CFD package. Trouble is that for a big company, surf just doesn’t justify a big technology R&D push and the $$ that go with it, even though there are good ideas out there.
A friend recently told me about a board he saw with pin holes that he was told were to let gases out. My question to him was “what stops the water from going in?” but maybe he was looking at an XTR board. Is it just that the XPS isn’t damaged by the water that does find its way in?
there’s a very aggressive intellectual rights patent lawyer that’s hunting down such discussions of methods very aggressively to protect someone’s 20 year work on this exactly solution for XPS foam core surfboards…
I hear they like to knock of people’s doors with pieces of paper.
generalizations at best unless you want the nuisance
+1, you would have liked it up here…but I don’t think these guys have been around that long. I think LeRoy is about my age - a year or 2 under 40 - and Dan is probably only 32, 33.
LeRoy describes himself as a ‘vacation surfer’. His wife is pretty core, I guess she is in Santa Cruz quite a bit. He joins her in the water when they’re in Hawaii or elsewhere warm.
But don’t worry, we’re hooking him up with a wetsuit & a Sunset out of John’s rental fleet
You nailed it. (It wasn’t me though!) I’m an ME, and have a minor in Physics, and a degree in Pure Mathematics. My program manager was Al Theilacker, and project manager was Jack Hotz. I was with GD, Space Systems Division, we made the Centaur which was a Cryo upper stage, we had to vent the boil-off to the outside of McDonnel-Douglas’ payload fairing while stacked on top of Martin Marietta’s main booster. We designed a tube that extended out of the side of the rocket which was called the vent fin. Note to self: if the vent fin is too short, hydrogen gas will cling to the rocket…
Since I worked on the subsequent Vent Fin re-design (no pressure at all), I had access to some good computational fluid dynamics programs. I ran many foils across a variety of Reynolds numbers amd transonic scenarios using the Cray XMP at Harlingen (via our Hyperchannel) (our company had a private Cray in the 80’s). One of the problems I found was the fluid medium in surfing (ie. the wave face) is NOT uniform… …it is accelerating.
To clarify, imagine a grid of ping-pong balls floating exactly 1 foot apart and then a wave comes. As the grid of balls goes up the face, the spacing of the balls gets wider and wider. The rate of this expansion is important in fact, this acceleration is substantial. Once the fluid parameters are dialed-in, the results are very surprising. Let’s just say that simple is best, and undercambering and twist/tip control is futile.
Lastly, attention must be paid in the relationship of the fin location(s). Clusters must relate to the acceleration AND also direction changes. IMHO more attention needs to be paid to the center fin.
Once the clock rates of desktops gets up to TeraHertz or multi-parallel processing, I think the right kind of computaional fluid mechanics can be rendered at home, then we just need someone to supply affordable software. Micro fluids can be scaled using Reynolds and density shifts for the flow regime. Also 3-D accelerations can be modeled into 2-D with constant velocity but variable density. (Remember the Reynold’s numbers change as the wave pitches or gets more energized over shallower parts of the reef).
Making boards doesn’t pay as well but man let me tell you, peace of mind and complete lifestyle is truly priceless…
) but a good take and an accurate respresentation of how a lot of nuts & bolts shapers feel…