I think I saw on social media someone call 2022 “the year of the mast.” Nearly every major brand introduced a new “performance” or “high modulus” mast after recognizing the importance of mast stiffness on foil control and for simply managing the ever increasing loads thanks to new forms of foiling. I’d like to take a little credit for the dramatic shift, though given my fairly low volumes and lack of marketing budget, I can’t take all the credit for what seems pretty obvious now.
But let’s talk about modulus. As a reminder, modulus of elasticity is a mechanical property which is used to characterize a materials’ stiffness. (https://projectcedrus.com/general/solid-mechanics-composites-101/). Since 2017, Project Cedrus has been manufactured using intermediate modulus carbon fiber. We use intermediate modulus because it is produced domestically and used heavily in aerospace thanks to a healthy balance of properties including strength and damage tolerance. High modulus fibers are typically used in military or space applications requiring high stiffness. For example, aligning a space telescope or rocket launcher is a good application for high modulus materials because the focus, accuracy, and quality of the images will depend on stiff members, but strength is not so critical because as long as it survives launch it shouldn’t see any crazy loads. Unless it gets hit by a meteor, in which case it doesn’t matter what it’s made of. Foils on the other hand, see a variety of loads in use and under abuse conditions where super stiff fibers can actually cause failures that wouldn’t occur in standard or intermediate modulus masts. The stiff materials essentially act as stress concentrators, and fail in a much more brittle fashion. The super stiff stuff (often referred to as ultra high modulus or UHM) such as M55J can’t even be procured in international markets where most masts are made, due to ITAR regulations. I assume, without firm knowledge, that most “high modulus masts” are using material in the M35-M40J range, which per the below chart suffers from a fairly large reduction in tensile strength, with a less substantial increase in stiffness.
Toray’s Carbon Fiber Product Line
The stiffness of a mast depends on more than just the modulus of the material. As discussed heavily throughout the site and various blog entries, design (section shape) impacts stiffness significantly. You can use UHM fibers but still have a soft mast if the thickness and chord length are not adequate. Conversely, standard or intermediate modulus fibers can yield a very stiff mast thanks the cubic relationship of thickness on stiffness. Aluminum has a much lower modulus than intermediate carbon fiber at 10,000ksi, but by using more material (thicker walls, more weight) we can achieve the exact same properties in Cedrus aluminum vs. Classic Carbon. I still find myself correcting people on forums when they say things like “I prefer aluminum masts because they are stiffer.” I believe what they mean to say is “I prefer cheaper aluminum masts over poorly designed expensive carbon masts.” A generic “carbon mast” may not be stiff not because of the material, but because of the design: it may lack material, chord length, or thickness where it needs it. A soft carbon mast is not carbon’s fault, it’s the designers fault.
This brings me to my next topic: mast thickness. And this is going to be the last time you ever see this topic addressed; I am officially burnt out. A common thread in my recent survey was “MAKE THE MAST THINNER.” Some responders even used explatives! This is likely my own fault, because I am honest and open about Project Cedrus’ profile and the trade off I made to slightly increase drag in exchange for massive increases in stiffness, people are getting hung up on thickness. I see brands on Instagram holding calipers to their masts now, to show a 12mm thick profile. But like modulus, that’s only half the story. A 12mm thick section with 130mm chord length has the same amount of drag as a 19mmx120mm Cedrus! Chord length has a massive impact on drag, because it influences wetted area. Increasing chord length by 10% for example, from 100->110mm, increases drag by almost 20%. Changing thickness 10%, going from 18->20mm, increases drag by less than 10%, but increases stiffness by almost 40%! As mentioned before, I am not going to get hung up on thickness and have performed a complex multi-disciplinary optimization of Evolution Cedrus with respect to drag. And as it stands however, Project Cedrus (Classic/Aluminum) is currently at the industry average for mast drag.
Cedrus is about average in terms of drag, but we’re excited to be be better with Evolution.
This brings me to my final topic, and this is a hot one: ventilation. I am now getting emails from foilers all over the world asking me to 3D print them a fence for their [insert brand here] mast. Truth is: ventilation is happening on all masts, to some extent. As riders push boundaries, and wings get faster, it’s becoming more and more common. It is incredibly complicated, and I’ve already addressed it here. We have developed some very innovative ways to reduce mast ventilation that will launch with Evolution Cedrus, so stay tuned by signing up for our newsletter to be the first to know when this new groundbreaking mast launches.
In other news, we have been pretty quiet on social, and light on blog entires and newsletters, because we have been extremely busy. Test Pilot masts are in assembly, targeted to ship end of the month. We are excited to announce that we moved operations to a proper commercial facility; no more foils on the dining table or house filling with packing materials! And I say “we” because we have hired our first part-time employee, which is a huge step in the direction of growth. Our new fiber laser is up and running, and we’re now engraving adapters with model names and hardware lengths, to make everyone’s life easier. We’ve also converged adapter hardware around 40mm long A4-80 bolts, which was a huge lift for us and our machinist. The modular fuselage family is complete, with heads and tails for Armstrong, Takuma, and GoFoil. Our recent co-lab with Foil Drive has been a huge success, and we are very excited to see where this partnership goes. Thank you for your patience while we adjust to new demand for various adapters; hopefully soon we’ll be able to offer more at our standard $120 price point!
Laser-etched Axis and Lift Adapters
Preliminary design of Evolution Cedrus is complete, patents have been filed, and we’re moving into tooling shortly. Please register for the newsletter if you want to know when the launch customer program becomes available.
We’re going to make 2023 the year of the mast, again.
Kyle
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