No, hf mast structure does not have any defined parameters - only cheap extrusion alu masts do. You can and you should vary both chord length and profile thickness according to existing forces, this is of course only possible with composite masts.tomtom wrote: ↑Thu Jul 25, 2019 7:25 pm
In hydrofoil mast almost all that matters is stiffness. This structure has defined thickness - So what define it stiffness is young modulus of material. Normal woven CF composite has ca. 70 Gpa and significantly less than that in any other than 0 and 90 direction. UD have 135 GPA but only 10 Gpa perpendicular to fibers. So we can assume that mean YM for carbon composite in Foil mast is in 50 Gpa range.
Your assuming "mean YM" for carbon composite makes no sense because hf builders aren't idiots. In reality they think carefully fiber orientations. Mast is a simple shape itself, so it is not difficult to achieve very good fiber/resin relation in the structure. Pre-pregs or HM fibers could only improve stiffness marginally. Heat curing is easily done.
If really stiff mast is needed it just have to be slightly thicker. For usual freeride use then marginally increased drag is insignificant.
Yes, it is easy to order alu masts after molds for extrusion are available somewhere. Manufacturing costs are of course very low, and result is quite stiff and heavy mast. Or you can have stiffer light weight mast in carbon, but it is not cheap. After getting used to light carbon equipment heavy aluminium feels so cheap.tomtom wrote: ↑Thu Jul 25, 2019 7:25 pm
Aluminum alloy have 72 GPA /and this 72 GPA is 72 gpa in all direction/ - and its death easy to made it repeatably good with internal I beams. Usually it has also much thicker wall because alu is much weaker /ultimate strength not stiffness/ So you end up with stiffer alu mast much easier than carbon.
Wrong, wrong, wrong. Apparently you don't know much about working with carbon and you don't know what is possible.
Core is not at all important for the stiffness, as long as structure does not collapse under strain. All sporting equipment which need highest possible stiffness/weight ratio are hollow and they are essentially carbon composites. Simple hf mast is no exception.