Gong Mast rigidity: Carbon pro v Alu V2 v Others

[Flyboy]

I have both the 85cm and 100cm V2 mono bloc masts. They are significantly heavier built (and heavier) than the V1 mono bloc masts. Gong was one of the first manufacturers to introduce beefed up carbon masts, presumably as a response to the growing popularity of wing foiling. I also had what was possibly the lightest carbon mast/fuselage combo made - the original LP foils set-up - which was very noticeably flexy. I really have no idea what the difference in performance is on the water, since I never used these different foils back-to-back. Stiffness has been touted as being more important than light weight, but I'm thinking that - as with a lot of kiting gear - you learn to adjust your technique to the equipment you're using.

[faklord]

Which front wings do you have?

The new high aspect ones?

I have an "H" wing, and also Fluid T wings, and have no problems using a "fast" wing as really small and low drag - cant see advantages of a higher AR stab as it operates at low aoa's?

Unless it is for looks of course

Or is it the lower drag fuselage-stab connection you like, which is of course more sleek

Peter

Front wings are Fluid Ts and Veloce T (Still undecided about High Aspect front wings yet..they still seem to be getting mixed reviews, particularly the fluids? )
I was trying too loose weight
85cm monoblock no longer available. High AR stab (fluid 38) + short fuse (Al) + Carbon mast is significantly lighter than Fast stab + Al V2 fuse & Al mast.
Drag is noticeably less which is nice.
Also you can also go significantly smaller with the hi AR stabs.
And they look nice

[faklord]

Test report ( https://docs.google.com/document/d/1cSz ... sp=sharing ) updated to add test data from Gong Aluminium V2 85cm and Project Cedrus 90cm.

A surprise was the performance of the Project Cedrus mast which I expected to be a chart topper, as these have a reputation for being both very Light and Stiff.
This (PC) test was repeated a number of times and with different baseplate configurations (& monitoring for baseplate flex) but no significant improvement could be achieved.
It is suspected the Gong alu masts benefitted from the very rigid collar that extends ~4.5 cm from the surface of the baseplate, thus effectively reducing the mast length by 45mm. Similarly the Gong carbon mast is reinforced around the the baseplate.

As previously noted, the above type of bending test doesn't represent real use and rather focuses on the mast/baseplate connection. A more representative test would be to apply torque to both ends of the mast but this is difficult to achieve in a manner that avoids fuselage connection effects. I suspect such a test would somewhat change the ranking!?

[consumer]

dang faklord you are an absolute BOSS. thank you for doing these.

I love my Gong Alu 85 even more now!!

[BayAreaKite]

It's really great to see riders recognize the importance of a stiff mast when it comes to control of your foils, and it's even better that we are moving beyond marketing fluff to testing and engineering. However, this is not a proper method for characterizing mast stiffness. It is a good test method for mount strength. Hydrofoil masts are subject to an eccentric compression load, which results in a CONSTANT bending moment throughout the length of the mast. This "cantilever beam" test however causes a MAXIMUM moment at the mount, reducing to zero at the fuselage and completely ignores axial compression loads, and the fact that max moment actually occurs below the mount due to mast deflection increasing the moment arm. I realize that pretty much all brands test their masts this way, but that does not make it correct. This method leads to inaccurate conclusions, for example the most obvious, you can taper your mast to basically zero at the fuselage, but you will still yield a high bending stiffness result. Even a 3 point bend test would give more accurate result than this cantilever beam test, but the most representative load-case is an eccentrically loaded column. Kyle @ Project Cedrus.

[faklord]

It's really great to see riders recognize the importance of a stiff mast when it comes to control of your foils, and it's even better that we are moving beyond marketing fluff to testing and engineering. However, this is not a proper method for characterizing mast stiffness. It is a good test method for mount strength. Hydrofoil masts are subject to an eccentric compression load, which results in a CONSTANT bending moment throughout the length of the mast. This "cantilever beam" test however causes a MAXIMUM moment at the mount, reducing to zero at the fuselage and completely ignores axial compression loads, and the fact that max moment actually occurs below the mount due to mast deflection increasing the moment arm. I realize that pretty much all brands test their masts this way, but that does not make it correct. This method leads to inaccurate conclusions, for example the most obvious, you can taper your mast to basically zero at the fuselage, but you will still yield a high bending stiffness result. Even a 3 point bend test would give more accurate result than this cantilever beam test, but the most representative load-case is an eccentrically loaded column. Kyle @ Project Cedrus.

@Kyle. 100% agree and I hope the disclaimers I included in both my 1st and last posts, to this effect, were clear.
My intention when embarking on this journey was simply to compare my hardware with test data that already existed.

At some point in the future I may look into “eccentrically loaded column” testing to make comparisons between the hardware I have to hand.

[BayAreaKite]

The disclaimers are clear, however the data is still very misleading. Without any testing, one knows that a 19mm thick Cedrus is going to be stiffer than the 16mm thick Slingshot Aluminum. But because you tested without a mount, and even tested different lengths, the calculated stiffnesses are completely inaccurate.

[consumer]

I disagree . Even a tapered mast would deflect more than a mast of constant thickness vs length. Besides, that is a hypothetical that doesn’t apply here - what mast designs are ‘ cheating’ on this test ? I believe the data are useful , despite that the loading may not perfectly recapitulate what is experienced while riding.

Would you produce data to support your claims and refute the data here?

[BayAreaKite]

post removed.

[consumer]

Thanks for drawing these out and explaining this, Kyle. Your diagram is excellent at explaining the different modes of loading.

So you are arguing that results and conclusions about bending and torsional stiffness would be discordant based upon how the masts are tested. But is that necessarily true ? I challenge that. Wake thief's results and conclusions in his video are analogous to the ones here (alu being superior in torsional resistance).

I'd love to learn that the project cedrus mast was superior to Alu gong or slingshot masts. Citing specs and theoretical considerations are not as powerful as the data furnished through tests. I commend the ones here as Faklord has exercised some scientific rigor.