Flapping Dolphin Tail for Hydrofoils & AXIS rear wing / stabilizer review
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- čas přidán 12. 09. 2024
- Flapping Dolphin Tail for Hydrofoils & AXIS rear wing / stabilizer review | Foiling NY
We're trying to Wake Thief. To do so we need to launch from our docks (or from a boat), ride the wakes on the lake, and move between them to create an endless wave. In this video we're exploring whether a flexible rear wing or "dolphin tail" can help us pump longer and farther, allowing us to create an endless wave from the wakes of passing boats. In this video we will review five AXIS rear wings to try to figure out which one is our favorite, and also share what we're learning about a dolphin tail ... a flexible, flapping tail that might help us pump farther.
Promotion Disclosure: I was not paid to make this video. I was not paid to promote any products. I would like to thank AXIS foils for loaning me some demo rear wings for me to try, so I could share what I learned in this video.
I'm always blown away by the incredible detail in your analysis and the excellent way you edit the video to show your results. Thanks so much for all the work that goes in to your research.
Thank you! I really enjoy it. And get so many thoughtful comments that help me take a next step. This is crowd sourcing at its best!
Love your videos and especially the dolphin tail experiment. So you know, aluminum only returns about 40% of spring energy, steel returns about 60%, titanium and carbon fiber both return 80% to 85% so would be preferred for the spring tail. This is one less understood reason for example that carbon fiber SUP paddles are so much better than aluminum ones, its partly the weight, though also alot is the better spring energy return from the carbon fiber. For your flexible member on the dolphin tail for sure titanium or carbon fiber would work better than steel or aluminum. PS - The aluminum fuselage doesn't hurt that much as its very stiff from its thicker cross section so this only really effects the things that flex alot.
Wes! I didn’t know any of this. Thanks for sharing. I guess I should look for titanium now! Just when we were thinking we had a cheap solution! Thanks for sharing. Really appreciate it
love this guy, I had to subscribe
I'm one light year away from foils , that's why we need these guys ... testing without BS
I’m so glad you appreciate it! This comment made my day! Thank you.
@@WakeThief well ... wait until living legend Laird Hamilton finds out you are experimenting on foils and are a upper NY local ... he's gonna get terribly frustrated ... LOL
jokes aside, we need guys like you ... it's the irony of the destiny , you can be an alaskan Inuit, and still have the mad scientist approach that could lead to new ideas, despite other guys living on the So.Cal. coast, who are going to keep on surfing for the next 2 millions years ... evolution and out of the box thinking is what makes us humans ... keep us posted! good Job !
Very interesting results,great job.
I think not even manufacturers are putting as much effort in testing and comparing the gear they make as you are!.
Lol. Thank you. I love this sport, and love sharing my learnings with all those who can advance it. I can tell you, I am always amazed when I talk to those who build our equipment. They are still a few steps ahead! Thankfully ... and I certainly hope I can break the 3min mark of pumping during the summer of 2021!
Great video. I think the next big leap in efoil innovation will come with a new propulsion system that mimics dolphin tail propulsion. The robotics crowd has already done this work with things like soft body pneumatic designs using pulsed compressed air, but no one has yet applied that knowledge to efoil designs. You are moving in that direction though. 😊
Thanks for the comment! I never thought of an efoil using it!
I thought up the dolphin tail this morning, searched to make sure nobody already thought of it and found this. You're 2 years ahead of me lol. Great job experimenting with it, was cool to see.
I wonder if a far less aggressive form would be beneficial like relief cuts into the back of the fuse maybe even filled with silicone or something to keep the water flow, yet allow for a touch of give only near the tail. I was thinking not just the pump, but in a big carve - if the fuse could arc a touch, the tail would better follow the front wing and create less drag, then spring out of the turn. I never thought about the lack of stability you mentioned thought. Makes sense.
I'm glad I stumbled across your videos. I recognized a chart from NASA's Bioastronautics Data Book immediately in one of your other videos. I've had similar thoughts on flapping foils, but more along the lines of a flexible trailing edge on the wings, not a flexible fuselage - maybe that would give you the flap AND the stability you seek. You should also trademark and sell T-shirts that say, "I'm pumping it like an animal!" That works on so many levels! I would've said pumping it like a fish, and if you look at a big fish like a tuna, the amplitude of their flap is small, but the frequency is fast - sort of like the stutter hop pumping motion you discovered. Maybe with a flexible wing, you can reduce the amplitude and increase the frequency get closer to how an animal really pumps! Keep up the great work.
John! I love your comment. Thanks so much for taking the time to leave it ... this has been a super fun journey. There's so many ways this can go. The flapping foil is no doubt going to be key to unlocking lower power levels. The rigid setup is just too limiting and it becomes a battle between speed and drag. We want to slow down a ton, then reduce drag a ton. Both hard aerodynamically. Please stay in touch and keep the ideas flowing!
I’m happy that my new $700 Zetti Coast 1800 has a compatible rear bolt pattern to Axis!
This clip is soooooo cool!!!!! Thank you... I am a wing foiler and this clip helped me so much in choosing my additional rear wing. Thank you... Thank you... 😍😘
So glad to hear it. We hope these videos helps folks out. Thanks for taking the time to share your thanks!
Great video. I'm using the 400 and the 460. I really feel a difference in speed in the 460, and I can't wait to try the 420.
Thanks! I suspect the feeling is more pronounced at speeds higher than I can achieve pumping.
I would try some 1 or 2 mm carbon fiber flat sheets off eBay. You can stack different amounts to vary the stiffness in order to see what works best. They are not too expensive either. Keep up the good work and stay warm!
Awesome idea, Tim! I’ll give it a try and share in a future video
Yes I agree and also when stacking it the end should go long to short on top and bottom...like a car suspension
Great suggestion, Ragu. Thank you
Just discovered your channel, subbed immediately. Just got into foiling a year ago with the wakefoil 2.0 from liquid force. Planning on stepping up to something from the Axis foil line this spring.
Thanks, Toey! I appreciate the comment. If I can ever be of help, please let me know.
This is a great idea and when you mentioned that the rear wing is also for stabilization, one problem came to mind. A dolphin can use muscular effort to hold his fluke steady or to flex it and pump. On the foil, it is kind of always in a flex mode. I can't imagine how you could turn the flex on and off when you needed it. As an ice skater, you know what it is to be kind of 'one with your skate'. Your boot needs to be snug enough to completely connect you to your blade to make the blade go where you want on the ice. Boots that are too loose break the connection. Here it seems the connection is sort of broken or ends at some point- probably at your ankles. I'm just guessing and as the son of a lawyer, my legal disclaimer is that everything I say might be wrong!
Thanks, Pete! I think you're right. A small flapping force might be all we need! It might not even be that much.
@@WakeThief I also thought about how I can use my fins when I scuba in the same manner, kick for propulsion or not for stability. I also had a really dumb idea, if you had a sort of brake cable that connected to the rear wing and ran up the mast and through the board so you could squeeze it to stiffen and stabilize it and release it to flex but that seemed pretty extreme and way more trouble than it is worth or most likely not possible at all. My original comment was getting too long, so I left all this out. ; )
Now that’s innovation! I think there’s lots of ways to improve what we have for pumping. Thanks for this
After watching your prototype, I briefly watched a video on how dolphins swim underwater. What I noticed is that not only does their rear fin kick, but the rear half of their body also moves significantly while they're swimming. I drew out something on a sticky note, but I don't event know how to describe it to you with writing you a 3 paragraph comment lol. The main idea would be to have a pivot point behind the front wing where it connects to the fuselage and another pivot point where the fuselage connects to the rear wing. There would also need to be a way for the fuselage to stay connected to the mast while it is pivoting during the "dolphin kick". Hope that makes sense :/ I guess I need to find a fabrication facility and build my own prototype lol
Makes a ton of sense! I took a look a videos too and had the same conclusion. If you build something, let me know! I'd love to try it. Thanks for the comment, Thomas.
@@WakeThief For sure!
Maybe if you can make it so it can flex more down than up you can get more strust out of it because by pushing it down it creates trust but by pulling it up it does not give more resistance.
I think you’re right, Arno
Holy Flipper Batman! Check out that foil wake while you're pumping at 8:10! That's so cool. Yeah like Arno said, maybe a variable spring rate to increase stiffness on the down stroke while making it more flexible on the upstroke would increase forward thrust. Rad idea! :P
I never noticed it until you pointed it out! Wow. That can’t be good. Thanks for sharing.
Great video love the innovation
Cool project 👍 I can’t wait to see the next one !
Thank you!
Thanks for your great learning video !
You’re welcome, JP. Great to hear from you again and thanks for the comment
Anhedral wings might reduce the tip vortices that form on the wingtips during the downstroke, which would reduce drag. As for the dolphin tail, I wonder if adding a third smaller wing might be the way to go. I think a very high aspect ratio (maybe 12x1) carbon fiber strip held in about 3" behind the rear wing by a couple of pieces of flexible carbon fiber rod might do the trick. This would not compromise the fore aft stability while being in the best position to have the greatest vertical movement for generating thrust. It might be too draggy, but I think it is pretty low investment in time and materials.
Michael - I love this idea. Will give it a try. Carbon will be the way to go!
I love the dolphin tail experiment. Try a hinged rear wing. If the rear wing can pitch up, the board will pitch down with less resistance because you aren’t forcing the rear wing to change its angle of attack relative to the water flowing across its surface. This should let the board build speed quicker on the press. then when the board is leveled out the rear wing will stop at the level position parallel to the front wing to increase glide. I imagine it would feel super weird at first because even slightly increased front foot pressure would drop the board like there’s no stabilizer, but if it works it would be long easy pumping cadence.
You’re one step ahead. We tried that subsequent to this test and it did work better! I think we need more spring force and more displacement. Our lake froze at this point in time so we will pick this up soon. Thanks so much for your comment, Marvin.
@@WakeThief The miracle drive trailing edge has the built in spring and different miracle drive fins seem to have different tension of spring (stiffness of fin). I think it is quite direct copy when thinking of whale tail "twist" what you see the tail being above water.
I got to check that out! You don't have a link, do you Jorge?
@@WakeThief not sure if links can be put into comment. But when on pedal drive mode the miracle fin leading edge is stiff, and trailing edge flexes side to side. Just take any hobie kayak underwater video.
So my prediction would be that on hf pumping the te flexes the same, but stiff le limits AoA change related to front wing, and if pumping stops the fin returns to neutral position. Like a spring.
it would be good to ditch the full height nuts on the dolphin attachment for subsequent tests, the drag from those 2 nuts is possibly equal to the entire front foil , depending on the speeds of course. With water at 800x more dense than air small things make a much bigger difference in water . Perhaps you could also try your fav stock foil setup but fill all the exterior voids with silicone and fair them in inc the screw head voids, a bit like caulking a bathroom and see what difference you got from that. maybe a couple percent, the silicone should peel off once done so long as you fill it After it was assembled.
Great to hear from you, Wayne. All good points and ideas. Will incorporate. Thank you
I've got a 390 and 370 (IIRC!) at the moment, and kitefoil 90% of the time with a 660 and short fuse. Also have an 820 as a backup, as that and a 720 were my previous wings on a regular fuse with 400 stab.
I found with the 660 and the 370 I got some rough feeling while riding, which I suspected was turbulence from the gull of the wing impacting the stab's winglets...
I got a 390, and lo and behold the "rumble" is gone. That's as much testing as I've done... shut up and ride! :D
On the handling of the 390 stab -- I agree. It's more stable loaded up and in a carve. When you're a straight tack, it's a little roll-unstable, but it tips into a carve beautifully.
My theory for stable-while-carving is that the anhedral is "cupping" the water, and the downturned tips are cutting in, rather than plowing like the bottom of a spoon as the up-turned tips on stabs do.
I'm probably talking crap though :D
Thank you, Kevin. It's always helpful for me to hear what others are experiencing because sometimes I really wonder if what I'm feeling is real and others are feeling the same! Appreciate the comment. Thanks again.
Interesting trial. What was the material you used for the flexible section? Looks like Al but I may be wrong... I think a material with more energy return like carbon fiber may perform better? I freedive and use the long carbon blade fins as they have more 'spring', energy return and are the most efficient compared to glass and polymer. Seems like a similar application here where you are trying to minimize the losses during pumping. Any significant findings if you changed the stiffness by stacking less or more flex plates?
Spring steel 1/16". We will explore other materials. Great idea. We did try stacking plates, but unfortunately the friction between each plate limited its spring back. To be honest, the flexible tail would not unwind as the friction between plates held them together. I need to play with flex force and flex displacement. Your idea is a good one and worth considering. Thanks for taking the time to share, Scott!
Please keep us up to date of the "flexible stab" wing...I think you are deff into something revolutionary on the sport...specially and it pump category...great job....Just a question...it looks like you use aluminum for the "flex"...don you think carbon fiber will be better or it will be stiffer?
I think you’re right… carbon will store flex much better and is a better choice. Thanks for your comment
Great video!
Thank you for taking the time to write that! I appreciate it very much.
Great clip, love the innovation!
Thank you!
You should make "I'm pumping it like an animal" t-shirts
Love it!
I have slingshot everything.. in your experience are the axis parts interchangeable with the slingshot parts?
No. Unfortunately, only the board is compatible to other foils.
@@WakeThief thank you 😊
You’re welcome!
Great to see your progress here. Your assembly make all rear-wing Aoa to change on flex so maybe that is why stabilization is less as AoA difference to front wing AoA will go from positive to negative. I think Hobie Miracle drive would be more fixed AoA aka stabilization then trailing edge allows the flapping. So I hope you did not ditch the Miracle drive flipper idea yet, and I really hope you could IRL touch&build that idea and have proper testing. I am still so far behind to be at your level at foil pumping..
You will learn with practice, Jorge. I have clocked a lot of hours making all these videos and testing the foils. Practice does make perfect. We are not abandoning this idea. We are playing with a stopped that lets the rear wing hinge to a limit. Is that what you have in mind? Free flapping rear wing to plus or minus 15 degrees?
I figured that the flex would take away some energy from the pump, but if it changes the pumping motion to be more efficient then it would be negligible
So far it seems a wash. A different technique that isn't much less power. We have more work to do. Thanks for the comment.
Well, I think it's time TO GET PAID for making them videos!!
I’m open to ideas :)
Thanks Tenemax!
As a skateboarder who is used to pumping and slaloming to generate speed I wonder if a pair of "skyhooks" would allow you to pull up after pushing down, basically speeding up your pump and letting your legs oppose each other to generate more force
I think it really would! I am a former (very amateur) skater and it is a super similar feeling!
@@WakeThief I used to think about inventing a foil but with two foils coming off the board kinda like where trucks are on a skateboard and possibly flexing as they do to permit turning but I didn't do any engineering on it, it just seemed interesting to my skateboard centered mind
The concept seems intuitive. Especially if you could spring load them to get the foil in the ideal position at each point during the pump.
You can’t completely replace the tail stabilization with a flexible tail. you need to add a flexible tail in addition to the tail stabilization in order to add tail thrust to stabilization
It's so true, but the good thing was that a stiff flex provided good enough stabilization and actually helped thrust more. We're not done with this, so please stay tuned. I appreciate the comment.
It seems like a flexible rear wing would have some spring to it.
As if it would build up some tensions, then release all the pent up energy.
You’re exactly right and that’s where I think we need to go next. Thanks for sharing. Gives me more confidence it will work
First of all I'd apply for changing your name to Wave Chief !!?
I was just thinking about the effects of a flexible rear foil while you just did it. The better flexibility of carbon would be very usefull, as a better streamlining of the flexible device too.
How about to increase the length of both foils to achieve an slower pumping frequence in order to reduce power that's needed to 'fly ' !?
When you continue the possibilities one could even imagine that this principle could lead to success in human powered flight.
Ha! Wake Chief! I ordered a piece of carbon that will be flexible. Slowing the frequency down would absolute help conserve energy, but the foil would need to be low drag enough to not lose enough a speed. It's really keeping the speed up that requires the pumping ... and drag is slowing us down. I have been told by an expert I just began collaborating with that endless flight (>10min) will be possible here. We just need the right setup. Exciting days ahead!
Perhaps mimic an actually fish tail, more of a triangular shape. Manatees have an interesting shape. Also thinking if it was tapered to make the edges more flexible.
That's a good thought. I did try cutting up a plastic cutting board, and it made me realize how important a foil section rear wing is, so a proper rear wing shape probably still needs to keep a foil shape. Thanks for the comment, Richard.
Cool ! What if make the soft edge(end) tail wing, but not the connect bar?
Yes. This is a good idea. Thank you. We will try this again soon.
So does the deck really matter? Wouldn't a skim board or a wake skate work ok? Would some kind of binding system be beneficial? Like tow in surfers use for really big swells. Thanks for the information and content man ur doing great!! Also i would maybe start looking into concave/convex designs and transition pitch thereof. I think of an airplane wing, naturally generating lift while air moves over it. Is there a particular layout that a convex design with a asymmetrical transition radius from front to back would improve efficiency and lower rider input/effort effectively deciphering an individuals wing choice based on stature, strength, skill level etc. Some people weigh more and have super strong and long legs, some do not. This has my attention and curiosity BIG time, i build drift/time attack cars for a living so this is just, right up my alley. With a few suspension adjustments and less downforce, a rear wheel drive grip car (with sufficient steering and Ackerman angle, limited bump steer, and ability to adjust for at least 12° of castor) can actually become a really fun and competitive pro-am drift car.
Thanks for the comment, AJ! The board definitely matters. Here are some thoughts on the perfect foil board for the lake. I love the drift car comparison! I know nothing about it. If I can ever help you figure out a foil for you, please let me know! czcams.com/video/A5kwC7eoPNU/video.html
@@WakeThief thank you man i really appreciate that!! Im definitely ordering one of these things it looks like WAY too much fun. I think i might give deep parts of the Truckee river a try. Where they form sort of a natural wave. I think it would be an easy spot to learn. I just hope i pick it up fast. Seems like just about the best way to burn calories except, well, i dont have to say it you know what im referring to.
Put a fix stabiliser in normal position and the dolphin one behind on the "flapper"???
Yes! Great idea. We eventually tried that and it did work a bit better.
How speed do you need when you trolling by boat?
7-9mph depending on front wing size/shape and weight of rider.
Sounds like Jimmy Chang
Have you had a chance to try the 420?
Yes! It’s very much like 460 but turns better. the tips could be dangerous.
Thanks for getting back to me so quickly. You think it’s better than the 460 you usually ride? Will you be changing your setup. If not, why so?
I’m looking to get my own setup in the near future. Your vid’s are really helping
My current favorite has been my favorite for over a year. We’re trying to find better, and not giving up on our search. If you’re in the US, please use our link and the WAKETHIEF22 coupon code to save $50. We earn a small commission. axisfoils.com/r?id=4ob1e6
420 will improve carving a small bit but we prefer the 460 because we think it’s better for pumping and carving when both matter a lot.
Question. Can you foil (not pump!) without a rear wing?
Yes. I can glide but I can’t pump or propel by myself. czcams.com/video/yUgfmvJLGy0/video.html
@@WakeThief Nice to know. My dad and I are building an efoil at this moment, but would love to try some pumping too (not with the efoil setup!). Thank you for all your videos I have learned a lot from them!
@@iamkian you’re welcome. Please send videos once you’re up and flying!
New lingo invented. Wake thief 😆
Yes, it's our new favorite word ... I hope you like it. Wake Thief (copyright). Let's discuss it when we chat! Really looking forward to meeting. I've been watching your other videos. I think we're going to have a blast chatting!
@@WakeThief going to be fun.
👀👍
Thanks Phil. Good to hear from you!
Whasup
Hey Weston! Good to hear from you