Author Topic: SURFFOILS Hydrofoil Design  (Read 3914 times)

SURFFOILS

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Re: SURFFOILS Hydrofoil Design
« Reply #15 on: March 06, 2017, 06:10:07 PM »
I think that's the message here is that there is diversity in foil design.
From the pics I posted above you can see there's 2, 3 and 4 mast or strut versions of varying dimensions and performance.
 The current foil derivatives of the Air Chair are AOA dependant and flutter like a Venetian blind in a draught. Even the use of a stabiliser that creates drag is not ideal design but it's where design is at the moment.
 Moving to Longitudinal foils you'll find there's a very controllable stall effect,
 all the area is devoted to lift,
 With very long chords you don't need any NACA foiling, flat plate will do so now you can make foils from ply or plastic sheet cutting the costs by 90%.
Check the pics of my black foil and Terry's and you'll see they are about 13-16 inches wide because much like a pushbike, with speed comes lateral stability.so you don't need a wide foil at all, safer for riding and paddling with the whole foil completely under the board. Use a mast that's only 12" and your complete foils setup is only slightly deeper than a longboard fin.
 An area of 250 sq in will be enough to lift at takeoff on even a small wave. These are the details of a foil designed to foil in the surf, you'll takeoff from the lip and by the time you're half way down the face you're already in the air.
 With foiling in the surf you're not gliding around looking for lift, you're flying through a tornado on a lunch tray.

A very cheap and fast lunch tray but it's that simple to build and you can forget glass and resin and build successfully with Aluminium, ply, or plastic sheet.

Do you want to put up some diagrams and discuss your ideas ?
« Last Edit: March 06, 2017, 06:14:27 PM by SURFFOILS »

PonoBill

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Re: SURFFOILS Hydrofoil Design
« Reply #16 on: March 06, 2017, 08:32:46 PM »
I found the screws--they were already in the clutch basket--duh. The bracket and 20 feet of stainless tube are still missing (really!?!) but I started working on a single foil design. Well, two really, but one is a rudder with a little lift.

So I get the long chord idea, sort of. Even a flat plate with a little positive AOA acts as a weak airfoil--seems like a symmetric foil would be more efficient, but we'll chase that later. So even a small foil coefficient multiplied by a lot of square inches gives adequate lift. What are the benefits of a flat plate other than cost and complexity? Wouldn't a little bit of foil be better so you don't have to stall any part of the foil?  I like those long tails on one of the boards--they scream stability to me, and as a geezer with limited balance, stability is a big deal.

I've long thought that all the mainstream kite and SUP foil designs have been slavishly following the airchair design, even to the extent of having long masts, that were originally only there to clear the rider's feet. What do you think of surface penetrating foils up front and a submerged foil in the rear on a long board. That the route I'm taking with the geezer foil, which is currently suffereing from too much flex.
« Last Edit: March 06, 2017, 08:36:05 PM by PonoBill »
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Re: SURFFOILS Hydrofoil Design
« Reply #17 on: March 06, 2017, 09:48:53 PM »
It's interesting, once you get used to the foil it becomes intuitive to use and does not seem so bad in terms of stability.  When I ask guys that are good at using the Go Foils what they would change, they say nothing needs to change, they are great the way they are.  I think there are a lot of things that can improve, it's like the first generation of SUP's, and I'm sure we will see a lot of development and refining in the next few years but I think the basic concept is good.  The longer mast is so you can keep the foil underwater and pump it up and down a bit without stalling or touching the board on the water surface, both of which dramatically decrease speed. On the air chair board, the feet are in straps on top of the board, not hanging over the edge, so that's not the reason for a longer mast. 
Surffoils, looking at your designs and videos, it seems like you are more skimming on the surface on a smaller, hand board sized board at speed rather than foiling with the foil flying under the water.   That's cool and I could see that working on a SUP but it's not the same as the almost frictionless hoverboard feeling you get when the foil is flying underwater and drag is dramatically reduced.  The problem with a 12" short mast is that it is hard to get the board fully out of the water without the foil breaching the surface.  On kite foils the mast is even longer up to 40" or longer to allow edging upwind at a steep angle to the water without touching the rails.  There is no doubt that a longer mast is harder to balance on and to control but it does allow for more up and down movement, pumping and turning without stalling the foil or touching the board.  I think it would be great to have a short mast to learn with and then use longer masts as your balance improves.
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PonoBill

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Re: SURFFOILS Hydrofoil Design
« Reply #18 on: March 06, 2017, 11:58:50 PM »
Bob Wolley, who was the designer of the airchair, said the mast of the air chair was long to keep the foil away from the rider's feet. The rider puts his feet into the straps once the ski is stable, but they don't generally start there, and don't necessarily stay there. Being strapped to a chair with metal foils close by that can lacerate your feet is not an ideal situation.

The basic concept is well refined, but that doesn't mean it's optimal to begin with. No one has been able to successfully replace reciprocating piston engines with rotaries. Not because engines with crankshafts, rods and pistons flying up and down, starting and stopping 12 thousand times a minute at 6000 RPM is the best design, but because they've been refined over the last hundred years, and that big head start in refinement, support, infrastructure, and acceptance is extremely difficult to overcome.

Foils aren't a new development, there are nearly a hundred years of development in hydrofoil craft, few of which use a single mast and submerged fuselage. It makes sense to see if there is a design that will work better for the applications were are attempting. The gofoil might be the pinnacle, or it might not.

Only one way to find out.
« Last Edit: March 07, 2017, 12:03:50 AM by PonoBill »
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SURFFOILS

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Re: SURFFOILS Hydrofoil Design
« Reply #19 on: March 07, 2017, 01:01:45 AM »
The Air Chair mast later found use as the springboard for all the tricks they now do, much like how it's used to pump a foilSUP along. Without the long mast there's no pumping from wave to wave.
 Each design has its benefits and drawbacks, if you're looking for my foils to replicate what Kai does, It's not going to happen.
But if you want to take off from behind the peak on a a basic surf wave, get airborne on the drop, bottom turn under the lip, pull in and get spat out at warp speed in silence to shoot 20 metres off the shoulder, then shorter masts and longer foils are for you. Sometimes you can catch up to the wave in front.

Foiling in the surf is completely different to flat water foiling, it's very intense in tubing waves. You'll pull in, come out and just say  'geezus...that was heavy !'

Here's a video of a right hand shoulder high tube breaking over a very shallow sand bottom. I was worried about the foil striking the sand and spearing into the bottom on the bottom turns so I stuck high on take off and just powered on the vertical face staying as high as I dared.

It's not meant to be an entertaining video. There's a lot of splash. Its the instants of foil and wave angle that show the positioning.

It's more to show that a flat plate Aluminium Shape you wouldn't look twice at ( or even recognise as a hydrofoil) can foil beyond the limits of whatever you're riding now. It's the same foil I've used prone, shortboard and SUP. My flat plate foils are a new type of hydrofoil.




 It's interesting that I can tell you, show you and explain why it works but all it takes is for Kai or someone else famous to do a video showing it works and then everyone will be all over this concept against the flow of current design.I think it's called Disruptive Technology.


« Last Edit: March 07, 2017, 01:32:17 AM by SURFFOILS »

surfcowboy

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Re: SURFFOILS Hydrofoil Design
« Reply #20 on: March 07, 2017, 01:47:32 AM »
I think the feeling is probably very similar actually, although I see that not having the splashing would probably feel smoother.

As far as not changing the gofoil design, I'd start with the fact that getting rid of the tomahawk that swings at your head in a wipeout would be job one for me, not that plate aluminum is much safer but there is less swing with a shorter mast. I think I'll probably mount wood slats and then a plywood disc/wing

I'll be slowly sourcing sheet metal to build a paipo rig for this summer and then I might start a Clearwater kit if I can stand chopping a plate mount into my Sim. That'll get me started with some testing until UK gets a real mold rig dialed.

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Re: SURFFOILS Hydrofoil Design
« Reply #21 on: March 07, 2017, 04:26:35 AM »
Do you want to put up some diagrams and discuss your ideas ?

I would be interested to hear what riders found using the various single delta designs pictured as well as that thin carbon rig you have pictured.  Are there any videos of any of these alternate designs in use?  I dig what you are doing and love your stoke for it.  I don't mean to be critical at all but it from the action images posted it is hard to distinguish this from non-foil body boarding and surfing.  That takes nothing away from the user experience (read fun) but it does make it harder from an outside perspective.

Kai brought nothing new, he was just the first to make it look good.  There were already a number of vids out there with guys up and foiling on waves but you had to look through your fingers and came away mildly nauseated.  Kai brought smoothness and that sense of soaring.  That aesthetic and perceived freedom is what is driving this surge. 

Some opinions: The better mousetrap will be simpler, safer and more refined.  It is not simply getting up above the water.  Mapping moth foils onto a SUP or that wild windsurf setup posted by SUPUK fail in this respect and fail to inspire the emotion mentioned above.  They may foil, but they look overly complex (not to mention painful).  Those will only reinforce the status quo design. 


SURFFOILS

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Re: SURFFOILS Hydrofoil Design
« Reply #22 on: March 07, 2017, 12:33:25 PM »
Admin, no doubt that safer and simpler are always the goal of designers. Sure the Widget has a purpose but it has to be safe. Personally I can't see how Amazon will use drones to deliver books or anything else, all it takes is one drone to slam into a car or motorbike and after a few deaths its game over for the drones.

Simplicity is a little harder for a designer. Combining the function, flexibility, cost and aesthetics. The good thing about prototypes is that they can be butt ugly yet provide lots of feedback that then goes into the next version. A meticulous attention to detail ands taking notes about every ride builds knowledge.  Eventually I drive the design into a corner and then sit back and redesign using what I know but none of the old components.

You can only design these current Twin blade foils so far until you make the jump to a different concept.

PonoBill

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Re: SURFFOILS Hydrofoil Design
« Reply #23 on: March 07, 2017, 08:02:00 PM »
Admin, no doubt that safer and simpler are always the goal of designers. Sure the Widget has a purpose but it has to be safe. Personally I can't see how Amazon will use drones to deliver books or anything else, all it takes is one drone to slam into a car or motorbike and after a few deaths its game over for the drones.

Probably not, but it takes personal benefit to overlook risk. When cars first came out there were all kinds of whacky safety requirements, but once they became personally useful, a certain level of carnage became acceptable. Now there's 1.2 million deaths per year in car accidents and five million injuries, without a murmur.
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surfcowboy

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Re: SURFFOILS Hydrofoil Design
« Reply #24 on: March 08, 2017, 01:31:33 AM »
Pono called it and check out my thread in Random. Once you get around a smart drone you will prefer them to humans driving cars any day. ;)

Now, about these disc foils...

SURFFOILS

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Re: SURFFOILS Hydrofoil Design
« Reply #25 on: March 08, 2017, 01:37:32 AM »
I'm amazed we're getting to 1000 views in 4 days with only 4 of us contributing...
 Maybe some of the 996 lurkers could add something ?  :D
« Last Edit: March 08, 2017, 01:41:55 AM by SURFFOILS »

Admin

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Re: SURFFOILS Hydrofoil Design
« Reply #26 on: March 08, 2017, 03:03:31 AM »
We are at that proof of concept phase.  I imagine the lurkers are pondering, "imaginative designs, do any of them work?"

The 2009 image below seems to show a great looking single foil on a short mast.  But, the foil is above the water and in the video (hard to tell) it seems to porpoise, surface and dive with the bodyboard slapping the water as it descends.  Is that your experience and if so how are you going to menage that for SUP, where each one of those surface slaps would seem to risk a grab and fall?

« Last Edit: March 08, 2017, 03:05:57 AM by Admin »

thatdeonguy

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Re: SURFFOILS Hydrofoil Design
« Reply #27 on: March 08, 2017, 11:04:14 AM »
As one of the many lurkers who check this thread daily...
I don't have anything useful to post. :0/
I am very thankful to the creative folks contributing their knowledge.
(Surfoils, Admin, Surf Cowboy, Pono Bill, BlueSurfPlanet, SUPUK)
As a Kitefoil rider of one year, I can't wait to SUPfoil.
Watching our sport evolve in real time online is amazing.

Thanks again to the "foil brain trust"!
Deon

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Re: SURFFOILS Hydrofoil Design
« Reply #28 on: March 08, 2017, 12:53:20 PM »
Hi Deon, thanks for adding. It's often the guys who don't think they have anything to add who see things from a different angle and often bring some real inspiration to the conversation.

 Admin,  that video shows lots of takeoffs spliced together so the boards looks to be slapping down. The video shows that as the speed increases the lift is so great that the foil lifts out of the water, then I started doing it on purpose. But it led me to understand that rather than FS foils ( fully submerged) I needed SP foils (surface piercing)  so that the foils self regulates the amount of submerged foil. Moths do it with a complex arrangement but we don't have that luxury or room to add levers and wires so for the surf the regulation has to be quick and linked to the speed of the craft. Lift on a hydrofoil multiplies by 4 when you double the speed so a surf foil needs to be stable at a wide range of speeds.
 Currently foils are in 2 dimensions but there is the 3rd dimension of height that's more important especially when the whole craft is based on vertical lift.

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Re: SURFFOILS Hydrofoil Design
« Reply #29 on: March 08, 2017, 01:36:13 PM »
Do you want to put up some diagrams and discuss your ideas ?

I would be interested to hear what riders found using the various single delta designs pictured as well as that thin carbon rig you have pictured.  Are there any videos of any of these alternate designs in use?  I dig what you are doing and love your stoke for it.  I don't mean to be critical at all but it from the action images posted it is hard to distinguish this from non-foil body boarding and surfing.  That takes nothing away from the user experience (read fun) but it does make it harder from an outside perspective.

Kai brought nothing new, he was just the first to make it look good.  There were already a number of vids out there with guys up and foiling on waves but you had to look through your fingers and came away mildly nauseated.  Kai brought smoothness and that sense of soaring.  That aesthetic and perceived freedom is what is driving this surge. 

Some opinions: The better mousetrap will be simpler, safer and more refined.  It is not simply getting up above the water.  Mapping moth foils onto a SUP or that wild windsurf setup posted by SUPUK fail in this respect and fail to inspire the emotion mentioned above.  They may foil, but they look overly complex (not to mention painful).  Those will only reinforce the status quo design.

Alrighty then...here's my dos centavos...I'm on the same thought plane...I don't think that foiling will ever be for ripe for mass consumption...

Me thinks that George Greenough pretty much nailed belly rides on a wave 50 years ago on a mat...



Tomo...



Don't try this on a standup at Rincon...you will get burned...;-)



Caveat...I'm all about foil progression...
I built a carbon windFoil/SUPfoil board last Summer and have a carbon windFoil with a couple of wings...and, have also paid in full since last year on a number of GoFoils that I haven't received yet...but, a couple are supposed to be shipping today...etc...etc...

I personally dig the ethereal feel of foiling...flying high above the water is pretty cool...
I've ridden some waves with my windFoil and it was scary as hell...can't wait until my shorter surf foils finally get here and I can play with them...but, it's really difficult to not love the simplicity and speed...skimming... from a modern inflatable surf mat...;-)


Mahalos...{:~)

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