Foiler Design

[Chris Ostlind]

Originally Posted by Doug Lord

Darryl Barrett, the designer of the Aussie Alpha Omega 14 Cat, has. Here is a rudder foil picture and he is using the same sweep on the main foils of a new foiler he is developing:

Betcha that's all about getting weed and other crap in the water off his foils while underway a whole lot more than it is about any supposed lift advantage he "may" gain.

If you look at the rudder block in the photo, you will see that it has no facility for kicking-up if it encounters any obstacles, or junk, underwater. This makes for a static weed collector, should he have non-swept foils on the cat.

Same problem that all lifting foil equipped boats have now and will probably always have. Like Bistros says... "there's no free lunch in design, boys"

Originally Posted by mark_m

@doug:I think I've posted this before but:


This was my prototype design based on a Rich Miller concept.

The first impression of sailing with it are on my site, but basically the long foils provided a lot of damping in roll and they took a lot of ankle stress to contol them.

Foilboarding is more about control than efficiency at the moment, as even the inefficient, almost flat plate, initial designs that Neil Pryde were using are way more efficient than a regular board. They just have much less control so you can't use all the available power.

==========================
Mark, have you tried jumping with your foils? If so, how well do they re-enter?

[Chris Ostlind]

Originally Posted by mark_m

... Foilboarding is more about control than efficiency at the moment, as even the inefficient, almost flat plate, initial designs that Neil Pryde were using are way more efficient than a regular board. They just have much less control so you can't use all the available power.

Originally Posted by Doug Lord

Mark, have you tried jumping with your foils? If so, how well do they re-enter?

Hello, Earth to Doug.... The guy flat-out says that he can't use all the available power due to less control and you blindly ask if he is jumping?

What's next, ask Mark if he can make controlled landings on the deck of a moving power boat some significant meters away? Some could actually deduce that you have a confined agenda, Doug, rather than a sense of open discovery in the process.

[Paul Scott]

Originally Posted by Tcubed

Some pretty gnarly ones there ..

Hate to think of wiping out and getting into a little underwater 'encounter' with your own board, all bristling wit blades.


Anyone how you's supposed to embed utube vid in here?

Well here's the link since the video doesn't seem to want to embed

http://www.youtube.com/watch?v=g3AV1LJwQus

But they recover from crashes with little drama. ATTENTION MOTHIES!

[Tinman85]

Originally Posted by Tcubed

<<<<<<<<Swept foils either forwards or backwards help with reducing drag at higher speeds increasing the top speed.>>>>>>>>

You will find that all aircraft with swept wings have that for mach # reasons which is completely irrelevant in the case of a foil boat.

<<<<<<<<<<<winglets (little verticle fins on the wing tips) were created for some aircraft. Adding winglets to hydrofoils could increase lift by increasing the effective foil area.>>>>>>>

These winglets inhibit tip vortices yes but come at a price. If the area of the winglet were to simply be used to extend and augment the aspect ratio of said lifting foil you get a pretty similar result. Winglets are not a magic solution, otherwise all planes would have them.

<<<<<<<<It is forward swept foils that have interested me because they do not have the problem of wing tip vortices if designed correctly as span wise flow along foil is to the centre where the body of aircraft (or in our case the centreboard part of foil) acts like a winglet, but does not incur the additional drag penalties because it is already there.>>>>>>>

This is incorrect.
You cannot cheat induced drag by simply sweeping the loaded foils forward.
In general, for the kind of flow regimes we're disscusing, any devition from foils at right angles to the flow increases induced drag.

I am talking about incompressible attached non ventilating non cavitating flows at M << 1.

Thanks for explaining that.

[Munter]

Originally Posted by Paul Scott

But they recover from crashes with little drama. ATTENTION MOTHIES!

In other foilboarding vids you can see the rider using the bottom of the foil as a planing surface on the top of the water. I think this shows how these low aspect foils can work with only the bottom surface producing lift. I doubt you could do that on a foil with the aspect ratio of a moth.

Crash recovery is probably partly a function of the difference in lift between attached and ventilated flow over the top surface. I'd wager that the foilboarders traded some efficiency for handling in selecting that foil plan form.

Just found another vid showing a second or two of surface planing.
http://au.youtube.com/watch?v=Q8RhsSREkNk
The other thing that really stands out is how little of the available power the kiter actually uses throughout this vid. Apart from one brief port tack stint the better of the riders on the vid really stands very upright and has his kite quite depowered for most of the riding.

[Paul Scott]

Munter, you spark a few thoughts:

What I mean by crash recovery is that the shape of the surfboard itself turns a crash into a landing with speed: things go on, no stopping.

The planing of a foil when it pops out of the the water is in a way another type of crash recovery, or at least you could look at it as early onset crash prevention.

I have the pleasure of watching the foiling Moths at play when I walk my West Highland Terrier, and since the puppy likes to sniff (read not walk) A LOT, I have spent a lot of time watching the Moths, and it seems to me that even the good riders are crashing more than a little bit (I haven't seen any of the really world class riders in person), so I've been wondering if not spending time in the water recovering from a crash might make up for a bit slower hydrofoil that spends more of it's time sailing (not crashing). This is an argument that was going on with sinkers (to some extent) when slalom racing
first appeared in the windsurfing world.



Paul

Paul, you seem to be touching on an important and interesting consideration: using hydrofoils does not HAVE to be hard,does not have to result in a constant series of crashes. If the same development time that has been spent on making foils fast in the Moth class was spent on making an easy to sail foiler a truly fast,easy to sail boat could result. It might even be called a "Peoples Foiler". There are so many different ways that foils can be used to enhance sailing that the sky is the limit with all the configurations mentioned by Tom possible as well as others like the DSS concept. This is an exciting time in foiler design with some really interesting boats sure to result....

[sigurd]

"Anyway, the windsurfer/surfer/kitesurfer hydrofoils do present a different approach (but is the kitesurfer approach really appropriate?), and it seems to me, a 'softer' approach?"

What do you mean appropriate?

"Is this (the cultural aspect, I guess you might call it) something any of you are interested in, and does it belong on this thread?"

No, this is the "Foiler design" thread. Not that it cannot stand a diversion now and then, but since you ask.

[Paul Scott]

Originally Posted by sigurd

"Anyway, the windsurfer/surfer/kitesurfer hydrofoils do present a different approach (but is the kitesurfer approach really appropriate?), and it seems to me, a 'softer' approach?"

1) What do you mean appropriate?

2)"Is this (the cultural aspect, I guess you might call it) something any of you are interested in, and does it belong on this thread?"

No, this is the "Foiler design" thread. Not that it cannot stand a diversion now and then, but since you ask.

1) I've windsurfed on a foil (the Delta arrangement), and one foil seemed right for the feel of the balance of things (which, like on smaller boards, feels to me to be over one point, but that's straight line, not carving through a jibe), I've only kitesurfed a few times, but the feel on the board is really different, where the whole board feels loaded up, like the whole thing is consantly carving rather than just balancing over one point, so having one foil seems like an invitation to fall over the nose, so as it was pointed out, it's difficult really power up the kite.

2)Fair enough, sorry for the diversion.

Paul, I think the "cultural aspect" most certainly is appropo for Foiler Design and one of the much overlooked factors in aiding the focus on a foiler design that would have extremely wide appeal.

[Chris Ostlind]

Originally Posted by Doug Lord

Paul, I think the "cultural aspect" most certainly is appropo for Foiler Design and one of the much overlooked factors in aiding the focus on a foiler design that would have extremely wide appeal.

Likewise, there needs to be a very serious and pragmatic discussion as to the realities of market potential, marketing of said potential and the totally blunt reality of looking at the worldwide economic meltdown as an integral component of whether one of these boats is even ready to be put before the mass sailing market.

Yes, you see Bladerider and Mach2 and John Ilett's Prowler efforts and they are putting boats out on the water. But that sales volume is but a notated curiosity in the grand scheme of the greater sailboating world and its potential.

Lasers, Sunfish, O'pen BIC’s and a host of other, more traditional sailing craft, individually far outsell the various foiling boats combined and it's going to stay that way as long as foiling has the issues that it does in the eyes of the potential buyer.

Over the years, there have been tons of discussions about this topic on these pages and it always rotates back to the same group of things sitting in front of a mass market foiling boat like a fat gal in front of you at the supermarket checkout line.

They are fiddly

They are expensive (to buy and to maintain for a beginner)

They are hard to learn to sail for a Joe Sixpack kind of sailor

They are tough to repair due to expensive materials (the glass BR is a limited exception)

The foils are susceptible to any kind of junk in the water that disrupts flow

The foils are susceptible to serious damage should they be driven onto the bottom at speed

Did I say that they are expensive?


The boats, as cool as they might be for some, are decidedly not for the average guy, or gal. They live in that place of special vehicles that are really interesting to look at and watch, but typically well outside of the conciousness of the middle of the road user/buyer. I liken them to the high perf. roadrace style, street rocket motorcycles that are absolutely amazing as technological mechanical marvels. No matter how cool they are to the average motorcyclist's thinking, they do not sell in any kind of numbers like the street cruisers, which absolutely dominate the marketplace. Think about it. There's a reason for that reality and it's not a figment of my imagination.

Lastly, what is this very cool foiling ride going to get you when it's time to sell it off and get the newest trickest foiler (and there will be newer and tricker rides as the weeks go by) Want an idea, go look at the used prices for high perf sport bikes compared to what they go for when new. The very nature of the animal is that it runs on an ever-changing technology stimulus. This guarantees that you will very quickly be obsoleted, rendering your heavy cash outlay to the scrap pile... well, unless you really like driving last year's slow poke. But then, that's not why sailors buy these foilers, is it? They buy them to have the fastest and the snappiest thing on the water. Slowpoke foilers are like a leftover leaky tuna sandwich.

If you enter the fray, expect to pay... and pay handsomely.

There is a place for the highest of tech anything in this wanky world of ours. Those places, however, are going to get mighty few in the next several years as businesses, individuals and even countries get tossed around like dolls in an economic version of the nastiest roller coaster. Expect the already high prices of foilers to go even higher, putting an absolute premium on the game as you know it now.

That should get the discussion rolling along nicely.

[bistros]

Originally Posted by Chris Ostlind

That should get the discussion rolling along nicely.

Good points all.

Start thinking big - recreational boating in general.

Power boating and it's isotopes dominate North America without a doubt.

A tiny fraction of the power boating market describes the sailing market pretty accurately. Most Joe Sixpacks will never consider sailing as it has the ugly taint of effort required beyond a remote control, a joystick, electric start or a steering wheel.

Of the tiny sailing market, the bulk of the market is for keel boats that allow the adventurous Joes to have a beer while recreating.

A tiny fraction of the keelboat market describes the dinghy market.

A tiny fraction of the dinghy market can be called high performance racing boats.

A micro-tiny fraction of the high performance dinghy marketplace is the place that Bladerider, Prowler etc are vying for.

After gaining this perspective, and honestly assessing Joe Sixpack's willingness to endure any discomfort or learning effort, I think the marketplace for a People's Foiler is stillborn before it reaches term.

Face it, even "simple" performance sailboats are not for the average person. There is no profitable marketplace to be exploited here, and the best efforts out there are targeted towards cannibalizing people already involved in other race boats. Bladerider and Prowler aren't attracting new sailors - they are raiding people from 49ers and other classes.

Interesting concept, and I'd try one in a minute - I hope one day to get a ride in Sam's SR71, even if I have to drive to Colorado but it isn't a high appeal personal purchase for me. The venue I live in isn't foiling friendly average wind-wise, and I can't think of anything more uncomfortable or unpleasant than sitting two kilometers away from my club on an unstable ten inch wide foiler in no wind.

The fact is that most of the R & D that has gone into monofoilers has been in the direction of the highest possible round the cans performance.
Very little R & D has been put into making an easy to sail foiler and there is tremendous potential in that avenue of development-both for monofoilers and multifoilers. Any analysis that projects the downside of some high performance
foilers onto an as yet non-existent Peoples Foiler is very shortsighted and does not take into consideration what has already been learned that can produce(and already has produced ,in some instances) dramatic improvements in boat handling, ease of launching, ease of non-foiling handling etc.
Designs that allow a fixed keel boat to only foil downwind,a dinghy that only foils downwind, designs that increase RM of fast monohulls, that partially foil upwind and downwind and designs that plane with foil assist are all areas where foil technology will be applied to sailing in a completely new way with very little in common with the high performance boats we've seen so far.

[Chris Ostlind]

One might consider that post as a crystal ball session and not connected to anything in the here and now, save for the, "I'd like it to be that way".

Liking it to be and truly being able to get it there, are two entirely different issues. One is connected to stuff on a wish list, conjured-up by a quick consult with the Magic 8Ball and the other is grounded in reality.

Selling vapor is a cool craft, if you can actually do it and not get run.

I tend to look at things as a series of objective projects that are realized from known needs and then the dreaming can enter into the equation. Known needs are generated by the demand associated with the target audience/buyers. Since there is little in the way of an audience at present, the thing winds-up being a large guessing game that costs a lot of money, no matter which direction you wish to pursue.

The threshold is in the fabrication of a concept, getting it through a trial period to hammer-out the wrinkles and then seeing if it actually has any merit with a target group of typical customers as they beat the crap out of it in the normal fashion of consumers.

OR... you can spend your dough doing sample groups and show them cool pictures along with detailed descriptions of how it all works. The more info presented, the better the response data. Shoving vague concepts and lists of numbers in front of target groups is the best way to have the whole tamale discarded as DOA. You want responses, you gotta tweak the sex center of the imagination. You know, like that old advertising adage of selling the sizzle rather than the steak.

Lastly... the conceptual, whatever it is, has to move the bar in increments from the last iteration and not great leaps and bounds, or you'll lose the biggest part of your audience by simply flying the thing over their heads and out the door.... which is where they will go if they can't truly relate.