Author Topic: The ART 999 Thread  (Read 56943 times)

Wave Chaser

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Re: The ART 999 Thread
« Reply #150 on: December 12, 2021, 02:49:25 PM »
Actually, it rides sweet.  It's not trying to nose dive at all, and I don't feel like it needs more counter force.  I would lust like to, not sure how to say it, keep everything the same, but with higher nose attitude, if that makes sense.

I think I currently have what feels like a perfectly level ride.  What I want is to raise the nose 2 or 3 inches while keeping everything else the same.

I notice that many boards have zero tail rocker.  Fanatic boards have a bit of tail rocker.  Do any other boards have tail rocker?
Age:  61
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Axis HPS 830, Ultrashort fuse, P350 tail, 86cm carbon mast, 45l Axis Froth board

Dwight (DW)

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Re: The ART 999 Thread
« Reply #151 on: December 12, 2021, 03:51:14 PM »
The foil mounting face and deck are parallel on 99% of boards on the market. Rocker has nothing to do with it.

Riding nose low, is riding nose low, and you need to trim that out if you don’t like it. It can be trimmed out and still maintain foot pressure balance.

« Last Edit: December 12, 2021, 03:55:27 PM by Dwight (DW) »

jondrums

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Re: The ART 999 Thread
« Reply #152 on: December 12, 2021, 05:23:24 PM »
it sounds like you should get ahold of wizardhat shim kit
https://foilmount.com/products/trim-shim-stackable-hydrofoil-shimming-system

I've been happy to have the kit - it works really well.  People say that it shouldn't matter, but I found that it does matter quite a bit - if it is riding nose down I'd be willing to bet that it has an un-natural feel as it lifts off the water.  The foil has too much angle of attack versus the deck of your board, so it will jump up out of the water until you get the nose down.  The whole thing will work a ton better with some negative shim angle under the baseplate.

Keep in mind you'll need to slide the mount forward in the box a little bit when you negative shim the baseplate because it moves the center of effort backwards.  If you want to be exact, its mast length times cosine of shim angle - or 1.5cm per degree of shim on an 86cm mast.  Geek out much? yup.

PonoBill

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Re: The ART 999 Thread
« Reply #153 on: December 12, 2021, 07:51:41 PM »
The foil mounting face and deck are parallel on 99% of boards on the market. Rocker has nothing to do with it.

Riding nose low, is riding nose low, and you need to trim that out if you don’t like it. It can be trimmed out and still maintain foot pressure balance.

I must own most of the remaining 1%. Probably because I bought a few boards early on, but I have four boards with tail rocker, and one (my SIC Manta) that has a positively stupid amount of rocker. If the tail has rocker the deck won't be parallel with the tracks. This shot has three shim plates and the rear bolts are extra-long wizard hats. And it's still not parallel to the deck. Which is why I didn't mind cutting the thing up to put in a battery box.

Of course this is the exact opposite problem wavechaser is trying to fix. I'm not sure what the source of that issue is. Mu Flying Dutchman wing board is has a fairly flat tail that has tracks parallel to the deck. I don't do any tweaking with a 999 and any of the tails I own--just bolt it together and ride. the trim of the board seems perfect even though I'm a bit sloppy about where I put the mast. I don't use straps, so I generally have to move my feet a little to find the sweet spot for trim, but the 999 is so smooth and stable at speed with so little foot pressure to trim that shuffling around is easy.
« Last Edit: December 12, 2021, 08:01:36 PM by PonoBill »
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Wave Chaser

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Re: The ART 999 Thread
« Reply #154 on: December 15, 2021, 11:27:26 AM »
Dwight, jondrums, and Pono, thanks for the thoughts!  I'll just have to experiment with baseplate shim v. stabilizer shim to see if I can improve ride angle / comfort.  A couple things are driving this for me:

1.  My kite hydrofoil setup is perfect, so I know it's possible to get it dialed just right for me.  My Moses 633 had too much lift for my light weight at 64kg (older fuselage and mast), so a little stabilizer shim was all that was needed.  The ride angle and foot pressure balance ended up being just right. Sooo effortless to cruise and carve.

2.  A friend who is at the level of riding a sinker and jumping gave my setup a try.  He said the only problem with my setup is that, although it won't pearl when you are standing vertical and touch down, the nose will catch when you are carving hard, causing instant wipeout.  I am a long way from "carving hard", but still this is another reason to get it dialed.

Age:  61
5'9"
140lbs / 63kg
Axis HPS 830, Ultrashort fuse, P350 tail, 86cm carbon mast, 45l Axis Froth board

Dontsink

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Re: The ART 999 Thread
« Reply #155 on: December 15, 2021, 01:26:21 PM »
Foils ride nose low when they lack sufficient counter force. That’s why we have tail wings, to provide counter force. Otherwise we’d nose dive at speed.

It’s up to you the rider, to tune the foil appropriately, via tail wing size, shim, or fuselage length. All three affect counterforce.

The 999 being low drag, it’s easy to tune for a level ride throughout the speed range. Slower foils are more challenging to tune.

Not sure i understand this DW.
A given foil will have to be ridden at whatever angle it needs to hold you up straight and level.
Less speed,more angle.
More speed, less angle.

The tail only serves to make it more stable and we can optimize it (size,shape,wedge) to different speeds and feel.

IMHO if his foil&board combo is riding nose low at "cruise" speed it needs a mast plate shim,thick bit at the front.

jondrums

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Re: The ART 999 Thread
« Reply #156 on: December 15, 2021, 03:29:29 PM »
agreed completely dontsink

That said though - more tail angle will cause the nose to come up very very slightly (slightly more angle of attack at a given speed) because we need a little more lift to counteract the additional tail downforce.  But its gonna be a really small effect and doubtful if we'll be able to feel that.

JohnnyTsunami

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Re: The ART 999 Thread
« Reply #157 on: December 15, 2021, 03:53:18 PM »
I moved from a 420 rear to a 375p (never shimmed anything) on my 999 and I find that I need to move my mast a cm forward.

I only have a short fuse. Comes up about the same, or maybe slightly harder to get going. Turns are better for sure. I found myself touching down more, so maybe more pitch sensitive - but maybe that's the result of the mast too far back. I need another session to get used to it.

Hard to give a good review as I was in super difficult windy/chopy conditions at a new spot and I haven't winged in over a month due to my 9-5 and CA winter winds seemingly only coming up M-F.  :'(   Anyone have a spare room in Maui?

Wave Chaser

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Re: The ART 999 Thread
« Reply #158 on: December 18, 2021, 09:20:10 AM »
In thinking about this further, getting a board with some tail rocker to try and solve my problem (which isn't really a problem, rather just a comfort preference), is a bad idea.  Tail rocker would increase surface drag and make lift off a lot harder.  Plus the angle of attack on the hydrofoil would be changed and would push the nose down while on the surface, also creating more drag.  My guess is that ideally you want lift to be parallel to the surface of the water to aid surface speed, especially for a high aspect foil like the 999.  Shimming the mast base would do the same thing (down force while on the surface) so I think this is not a great idea also.

So it seems like Dwight's idea of shimming the tail wing is the best way for me to go, especially if I can do so without creating a situation where lift increases with increased speed.  One of the great things about the 999 is that I don't have to shift my weight forward to counteract lift as speed increases.  Wouldn't want to mess that up.  A little bit of tail shim could also have the benefit of increasing turning speed (carved turns)?

Another idea would be to get a board with enough nose rocker so that my front foot would be elevated an inch or two above parallel, but of course with flat rocker all the way out the back.  Some kite hydrofoil boards have this.  This would add surface drag compared to flat between the feet, but would it be noticeable at, say, above 5 mph on the surface?
Age:  61
5'9"
140lbs / 63kg
Axis HPS 830, Ultrashort fuse, P350 tail, 86cm carbon mast, 45l Axis Froth board

jondrums

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Re: The ART 999 Thread
« Reply #159 on: December 18, 2021, 03:34:03 PM »
4 different adjustments all do different things

#1 figure out where you want your foot position - this should be based on how the board floats and takes off on a wave
#2 decide on the tail angle - generally this will set up your ideal turning radius, more angle for tighter turns.  Also more angle gives you a more low end grunt for pumping.  Less angle has less drag but doesn't turn as tightly.
#3 move the foil fore/aft to balance the forces on your feet
#4 optional: baseplate shim if the board is riding nose up or nose down


headmount

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Re: The ART 999 Thread
« Reply #160 on: December 21, 2021, 08:23:52 PM »
4 different adjustments all do different things

#1 figure out where you want your foot position - this should be based on how the board floats and takes off on a wave
#2 decide on the tail angle - generally this will set up your ideal turning radius, more angle for tighter turns.  Also more angle gives you a more low end grunt for pumping.  Less angle has less drag but doesn't turn as tightly.
#3 move the foil fore/aft to balance the forces on your feet
#4 optional: baseplate shim if the board is riding nose up or nose down
More angle, meaning raising front or back screw on the tail?  Or to put it another way, leading edge angled more up or leading edge angled more down.

jondrums

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Re: The ART 999 Thread
« Reply #161 on: December 21, 2021, 08:36:09 PM »
#2 decide on the tail angle - generally this will set up your ideal turning radius, more angle for tighter turns.  Also more angle gives you a more low end grunt for pumping.  Less angle has less drag but doesn't turn as tightly.
More angle, meaning raising front or back screw on the tail?  Or to put it another way, leading edge angled more up or leading edge angled more down.

more angle means more downforce with the tail, trailing edge raised, leading edge lowered. 

headmount

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Re: The ART 999 Thread
« Reply #162 on: December 21, 2021, 09:06:28 PM »
#2 decide on the tail angle - generally this will set up your ideal turning radius, more angle for tighter turns.  Also more angle gives you a more low end grunt for pumping.  Less angle has less drag but doesn't turn as tightly.
More angle, meaning raising front or back screw on the tail?  Or to put it another way, leading edge angled more up or leading edge angled more down.

more angle means more downforce with the tail, trailing edge raised, leading edge lowered.
Thanks.  That's much clearer

VB_Foil

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Re: The ART 999 Thread
« Reply #163 on: December 22, 2021, 05:04:27 AM »
Great advice Jondrums.

I like to make the analogy for tail wings like this: Imagine a paper airplane with the little tail flaps. If you put them up, the plane will maintain a more stable, slower flight (unless you really throw it hard (backflip)). If you put the tail flaps neutral, the wing will be faster, less predictable, and make it to the ground sooner.

Makes sense if you imagine a plain trying to make a banking turn with tail flaps down/neutral versus tail flaps up. The tail flaps up will allow a tighter and lower speed banking turn with less likelihood of stalling.
I’m a 5’9” 65kg rider:

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PonoBill

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Re: The ART 999 Thread
« Reply #164 on: December 22, 2021, 10:42:41 AM »
At the risk of being tedious, in simple turns, airplanes actually turn with their elevators and ailerons, which translate into bodyweight banking and tail angle for hydrofoils. People think airplanes turn with their rudder, but that's two-dimensional thinking. Rudder only turns mostly slip (skid) though there are some techniques in both design and flying controls to make the rudder useful. To turn an airplane you rotate it with the ailerons (bank) and then use the elevator to turn. The tightness of the turn is a function of mostly the banking angle and to a lesser degree how much elevator you crank in. If the airplane is at a 45-degree bank angle half the force applied by the up elevator turns the airplane and half lifts the nose. If the airplane is banked at 90 degrees, all the elevator force goes to turn the airplane.

This is relevant to us because one of the reasons it's hard to learn to turn a foil sharply is how complex the turning forces are and how limited our control options are. We can learn to turn by applying a rotating force between our front and back legs, but this is a skid. We can just bank, but this only applies as much turning force as the fixed rear wing position applies. The people who are making beautiful banked turns on wave faces are delicately modulating the bias in foot pressure front to back and well as rotating and banking, all at just the right proportions to not fall off to the inside, stall, nosedive, or any of the myriad other ways I've found to crash. The shorter, lighter, more flexible, and better balanced you are, the easier this all is. Experience helps, but it's unlikely to overcome a pile of limitations.

In other words, small, light, young people with lots of water or snowboarding experience rock at this. And I'm fucked. It's a good thing it's still fun.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

 


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