Author Topic: Geezer Foil  (Read 5048 times)

PonoBill

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Geezer Foil
« on: June 25, 2016, 10:57:34 AM »
I fear I'll never have good enough balance for a single strut, short fuselage, kiting-style foil, but I want to fly, so I'm going to try to build a useful Geezer Foil. First try is going to be an anhedral, surface piercing foil on the nose of a board. I'm not going to worry right now about lifting the tail, though that's absolutely necessary in the long run. If I build this right the foils will be strongly self-righting, so steering with rail pressure is probably going to be pretty subtle unless I do something slick with the mounting system (like weight actuated flaps) I don't want to start with that kind of complexity, so the tail will probably be a lifting rudder.

If this stuff works I want to build the real gear out of carbon and push the lifting surfaces to the minimum size that works. But for now I'm going to make try#1 a little oversize, and I think the easiest way to make it is to weld and or rivet it up out of aluminum. Got to get my monstorusly heavy TIG welder out of the space under the home garage and get it up to the shop. It just about killed me getting it in there by myself, I'm gonna get three guys and few dogs to help me this time. I thought about getting the wing carved out of billet, but given the simple airfoil shape I don't think that's necessary. If nothing else I might get my TIG mojo back. It's been ten years since I fired that thing up to build Nero, my Airstream trailer.

I'm cutting templates today. My calculations show the wings should be ridiculously dinky, but I'm going bigger. I used to have a four foot piece of 12" diameter aluminum tubing, about 1/8" thick. I wish I still had it. It would be easy to make wings out of a section of that pipe--already curved. Press a little reflex into the trailing edge--or don't. Just weld a flat on the bottom and there you go--a primitive ogive wing that would probably work just fine.

If anyone else is contemplating a similar lunacy, I recommend Ray Vellinga's book: Hydrofoils--design. build. fly. I have six or seven hydrofoil books, but this one is the most useful by far.
« Last Edit: June 25, 2016, 11:05:13 AM 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.

cnski

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Re: Geezer Foil
« Reply #1 on: June 25, 2016, 01:05:32 PM »
Hey alright!! That is exciting! Can't wait to see what you come up with. Where do you plan on trying it out? Swell City to China Cove seems like a good place to start SUPfoiling. If things go well you could even go all the way down to the White Salmon sandbar. Getting to land would be easy that way. That's what I would do. It surely won't be pretty. And all the windsurfers won't be too impressed with some geezer flailing through the Hatch on some Frankenstein abomination SUP. But I'm pretty sure you don't, nor ever have been too concerned with people's thoughts toward yourself. And incorporating hotdogs is brilliant. I can't really think of any scenario that wouldn't benefit from a good Frank. The guys will probably want beer too you know.

PonoBill

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Re: Geezer Foil
« Reply #2 on: June 25, 2016, 02:23:37 PM »
Hey, if you're around, we need someone to push that TIG from behind. Steep little hill.

The folks at the hatchery are already tired of my misuse of the swells. Personally I think if you're going 90 degrees to the river flow, you can't bitch too much, but some do. Then again some guys yell at the barges. Fortunately there's enough turnover these days so the same folks rarely see me twice.

Didn't get anywhere today so far, mis-spent the morning opening 200 two-pack LiPo bags. My order for 400 batteries came in all these little bags. Bastards. I knew the price was too good to be true.

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.

PonoBill

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Re: Geezer Foil
« Reply #3 on: June 25, 2016, 03:14:30 PM »
I'm glad I didn't start cutting stuff. I spent some time recalculating foil sizes and I've convinced myself that small is good. I'm going to use a bridged wing with a flat center wing and reverse tapered dihedral legs. As the board rises the reverse taper makes the wing width decrease quickly, which should reduce drag and increase speed. Pretty pumped about this, it should be pretty easy to build and the connection to the board will be simple. The thin vertical struts serve a dual purpose, providing a fence to stop ventilation from reaching the middle foil. I might go straight to carbon, this thing should be an easy build--no complex curves, which I was dreading with the strut/foils I was envisioning.



It's a similar but simpler design to the Hydro-ped, a pedal driven hydrofoil craft.

« Last Edit: June 25, 2016, 03:22:24 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.

cnski

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Re: Geezer Foil
« Reply #4 on: June 25, 2016, 04:02:22 PM »
I can see now where you're headed. Has anyone tried foiling a SUP in the gorge yet this summer? I bet Dan G. or Mark R. will be on it soon. Talked to a friend today who said the wind hasn't been that great so far. Real interested to see how thing goes for you. Sounds like a quick build.

PonoBill

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Re: Geezer Foil
« Reply #5 on: June 25, 2016, 04:14:46 PM »
T.J. tried it about a week ago. Didn't go well. I bet it made for a long afternoon.  The wind was decent but not nukin'. I really can't see the kite foils working well in the Gorge. It ain't Maliko. A big, big wind might make it easy with a widebody as a sail, but I think it's gonna be iffy. We'll see. The same factor that makes the foil so fast--low drag--also make it pretty inefficient for taking power from a swell. Gravity still works, and if the drops are long enough it might be all you need, but other than Swell City and the Hatchery, the only place to get that kind of swell is out east. Might be the right gear for The Wall.
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.

PonoBill

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Re: Geezer Foil
« Reply #6 on: June 26, 2016, 02:23:03 PM »
I've looked at every SUP foil video I can find. I think I'm seeing ventilation down the strut that might get to the rear wing. The videos of Zane surfing got me looking for it. Could make it to the front one if it's close enough to the strut. I wonder if anyone puts a fence on their strut down close to the fuselage. I don't think it would do anything except block ventilation if it was done cleanly.
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.

Dwight (DW)

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Re: Geezer Foil
« Reply #7 on: June 26, 2016, 03:28:35 PM »
I've looked at every SUP foil video I can find. I think I'm seeing ventilation down the strut that might get to the rear wing. The videos of Zane surfing got me looking for it. Could make it to the front one if it's close enough to the strut. I wonder if anyone puts a fence on their strut down close to the fuselage. I don't think it would do anything except block ventilation if it was done cleanly.

Water flows up the strut and sprays out the back sometimes. Is that what you're seeing.

surfcowboy

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Re: Geezer Foil
« Reply #8 on: June 26, 2016, 04:03:57 PM »
Pono, i think there's a lot to be said for ease of construction. The cut pipe method sounds interesting.

I'm also watching to see who's going to give us the dimensions of a wing for CNC or 3D printing. (I'm even wondering if a foam cut would work, SUPuk, you wanna cut a few dozen out of a sheet of foam?)

Seems like there's a whole bunch of options out there. I am checking access to a CNC that would cut aluminum wings down here.

PonoBill

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Re: Geezer Foil
« Reply #9 on: June 26, 2016, 04:07:31 PM »
No, I'm seeing the foil appear to suddenly lose lift. I think air might be getting down to the foil.

I was just looking at my Big Kahuna board, thinking about sacrificing it for good strong parts when I remembered the mountain board I stripped the trucks and wheels off. It's perfect for the bridge piece. And the downward angled tips mean I can make simple extensions to get the right width and gain some height over water without making the foils super long. I'm liking this. I might try a super-quick experiment with just some L-shaped foils that would bolt to the bridge.



Cowboy--I'm looking around for a cheap aluminum tank. Probably the easiest way to get large diameter, thinwall aluminum.
« Last Edit: June 26, 2016, 04:25:24 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.

Dwight (DW)

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Re: Geezer Foil
« Reply #10 on: June 26, 2016, 06:53:17 PM »
When my foil loses lift, I fall straight down, smack hard. It happens in light wind when I'm milking it. Flying along and sail into wind hole, but keep it up in the air as long as possible, then it just can't hold me up any longer. It falls straight down and really smacks the water hard from 3 feet up. Mine falls perfectly straight. No tip stall. The forward swept wing helps I think



Here I'm on a 4.5m in only 15-16 mph wind and keeping it flying with no effort at all.
« Last Edit: June 26, 2016, 07:02:29 PM by DW »

PonoBill

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Re: Geezer Foil
« Reply #11 on: June 26, 2016, 08:28:13 PM »
Pretty cool. Look like you fly a lot lower than most of the kiters I see.

A lot of hydofoil systems have a surface-sensing arm that sticks out in the front or back that adjusts the angle of attack of the front foil to maintain the level. If you go high the angle of attack decreases to drop the foil lower. the primary tuning aspect is adjusting the gain of the sensing arm so the foil doesn't hunt.
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.

surfcowboy

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Re: Geezer Foil
« Reply #12 on: June 26, 2016, 08:51:21 PM »
Ok Pono, you just gave me an excuse to go hit the aerospace salvage spots down here. Post up the rough dimensions and I'll start poking around.

PonoBill

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Re: Geezer Foil
« Reply #13 on: June 26, 2016, 09:04:43 PM »
Ok Pono, you just gave me an excuse to go hit the aerospace salvage spots down here. Post up the rough dimensions and I'll start poking around.

I think minimum is 12" by a few feet--three might be enough. I marked up a 12" cardboard tube I have handy, just futzing around. You could make all kinds of wings out of just a few feet. reflex curves! Could be very cool. If it's really thin I'd just spot weld a flat bottom on and then glass it. If you wanted a more refined foil, like a Clark-Y, it would be pretty easy to do a little body hammer and dolly work, or roll it over a small diameter tube and weld the tube in for reinfocement of the leading edge. Not a sophsticated eppler-tyle foil, but it could be pretty good. I keep oscillating between carbon and welding something up. I have a talented lady coming in on monday to help me organize and clean out my shop. Talk about the labors of hercules. But one major element is dedicating the second section behind the wall with the car body on it to metal forming and welding. I have a laser cutter and a better CAM mill on the way--sooner or later. Kickstarter deals. This kind of project is why I wanted them in the first place. Of course being kickstarter means I might be eighty before I see them.
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.

surfcowboy

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Re: Geezer Foil
« Reply #14 on: June 26, 2016, 09:41:48 PM »
I'm taking a cutter class, when I can, my schedule is like yours.

I'll keep an eye out.

 


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