Home Grown Laser Hydrofoils

Thread starter #1
After 3 years of nights and weekends researching and designing hydrofoils, learning how to hot wire foam, make mold plugs, make molds from said plugs, learning how to do resin infusion, creating hinges and control mechanisms, and lots of sanding, my carbon fiber hydrofoils for my Laser lifted off for the first time!
 

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#2
Really impressive Kevin! Is that a 'magic wand' like control system sensor hanging from the bowsprit? Can you tell a little bit about the control system you are using?
I would love to see a movie clip of your boat taking off.
 
Thread starter #3
Yes, that’s a wand connected via teleflex to the main foil, actuating the flap on the back of the foil.

I’ll post video as soon as I get some. I had two people with cameras shooting away for a while to get those shots. Gonna try to borrow a GoPro or something with good image stabilization for the next time. I’m shooting for Tuesday or Wednesday here, since that’s the next time the wind is forecast to get to 11-12 knots. It’ll definitely fly in 12 knots, but since I’m 225 lbs, 11 knots is hit or miss depending on how long the gust lasts.
 
Thread starter #4
After 3 years of nights and weekends researching and designing hydrofoils, learning how to hot wire foam, make mold plugs, make molds from said plugs, learning how to do resin infusion, creating hinges and control mechanisms, and lots of sanding, my carbon fiber hydrofoils for my Laser lifted off for the first time!

I forgot to mention that the flap on the rudder foil is actuated by twisting the tiller extension. Apparently this is how they do it on the Moth these days, which is where the idea comes from. I couldn’t find any pictures or detailed descriptions of the way they do the twist mechanism on the Moth, so I did some Disney engineering with a 90 degree drill attachment, some 1/4 inch stainless steel tubing, and some 8mm acme threaded rod from a 3D printer rebuild kit.

It works ok. Not great, but well enough to do the job.
 

67713

New Member
#5
Yes, that’s a wand connected via teleflex to the main foil, actuating the flap on the back of the foil.

I’ll post video as soon as I get some. I had two people with cameras shooting away for a while to get those shots. Gonna try to borrow a GoPro or something with good image stabilization for the next time. I’m shooting for Tuesday or Wednesday here, since that’s the next time the wind is forecast to get to 11-12 knots. It’ll definitely fly in 12 knots, but since I’m 225 lbs, 11 knots is hit or miss depending on how long the gust lasts.
 

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Thread starter #7
Young man... Thank you! I like that! I’m so flattered!

I started this project at the tender age of 53, and finished it at 56.

As soon as I get footage it will be on here. I’m going to the Yacht Club now, so I’ll try to get some video of rigging it up. Maybe someone can shoot me out in the water. We’ll see.
 
#8
I was wondering if you performed CFD simulations in designing the foils? Your foils seem to have a higher aspect ratio than the commercial ones.
I was also wondering how the load of the hydrofoil is transferred to the hull.
This is such a fascinating project!
 
Thread starter #9
I was wondering if you performed CFD simulations in designing the foils? Your foils seem to have a higher aspect ratio than the commercial ones.
I was also wondering how the load of the hydrofoil is transferred to the hull.
This is such a fascinating project!

I did not do any CFD simulations on the hydrofoils. I kinda figured that had been done already by more knowledgeable people than I. I’m not saying that I couldn’t have taught myself enough to competently do so. I just figured the ROI would be minimal compared to what others have already accomplished.

That being said, I choose an airfoil section published by Tom Speer, it having been shown to produce a little more lift per drag at low speeds, and an airfoil for the verticals from the online database of NACA airfoils that has been widely used for daggerboards/keels/etc.

I tried to keep the aspect ratio roughly the same as Moths and what the other hydrofoils for Lasers are. See the accompanying photo of Moth daggerboard foil.

I’ve also attached a photo of the daggerboard, looking up at the attachment that fits into the Laser daggerboard opening in the bottom of the hull. This piece has a flange that distributes the load to the daggerboard trunk directly. This is the one place where the two halves of the hull meet in the center of the hull that is also reinforced to take a lot of load, and it's also where almost every other foiling dingy transfers the load. I figured when in Rome.
 

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Daiv

New Member
#10
I'm not likely to build one of these any time soon....
but
I'd love to know the details of your process and what do you plan next?
Wings perhaps...
Maybe you've created a new class, "Flying Lasers"
 
Thread starter #11
I'm not likely to build one of these any time soon....
but
I'd love to know the details of your process and what do you plan next?
Wings perhaps...
Maybe you've created a new class, "Flying Lasers"
Version 2 is next, based on what I’ve learned so far. For example, the cord of the daggerboard and rudder, while similar to foils on the Moth, is too little for the Laser and the sideslip is noticeable. I’ll probably try to reduce the thickness of the foils and improve their overall profile since I can now print a plug with a 3D printer to pull the molds from.

Essentially the process is pretty standard: create a full size model of the foil and use it as a plug to pull a female mold from (top half and bottom half, right side and left side, plus top and bottom of the vertical foil), use the molds in a vacuum bagging, resin infusion process, having laid the carbon fiber layers beforehand, pull the molded foils out of the molds, trim and sand, then glue the halves together (having glued in a tube for the control rod in the vertical), cut the flap off, cut a indent in the flap and glue in a sliding barrel nut, attach the horizontal to the vertical with multiple carbon layers on the outside of the T-joint and sand to blend, attach the flap to the foil using the same stuff the Moth guys use (I forget the name but it’s curable rubber seal in a tube), run the control rod down the tube and screw into the barrel but, add rocker arm with quick connect to the top and attach to the control arm, create and attach to vertical the insert for the Laser daggerboard trunk on the bottom of the boat, drill into vertical holes and glue in vertical threaded rods to bolt to top insert for the Laser daggerboard, and your done with the daggerboard. The rudder is roughly the same. The controls that attach to the rudder and daggerboard are essentially the same as on a Moth.

Teaching yourself hot-wire foam cutting, how to make molds, how to do vacuum bagging resin infusion, and how to make control mechanisms, not to mention enough design and theory knowledge of hydrofoils to believe you might know what you’re doing was the hard part.

Unless I can successfully make foils that function for the Laser at all points of sail, I doubt there’d ever be a reason to contemplate even racing 2 of them, much less start a class, but of course you were kidding.
 
Thread starter #12
Ok. I don’t get it. Can’t upload an mp4 file. Sorry folks. No video. I converted to something else but it still wants to upload as an mp4.
 

Wavedancer

Upside down?
Staff member
#15
Yes, impressive undertaking!
How do your foils compare to the (commercially available) Glide Free ones?
I have never had a chance to try foiling, but have read that the Glide Free version only allows foiling on reaches, preferably on a Radial (I don't understand why that is).
 
Thread starter #17
Yes, impressive undertaking!
How do your foils compare to the (commercially available) Glide Free ones?
I have never had a chance to try foiling, but have read that the Glide Free version only allows foiling on reaches, preferably on a Radial (I don't understand why that is).
So far I can’t claim any better, and I’m still trying to get the hang of weight balance vs rudder foil trim. I don’t get to make long runs on my lake. The winds aren’t what you’d call steady, puffs and 20 degree shifts being the norm. I’m lucky to get a 30 second run in before having to tack or losing the wind and setting down again.

In reality I think I’ll need to take my boat to a more steady environment sometime in the fall when the wind is good on the Chesapeake Bay to be able to more accurately judge Judy what these foils can do reliably.

Right now, though, I’m just having a blast taking flight 30 seconds at a time!!
 
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