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Wing profile info for backyard hydrofoil builders

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salvatoreone
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Re: Wing profile info for backyard hydrofoil builders

Postby salvatoreone » Thu Oct 15, 2020 4:32 am

Hi PrfctChaos,

I'll be attempting to 3D print a front wing and then laminate it with fibreglass/epoxy. I've read the whole topic and I've done tons of other research over the past 2 days. (two days ago I've had literally zero idea about any of this but I'm making good progress, I'm really trying to understand the physics of the hydrofoil)

My question is if you could help me chose the profile assuming that:
- I want to ride the foil in marginally low wind for my Naish Boxer 10m which would probably be at around 8-12 knots (I'm talking wind speed)
- I'm around 85kg without the gear
- Saltwater use (also gets quite choppy, but obviously on calmer days it's not as bad)

The reason I'm not giving you the riding speed, chord and span is because I have no idea what would be optimal for these conditions. I guess something around 75cm span? But maybe you can propose something else. From what I noticed the light wind foils aspect ratio is on the lower side, this would also probably help with the stiffness of the wing (which I'm a bit worried about given manufacturing method).

I'd appreciate some help!

PS I just noticed you're the same person I messaged on the Seabreeze with that :lol:

hyptocrypto
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Re: Wing profile info for backyard hydrofoil builders

Postby hyptocrypto » Thu Oct 15, 2020 4:43 pm

PrfctChaos wrote:
Thu Oct 15, 2020 3:16 am
No worries mate.

Yea, after much thinking I've settled on using body weight and ignoring lifting up or pushing down effect of wing or kite, at least for winging and the type of underpowered freeriding I do. Yes maybe should start adding all the little bits such as board and wetsuits etc. The weight will be true when you have the wing just dragging behind or if kiting downwind with very depowered small kites. For powered kiting, holding the kite at a high angle would likely decrease load on the foil by a lot. On the other hand for a racer for example, the kite is held close to water and with lots of pull, so increasing weight on the foil.

I don't think it is a simple matter to get a definitive answer on, one would need to look at plenty of photos of yourself riding and measure out the angles to get a good idea of what sort of weight your riding style is adding or subtracting to the foil load. For me I enjoy riding downwind and underpowered so spend a lot of the time standing upright of the foil with kite well depowered. So have ended up just using bodyweight in the calc. In reality it probably varies up and down by a good % through a session, but difficult to define. Similarly to the speed range used in the calcs, I do not see it as absolute truth, but it is rather the range where I would like the foil to perform at its best.
[/quote]


Makes total sense, each discipline loads up differently, I don't think winging nearly as much as kiting but not nearly as little as prone either. Like you said if going upwind/downwind, reaching all have different dynamics of load. I guess trying computing all these dynamic forces is futile, sticking with your birthday suit weight makes the most sense. Looking forward to reporting back how my wing turns out.
Thanks again.

ericmsil
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Re: Wing profile info for backyard hydrofoil builders

Postby ericmsil » Thu Oct 15, 2020 6:09 pm

PrfctChaos wrote:
Tue Oct 13, 2020 11:46 pm
ericmsil wrote:
Tue Oct 13, 2020 10:43 pm
Eric
Hi Eric,

If you are increasing wingspan or chord by a lot, then let us know the final wingspan and chord size you settle on and I'll rerun the profile selection to check best option for that size.

The models are looking good. Are you planning on making the mast and fuse as well?

Cheers
HI PrfctChaos.

I increased the wingspan and the chord a little, but it was just because I was still taking the technique of modeling the profiles, but I will return to the initial size predicted. I intend to design the td set. But it's still at the beginning.

I do not want to give you trouble, but the wingspan was 1.20 and the chord 0.24 cm and the angle of attack of the front wing is 3 degrees and the rear wing is 0 degrees.The profiles used are those suggested by you for the front and rear wings.

Tks again.

Best regards

Eric

PrfctChaos
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Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Fri Oct 16, 2020 6:15 am

salvatoreone wrote:
Thu Oct 15, 2020 4:32 am
Hi PrfctChaos,

I'll be attempting to 3D print a front wing and then laminate it with fibreglass/epoxy. I've read the whole topic and I've done tons of other research over the past 2 days. (two days ago I've had literally zero idea about any of this but I'm making good progress, I'm really trying to understand the physics of the hydrofoil)

My question is if you could help me chose the profile assuming that:
- I want to ride the foil in marginally low wind for my Naish Boxer 10m which would probably be at around 8-12 knots (I'm talking wind speed)
- I'm around 85kg without the gear
- Saltwater use (also gets quite choppy, but obviously on calmer days it's not as bad)

The reason I'm not giving you the riding speed, chord and span is because I have no idea what would be optimal for these conditions. I guess something around 75cm span? But maybe you can propose something else. From what I noticed the light wind foils aspect ratio is on the lower side, this would also probably help with the stiffness of the wing (which I'm a bit worried about given manufacturing method).

I'd appreciate some help!

PS I just noticed you're the same person I messaged on the Seabreeze with that :lol:
Hi Salvatore,

Happy to help. 3D printing a wing is fun, but man does it take patience. If I was to do it again I would think about printing a mold instead of a core, because the mold parts will end up being flat, wide easy to print sections and wing section end up being tall and thin.

Anyways, I think 8-12 knots is still very much in the fun zone for kit foiling. So I've ran the calcs for a wing that is not huge (1045 cm^2) and has a wide fun range 12.5-35 km/hr. Wingspan 750mm as you mentioned. Winning profile is SG6041, which is not very thin (around 10% thickness) so should result in a strong enough wing. At the centre chord of 177mm it will mean maximum thickness of 17.7mm.
Capture.PNG
Capture2.PNG
Capture2.PNG (20.55 KiB) Viewed 365 times
Cheers
These users thanked the author PrfctChaos for the post:
salvatoreone (Sat Oct 17, 2020 9:49 am)
Rating: 8.33%

PrfctChaos
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Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Fri Oct 16, 2020 8:44 am

And also noticed that the areas of 1045 cm^2 and 1210 cm^2 came up tied in the results. So here are the results for 1210 cm^2 option. It needs a s2055 profile, that profile is a bit thinner (around 8% max thickness), so the longer centre chord of 205 mm and thinner profile sort of balance out and give max thickness of 16.4mm.
Capture3.PNG
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salvatoreone (Sat Oct 17, 2020 9:49 am)
Rating: 8.33%

PrfctChaos
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Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Fri Oct 16, 2020 9:22 am

ericmsil wrote:
Thu Oct 15, 2020 6:09 pm
PrfctChaos wrote:
Tue Oct 13, 2020 11:46 pm
ericmsil wrote:
Tue Oct 13, 2020 10:43 pm
Eric
Hi Eric,

If you are increasing wingspan or chord by a lot, then let us know the final wingspan and chord size you settle on and I'll rerun the profile selection to check best option for that size.

The models are looking good. Are you planning on making the mast and fuse as well?

Cheers
HI PrfctChaos.

I increased the wingspan and the chord a little, but it was just because I was still taking the technique of modeling the profiles, but I will return to the initial size predicted. I intend to design the td set. But it's still at the beginning.

I do not want to give you trouble, but the wingspan was 1.20 and the chord 0.24 cm and the angle of attack of the front wing is 3 degrees and the rear wing is 0 degrees.The profiles used are those suggested by you for the front and rear wings.

Tks again.

Best regards

Eric
Hi Eric,

Here are results for the new bigger size. It's got some size to it at 2260 cm^2 and still getting surprisingly low drag values. NACA2405 gets the best overall result, but NACA3505 also puts in a noteworthy result (With less drag at the start but more at the high end than NACA2405).
Capture.PNG

ericmsil
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Re: Wing profile info for backyard hydrofoil builders

Postby ericmsil » Fri Oct 16, 2020 6:17 pm

PrfctChaos wrote:
Fri Oct 16, 2020 9:22 am
ericmsil wrote:
Thu Oct 15, 2020 6:09 pm
PrfctChaos wrote:
Tue Oct 13, 2020 11:46 pm


Hi Eric,

If you are increasing wingspan or chord by a lot, then let us know the final wingspan and chord size you settle on and I'll rerun the profile selection to check best option for that size.

The models are looking good. Are you planning on making the mast and fuse as well?

Cheers
HI PrfctChaos.

I increased the wingspan and the chord a little, but it was just because I was still taking the technique of modeling the profiles, but I will return to the initial size predicted. I intend to design the td set. But it's still at the beginning.

I do not want to give you trouble, but the wingspan was 1.20 and the chord 0.24 cm and the angle of attack of the front wing is 3 degrees and the rear wing is 0 degrees.The profiles used are those suggested by you for the front and rear wings.

Tks again.

Best regards

Eric
Hi Eric,

Here are results for the new bigger size. It's got some size to it at 2260 cm^2 and still getting surprisingly low drag values. NACA2405 gets the best overall result, but NACA3505 also puts in a noteworthy result (With less drag at the start but more at the high end than NACA2405).

Capture.PNG
HI PrfctChaos

Thanks again. I just didn't understand why you changed the profiles? The previous profiles calculated by you were the s7075 for the front wing and the naca0015 for the rear wing.

I thought you would recalculate the foil with the new wingspan and chord but based on the original profiles mentioned.

I thank you again for your attention.

Best Regards

Eric

PrfctChaos
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Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Fri Oct 16, 2020 11:36 pm

ericmsil wrote:
Fri Oct 16, 2020 6:17 pm
PrfctChaos wrote:
Fri Oct 16, 2020 9:22 am
ericmsil wrote:
Thu Oct 15, 2020 6:09 pm


HI PrfctChaos.

I increased the wingspan and the chord a little, but it was just because I was still taking the technique of modeling the profiles, but I will return to the initial size predicted. I intend to design the td set. But it's still at the beginning.

I do not want to give you trouble, but the wingspan was 1.20 and the chord 0.24 cm and the angle of attack of the front wing is 3 degrees and the rear wing is 0 degrees.The profiles used are those suggested by you for the front and rear wings.

Tks again.

Best regards

Eric
Hi Eric,

Here are results for the new bigger size. It's got some size to it at 2260 cm^2 and still getting surprisingly low drag values. NACA2405 gets the best overall result, but NACA3505 also puts in a noteworthy result (With less drag at the start but more at the high end than NACA2405).

Capture.PNG
HI PrfctChaos

Thanks again. I just didn't understand why you changed the profiles? The previous profiles calculated by you were the s7075 for the front wing and the naca0015 for the rear wing.

I thought you would recalculate the foil with the new wingspan and chord but based on the original profiles mentioned.

I thank you again for your attention.

Best Regards

Eric
Hi Eric,

The profile changed because the wing size changed. It is a whole new case for a 1m span-1250 cm^2 wing versus a 1.2m span-2260 cm^2 wing.

I have shown the S7075 on the same graph for comparison. It has a similar drag profile to the NACA3505 result, but 7% worse. And 15% worse that the NACA2405.
Capture.PNG
Cheers
These users thanked the author PrfctChaos for the post:
ericmsil (Sat Oct 17, 2020 12:48 am)
Rating: 8.33%

ericmsil
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Posts: 36
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Re: Wing profile info for backyard hydrofoil builders

Postby ericmsil » Sat Oct 17, 2020 12:50 am

PrfctChaos wrote:
Fri Oct 16, 2020 11:36 pm
ericmsil wrote:
Fri Oct 16, 2020 6:17 pm
PrfctChaos wrote:
Fri Oct 16, 2020 9:22 am


Hi Eric,

Here are results for the new bigger size. It's got some size to it at 2260 cm^2 and still getting surprisingly low drag values. NACA2405 gets the best overall result, but NACA3505 also puts in a noteworthy result (With less drag at the start but more at the high end than NACA2405).

Capture.PNG
HI PrfctChaos

Thanks again. I just didn't understand why you changed the profiles? The previous profiles calculated by you were the s7075 for the front wing and the naca0015 for the rear wing.

I thought you would recalculate the foil with the new wingspan and chord but based on the original profiles mentioned.

I thank you again for your attention.

Best Regards

Eric
Hi Eric,

The profile changed because the wing size changed. It is a whole new case for a 1m span-1250 cm^2 wing versus a 1.2m span-2260 cm^2 wing.

I have shown the S7075 on the same graph for comparison. It has a similar drag profile to the NACA3505 result, but 7% worse. And 15% worse that the NACA2405.

Capture.PNG

Cheers

HI PrfctChaos
I thank you again for your attention, time and quick response. Thank you

Eric

salvatoreone
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Re: Wing profile info for backyard hydrofoil builders

Postby salvatoreone » Sat Oct 17, 2020 9:52 am

PrfctChaos wrote:
Fri Oct 16, 2020 6:15 am
salvatoreone wrote:
Thu Oct 15, 2020 4:32 am
Hi PrfctChaos,

I'll be attempting to 3D print a front wing and then laminate it with fibreglass/epoxy. I've read the whole topic and I've done tons of other research over the past 2 days. (two days ago I've had literally zero idea about any of this but I'm making good progress, I'm really trying to understand the physics of the hydrofoil)

My question is if you could help me chose the profile assuming that:
- I want to ride the foil in marginally low wind for my Naish Boxer 10m which would probably be at around 8-12 knots (I'm talking wind speed)
- I'm around 85kg without the gear
- Saltwater use (also gets quite choppy, but obviously on calmer days it's not as bad)

The reason I'm not giving you the riding speed, chord and span is because I have no idea what would be optimal for these conditions. I guess something around 75cm span? But maybe you can propose something else. From what I noticed the light wind foils aspect ratio is on the lower side, this would also probably help with the stiffness of the wing (which I'm a bit worried about given manufacturing method).

I'd appreciate some help!

PS I just noticed you're the same person I messaged on the Seabreeze with that :lol:
Hi Salvatore,

Happy to help. 3D printing a wing is fun, but man does it take patience. If I was to do it again I would think about printing a mold instead of a core, because the mold parts will end up being flat, wide easy to print sections and wing section end up being tall and thin.

Anyways, I think 8-12 knots is still very much in the fun zone for kit foiling. So I've ran the calcs for a wing that is not huge (1045 cm^2) and has a wide fun range 12.5-35 km/hr. Wingspan 750mm as you mentioned. Winning profile is SG6041, which is not very thin (around 10% thickness) so should result in a strong enough wing. At the centre chord of 177mm it will mean maximum thickness of 17.7mm.

Capture.PNG

Capture2.PNG

Cheers
Oh beautiful! Yeah, I think I'll go with the thicker option so SG6041. Is the front wing at 0° AoA relative to the fuselage? I know that stab is usually at negative 1-3° but I'm not sure about the front wing.

I was thinking about printing the mould but I'm a bit worried this will be more difficult to laminate than 3D printed foil. I think I'll go with the easiest way for my first foil but I already have some ideas I want to try out later such as making a mould for expanding foam which will later be laminated... I'm sure someone has already done it.


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