Contact   Imprint   Advertising   Guidelines

Wing profile info for backyard hydrofoil builders

Here you can exchange your experience and datas about your home build boards
PrfctChaos
Medium Poster
Posts: 172
Joined: Fri Apr 27, 2018 6:16 am
Local Beach: Perth
Style: Wave
Gear: Peak4's, Chrono V3, Skimboards, foils
Brand Affiliation: None
Has thanked: 19 times
Been thanked: 40 times

Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Fri Oct 02, 2020 1:28 am

ericmsil wrote:
Thu Oct 01, 2020 3:24 pm
Hi PrfctChaos.


I'm trying to make my wing high A.R to wing. I was thinking about a 1.0 m wide wing with 16 cm of chord. That she could have a good head forward / good glide ratio after reaching her cruising speed I thought something between 10 km/h min. and 20 km / h max. I imagine using the shape of the image attached.

Which profile would be most suitable for this condition?


My weight is 90 kgs

Best regards

Eric
Absolutely. Just one note, it looks like that wings size is getting pretty small for lifting 90 Kg at 10 Km/hr (1000mm span, 160mm centre chord, working out at about 1250 cm^2 area). So I have run 2 scenarios. The one scenario shows the results for that wing size at 10-20 km/hr range (NACA7413). The second scenario shows results for slightly higher speed 12.5-22.5 km/hr, which results in profile selection with significantly less drag once up to cruising speed (S7075) (Around 2.7 Kg instead of 3.6 Kg). That s7075 would probably be the profile I would go for.

10-20 Km/hr (NACA7413 profile):
Capture.PNG
12.5-22.5 Km/hr (s7075 profile):
Capture2.PNG
That photo shown below is very close to a elliptical area distribution, see comparison below for elliptical shape. Looks very similar to me.
Capture3.PNG
Capture3.PNG (3.29 KiB) Viewed 416 times

fluidity
Frequent Poster
Posts: 278
Joined: Sat Mar 19, 2016 11:20 pm
Kiting since: 2015
Local Beach: Ngati Toa, Plimmerton, Titahi Bay, Waikanae, Petone, Seatoun, Lyall Bay, Eastbourne, Lake Wairarapa
Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Late model Switch kites element and nitros,
DIY CAD ultra-concave wave twintips 1500 and 130mm with my own fin designs. Easy upwind, awesome carving. Switch Nitro 10m V7, Naish 5.3m Wing. Now focussing on Wingsurfing to rise to a new challenge. Building my own foils from my CAD design and 3D prints, built a CNC machine last year and now cutting designs with CNC as well as 3D printing.
Location: Porirua New Zealand
Has thanked: 18 times
Been thanked: 17 times

Re: Wing profile info for backyard hydrofoil builders

Postby fluidity » Fri Oct 02, 2020 9:53 am

PrfctChaos wrote:
Thu Sep 24, 2020 11:09 pm
<cut>
Even with this fabrication technique, I thin it is possible to do it with any profile. When making the wood templates, one just needs to include a little stand on the trailing edge, to set the angle of attack, so that the template will stand on a flat surface with the correct AOA. Simple sketch below:
Capture3.PNG
PS: The other flat bottomed profiles, Aquela93, Clarky did not feature in the top 100 of the list of results. Neither did the wings that were cambered enough to stand by themselves on a flat surface.
That profile comes out well in your tests?
That pleasing if it does because I didn't use a NACA foil but I generated a very similar shape with some maths in the foils I've been building. Below is an under view from my 3D printing setup which shows a slightly thicker version but they are remarkably similar. I have it on PINSHAPE for anyone interested here: https://pinshape.com/items/93677-3d-pri ... -hydrofoil and I added a copy of the wing supersized to fit the OPENFUSE design I've been working on here: https://pinshape.com/items/102151-3d-pr ... elage-body There's some downward curve in the tips which caused me some grief in the thick profile getting my short CNC bit to clean material right down to bed level but after 6 consecutive evening supervising CNCing of a 1200mm x 330mm x 75mm block I removed it completed this evening. Not light like the EPS wings people are carving up but solid :D
They are easily flattened, stretched, shrunk etc in any CAD program. I'll likely mill a flatter one with less chord but the same wingspan out of a solid plank of wood next time.
Attachments
fluiditywing.PNG
Last edited by fluidity on Fri Oct 02, 2020 9:56 am, edited 1 time in total.
These users thanked the author fluidity for the post:
ericmsil (Sat Oct 03, 2020 2:42 pm)
Rating: 8.33%

fluidity
Frequent Poster
Posts: 278
Joined: Sat Mar 19, 2016 11:20 pm
Kiting since: 2015
Local Beach: Ngati Toa, Plimmerton, Titahi Bay, Waikanae, Petone, Seatoun, Lyall Bay, Eastbourne, Lake Wairarapa
Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Late model Switch kites element and nitros,
DIY CAD ultra-concave wave twintips 1500 and 130mm with my own fin designs. Easy upwind, awesome carving. Switch Nitro 10m V7, Naish 5.3m Wing. Now focussing on Wingsurfing to rise to a new challenge. Building my own foils from my CAD design and 3D prints, built a CNC machine last year and now cutting designs with CNC as well as 3D printing.
Location: Porirua New Zealand
Has thanked: 18 times
Been thanked: 17 times

Re: Wing profile info for backyard hydrofoil builders

Postby fluidity » Fri Oct 02, 2020 9:54 am

(doublepost)
Last edited by fluidity on Fri Oct 02, 2020 10:19 pm, edited 1 time in total.

ericmsil
Rare Poster
Posts: 36
Joined: Wed Jul 29, 2020 12:21 am
Kiting since: 2012
Local Beach: Brazil/Floripa
Gear: kitesurf,hydrofoil
Brand Affiliation: None
Has thanked: 36 times
Been thanked: 2 times

Re: Wing profile info for backyard hydrofoil builders

Postby ericmsil » Fri Oct 02, 2020 5:12 pm

PrfctChaos wrote:
Fri Oct 02, 2020 1:28 am
ericmsil wrote:
Thu Oct 01, 2020 3:24 pm
Hi PrfctChaos.


I'm trying to make my wing high A.R to wing. I was thinking about a 1.0 m wide wing with 16 cm of chord. That she could have a good head forward / good glide ratio after reaching her cruising speed I thought something between 10 km/h min. and 20 km / h max. I imagine using the shape of the image attached.

Which profile would be most suitable for this condition?


My weight is 90 kgs

Best regards

Eric
Absolutely. Just one note, it looks like that wings size is getting pretty small for lifting 90 Kg at 10 Km/hr (1000mm span, 160mm centre chord, working out at about 1250 cm^2 area). So I have run 2 scenarios. The one scenario shows the results for that wing size at 10-20 km/hr range (NACA7413). The second scenario shows results for slightly higher speed 12.5-22.5 km/hr, which results in profile selection with significantly less drag once up to cruising speed (S7075) (Around 2.7 Kg instead of 3.6 Kg). That s7075 would probably be the profile I would go for.

10-20 Km/hr (NACA7413 profile):
Capture.PNG

12.5-22.5 Km/hr (s7075 profile):
Capture2.PNG

That photo shown below is very close to a elliptical area distribution, see comparison below for elliptical shape. Looks very similar to me.

Capture3.PNG


Thanks a lot for the help.i will analyze your graphics calmly.

And as for the rear stabilizer, it certainly needs to be larger in size than conventional stabilizers. What about this profile of the rear stabilizer would you risk any profile? For this 1.0 x 0.16 m front wing? What would be the most favorable angle of attack for this mine to have a good reason for planning.? Thanks again.

Best regards

Eric

dirk8037
Rare Poster
Posts: 15
Joined: Wed Jan 29, 2014 10:57 am
Gear: 145 Underground, SP 19 DL, 13m Takoon Furia, 9/7 Waroo 2007
Brand Affiliation: None
Has thanked: 0
Been thanked: 3 times

Re: Wing profile info for backyard hydrofoil builders

Postby dirk8037 » Fri Oct 02, 2020 10:14 pm

Hi,
seeing the graphs first thing that shot through my mind was that it prooved what I read before, that plane surffaces on a wing are super ineffciant.I always wondered if that flat surf fins are just because fo the cheapness of shaper and industry ...anyway.
What stroke me, too, is how close the pther foils where together. I looks like more of a principle concept decision - 20% that make 80% of the performance.

Second is what about the lift.
Planning my self at the moment some big wing for some pumping through the winter down at the river, I would go with my speed estimates much lower than the 10 kmh. Also for wing foiling (step 2 in the 5Y Plan) I would rather have a second wing to cover the marginal are where staying up is work. It would be more 5km (mid to fast walking speed) up to maybe 20 with a good drag starting at 10-15.

Do I interprete the graphs right by saying that the the necessary angle of attack at lower speeds is the reason for the high drag, which is much higher than the fluid and surface induced drag by speed increase?

Also with that, maybe I have missed something out, I do not see the Drag to Speed relation but rather the lift to drag as more important, since i want to be as efficiant in the lower range. While pumping with teh least possibler Imput to fool arround as much as possible - same with winging since I think law mowing is better with other tools. Here the comparison of the Aquila against the others would be interesting, especially at low speeds.

Would be there a way to calculate the kg lift per wing size and angle of attack and from there choose a foil out of a data base of pre analysed foils. Like feeding the computer with letting him calculate and the make choice based on requirement.

PS I most likely will come from the other side.
Just received my cnc bits and will start to carve out of wood some different variations (cnc training), glass them, get wet and see what happens. All the same size 100cm x 30cm. Two weeks of vacation left with no where to go ......
These users thanked the author dirk8037 for the post:
ericmsil (Sat Oct 03, 2020 2:43 pm)
Rating: 8.33%

fluidity
Frequent Poster
Posts: 278
Joined: Sat Mar 19, 2016 11:20 pm
Kiting since: 2015
Local Beach: Ngati Toa, Plimmerton, Titahi Bay, Waikanae, Petone, Seatoun, Lyall Bay, Eastbourne, Lake Wairarapa
Favorite Beaches: Plimmerton
Style: Wave, jump
Gear: Late model Switch kites element and nitros,
DIY CAD ultra-concave wave twintips 1500 and 130mm with my own fin designs. Easy upwind, awesome carving. Switch Nitro 10m V7, Naish 5.3m Wing. Now focussing on Wingsurfing to rise to a new challenge. Building my own foils from my CAD design and 3D prints, built a CNC machine last year and now cutting designs with CNC as well as 3D printing.
Location: Porirua New Zealand
Has thanked: 18 times
Been thanked: 17 times

Re: Wing profile info for backyard hydrofoil builders

Postby fluidity » Sat Oct 03, 2020 8:55 pm

dirk8037 wrote:
Fri Oct 02, 2020 10:14 pm
Hi,
seeing the graphs first thing that shot through my mind was that it prooved what I read before, that plane surffaces on a wing are super ineffciant.I always wondered if that flat surf fins are just because fo the cheapness of shaper and industry ...anyway.
What stroke me, too, is how close the pther foils where together. I looks like more of a principle concept decision - 20% that make 80% of the performance.

Second is what about the lift.
Planning my self at the moment some big wing for some pumping through the winter down at the river, I would go with my speed estimates much lower than the 10 kmh. Also for wing foiling (step 2 in the 5Y Plan) I would rather have a second wing to cover the marginal are where staying up is work. It would be more 5km (mid to fast walking speed) up to maybe 20 with a good drag starting at 10-15.

Do I interprete the graphs right by saying that the the necessary angle of attack at lower speeds is the reason for the high drag, which is much higher than the fluid and surface induced drag by speed increase?

Also with that, maybe I have missed something out, I do not see the Drag to Speed relation but rather the lift to drag as more important, since i want to be as efficiant in the lower range. While pumping with teh least possibler Imput to fool arround as much as possible - same with winging since I think law mowing is better with other tools. Here the comparison of the Aquila against the others would be interesting, especially at low speeds.

Would be there a way to calculate the kg lift per wing size and angle of attack and from there choose a foil out of a data base of pre analysed foils. Like feeding the computer with letting him calculate and the make choice based on requirement.

PS I most likely will come from the other side.
Just received my cnc bits and will start to carve out of wood some different variations (cnc training), glass them, get wet and see what happens. All the same size 100cm x 30cm. Two weeks of vacation left with no where to go ......
Hi Dirk,
Seems I'm at a similar newbie CNC stage to you and working through understanding many of the same questions on wings too. Took my first CNC'd plywood laminated wing out of my CNC Friday, Sanded and filled the plywood yesterday morning and glassed the underside with 300gsm glass twill mid day, later I added fill epoxy for the weave, a uni carbon patch under the mast socket and surface tissue I can fill/ sand into later. The twill is horrid to drape around corners so I taped the edges around midnight at this morning removed the tape. Trickiest thing with the CNC on wood is that for a wing with any useful tip curvature you need either an extra long bit, or a bit wider than the chuck or design modifications to stop the chuck fouling on your piece as the bit is doing the lower cuts.
Regarding flat(plane) surfaces on wings, I think the key is more curve at the front. Look up Coanda effect, a rounded leading edge is better at maintaining flow cohesion at high angles of attack than a sharp leading edge. I think the problem for a sharp leading edge is that at high angles of attack the fluid around the leading edge has to very suddenly change direction and it's inertia resists which will create turbulence and flow separation just behind the top of the leading edge. Why this doesn't apply at climbing angles for the bottom of the leading edge I don't know though, this is where my intuition confuses me, I'm missing some information on how perhaps turbulence might occur UNDER the front of a leading edge if the bottom is sharp with only the top curved. For an aerobatic plane it's different, you need negative lift to fly effectively upside down with a negative angle of attack. I am making some assumptions for the above around differences in behavious of water being bused by an object(the wing) and "pulled" which is actually not a pull but a maintenance of pressure by air and water pressure abhoring a vacuuum. It would be nice to see a comprehensive explanation that applies to non compressible fluids.
Using estlcam for the CAM on my CNC
Graham

nemoz
Medium Poster
Posts: 94
Joined: Tue Sep 13, 2005 9:02 am
Has thanked: 2 times
Been thanked: 9 times

Re: Wing profile info for backyard hydrofoil builders

Postby nemoz » Sat Oct 03, 2020 10:20 pm

If someone need help with cad design or gcode I can help for free just pm me..
These users thanked the author nemoz for the post:
ericmsil (Sat Oct 03, 2020 11:12 pm)
Rating: 8.33%

PrfctChaos
Medium Poster
Posts: 172
Joined: Fri Apr 27, 2018 6:16 am
Local Beach: Perth
Style: Wave
Gear: Peak4's, Chrono V3, Skimboards, foils
Brand Affiliation: None
Has thanked: 19 times
Been thanked: 40 times

Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Sun Oct 04, 2020 3:34 am

ericmsil wrote:
Fri Oct 02, 2020 5:12 pm

And as for the rear stabilizer, it certainly needs to be larger in size than conventional stabilizers. What about this profile of the rear stabilizer would you risk any profile? For this 1.0 x 0.16 m front wing? What would be the most favorable angle of attack for this mine to have a good reason for planning.? Thanks again.
I have been meaning to set up a program to optimise stab selection as well, but haven't gotten around to it. Also not too sure how feasible it is, since so many more details will be needed (More of a chore than needed I think). I usually just choose a neutral profile, that works for the expected Angle of attack range and Reynolds numbers. Then set it up with a angle of around 2-3 degrees to the front wing. Then tune it over a few sessions with some light shimming or fuse length changes as needed.

Can definitely help with some thumbsuck level checks when it comes to selecting a profile for low drag and to work in the expected AOA range and Reynolds number range though. But as noted you might need to tune it a bit to your liking with shimming etc. See below:

I have assumed something around the same size as the Axis 460mm Stab would suit in this case, a nice fast stab that seems to be very popular. Span of 460 mm and chord of 61 mm. So covering a Reynolds number range of about 150000 - 250000 in this case.

Angle of attack:
For the 12.5-22.5 Km/hr (s7075 profile) front wing the expected angle of attack range is +7.5 degrees at 12.5 Km/hr and -0.5 degrees at 22.5 km/hr. So assuming stab to be inclined about 2.5 degrees down compared to main wing it needs to have low drag and work in angles of attack in the range of +5 to -3 degree range.

Neutral profiles are generally the NACA00XX series. The last 2 digits indicating thickness as a percentage of chord. Looking at the range of 5% (NACA0005) to 15% (NACA0015). The Drag doesn't change that much with 10-11% doing best at the lowest end of the speed range and the thinnest profile (NACA0005) getting better as speed increases and AOA decreases. However the 5% profile would likely be impractically thin, only 3mm thick at the max chord of 61mm, the other negative is that it is very close to stall at the low speeds (stalling at about 5 degrees. While the 10% thickness profile (NACA0010) has a much safer stall angle of 10 degrees at these speeds and a more practical thickness of 6mm at the 61mm chord. So I would very likely recommend the NACA0010 for a stab profile in this case. And then tuning the angle to suit.
These users thanked the author PrfctChaos for the post:
ericmsil (Sun Oct 04, 2020 6:00 pm)
Rating: 8.33%

PrfctChaos
Medium Poster
Posts: 172
Joined: Fri Apr 27, 2018 6:16 am
Local Beach: Perth
Style: Wave
Gear: Peak4's, Chrono V3, Skimboards, foils
Brand Affiliation: None
Has thanked: 19 times
Been thanked: 40 times

Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Sun Oct 04, 2020 3:58 am

dirk8037 wrote:
Fri Oct 02, 2020 10:14 pm
Hi,
seeing the graphs first thing that shot through my mind was that it prooved what I read before, that plane surffaces on a wing are super ineffciant.I always wondered if that flat surf fins are just because fo the cheapness of shaper and industry ...anyway.
What stroke me, too, is how close the pther foils where together. I looks like more of a principle concept decision - 20% that make 80% of the performance.

Second is what about the lift.
Planning my self at the moment some big wing for some pumping through the winter down at the river, I would go with my speed estimates much lower than the 10 kmh. Also for wing foiling (step 2 in the 5Y Plan) I would rather have a second wing to cover the marginal are where staying up is work. It would be more 5km (mid to fast walking speed) up to maybe 20 with a good drag starting at 10-15.

Do I interprete the graphs right by saying that the the necessary angle of attack at lower speeds is the reason for the high drag, which is much higher than the fluid and surface induced drag by speed increase?

Also with that, maybe I have missed something out, I do not see the Drag to Speed relation but rather the lift to drag as more important, since i want to be as efficiant in the lower range. While pumping with teh least possibler Imput to fool arround as much as possible - same with winging since I think law mowing is better with other tools. Here the comparison of the Aquila against the others would be interesting, especially at low speeds.

Would be there a way to calculate the kg lift per wing size and angle of attack and from there choose a foil out of a data base of pre analysed foils. Like feeding the computer with letting him calculate and the make choice based on requirement.

PS I most likely will come from the other side.
Just received my cnc bits and will start to carve out of wood some different variations (cnc training), glass them, get wet and see what happens. All the same size 100cm x 30cm. Two weeks of vacation left with no where to go ......
The reason why the results are close together is:
Firstly, I'm showing the top 3 results out of 2500 profiles, you can expect them to be close together. The lift to drag ratios for the selected s7075 profile is excellent, ranging from 68 to 106 over the speed range. I don't know what a "principle concept decision" decision is and I don't know what it means to "come from the other side", but I would be interested to see either of those methods getting L/D ratios that good.

Secondly. As I mentioned, the 1m x 160mm wing is on the small side for lifting 90 kG at the low speed of 10 or 12.5 km/hr. Most of the drag being shown (and thus largely forming the shape of the graph) is induced drag. It is not dependent on the profile selection, being proportional to the required lift and inversely proportional to speed squared as well as inversely proportional to wingspan squared. I have included the induced drag in the below graph for reference.

The only ways to reduce that component is to:
- Weigh less
- Increase speed
- Increase wing span
- Or start writing your PHD in wingtip design. Go work for Boeing, decrease their fuel usage by another 1% and retire a rich man.
Capture.PNG
PS, for going 0-5 Km/hr on the river: A 140l SUP will let you stand on the river the whole day at 0 Km/hr and have absolutely no drag. LOL

ericmsil
Rare Poster
Posts: 36
Joined: Wed Jul 29, 2020 12:21 am
Kiting since: 2012
Local Beach: Brazil/Floripa
Gear: kitesurf,hydrofoil
Brand Affiliation: None
Has thanked: 36 times
Been thanked: 2 times

Re: Wing profile info for backyard hydrofoil builders

Postby ericmsil » Mon Oct 12, 2020 5:23 pm

PrfctChaos wrote:
Sun Oct 04, 2020 3:34 am
ericmsil wrote:
Fri Oct 02, 2020 5:12 pm

And as for the rear stabilizer, it certainly needs to be larger in size than conventional stabilizers. What about this profile of the rear stabilizer would you risk any profile? For this 1.0 x 0.16 m front wing? What would be the most favorable angle of attack for this mine to have a good reason for planning.? Thanks again.
I have been meaning to set up a program to optimise stab selection as well, but haven't gotten around to it. Also not too sure how feasible it is, since so many more details will be needed (More of a chore than needed I think). I usually just choose a neutral profile, that works for the expected Angle of attack range and Reynolds numbers. Then set it up with a angle of around 2-3 degrees to the front wing. Then tune it over a few sessions with some light shimming or fuse length changes as needed.

Can definitely help with some thumbsuck level checks when it comes to selecting a profile for low drag and to work in the expected AOA range and Reynolds number range though. But as noted you might need to tune it a bit to your liking with shimming etc. See below:

I have assumed something around the same size as the Axis 460mm Stab would suit in this case, a nice fast stab that seems to be very popular. Span of 460 mm and chord of 61 mm. So covering a Reynolds number range of about 150000 - 250000 in this case.

Angle of attack:
For the 12.5-22.5 Km/hr (s7075 profile) front wing the expected angle of attack range is +7.5 degrees at 12.5 Km/hr and -0.5 degrees at 22.5 km/hr. So assuming stab to be inclined about 2.5 degrees down compared to main wing it needs to have low drag and work in angles of attack in the range of +5 to -3 degree range.

Neutral profiles are generally the NACA00XX series. The last 2 digits indicating thickness as a percentage of chord. Looking at the range of 5% (NACA0005) to 15% (NACA0015). The Drag doesn't change that much with 10-11% doing best at the lowest end of the speed range and the thinnest profile (NACA0005) getting better as speed increases and AOA decreases. However the 5% profile would likely be impractically thin, only 3mm thick at the max chord of 61mm, the other negative is that it is very close to stall at the low speeds (stalling at about 5 degrees. While the 10% thickness profile (NACA0010) has a much safer stall angle of 10 degrees at these speeds and a more practical thickness of 6mm at the 61mm chord. So I would very likely recommend the NACA0010 for a stab profile in this case. And then tuning the angle to suit.

hi


I'm modeling my wings for wing foil based on the airfoil profiles indicated by PrfctChaos in
in previous posts.


follow the pictures

the wingspan of the front wings was slightly more than 1.0 m and the chord around 0.24 m. I think I exaggerated a little.


the rear wing had a wingspan of 0.55 m and a chord of 0.095 m.

I used a little inclination on the tips of both wings so that wings could make the curves better I imagine.

I haven't finished modeling yet.


best regards

Eric
Attachments
Screenshot_6.jpg
Screenshot_6.jpg (74.67 KiB) Viewed 135 times
Screenshot_5.jpg
Screenshot_5.jpg (48.17 KiB) Viewed 135 times
Screenshot_4.jpg
Screenshot_3.jpg
Screenshot_3.jpg (45.23 KiB) Viewed 135 times
Screenshot_2.jpg
Screenshot_2.jpg (27.3 KiB) Viewed 135 times
Screenshot_1.jpg
Screenshot_1.jpg (60.1 KiB) Viewed 135 times


Return to “Gear Builders”

Who is online

Users browsing this forum: No registered users and 3 guests