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Wing profile info for backyard hydrofoil builders

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windmaker
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Re: Wing profile info for backyard hydrofoil builders

Postby windmaker » Tue Oct 13, 2020 6:19 am

The new trend seems to be for the front wing to be more arched and the wing tips turned upwards. This apparently allows the wing to breach without loosing control.

ericmsil
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Re: Wing profile info for backyard hydrofoil builders

Postby ericmsil » Tue Oct 13, 2020 2:02 pm

windmaker wrote:
Tue Oct 13, 2020 6:19 am
The new trend seems to be for the front wing to be more arched and the wing tips turned upwards. This apparently allows the wing to breach without loosing control.
tks windmaker


in which brand did you see what you are saying for me to analyze?

best regards

Eric

windmaker
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Re: Wing profile info for backyard hydrofoil builders

Postby windmaker » Tue Oct 13, 2020 5:03 pm

ericmsil wrote:
Tue Oct 13, 2020 2:02 pm
windmaker wrote:
Tue Oct 13, 2020 6:19 am
The new trend seems to be for the front wing to be more arched and the wing tips turned upwards. This apparently allows the wing to breach without loosing control.
tks windmaker


in which brand did you see what you are saying for me to analyze?

best regards

Eric
F-One, Chubanga, Mike's lab etc

BTW when I said the tips turned upwards they are not actually facing upwards, I meant the tips of the wing turning back up, so they are rather horizontal in relation to the rest of the wing.
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ericmsil (Tue Oct 13, 2020 5:38 pm)
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ericmsil
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Re: Wing profile info for backyard hydrofoil builders

Postby ericmsil » Tue Oct 13, 2020 10:43 pm

windmaker wrote:
Tue Oct 13, 2020 5:03 pm
ericmsil wrote:
Tue Oct 13, 2020 2:02 pm
windmaker wrote:
Tue Oct 13, 2020 6:19 am
The new trend seems to be for the front wing to be more arched and the wing tips turned upwards. This apparently allows the wing to breach without loosing control.
tks windmaker


in which brand did you see what you are saying for me to analyze?

best regards

Eric
F-One, Chubanga, Mike's lab etc

BTW when I said the tips turned upwards they are not actually facing upwards, I meant the tips of the wing turning back up, so they are rather horizontal in relation to the rest of the wing.
hi windmaker


I redesigned the profile of the front wing and the rear wing as these indications

best regards

Eric
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PrfctChaos
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Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » 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

hyptocrypto
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Re: Wing profile info for backyard hydrofoil builders

Postby hyptocrypto » Wed Oct 14, 2020 4:41 am

Hi @PrfctChaos

I am designing a wing with a 965mm wingspan/216mm center chord/ 1340 sq-cm. The wing kinda scallops in creating a medium aspect near the center and high as you go further out (think cloud9 f-series kinda). I weigh about 90 kg's without any gear on, almost always use a wetsuit here on the Columbia river (fresh water) and in winter I use a drysuit. Looking to for a wing profile that's going to get my up on the wing-ding without too much trouble (maybe 8 - 10kmh) but also be glide effortlessly on the river swell here, top speed around 25-30 km/h. I am going to have to thicken the center chord to about 14% to get my fuselage connection to fit, but will taper back to 9-10 likely a few inches out.

I was going to use rg14 but want to make sure i am making a good choice for my specific needs.

I would be super appreciative if you could run the numbers for me sometime.

Thanks a million.

PrfctChaos
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Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Wed Oct 14, 2020 5:46 am

hyptocrypto wrote:
Wed Oct 14, 2020 4:41 am
Hi @PrfctChaos

I am designing a wing with a 965mm wingspan/216mm center chord/ 1340 sq-cm. The wing kinda scallops in creating a medium aspect near the center and high as you go further out (think cloud9 f-series kinda). I weigh about 90 kg's without any gear on, almost always use a wetsuit here on the Columbia river (fresh water) and in winter I use a drysuit. Looking to for a wing profile that's going to get my up on the wing-ding without too much trouble (maybe 8 - 10kmh) but also be glide effortlessly on the river swell here, top speed around 25-30 km/h. I am going to have to thicken the center chord to about 14% to get my fuselage connection to fit, but will taper back to 9-10 likely a few inches out.

I was going to use rg14 but want to make sure i am making a good choice for my specific needs.

I would be super appreciative if you could run the numbers for me sometime.

Thanks a million.
Hi hypto,

Looks like a good stats for a wing to me. The rg14 does pretty well in the calcs, but mh32 still makes another 6% or so improvement, so I would likely go for the mh32 option.

I have used your selected wingspan and area, that is used to calculate the "average" chord which is used for the calcs. Actual centre chord does not have a real influence.

Speed:
I think the low speed limit used in the calcs should not be interpreted very literally. It will be the limit during steady flight. But for starting other things like pumping or momentarily hanging off the wing / kite will play a bigger roll I think. Where a low drag wing can quickly accelerate up to speed and start flying. Just something to keep in mind.

Ran 2 sets of calcs, one for 10-30 km/hr and another for 12.5-30 km/hr.
I would ignore the 10-30 km/hr results, it is close to the limit of what that size wing can do and results in draggy fat wings.
Capture2.PNG
12.5-30 km/hr, starts to give better looking results, this is what I would use:
Capture.PNG
Table shows that the area of 1340 looks to be in the sweetspot for this combo. And what drag improvements can be expected with increased wingspan.
Capture3.PNG
Capture3.PNG (21.81 KiB) Viewed 257 times
Cheers

fluidity
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Re: Wing profile info for backyard hydrofoil builders

Postby fluidity » Wed Oct 14, 2020 10:57 am

windmaker wrote:
Tue Oct 13, 2020 5:03 pm
ericmsil wrote:
Tue Oct 13, 2020 2:02 pm
windmaker wrote:
Tue Oct 13, 2020 6:19 am
The new trend seems to be for the front wing to be more arched and the wing tips turned upwards. This apparently allows the wing to breach without loosing control.
tks windmaker


in which brand did you see what you are saying for me to analyze?

best regards

Eric
F-One, Chubanga, Mike's lab etc

BTW when I said the tips turned upwards they are not actually facing upwards, I meant the tips of the wing turning back up, so they are rather horizontal in relation to the rest of the wing.
I suppose it depends how far the breach is into the air if it makes much difference?
Lots of manufacturers put out false rationalisations to make their normal seem advantageous. Having recently started cutting CNC wings it's very obvious to me that cutting time on any machine with the lower cost CAM programs is going to be higher for wings with more top to bottom height and any continously machined single core block whether wood, PVC foam, EPS foam is going to be bigger volume and more expensive for a greater wing height. The same with moulds.
For riding, the downwards curve reduces tip height which is great in a heeled over turn. And for lift, the downward bent tips likely reduce spill off of water escaping sideways off the tips so they should improve lift especially at lower speeds. When I look at those modern curves I'm thinking it's a production cost saving measure. And for that to be useful, I like the other curvature, bowed up slightly around a third towards the tips and then curved back down. Again, it should reduce side spill and allow a bit more heeling over before breaching.
However all these theories are missing another element which I'm not up and riding yet properly to test: Steering forces and induced roll in turns. If you turn flat and stall not the wing but the mast then you are side slipping the wing and it's going to follow the rotation of any overall curve away from the horizontal plane. I imagine stalling the mast would aerate the wing and so you'll possibly come off the foil anyway and change angles for the next turn.

hyptocrypto
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Re: Wing profile info for backyard hydrofoil builders

Postby hyptocrypto » Wed Oct 14, 2020 3:51 pm

PrfctChaos wrote:
Wed Oct 14, 2020 5:46 am
hyptocrypto wrote:
Wed Oct 14, 2020 4:41 am
Hi @PrfctChaos

Hi hypto,

Looks like a good stats for a wing to me. The rg14 does pretty well in the calcs, but mh32 still makes another 6% or so improvement, so I would likely go for the mh32 option.

I have used your selected wingspan and area, that is used to calculate the "average" chord which is used for the calcs. Actual centre chord does not have a real influence.

Speed:
I think the low speed limit used in the calcs should not be interpreted very literally. It will be the limit during steady flight. But for starting other things like pumping or momentarily hanging off the wing / kite will play a bigger roll I think. Where a low drag wing can quickly accelerate up to speed and start flying. Just something to keep in mind.

Ran 2 sets of calcs, one for 10-30 km/hr and another for 12.5-30 km/hr.
I would ignore the 10-30 km/hr results, it is close to the limit of what that size wing can do and results in draggy fat wings.
Capture2.PNG

12.5-30 km/hr, starts to give better looking results, this is what I would use:
Capture.PNG

Table shows that the area of 1340 looks to be in the sweetspot for this combo. And what drag improvements can be expected with increased wingspan.
Capture3.PNG

Cheers
Thanks so much for running this so quickly, made that post before bed last night and first thing in the morning you have already responded.

I think 6% improvement is worth changing, good thing I checked I was going to machine the mold today. I notice you use the exact body weight in your model, do you think there is any merit in running the model with extra weight included (mast, fuse, board, wettie, leash etc?) I bet that adds quite a bit of extra lifting weight?

Thanks again.

PrfctChaos
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Re: Wing profile info for backyard hydrofoil builders

Postby PrfctChaos » Thu Oct 15, 2020 3:16 am

hyptocrypto wrote:
Wed Oct 14, 2020 3:51 pm
Thanks so much for running this so quickly, made that post before bed last night and first thing in the morning you have already responded.

I think 6% improvement is worth changing, good thing I checked I was going to machine the mold today. I notice you use the exact body weight in your model, do you think there is any merit in running the model with extra weight included (mast, fuse, board, wettie, leash etc?) I bet that adds quite a bit of extra lifting weight?

Thanks again.
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.


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