Contact   Imprint   Advertising   Guidelines

Rear foil. surface area? airfoil or symetrical? dihedral ?

A forum dedicated to Hydrofoil riders
tahoedirk
Frequent Poster
Posts: 219
Joined: Sun Aug 31, 2014 5:02 pm
Local Beach: Kings beach, CA
Favorite Beaches: All clean beaches
Style: out of control
Gear: Homemade gear
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Rear foil. surface area? airfoil or symetrical? dihedral ?

Postby tahoedirk » Wed Sep 17, 2014 3:48 am

What do you guys think about the rear foil. I done some refinements on all my other parts so now I want to improve my rear stablizer/foil. So far I've been using a foiled airplane stab 1/2 size facing down.

I'm looking for opinions and experiences, I know there is no one correct answer. It all seems to work.

Surface area: 1/2 to 1/3 relative to the front foil? Probably related to the distance from LE to LE?
Airfoil: Lift facing down? or symetrical? does it matter?
Anhedral , dihedral , flat , flip tips ?

Thanks for your thoughts, Dirk

User avatar
Hawaiis
Very Frequent Poster
Posts: 1375
Joined: Wed Aug 24, 2011 11:39 am
Local Beach: Kailua
Brand Affiliation: None
Has thanked: 10 times
Been thanked: 2 times

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby Hawaiis » Wed Sep 17, 2014 6:20 am

I like to have the rear wing 1/3 the surface area of the front wing.
24" fuselage length
If the front wing has anhedral, then the rear should have diehedral to avoid turbulence.
I like both wings to have zero lift, only use angle of attack for lift.

revhed
Very Frequent Poster
Posts: 1373
Joined: Sun Feb 24, 2008 6:15 pm
Local Beach: france
Gear: kites
Location: France
Has thanked: 106 times
Been thanked: 34 times

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby revhed » Wed Sep 17, 2014 9:20 am

Hi,
dsc_1512.jpg
dsc_1512.jpg (50.79 KiB) Viewed 2856 times
I had the nice chance to test the flat r wing with vert fin and then the tips angled up right after, no doubt the latter is better .
stabilo-freeride.jpg
stabilo-freeride.jpg (32.7 KiB) Viewed 2856 times
I firmly think that f wings need at least some anhedral, either wing tips angled down or curved down.
Also seems that the foil r wing just flys better if it is opposite of the front including the profile.
I will agreee with H in that I fly 0° a o a front and back but I let a super experienced guy tune my foil and it flies better now with about 1.5° negitive r wing A O A.
I have made F wings that are almost flat on the bottom and r wings that are almost flat on the top.
This will work for learning and slower speeds for sure and much easyer to make.

A very basic curved f AND r wing male mold for carbon and,or f glass layups with , or without vac sac.
The curve measures 5cm vert, at the center, for 50 cm wide ,horizontal.
I have made on of my favorite Low A R wings on this.
And note that the front wing is mounted as seen curve down BUT the r wing is mounted 180° to have curve up.
Then after plan form has been cut out, one could add uni to get profile and fine tune with micoballon epoxy.
R H
PC060013.JPG

User avatar
vvs
Rare Poster
Posts: 40
Joined: Thu Jan 16, 2014 9:28 am
Gear: flysurfer, best, slingshot
Brand Affiliation: None
Location: Ukraine
Has thanked: 0
Been thanked: 0

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby vvs » Wed Sep 17, 2014 10:03 am

information about the installation of angles of the rear wing
if there is a possibility to disconnect the keel, it is possible to conduct a simple and accurate test. We need to take a fuselage with wings set, dive under the water and push forward. Carefully look at the character of the movement. Foil should move smoothly, slightly going down. Then flip the foil back up and repeat the test. Movement should be similar. If the second test foil moves upward, then need to add the adjusting element on the rear edge of the rear wing. If the second test foil moves strongly down, then add the adjusting member under the front edge of the stabilizer. These simple tests allow one to accurately set the rear fender.

Tone
Very Frequent Poster
Posts: 2291
Joined: Tue Dec 23, 2003 2:34 pm
Has thanked: 5 times
Been thanked: 29 times

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby Tone » Wed Sep 17, 2014 1:27 pm

revhed wrote:Hi,
dsc_1512.jpg
I had the nice chance to test the flat r wing with vert fin and then the tips angled up right after, no doubt the latter is better .
stabilo-freeride.jpg
I firmly think that f wings need at least some anhedral, either wing tips angled down or curved down.
Also seems that the foil r wing just flys better if it is opposite of the front including the profile.
I will agreee with H in that I fly 0° a o a front and back but I let a super experienced guy tune my foil and it flies better now with about 1.5° negitive r wing A O A.
I have made F wings that are almost flat on the bottom and r wings that are almost flat on the top.
This will work for learning and slower speeds for sure and much easyer to make.

A very basic curved f AND r wing male mold for carbon and,or f glass layups with , or without vac sac.
The curve measures 5cm vert, at the center, for 50 cm wide ,horizontal.
I have made on of my favorite Low A R wings on this.
And note that the front wing is mounted as seen curve down BUT the r wing is mounted 180° to have curve up.
Then after plan form has been cut out, one could add uni to get profile and fine tune with micoballon epoxy.
R H
PC060013.JPG
Great photos and explanation Revhead.

How many layers of carbon are you using to create a wing that is strong enough from your former?

Thanks

Tony

tahoedirk
Frequent Poster
Posts: 219
Joined: Sun Aug 31, 2014 5:02 pm
Local Beach: Kings beach, CA
Favorite Beaches: All clean beaches
Style: out of control
Gear: Homemade gear
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby tahoedirk » Wed Sep 17, 2014 3:24 pm

Great informative responses , thanks.

Yeah how many layers? how thick?

I have a new front foil design that is very thin, 5mm at the moment , I was going to thicken it up to around 6 or 7 ,it is a very accurate foil, is there any reason to go thicker? I am getting 1mm per 2 layers of 20 oz cloth.

I was thinking about going symetrical so I could flip it over and try both up and down.

tahoedirk
Frequent Poster
Posts: 219
Joined: Sun Aug 31, 2014 5:02 pm
Local Beach: Kings beach, CA
Favorite Beaches: All clean beaches
Style: out of control
Gear: Homemade gear
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby tahoedirk » Wed Sep 17, 2014 3:28 pm

Oh yeah, do any of you guys have a cool jig or method of measuring AOA on your foils?

tahoedirk
Frequent Poster
Posts: 219
Joined: Sun Aug 31, 2014 5:02 pm
Local Beach: Kings beach, CA
Favorite Beaches: All clean beaches
Style: out of control
Gear: Homemade gear
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby tahoedirk » Sun Sep 21, 2014 3:47 am

Please , info on how you measure AOA on your foils. New pics coming soon . I'm in the laboratory with my head down . New fuse, foil and stab this week!

User avatar
vvs
Rare Poster
Posts: 40
Joined: Thu Jan 16, 2014 9:28 am
Gear: flysurfer, best, slingshot
Brand Affiliation: None
Location: Ukraine
Has thanked: 0
Been thanked: 0

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby vvs » Sun Sep 21, 2014 5:03 am

during the steady movement of the front wing AOA will always be such as is necessary). It will only will determine how to the board will be located (nose up or down). AOA rear wing is very important. But the weight of the rider may prevail over the forces which create wings and could theoretically fly any foil, but his movement will not be a simple and optimal. . If possible, do a test about which I wrote above, and you'll get the desired AOA rear wing.

tahoedirk
Frequent Poster
Posts: 219
Joined: Sun Aug 31, 2014 5:02 pm
Local Beach: Kings beach, CA
Favorite Beaches: All clean beaches
Style: out of control
Gear: Homemade gear
Brand Affiliation: None
Has thanked: 0
Been thanked: 1 time

Re: Rear foil. surface area? airfoil or symetrical? dihedra

Postby tahoedirk » Sun Sep 21, 2014 3:59 pm

The test you suggested is brilliant , but my fuselage is not detachable. The AOA I want to fine tune and consistently monitor is the relative angles of front and rear foils. Thanks


Return to “Hydrofoil”

Who is online

Users browsing this forum: cglazier, Peter_Frank and 71 guests