Contact   Imprint   Advertising   Guidelines

Do the wings even need to be aerofoil shaped?

A forum dedicated to Hydrofoil riders


Tone
Very Frequent Poster
Posts: 1921
Joined: Tue Dec 23, 2003 2:34 pm

Do the wings even need to be aerofoil shaped?

Postby Tone » Wed Jan 15, 2014 3:58 pm

In the process of designing a foil to build.

Does the front wing even need to be wind shaped (aerofoil section)?

Seen plenty of evidence that a flat sheet of carbon would work to a point.

Anyone care to comment?

Tony

ronnie
Very Frequent Poster
Posts: 3631
Joined: Sun Jul 24, 2005 6:39 pm

Re: Do the wings even need to be aerofoil shaped?

Postby ronnie » Wed Jan 15, 2014 4:08 pm


Bradn
Medium Poster
Posts: 115
Joined: Sun Jul 15, 2012 9:32 am
Kiting since: 0
Favorite Beaches: Pukehina
Shakespear
Samoa
Style: Race
Gear: Switch kites Nitro
Location: Tauranga, New Zealand

Re: Do the wings even need to be aerofoil shaped?

Postby Bradn » Wed Jan 15, 2014 7:29 pm

if you want to get a competitive foil - yes

User avatar
edt
Very Frequent Poster
Posts: 4201
Joined: Fri Jul 16, 2010 6:27 am
Kiting since: 2010
Local Beach: ford lake Michigan
Style: boots only
Gear: fuel envy wainman pansh naish jaime cwb

Re: Do the wings even need to be aerofoil shaped?

Postby edt » Wed Jan 15, 2014 8:12 pm

Tone not sure exactly what you mean by "Aerofoil", but there is a reason why all airplanes and boat propellers have the same shape.

Friction.

There is a huge amount of friction if you build a foil and you make it a square box.

Now there's no particular reason you have to make it exactly the same. Just like how there are some airplanes with two wings like the biplane or airplanes with the propeller in the back (pusher airplanes) swept wing aircraft, gliders with long wings but they all have in common an aerodynamic shape which lets air pass it without much friction.

You can't just cut a square plank and stick it in the water. make sure you round the edges, smooth out the joins, do stuff like that and you can find plenty of room to experiment.

does it have to look like a little airplane? No. Does it have to share the properties of an airplane such that it glides easily through the water? yes.

Arcsrule
Very Frequent Poster
Posts: 866
Joined: Wed Jun 12, 2002 1:00 am
Kiting since: 0
Brand Affiliation: None
Location: Florida--JACKSONVILLE
Contact:

Re: Do the wings even need to be aerofoil shaped?

Postby Arcsrule » Wed Jan 15, 2014 8:39 pm

the foil must generate lift. a doubt 'flat' will generate enough lift to make you smile. i'm not an engineer but i have slept in a Holiday Inn Express.

User avatar
edt
Very Frequent Poster
Posts: 4201
Joined: Fri Jul 16, 2010 6:27 am
Kiting since: 2010
Local Beach: ford lake Michigan
Style: boots only
Gear: fuel envy wainman pansh naish jaime cwb

Re: Do the wings even need to be aerofoil shaped?

Postby edt » Wed Jan 15, 2014 9:21 pm

Arcsrule wrote:the foil must generate lift. a doubt 'flat' will generate enough lift to make you smile. i'm not an engineer but i have slept in a Holiday Inn Express.


This is not true. Check out any angle of attack / lift coefficient diagram for instance here's one with a cesna and british jet

Image

Cl is about .3 at 0 for a cesna and actually there is no lift in a jet flying flat without any angle of attack. Yet it flies!

Angle of attack is the #1 reason that planes have lift and are able to fly. More angle of attack = higher lift coefficient = you climb up in the air.

Now the question remains why are airplane wings shaped like they are and the reason is drag. If you can get the plane to have a bit more lift with a lower angle of attack this means you will have less drag.

The purpose of the shape of an airplane wing is to reduce drag. Sure the camber creates a little lift but the main purpose is not to lift it into the air (angle of attack does that), it is mean to reduce drag and make the plane fly faster and more efficiently by allowing the plane to have a lower angle of attack than it would otherwise have for that Cl.

Hydrofoils are the same way. Water is a lot thicker than air, so it is very important to create shapes that don't have much drag.

Does it need camber? No of course not. Design your hydrofoil and don't be afraid to experiment. You don't need camber but pay attention to how much drag your shape is making.

Arcsrule
Very Frequent Poster
Posts: 866
Joined: Wed Jun 12, 2002 1:00 am
Kiting since: 0
Brand Affiliation: None
Location: Florida--JACKSONVILLE
Contact:

Re: Do the wings even need to be aerofoil shaped?

Postby Arcsrule » Wed Jan 15, 2014 9:24 pm

There you have it! Told you i'm not an engineer.

Tiago1973
Very Frequent Poster
Posts: 763
Joined: Mon Jun 28, 2010 6:58 pm
Kiting since: 2008
Local Beach: Portugal
Style: Freeriding
Brand Affiliation: None

Re: Do the wings even need to be aerofoil shaped?

Postby Tiago1973 » Wed Jan 15, 2014 9:31 pm

i wonder if in practical terms there is tons of a difference between a crude airfoil shape and a flat plate

Bradn
Medium Poster
Posts: 115
Joined: Sun Jul 15, 2012 9:32 am
Kiting since: 0
Favorite Beaches: Pukehina
Shakespear
Samoa
Style: Race
Gear: Switch kites Nitro
Location: Tauranga, New Zealand

Re: Do the wings even need to be aerofoil shaped?

Postby Bradn » Wed Jan 15, 2014 10:20 pm

Tiago1973 wrote:i wonder if in practical terms there is tons of a difference between a crude airfoil shape and a flat plate


I assume the difference is about 15kn difference in top end :lol:

User avatar
edt
Very Frequent Poster
Posts: 4201
Joined: Fri Jul 16, 2010 6:27 am
Kiting since: 2010
Local Beach: ford lake Michigan
Style: boots only
Gear: fuel envy wainman pansh naish jaime cwb

Re: Do the wings even need to be aerofoil shaped?

Postby edt » Wed Jan 15, 2014 10:43 pm

Tiago1973 wrote:i wonder if in practical terms there is tons of a difference between a crude airfoil shape and a flat plate


Not "tons". But enough that the only airplanes that have symmetric airfoils are supersonic airplanes and stunt planes. Then there are boat props, airplane props, helicopter propellers, some are symmetric some not, depending.


Return to “Hydrofoil”

Who is online

Users browsing this forum: No registered users and 1 guest