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Collaborating Ideas - Long distance board

here you can exchange your experience and datas about your home build boards


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ChristoffM
Medium Poster
Posts: 196
Joined: Tue Jul 19, 2011 5:26 pm
Kiting since: 2005
Local Beach: Langebaan and Cape Town.
Favorite Beaches: Anywhere in the Cape, South Africa.
Style: Hydrofoils! (And surf and old school)
Gear: Cape Town Foilboard and Spotz hydrofoils.
Any kite that can keep up with the hydrofoils.
Brand Affiliation: Cape Town Foilboards
Location: Langebaan (Cape Town)
Contact:

Re: Collaborating Ideas - Long distance board

Postby ChristoffM » Sun May 26, 2013 1:01 pm

How good is the simulation? Does it take the characteristics of water into account at the correct speeds?

You can maybe try to import these sections into your program and let me know how it compares. For symmetrical (keel and rear wing) I would try e836. For lift (front wing) I would try e904. You can get them and more from here: http://www.ae.illinois.edu/m-selig/ads/ ... abase.html

Then there is a nice article here: http://www.foils.org/hysecdes.pdf

Let me know your progress.

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: Collaborating Ideas - Long distance board

Postby Bradn » Thu May 30, 2013 5:14 am

It takes into account water but does not take into account cavitation
I have now changed the main foil to E908 profile
AR is around 11
still undecided about the rear foil (shape/size)
Attachments
complete2.jpg

User avatar
ChristoffM
Medium Poster
Posts: 196
Joined: Tue Jul 19, 2011 5:26 pm
Kiting since: 2005
Local Beach: Langebaan and Cape Town.
Favorite Beaches: Anywhere in the Cape, South Africa.
Style: Hydrofoils! (And surf and old school)
Gear: Cape Town Foilboard and Spotz hydrofoils.
Any kite that can keep up with the hydrofoils.
Brand Affiliation: Cape Town Foilboards
Location: Langebaan (Cape Town)
Contact:

Re: Collaborating Ideas - Long distance board

Postby ChristoffM » Thu May 30, 2013 4:15 pm

What is the surface area of the main wing?

The rear wing area should be about 1/3 normally, but with your long fuselage you can aim at 1/4 I think.

Why do you have the wing tips curving back and ending sharply? I would suggest just plain elliptical shapes to make manufacturing easier and reduce the risk of injuries.

It looks very beautiful so far, but whether it will work- who knows? Do you ride hydrofoils Bradn, or will this be your first try?

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: Collaborating Ideas - Long distance board

Postby Bradn » Thu May 30, 2013 10:31 pm

Haven't had time to work out area too much study, but roughly sqr( 450^2 + 50^2 + 60^2) x 8

The tips were to try reduce the turbulence at the end of the foil, similar to what is on some plane wings. But I guess in water it might not be necessary.

Until its made, who knows haha
No, this would be my first. :D

Is the rear wing usually symmetrical in profile?

User avatar
ChristoffM
Medium Poster
Posts: 196
Joined: Tue Jul 19, 2011 5:26 pm
Kiting since: 2005
Local Beach: Langebaan and Cape Town.
Favorite Beaches: Anywhere in the Cape, South Africa.
Style: Hydrofoils! (And surf and old school)
Gear: Cape Town Foilboard and Spotz hydrofoils.
Any kite that can keep up with the hydrofoils.
Brand Affiliation: Cape Town Foilboards
Location: Langebaan (Cape Town)
Contact:

Re: Collaborating Ideas - Long distance board

Postby ChristoffM » Fri May 31, 2013 4:59 am

Yip, rear wing should be symmetrical. You want all the lift from the front wing so that your centre of pressure (and thus centre of gravity with riding) are further forward and the rear wing can act as a stabiliser. Obviously the rear wing has no angle of attack (if you can adjust this afterwards to tune the foil it would be good). Front wing angle of attack depends on how much lift the profile makes and how much area it has and what minimum speed you want. I would imagine with AR=11 you want high speeds, so maybe aim for AOA on the front of 0 as well and only rely on the asymmetrical profile for lift?

For the front wing, multiply the wingspan in cm by the average chord length in cm. It should come to around 500cm of front wing area. Rear wing maybe 1/4 of this.


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