Anybody out there!

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k1w120
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Joined: 08/04/2010, 19:52

Re: Anybody out there!

Postby k1w120 » 13/12/2010, 13:23

May have missed the point ... looking at the bulb profile, my thinking was the moment the bow dips down, this bulb shape would cause the boat to dive deeper into water (submarining) would beome worse as wind speed builds up.

Yes in very light air it may not, but the moment the boat gathered any speed this bulb would act like a brake, slowing the boat down again ...

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matthias72
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Joined: 04/07/2008, 16:33
Location: ROMA

Re: Anybody out there!

Postby matthias72 » 13/12/2010, 14:09

ah, yes, this shape is very dangerous, you have to use a 3° of angle to avoid this problem. But you risk to increase a lot the resistence. I never tested this kind of shape so mine are only ideas. For sure the bulb center mass could be lower may be also 10mm, that is a lot but we have to check if the gain is major respect the resistences...
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THE LIFE IS SHORT: SAIL HARD!
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growjd8888
Posts: 69
Joined: 03/11/2009, 14:22

Re: Anybody out there!

Postby growjd8888 » 14/12/2010, 2:58

.
Last edited by growjd8888 on 14/12/2010, 3:14, edited 1 time in total.

growjd8888
Posts: 69
Joined: 03/11/2009, 14:22

Re: Anybody out there!

Postby growjd8888 » 14/12/2010, 3:06

This is a website that will help you
http://web.mit.edu/2.972/www/reports/hy ... ofoil.html

Videos that may help
http://www.youtube.com/watch?v=YZU_SqMW_5Y


This is an AWESOME SAILING MACHINE
http://www.youtube.com/watch?v=LmakeKMG ... re=related

These videos will help describe my theory, both use this exact same shape to create lift

???

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k1w120
Posts: 157
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Re: Anybody out there!

Postby k1w120 » 14/12/2010, 12:58

Foiling Moth ! now I understand where your coming from ... a mutual friend of Matthias & I is building one in Bologna, Tiziano from TD models, this is extremely interesting concept with "adjustable fin tabs" on keel & rudder fins which the skipper adjusts while sailing according to conditions to get right angle of attack of the foils to go hydro ..... but hydro-foiling fins do-not have bulbs hanging off them (60% of the total boat weight under the water) but I'm sure you did not imagine you IACC 120 would go hydro ...did you ? :lol: (kidding)

Anyway, don't let this stand in the way of learning through creative thinking, at least you are trying it bravo !!! and I for one am very interested what affect this "foil bulb" has.

I was thinking myself in the direction of having a profiled keel fin completely made of lead (no bulb) wrapped in carbon to eliminate the drag of the bulb hanging on end of the fin, this would affect the righting moment, CLR and boat balance would be interesting of course ...but it would be interesting light wind experiment, just one of those wild imaginative ideas (thinking outside the box) thing.

Cheers Alan

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matthias72
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Location: ROMA

Re: Anybody out there!

Postby matthias72 » 14/12/2010, 17:14

Nice Idea. Probably in perfect wind condition and stationary water, the hull could decrease its wet surfice, but it depends on boat weight, and speed; as told by Alan a IACC120 is much more heavy respect a hydrofoil boat and the foil surface is small, so I don't know how much the decreasing of wet surface could be...
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THE LIFE IS SHORT: SAIL HARD!
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growjd8888
Posts: 69
Joined: 03/11/2009, 14:22

Re: Anybody out there!

Postby growjd8888 » 14/12/2010, 22:18

I dont expect to have much lift but I can only imagine it would create some sort of lift to "possibly" lift hull slightly decreasing water line drag.... Realistically if it only lifts the hull 1cm, that should significantly reduce the hull surface area in the water. But ill see, this could just be my boredom thinking.

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matthias72
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Location: ROMA

Re: Anybody out there!

Postby matthias72 » 14/12/2010, 23:46

I wait with interest your tests in water!
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THE LIFE IS SHORT: SAIL HARD!
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growjd8888
Posts: 69
Joined: 03/11/2009, 14:22

Re: Anybody out there!

Postby growjd8888 » 08/07/2011, 8:47

http://www.youtube.com/watch?v=3A77TEFT ... re=related

just wondering id u have any clue as how to make these hydrofoil fins because this is incredibly Fast for a R/C sailboat


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