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Old 15-06-2008, 12:30   #1
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Swing boards or keels

We are presently designing a new type of keel / board that is different from daggerboards/keels/centerboards.
The new type of board is a swing board made like a wing to create lift with a convex outer side and a flat inner side .
These 2 boards wil be movable outward with hydraulic actuators
to swing them from a vertical position ( straight down) to a horizontal position with a 3 degree angle of attack and a 30 degree position to come out of the water.

We have applied for patents on this new system.
The advantages are: with the windward keel/board in the vertical position lift for the windward hull ,the the windward side will be in the vertical position to give lift towards the wind side. so the cat will stay more horizontal , the leeward hull will be lifted slightly for less drag and better effect of the wind on the sails and higher pointing ability.

When sailing downwind both the boards can be set horizontal to create lift or out of the water to minimize drag.
Advantages :
Higher speed
higher pointing ability,s
No inside space used
Less draft.
Safer in storms

I will keep you posted on the development of this system and the actual advantages once the first Fastcat is launched with this system.

Greetings

Gideon Goudsmit


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Old 15-06-2008, 13:08   #2
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Will you be doing some tank testing, Gideon?
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Old 15-06-2008, 13:11   #3
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Quote:
Originally Posted by sandy daugherty View Post
Will you be doing some tank testing, Gideon?
Yes we will Sandy , the expensive to immediately equip a cat with this system
We have a basin in our old factory with a lenght of 12 meters and a width of 4 meters and can create a flow there .

Greetings

Gideon
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Old 16-06-2008, 05:27   #4
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Swingboard location

Gideon,

Where are the boards going to be positioned exactly?
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Old 16-06-2008, 08:47   #5
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The boards will be located on the outside of the hulls 300 mm below the dwl in order to make the swing outward and upward.
The boards will have 3 positions with indicators for these positions
down , 90 degrees and up .

Greetings

Gideon
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Old 16-06-2008, 08:50   #6
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This sounds really interesting. I can't wait to see the setup.
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Old 16-06-2008, 09:14   #7
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Quote:
Originally Posted by Pat Ross View Post
This sounds really interesting. I can't wait to see the setup.
It is the same with me , most of it is in my mind and on paper and we will order the first parts in 2 months
The first calculation show a 3 degrees better pointing ability and a decrease in resistance of 5 % upwind , a decrease of over 7 % downwind with wind speeds of 12 knots or more with the boards at 90 degree angle and with less wind we take the boards out of the water since than they only create extra resistance which we can do without at these low wind conditions.

Greetings
Gideon
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Old 16-06-2008, 12:40   #8
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Vortex Generators

I wonder what the similarity in function of your new swingboard is to the Vortex Generators that Bernd Kohler uses on his designs. He designs them so they are fixed and on the inboard hulls.
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Old 16-06-2008, 13:39   #9
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I understood Bernds' boards to be more in line with anti-vortex panels, creating a kind of "gate" between the different pressure zones.

I would love to see a sketch of Gideons idea. As far as I understand, the foil can work in either the horisontal plane to create a vetrical (upward) force, or in the vertical plane to create a force against leeway. Is this correct Gideon?

The ORMA tris, or at least some of them use banana shaped foils to create the vertical lift in the amas, and a centreboard to resist leeway. The banana foil works on the leeward ama to create lift that lets these boats sail with a slight "nose up" attitude that is benefecial under certain conditions.

The same effects are sometimes created by using a T-shaped foil. The angle of attack of the horisontal foil can be adjusted by tilting the whole board, and thereby adjusting the lift.

Google for sailing Moths, and look at the pictures....

Gideon, the areas and aspect ratios of the board surely need to be different? I would expect the daggerboard function to need to create more lift. If you loose the end plate mirror effect to some degree, then surely the problem gets bigger? Will you be able to dial in the angle of attack in the different positions?

Looking forward to see some more..

Regards

Alan
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Old 16-06-2008, 13:56   #10
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I understood Bernds' boards to be more in line with anti-vortex panels, creating a kind of "gate" between the different pressure zones.
Ugh, my mistake, yes Anti-Vortex Generators/panels.
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Old 17-06-2008, 01:42   #11
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with the boards at 90 degree angle
Hi Gideon, of course this has me thinking. The 90 degree angle you mention, is that angle 90 degress to the hull or the water?

Greetings, Pat
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Old 17-06-2008, 02:21   #12
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Quote:
Originally Posted by Nordic cat View Post
I understood Bernds' boards to be more in line with anti-vortex panels, creating a kind of "gate" between the different pressure zones.

I would love to see a sketch of Gideons idea. As far as I understand, the foil can work in either the horisontal plane to create a vetrical (upward) force, or in the vertical plane to create a force against leeway. Is this correct Gideon?

The ORMA tris, or at least some of them use banana shaped foils to create the vertical lift in the amas, and a centreboard to resist leeway. The banana foil works on the leeward ama to create lift that lets these boats sail with a slight "nose up" attitude that is benefecial under certain conditions.

The same effects are sometimes created by using a T-shaped foil. The angle of attack of the horisontal foil can be adjusted by tilting the whole board, and thereby adjusting the lift.

Google for sailing Moths, and look at the pictures....

Gideon, the areas and aspect ratios of the board surely need to be different? I would expect the daggerboard function to need to create more lift. If you loose the end plate mirror effect to some degree, then surely the problem gets bigger? Will you be able to dial in the angle of attack in the different positions?

Looking forward to see some more..

Regards

Alan
Good Morning Alan / Pat

to start with the last question the angle of attack will always be 3 degrees , the ability to change the angle of attack would be ideal but a very costly and vulnarable affair.
At a speed of 10 knots or more the lift of the 90 degree board ( to the hull Pat )will be enough to actually lift the leeward hull out of the water enough to make a real difference in resistance .The angle at which the hydraulic actuator sits is 3 degrees so when the board changes from 180 to 90 degrees the angle is preset by way of the position of the actuator.
The board will be optimally designed for the keel function since the hydrofoil function is secondary to the ability to point.
The 3 functions of the board are in sequance of importance :
1. Creating a force against leeway by way of lift creation with a optimal designed board
2. Creating upward lift for the leeward hull to minimize drag.
3. diminishing or minimalizing drag by lifting the boards out of the water going downwind.
The positions can be chosen to be at any location between the straight down and all, the way up and there will be an indicator to show what the position of the boards is.

Once the first tech drawings are available i will post them

Greetings

Gideon
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Old 18-06-2008, 06:03   #13
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Hi, Gideon,

just out of interest, how did you figure out a 3° AoA / angle of incidence?
Are you using some kind of NACA profile?

Greetings

Ralph
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Old 18-06-2008, 11:03   #14
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Quote:
Originally Posted by pilot View Post
Hi, Gideon,

just out of interest, how did you figure out a 3° AoA / angle of incidence?
Are you using some kind of NACA profile?

Greetings

Ralph
Hallo Ralph
a 3 degree angle of attack seems to be the perfect combination in preventing drag but creating enough lift to make a difference
It will only help in speeds above 8 knots but one has to set a mark somewhere and 8 knots is a speed we can easy get to in most conditions.
The nice thing is if it works the way I envision that at lower speeds one can just lift the board out to decrease resistance to almost zero and at low wind conditions there is no reason to be able to lift the hull since there is hardly any heel.
Since we are still working on getting more weight out out of the FastCats
The effect will be better and better.
We have now switched to a nomex interior ( kevlar honeycomb )A material that you fly with every day since it is used in most passenger aircraft .
The weight for this material is 1.35 kilo per squire meter compared with 2.1 for resin infused paneling only a weight saving of .8 of a kilo but 145 squire meters in one boat is a weight saving of 120 kilo.
We now have approval to build in Basalt fiber and that will save another 300 kilo.
A fully electric Fastcat 455 with all options and generator installed will come out below 6000 kilo.or a diesel version without generator and options will be around 4500 kilo .

Warm Greetings and looking forward to that testsail

Gideon

p.s. yes we are using a naca profile , pretty much the same profile as is used on a mooney 231 airplane
We will first do basin testing to see the lift we are generating at what speed and than will finalize the design.
By the way , the hydraulic actuators we are using are almost the same type as are used in a elevator of a 737 just not yellow tagged .
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Old 18-06-2008, 15:02   #15
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Gideon,

very interesting developments! Chapeau!

Greetings

Ralph
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