Today the forward rudder was added.
The result is awesome!
The boat is designed so that the ce(centre of effort, aerial) is far forward this enables it to carry the same rigg through a broad wind range.
The boat has a wide stern, a nose down tendecy is expected when sailing upwind. In addition the Rc components are placed far forward in the bow. These are the reasons why cg of the boat is set far aft(12% aft of midship), the result is a "light bow" (the boat is happy to change direction, and does not digg into waves)
With the second rudder, the ce of foils(center of effort, hydrodynamic) is moved forward and the boat should gain weather helm at first glance.
But it becomes more neutral!
Normally in order to have weather helm a boat must rotate around a certain point.
The forward rudder is added in front of this point so it stops rotation, because the boat would have to move it sideways throught the water in order to rotate.
In addition this added surface(the fore rudder) is controlable.
Sailing bluelife with twin rudders i could eliminate leeway by moving both rudders so that they pulled the boat into the wind.
With evoulution i can, not only eliminate leeway, but make the boat go to the wind.
Later i measured thatgood angles off the centerline for the rudders were up to 5deg.
More than 5 and boat speed would drop.
When pushing the boat to windward the speed is offcourse lower than sailing in a straight line, but the height gained is excellent(compared to speed loss).
Once the aluminum keel finn is replaced with a carbon strut, the boat will be able to sail even higher.
Many clips sailing with Fila will be shot, to show the difference between the two.
The above are the reasons why canting keel twin rudder boats will be able to have the mast far forward and still sail almost neutrally.
This is the only clip i got yesterday, because this boat requires both hands to be sailed properly.
There are two more positive effects gained with the fore rudder.
Firstly, control is not lost a very very high heel angles.
Yesterday was gusty and i managed to sail the boat at heel angles above 50deg, i don't know many boats that can sail at such an angle, maintain speed and tack!!, the forward rudder stayed in the water the whole time, providing enough control to sail the boat confortably. Speed was not ideal but it survived the strongest gusts well above 15 knots, at times sailing so heeled that the aft rudder would go completely out of the water.
Even at that state the fore rudder could iniciate a tack!
Secondly, the fore rudder adds directional stability. As a result this boat does not fall to the side when it nosedives sailing downwind. It just diggs deeper and deeper and eventually stops when the drag is really big.
Then it just surfaces and sails on.
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| the cg of the bulb/finn is marked green, black is boat cg, bulb/finn cg will be moved further aft with the carbon strut the deck is 2x80g/2 cloth, some of it died today |
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| forward rudder setup, the aluminmum rod to the right is a quick relese sistem for the servo plate(it is pushed into the bow, and easily removable. |
In the near future evolution will get a 50cm long carbon strut finn, instead of the aluminum finn. With the strut bulb cg will be moved 4cm to the back.
Paintjob also follows.
At the moment i still would not choose Evolution over Fila at a race.
Since i know everything about #87, it is damn fast up and down wind.
But Fila does make alot more leeway and Evolution beeing almost 300g lighter than Fila, it gets up speed quicker out of turns.
Evolution will serve as a foil testing platform,
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| hq3.5, 60mm chord low Re. profile foil |
Quote: "in the future they will all fly" says the father of Hydroptere the true fastest sailiboat in the world(not the fastest water skimming UFO)
So i've been messing around with some numbers. They tell me that a boat such as evolution can fly. But they did not tell me anything about drag, meaning that i do not now how much power is required to get the thing foilborne.
To start with i will fit this foil to evolutions forward rudder, and make it adjustable in angle. Then i will tow the boat(with no rigg) behind a model powerboat.
I know aproximately how fast i have to walk to match the boats speed sailing in different conditions.
Assisting me will be a stepcounter and a runtastic app.
The foil above is a 180cm2 foil, it has a 15-15(deg) V form.
Theprofile is a hq3.5, designed for model planes. It works best with renolds up to 130isk thousand.(i wont reach that probably)
The thickness is just above 10%
It is 3d printed in black Pla, and will get painted and wet sanded.
The goal for now is to try different foils and get the boat to raise its bow. The bow has to be raised just 1-2cm from the static wl, in order to reduce the wetted surface area greatly.
Under sailpower this should already mean a great increase in speed.
After that a foil will be added to the back rudder.
At that point the boat will get very ustable and stability calculations will have to be performed for future foils.
There is a problem to the "moth style" concept, such foils are unwanted upwind, they have to be manipulated somehow in order to make profit sailng in all directions.
But this is some brainfood for the future at the moment
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