This new improved rotor sail is well balanced. This was possible by building several sections and balance each one individually. See the first video about rotor sails for a bit more explanation about what is going on.
Do you have plans to build a larger Catamaran with perhaps two or three rotating sails? Maybe even make them taller? I would imagine that would help with the overall speed. It would be cool to see more of this! And perhaps develop a mechanism that allows you to assemble and disassemble the mast and pivot it into position and have a simple yet strong lock mechanism.
Good effort still not big or fast enough. I'm building a 3m x .3 dia rotor for 600 rpm, should produce about 5hp in 15 knots. I want it capable of more than a sunny day sail.
We measured just once (7 km/h) when both (2x80kg) were onboard, so that was significantly slower than top speed. would guess 10-11 km/h was top speed. And regarding power usage the papers on the topic says about 15 % of total power is to drive the rotor, the other 85% is the wind - so well invested energy..
@@stigantonnielsen the trick is to use a wind turbine to get that 15% energy. maybe a Twisted Savonius Wind Turbine www.saltireserver.com/gx/vawt/PDFs/Board.pdf
Imagine if you had access to stronger materials that are just as light as that foam! Imagine if you had it made out of carbon nanotubes or graphene carbon fiber! But that would be for larger ships, like container ships, oil tankers, and cruise ships
The rotation speed would need to be multiple times the windspeed to have the most effect, so a direct wind powered rotation is not so easy, requires at least some transmission and of course sufficent wind power in the first place. However, the problem is that in order to change direction for the boat (or when wind direction changes), the rotational direction also needs to be changes. That complicates things a bit mechanically if it was directly windpowered. So just having a battery that powers the motor is definitely a much easier solution.
Beautiful project. I am curious how it would compare to a wing the same area as the rotor and if you could drive the rotor with a water turbine. Having the rotor be inflatable instead of rigid would allow easier reefing.
Litterature suggest that the area of a sail equivalent to a cylindrical rotorsail is the diameter of the rotor x 4. Yes, inflatable rotorsail is interesting since the shape of an inflatable naturally converges to round. Maybe you already saw my video with a model scale inflatable rotorsail and this indeed holds the potential to be reefed easily.
The video where we are testing the first version of the rotor shows a little more explanation.. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JhAlWHSez90.html But in short, the cylinder rotates, driven by a motor. The wind passing by the cylinder flows around say two sides of the cylinder. On one side of the cylinder the surface moves same direction as the wind causing the wind to pass faster, whereas the other side surface moves against the wind direction causing more friction and slower flow. The faster flow means lower pressure which in turn means lift on the cylinder. The principle is referred to as 'Flettner rotor' and 'Magnus effect' if you would like to search for more info.
De hecho se aprovecha el viento, y hay bastantes estudios sobre el tema, puedes buscarlo como efecto Flettner, para darte un ejemplo es lo que da la curvatura a una pelota en un tiro libre, la.ventaja de esto es la economía que produce para mover una embarcación, menos energía, ya se están usando en algunos barcos, para economizar combustible
Отличный проект с использованием эффекта Магнуса! По данным Флеттнера, скорость вращения ротора (линейная) должна быть выше в несколько раз скорости вымпельного ветра для достижения максимальной тяги. Ротор должен быть отполирован как можно лучше чтобы снизить требуемую мощность его привода. Удачи!
This is using what is referred to as the Magus effect. The cylinder is spinning and air that moves past it (wind) very near it's surface will be slowed down on one side (the side moving against the wind) and sped up on the other side (the side moving with the wind - if the surface of the cylinder is moving faster than the wind). Air that is moving faster is at a lower pressure than air with the same properties moving slower. This produces a net force on the cylinder. If you imagine the wind coming from the starboard (right side looking forward) and the cylinder turning counter clockwise, the net force will push the boat forward. If course, as the boat gains velocity, the apparent wind direction will change - you still have to know how to sail.
The max possible for the motor at this setup is 1000 RPM which is fast for this large a body.. but a rotor sail achieves good results at surface speed 3 times the wind passing the rotor. At a wind speed of 7 m/s and a circumference of 0,91m it is 23 rounds/sec which is 1380 rpm..so maybe not quite fast enough for the gusts that day..
@@stigantonnielsen There is an advantage of the decrease when a gust occurs. Points on the drag coefficient curve 0.0 1.2 ratio 1.2 at 1 ratio lowest 0.7 4 ratio 2.5 goes flat at about 5 around 3.5 this is for a Reynolds number 16000 for all the data and 32000 for the first three ratios at the higher Reynolds. the spinning cylinder lift coefficient about a 4 ratio at about 8.5 and for the higher RE ratio of 5 at a coef of 11. A sail will continue to create lift if it is not stalled which it would be for a gust as a ratio of the square of the velocity. Same square applies to the cylinder but the ratio decrease which lowers the coefficient as the square increases.
