flutterby drive

I agree. What if you could sit inside in comfort in any weather and sail in any direction?
The windmill I designed and built was for irrigation in third world countries, but it reciprocates--- up and down or side to side. I wonder about its efficiency on a boat. It gets its drive from a percentage of its swept area--- theoretically, about 59 percent of the wind's power maximum.
Maybe I should try it out on a small boat. That would be interesting. The rig would always orient to the wind like a normal windmill. All I'd have to do would be to steer the boat. Add a tiller pilot self-steering and I could sit inside reading a book I suppose. The wind direction could shift 180 degrees and still I'd just continue towards my destination without adjusting a thing.

 

That's pretty slick. I'm wondering now if you could extract some power from the excursion of the minor pivot axis. It wouldn't be much, maybe enough to run some little lights or something, but it might also serve as a dampening effect to reduce the noise. I'd approach this with a little electrical generator to bypass added mechanical complexity. No moving parts needed; mount a coil on the yoke and a magnet on the sail. The power wouldn't be steady, but a series of pulses, but it could feed a battery charger.

I might be off in my thinking, though; would dampening the sail take too much power away from the major pivot, or would it just slow it down some?

 

Of course you could extract electrical power using as Faraday coil. The power you get depends on a lot of factors having to do with stall characteristics, and how the charging controller is programmed. I'm no electronic expert though.

 

Damping the foil as it 'comes about' is quite interesting, necessary even. And of course extracting energy out of it makes it all the more interesting.

This subsystem can't be too greedy though as the foil needs to 'snap' through the dead angle quickly and smoothly. I guess ideally one would apply a powerful damping force in the final part of the transition, just before it comes to the stop. This would translate into brief but relatively intense bursts of electricity.

The ideal underwater propulsor for this would be a single oscillating foil. That way the cyclical forces are mirrored both above and underwater (as per the original idea) and if paired correctly, yaw torque effects could be minimized.

 

Remember, the foil underwater can be on a horizontal axis like a whale or dolphin's tail. I've seen bendy drive blades used on kayaks, but never up and down, which to me makes more sense because an individual stroke won't have much effect on boat wiggle if it works against the whole boat as a lever.

 

Up and down of course works just the same. The problem i see though, with up and down is how to keep the yokes (levers, actuator arms, whatever you want to call them) out of the water. With a vertical propulsor the yokes would be above water and the foil pierces the water surface, with a minimum of parasitic drag. Also there are no through-hulls.

 

But the up and down motion allows the windmill to re-orient automatically. A vertical axis type would have to be intelligently controlled. Or do you know how to make it self-reindexing? It's a lot like reindexing a wind vane self-steerer. What I'm talking about would only require helm steering, but not wind direction adjustments.

 

Indeed. I was not thinking about a self trimming system.

However, i think the nature of the oscillating force vectors upon the entire boat merit close analysis.
In the case of the horizontal setup the reaction on the boat would vary with the apparent wind angle; from pitching when up or downwind to a rolling effect when reaching. When it's vertical the yawing reactions should be able to be mostly eliminated. This could also be done with the horizontal setup but only for up/downwind. On a reach the foil would roll the boat with a corresponding loss of power (the force being partly wasted to roll the boat instead of going directly to the underwater foil).

There might even be a way of linking the vertical system such that it is self indexing but i can't think of it right now.

Another thing is that the yokes would need to be adjustable, such that the foil is allowed to rotate about the minor axis by greater or lesser degrees. This is directly equivalent to pitch adjustment in a propeller. The underwater foil should likewise have an adjustable amount of play to handle varying conditions.

This type of oscillating underwater foil has a remarkably high level of efficiency.

In a previous sketch i had drawn the angle of foil freedom being restrained by a line, which is a very simple and adjustable method.

 

When looking at the comparison between the vertical and horizontal axes, it was easy to see that the means of staying the vertical axis type was problematic; if it was to rotate 360 degrees, it would have to be free-standing except to just below the vane. The horizontal axis type brought the stays up to the halfway point of the vane--- a substantially higher point.
The flag type vane I came up with should also work very well on a horizontal axis at low wind speeds when gravity would distort the vertical axis vane.
Just like a flag, which at higher wind speeds follows a serpentine motion, but at low speeds sags and loses its nice serpentine motion.
I agree the vertical axis type underwater propulsion vane could be better, however. But it would take only a simple linkage mechanism to change up and down to side to side. so the upper wind vane could be horizaontal, converting to vertical for the hydraulic part.

 

There is a way for a vertical axis type to self index, by the way. If the upper part has a bevel gear (100 tooth) and the lower has one also (100 tooth), a bevelled pinion gear between (10 tooth) with a flywheel attached, horizontal shaft axis, each swing will cause the flywheel to absorb and store a little torque (but the flywheel has too much inertia to rotate very much, so by the time the vane has swung back, it's only lost a small fraction of its power, which is of course reclaimed by over-swinging the other side.
I designed this part so that a windmill could self-adjust to wind direction gradually without reacting to gusts.
Of course the horizaontal axis type solved the problem for good, eliminatinf the need for gears.

 

it could only work on a really light boat or WIG craft, mybe even a hybrid a katamaran with small wings and thin floatsat the end of them.

 

I would think a catamaran would work. It could go directly to windward. I would choose the horizontal axis type hooked directly to a bellcrank and a vertical axis propulsion vane. The wind vane could double as a stationary sail for downwind sailing in heavy wind.

 

ok, I didnt mean one part exactly, but a solid system with no drive train. I know I still have steer the thing and like that.

 

thats very helpfull, I'm tickled pink by all the replys, sorry for the delay

 

It would help if you provide a sketch of what you are proposing. I expect it will end up a complex system and impart nasty oscillating forces into the boat.

Rick W