Electric Sculling Drive.

Electrical Sculling Drive with forward and backward propulsion. (Prototype) For small Boats
Kjell

 

Hi Kjell,

What application do you forsee for this drive that a prop drive could not do in a simpler & more reliable manner? Just curious.

Take care.

Tim

 

This is the first prototype. I am installing it in a model boat and the video I will show will demonstrate how good or bad it is.
Kjell

 

I would say that what you have there is a Kinda surface drive.

Ive been saying this all along that a surface drive propeller is a rotating sculling device.

If you imagine a surface prop in very slow motion does not each blade dip into the water and scull along and then out of the water and then the next blade comes in.

 

I don’t know the Kinda surface drive. My Sculling drive is using a Wiggle Drive to obtain the Sculling movement.
Kjell

 

I have now tested the Scull Drive with good result. See the video.
http://www.youtube.com/watch?v=XoBtz4cdojg
The Sculling arm and tail is made of Carbonfibre.
Kjell

 

kjell,

Hey that is terrific, everything old is new again! Just love it! Thanks.

We once moved our dinghies that way, till small outboards came along.

Which reminds me, why do people today face forward in a dinghy as they motor away from their yachts on the mooring,..... it is because their yachts are so ugly!

 

If you had four of those blades (or more) and rotated them instead of using the same one backwards and forwards you would have a surface propeller but non cavitating or airiating.

You've obviously put a lot of work into it.

The only problem is the stop and start of the mechanism, whilst it is stopped ready to go backwards it is doing no work.

 

efficiency

Indeed, when reversing the movement, the drive does nothing.
But drive does not consume power at that moment.

The surface drive consumes power all the time, but part of that power is wasted bij lifting and pushing the stern of the boat.

So Kjell's system will be better where efficiency is important : electrically driven boats.

 

It may be using less power at the reversing moment but thats because there is no work being done.

If there were two paddles attached in such a way so that wasted energy was consumed into motion.

 

The propulsion produced by an oscillating tail is different to a rotating propeller. The propeller produce a continues thrust, limited by the cavitation. The pulls propulsion has no problem with cavitation and can use a more efficient AoA.

KJELL

 

Oscillating foils are very complex to engineer to get efficiency much above 50%. On the other hand it is not hard to get rotating foil (propeller) efficiency above 80%.

If nature had the equivalent of a shaft and bearing we would see birds and fish propelled with rotating foils because they are a more efficienct form of propulsion.

On the other hand if oscillating foils (wings and tails) were more efficient we would see boats using flapping tails and aeroplanes using flapping wings. They don't because they are complex to engineer and inevitably less efficient.

Rick W.

 

Hi Rick.
I have been looking to your nice web site. You have been working hard with your projects. May I comment two details on your tail experiments? The oscillating foil you are using is not the most powerfully tail propulsion. No fishes are using this foil movement for fast swimming. If you try to eliminate waves you must start to combine the flapping frequency to the boat speed.
Kjell

 

Kjell
The wave drag on my latest hulls is minute (thanks to Godzilla) so no need to eliminate it because it would be a waste of effort. So my propulsion system does not need to cancel wave drag.

If you could work out ways to eliminate/reduce viscous drag with a simple solution it would be a significant development and this would be of interest to me and most of the boating world.

I developed oscillating foils till I understood the science and then determined you could not do better than a rotating foil.

When you can show hard data on efficiencies in the high 80s to low 90s you might have something that is more than curiousity value. I agree that there could be merit in getting wave cancellation for a short hull but I would need to see proof in the form of hard data.

Rick W.

 

Rick

Have a look to this web site

Dr.Evgeny Sorokodum

http://www.vortexosc.com/modules.php?name=Content&pa=showpage&pid=11

Kjell