An excellent explanation - except at the very end where you explain how the propeller will automatically open with low pitch in normal operation and then show it opening in the opposite way. A very clever design!
As noted it is for low load conditions, of which motor sailing is the best example followed by calm weather. When you have over-drive the pitch is higher than the ideal pitch (for maximum power). That means the prop transfers more power into the water at lower RPMs, and that means the engine cannot reach maximum RPM, which for most engines means it cannot produce full power. So never use over-drive when powering into the wind or in rough seams when you need the most power available. When you are in low load conditions the lower RPM's providing the same power into the water means there are fewer power losses inside the engine and therefore better fuel economy. At least that is what Gori says. I have one to test in a few months to see what happens to fuel economy, but they have many customers swearing by it.
I feel that there is some misleading sales talk in this presentation. The propellor has a good design and I feel that it operates in the following manner. 1. The slot in the hub permits the blade to swing 180 degress taking a backward path. 2. The blade is unbalanced in its area and the center of pressure is away from the pivot line and so when the engine rotates the biased center of pressure on the blade will open it in either the forward or the reverse direction. 3. The blade section is not symmetrical and is cambered ( curved) so that the water will accelerate in the back direction as it goes along the blades and this means that the angle of attack at the leading edge is lower than that at the trailing edge. This could be interpreted as if the leading edge has a lower pitch than the trailing edge. ( From now on the presenter is forgetting the apparent entry velocity into the leading edge to ensure the requirements of a good propeller) 4. Now what the presenter is calling an overdrive, is only a normal propeller with camber blades going into reverse which makes the trailing edge become the leading edge............and a very inefficient propeller it will become and it is no overdrive, it is a normal propeller going into reverse and the fact that the trailing edge has a higher angle of attack than the leading edge does not make it an OVERDRIVE PROPELLER. It is all a sales drive using foxy descriptions. The propeller is an excellent idea, but the overdrive claims can be taken with a pinch of salt! Congratulations on the design anyway, but I would forget about projecting the overdrive bit!
The propellers are never in right position. By docking a catamaran each propeller has his own life. It is very dangerous. Looks nice, but completely trash.
If only all UA-cam videos were so clear and informative. Thank you.
An excellent explanation - except at the very end where you explain how the propeller will automatically open with low pitch in normal operation and then show it opening in the opposite way. A very clever design!
At last, an explanation I can understand, Thanks Glen
Thanks for this video Very well explained operation of the folding propeller
Well done! Enjoyed your explanation.
Thats one of the coolest designs I've ever seen!!
Very clever and well engineered
That is a beautiful design.
thanks glen that was realy informitave
most propellers just twist the blades, but you think outside the box. nice.
If you ever do this again, color one side in white. It will be easier to follow.
that is so cool
if overdrive is more efficient ,,,why would you ever need the standard forward setting
As noted it is for low load conditions, of which motor sailing is the best example followed by calm weather. When you have over-drive the pitch is higher than the ideal pitch (for maximum power). That means the prop transfers more power into the water at lower RPMs, and that means the engine cannot reach maximum RPM, which for most engines means it cannot produce full power. So never use over-drive when powering into the wind or in rough seams when you need the most power available. When you are in low load conditions the lower RPM's providing the same power into the water means there are fewer power losses inside the engine and therefore better fuel economy. At least that is what Gori says. I have one to test in a few months to see what happens to fuel economy, but they have many customers swearing by it.
How big do these props get?
I would 3D print this just to fidget with it.
I feel that there is some misleading sales talk in this presentation. The propellor has a good design and I feel that it operates in the following manner.
1. The slot in the hub permits the blade to swing 180 degress taking a backward path.
2. The blade is unbalanced in its area and the center of pressure is away from the pivot line and so when the engine rotates the biased center of pressure on the blade will open it in either the forward or the reverse direction.
3. The blade section is not symmetrical and is cambered ( curved) so that the water will accelerate in the back direction as it goes along the blades and this means that the angle of attack at the leading edge is lower than that at the trailing edge. This could be interpreted as if the leading edge has a lower pitch than the trailing edge. ( From now on the presenter is forgetting the apparent entry velocity into the leading edge to ensure the requirements of a good propeller)
4. Now what the presenter is calling an overdrive, is only a normal propeller with camber blades going into reverse which makes the trailing edge become the leading edge............and a very inefficient propeller it will become and it is no overdrive, it is a normal propeller going into reverse and the fact that the trailing edge has a higher angle of attack than the leading edge does not make it an OVERDRIVE PROPELLER. It is all a sales drive using foxy descriptions.
The propeller is an excellent idea, but the overdrive claims can be taken with a pinch of salt!
Congratulations on the design anyway, but I would forget about projecting the overdrive bit!
So no need to transmission with this propeller??!!
lol
The high cost of these propellers is the #1 drawback.
The propellers are never in right position. By docking a catamaran each propeller has his own life. It is very dangerous. Looks nice, but completely trash.