Hi… Looking at the “double train” figures.
My initial thought is that there is no lifting force shown. Depending on the altitude you want to attain here, a lifting force is required more or less of equal force as the downwind pull of the blades/turbines if you want the general elevation angle to be 45 degrees. As all the blades are positioned directly downwind, they will not provide lift. I guess you could possibly tilt the props upwards slightly for a gyrocopter effect. Nevertheless, the lifting force required is pretty massive. But of course, thats just a matter of adding a large enough lifting surface above these.
Otherwise, the design seems sound to me, limited by practical issues concerning weight mostly. I think one would need to calculate the exact weight expected to compare the cost of lifting that relative to the power output. I am afraid that a regular HAWT could compare positively in such a “LCOE” kind of analysis.
I think there are some mechanical issues regarding the cable drives. One issue is how to get the amount of tension necessary to make the cable drive not slip. This means having spacers to keep either end of a cable drive apart. This essentially adds weight but only to counteract a force that you created yourself.
I think also of great importance is the material and design of the cable of the cable drive itself. It must be lightweight and durable, and not easily slip. So I expect regular UHWMPE (dyneema) may not be most suitable. Not my area of expertice this, still I am slightly concerned.
The cable drives incur each a loss of power. Look eg at this page:
It’s difficult to say how much the loss is, but I see that the upper turbines are connected to the lower level, which again is connected to a lower layer. For each pulley, you will certainly see some losses. If the loss is 2%, if you have 4 layers of pulleys, almost 8% is lost in the rope drives. I think more than 2% loss is pretty realistic in each cable drive to be honest.
To conclude, I don’t right now believe that you could build this in an economical manner, considering losses and lifting force required. You could perhaps convince me by supplying numbers that look more positive than what I am guessing at this point.
If I was to suggest a possible improvement, perhaps only have one rope drive (or none) and then make all the turbines move synchronized connected through cables connecting the generators electrically rather than mechanically. Finish the design by having a motor run the rope drive towards ground, or just transfer the power by cable to the ground. I’m not sure if this approach would be better though, as all this equipment is also rather heavy.
windmill.pdf (6.6 KB)
Showing my concept sketch ans a possible evolution of yours. A large frame with many smaller blades/generators, all connected together through wires, which are further just fed to the ground for extraction.
