Ultra-efficient toroidal propeller gets contra-rotating double upgrade

it's usually about how much energy your setup takes to recapture turbulence into useful energy after the first spin, and it's a tight-rope act trying to figure that stuff out.

So yes, I imagine you could, but at some point those hydrodynamic gains run into the physics problem of spinning mass even if you can walk the turbulence tight-rope.

What would be the point? Contra-rotation has limited use as it is. In this case the stated reason is to ensure the axial flow has no energy wasted in twisting (though this can also be achieved with a stator) - in any case two stages are enough for this. The other main use is dissipating more power when you are up against some sort of limit on prop size, but this is not a common problem underwater.

> I can see $9000 as a fair price, but also expensive enough to buy one, scan it, and then CNC one of your own.

Ironically, that also includes the price of purchasing the CNC machine to machine it on.

To me this looks like it would be very beneficial to research the viability of lost-casting from a 3d print and do away with even needing to CNC machine anything aside from the precision bearing surfaces. Though, admittedly, I don't know how viable cast propellers are.

I think the prop includes the gear box needed to making it contra rotating. I also think the lifetime warranty being a pretty decent reason to not try to rig your own.

I imagine it's the gearbox that they're sinking engineering and testing time into. They don't have any other contra-rotating products on market, so the gearbox will be new to them.

If I’m not mistaken, these shapes are rather difficult to CNC. Particularly, the inside of the outer part where a traditional CNC would be blocked. I think this might require robotic-arm CNC which is much slower and much more expensive.

I suspect they need two years to scale production

>I also wonder why it isn't coming out for two years, when they can already make them via CNC?

conditions testing and certification is a likely reason.

>I can see $9000 as a fair price, but also expensive enough to buy one, scan it, and then CNC one of your own.

the gearbox and the process itself are expensive. the materials analysis and selection are expensive. the cfd is expensive. You're going to need a 5+1 axis machine at the least to perform the manufacturing.

fwiw I think the price is ridiculous, but normal, because unfortunately I have experience with the marine prop market and realize that anything 'marine' or 'yacht' labeled has a 250% markup by default.

a line from a sitcom occurs to me : 'This boat shit is expensive.'.