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We caught a glimpse of the impeller and it looked very axial-flow. Streamlined but basically axial. Strange since they claim mixed flow? Could they publish a thrust vs speed curve with power as a variable based on tank testing? I would have thought that was possible?
It's subtle, but for about 5 seconds, I can see the shape of a mixed flow pump on the impeller, right at 2:35 in the video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jdppP-marfk.htmlsi=HPZjTYuWT4zhMZWj&t=155 The giveaway is the conic shape at the hub of the impeller. And the blades flow down that hub. The water flow doesn't cover the entire diameter of the impeller at the inflow. Water starts near the hub and gets pushed to the outer edges as it passes through the impeller. That is the mixed flow feature. And yes, they could publish thrust vs speed curves, but they don't. They have the data, but don't like to share it. If I called a sales rep, I might get a thrust curve. This goes back to the problem that waterjet manufacturers don't like to share performance data. They don't want us to see any potential negative features. For example, many waterjets perform great at their target speed. But as the ship slows down, the thrust from that waterjet decreases rapidly. I don't know if that's true in this case. But those negative features are why manufacturers don't like to share data.
Efficiency is probably a bit lower then on a normal surface drive. In RC boats 70 % is fine for mono hulls. 85-95% for cats and outriggers. An example: monohull with 45mm 1,4 pitch and 30.000 rpm is 45x 1,4x 30000 = 113,4 kmh at 100 % and 79,4 kmh at 70 % ... Same mono with A jet setup and 45 mm impeller and 30.000 rpm. would probably max out somewhere between 50 and 60 kmh and consume more power/ higher amps.
