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I’m the new propulsion engineer in a solar boat team (something like this https://energyboatchallenge.com/en/home-english/, solar class). This year I have to design and build a contra rotating propellor. It will exist of an inboard electric motor (approx. 8200 rpm at 11.5Nm) and a right angle transmission under water (something like this toy https://www.thingiverse.com/thing:3873918 ). The diameter of the driven gears (blue in picture of toy) are crucial for keeping the drag down, a maximum diameter of around 60mm would be preferred. For efficiency reasons a gear ratio of around 2:1 to 3:1 would be optimal.

Problem is that our previous gear supplier (assag) stopped doing small quantities. I’m having trouble finding a supplier that supplies small quantities and meets our requirements. I’ve so far been denied by Köbo, Elsto and Atlanta. I’m already in talks with a few others but any tips would be welcome.

cedric van sweeveldt
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  • shopping questions are off topic here ... there is no way to know if any suggested supplier will be a valid source in the future – jsotola Aug 25 '22 at 20:49

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It's always a challenge to find a supplier who is willing to sell in small quantities, which no one wants to do because there's no profit left after they factor in their overhead for "onesy-twosy" sales.

For this reason the resourceful engineer has to hunt out things which can be bought off-the-shelf and then hacked or modded into a useful state. This requires the rest of the design team to be willing to rethink some of their assumptions about the design which require custom components to implement. This particular engineering discipline is called prototype engineering and unfortunately there are not many practitioners available (I was one but am now retired!).

Let's take this discussion off-line. You can reach me via my website, www. nielsenkillowatt.com

-Niels Nielsen

niels nielsen
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