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28mm OD Low kv brushless motors

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  • 28mm OD Low kv brushless motors

    Spent a number of hours searching for some low kv rated 28mm brushless Outrunner motors today. Mainly I am after motors capable of spinning lower rpm’s for directly driven prop shafts.

    All the typical airplane and drone websites had listings for brushless Outrunner in this diameter but most of these motors still had kv ratings in the 1000’s. Lowest I could find was about 700kv in a 28mm OD.

    By dumb luck I stumbled upon some random listings on amazon for some 28mm 350kv and 500kv brushless Outrunner motors. Here’s a couple links.

    It appears these same motors are used in a number of thruster pod products available from a number of different sellers.

    I picked up a couple to test them out. Posting because I figured this might help someone else out.


  • #2
    Nice find! That will help a lot of people out-especially me...Sometimes I think that they are just outrunner motors run underwater-which they do well anyway. Its really nice that they are so low of a KV rating and small diameter size-that's very rare.

    I would also like to see the stats for maybe a 15mm outrunner (usually in the 1500KV-2000KV range) run slow and under load but in the wet-I bet it would survive due to the constant cooling of being underwater? I'll put that test on my list for someday...


    • #3
      I’m expecting these motors are probably just regular Outrunners without the cooling slots machined into the housings (which I’m not sure I like that). They claim the bearings are anti corrosive and that the motors can run in salt water.

      As you mentioned, finding small diameter low kv motors is rare and that’s is why I grabbed a couple of the 500kv and 350kv ones to test out. Down side they don’t already have a shaft but that’s not a big deal. A bolt on output shaft can be made easily. Should see the 500kv motors show up Thursday and the 350kv motors maybe arrive sometime next week. Will post here after I test them each.


      • #4
        I tend to buy my 300kv, 400kv and 500kv brush-less motors from Europe. As its hard to find them in the USA. When I needed a 28mm diameter 400k motor, I ended up buying a Graupner brushless motor model 7281. There hard to find as the company stop making them when closed and then reopened as a new company with less items for sale. But there out there yet. I think the shaft was 3.17mm.