Lehner 1940/5 in an Aquacraft Revolt 30?

Greetings, guys and girls. Been a while since I've been able to touch an RC boat. I bought this Lehner 1940/5-wind last year, I think, with the goal of putting it into a completely built Revolt 30 hull. The seller says this motor is 2,950kv. I honestly have zero experience with Lehner motors. This one is my first. The LMT website doesn't seem to list kv ratings for their motors (unless I just haven't flipped over the right rock, yet). Does anyone have experience with a 5-wind 1940 Lehner? I'm looking for some guidance on LiPo cell-count, expected peak Amp's, and prop selection. I was planning on pushing 6s through it, with a 240Amp, or higher, ESC and starting with a 2-blade prop below 40mm diameter, as I understand this thing might spin some crazy high RPM's. I just don't want to push it too far and roast it, simply because I'm ignorant of ideal operating conditions. Any help is greatly appreciated.

Thanks,
Michael P.

Attachment 166487

So 3,135kv is the actual rating with three-connector config? Is Lehner known for many custom builds? This motor has a 5mm shaft that sticks out the front and rear. It's hollow, to allow for a wire-drive the be clutched at the rear of the motor. I don't see an option for that on the website, so I'm wondering what else about this motor is atypical. I suppose the difference between 2,950kv and 3,135kv is negligible.

As for the intended setup - safe operating range, or a potential smoke show?

I think this motor is often used in riggers. Not sure how it would do in a heavier mono.

Lehner do custom builds, the hollow shaft is a pretty common Lehner customisation for Naviga racers with deep pockets, avoiding the coupling not only reduces the boats weight, but the lower inertia of the drive takes less power to spin up.

It is a bit of a strange build though, not a Naviga one for sure, the KV is consistant with a 3s mono1 or hydro1 25"ish <2.5lb boats, but much bigger, we would use a 1530, 1535 or 1920.

I wouldn't use it on 6s, is it a high amp? Maybe if it is a high amp variant you could get away with running SAWs with it for a while, but with over 60K rpm loaded you will be using a tiny prop to try to avoid burning it or your ESC, which would be very inneficient pushing along a big and heavy unstepped RTR. Honestly if you want to run 6s, selling it and buying even the cheapest of cheap Chinese motors with about half the KV would net you better performance.

Oval sprinting on 3s or SAWs on 4s would be much more appropriate for it.

It is a high-Amp version. Everything you mentioned is in-line with what I expected. I think I'll re-home this motor and put something else into the Revolt build...probably just a Castle or NEU. Thanks for confirming my suspicions.

Out of curiosity, what inside diameter is the hollow shaft? We typically use 1.5mm for Hydro1 that has a fair bend in the shaft, and 2mm for Mono1 that are run nearly straight with intermediate bearings to reduce whipping. 2.5mm might be appropiate for 4s SAWs.

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Originally Posted by NativePaul

Out of curiosity, what inside diameter is the hollow shaft?

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I don't remember. I'll get my calipers and measure, tomorrow afternoon.

The revolt hull can do real well on 3s.

I have an exceed shark mono 1 that I ran with the stock 4122kv motor, with the stock 36mm 3 blade prop on 2s. I also ran a tacon 5050kv , 2860 motor with a octura m435 3 blade on 2s in the exceed shark.

I also converted the shark to run bigger motors and bigger props. I once ran the shark with the stock revolt aquacraft 3656 1800 motor with an octura m545 on 3s.

I can tell I have ran my revolt much faster on 3s than the shark can possibly do.

Them mono 1 hulls does suck to the water when they hit a certain speed. The revolt is much boat than them mono 1 even on 3s with the right motor.

https://m.youtube.com/watch?v=31oDU_abqnc

This a video of my revolt on 3s.
With a Leopard 4092 2080kv, an octura x646 3 blade that I detounge.

Lehner 1940/5 motor is 2950kV , 3S setup ... Or 4S high RPM,

A 28" mono should be fine.

Proboat UL-19 30" Hydroplane can work too, look at MHZ :

https://www.mhz-powerboats.com/shop/...ls/mono-hulls/

For that lehner motor I think an m440 should be a good prop for a 3s setup in the revolt.

I personal does run m545 on 3s. But with much lower kV motors example 1740 to 2200kv. With a 1730kv leopard 4092 on 3s with the m545 my revolt would run almost identical to a stock revolt on 4s with a m545.

I have run the tp 4060 1950kv on 3s in the revolt with the m545 and that setup was faster than I achieve with the stock revolt, 4s and the m545.

I have done speeds on 3s with my revolt that was as fast as using 5s with the stock motor and a x642 in the same revolt.

I would think you should do speeds in the range of what a stock revolt on 5s with the stock prop or a x642 would do. With that lehner on 3s and an octura m440 or x642.

If the lehner is faster than the leopards and tp's you should be faster than I mentioned.