Rev Limit

[PowerDemon]

Hey guys I was wondering, what is the rev limit for a Lehner 2260? Im assuming its around 60,000rpms. Is this correct? I can’t seem to find it. Thanks!

[Fluid]

Why are you wondering? That is the bearing limit, some ESCs can commutate at a far higher rpm.



.

[PowerDemon]

I am wondering if there is a limit to how many rpms I can turn with this series Lehner motor. If the rev limit is 60,000 that is all I would need for my particular application. Can the 22 series Lehner motors turn 60,000 rpms?

[Fluid]

Very few motors have good efficiency at 60,000 rpm - what is the Kv of your 2260? Most are happier between 35,000 and 45,000 rpm (or less) regardless of whatever the "rev limit" may be. And getting a prop to hook up at 60,000 rpm will be very problematic. Why would you need this many rpm?


.

[PowerDemon]

Im not sure I do.. Im just seeing how much voltage I could apply to this motor for say one fast pass and stay safe. I am looking at which 2260 I’m going to buy.. I don’t have one yet.

[photohoward1]

Knock yourself out. I smell something burning!

Here you go. Google is a wonderful thing! (50K BTW)

http://www.lehner-motoren.com/doc/man_small_series_en_11_2013.pdf

[RaceMechaniX]

Lehner has a very good online motor calculator where you can input the under load voltage and motor with specific winding. http://www.lehnermotoren.com/calc/diagramm_en.php

I would stay below 50kRPM even for most SAW boats.

[PowerDemon]

Ok thanks guys I really appreciate it. I will keep this in mind when picking out the wind.

[Fluid]

When the fastest R/C boater in the world gives advice, I'd do more than just "keep it in mind"......




.

[Kaotic]

Lehner has a very good online motor calculator where you can input the under load voltage and motor with specific winding. http://www.lehnermotoren.com/calc/diagramm_en.php

I would stay below 50kRPM even for most SAW boats.

Tyler,

When you say to stay below 50k RPMs, are you talking 50k under load, like how Lehners are rated??

Thanks! And congratulations on the world record!!

[RaceMechaniX]

Thanks and yes,

LMT's on the table or in the calculator are listed under load with a fixed 15 Deg's of timing. I always talk about loaded RPM with LMT's and unloaded with Neu's and others. For Neu's and other's I factor in the efficiency and add 15-20% more KV to get a corrected loaded KV.

For example: I have a Q sport hydro and want to power it with 6S2P. I use the nominal voltage of the battery (22V for a 6S pack) and multiply by the KV listed in the table. Or inversely take the RPM you want and divide by the nominal voltage.

So if you wanted a 40kRPM motor under load with 6S 40,000/22=1818kV. Match this kv on the chart and there is your motor. If you want to err on the safe side use a higher voltage i.e. 40,000/24=1666kV.
As an example if you wanted a 2260 size motor on 6S for heat racing you would likely want a 2260/6 with 1644kV.

I have attached the LMT motor chart as well as a generic guideline for kv versus cell count for heat racing boats. Green is too low, yellow is good and red is too much.


rpm_all_en_11_2013.pdfBrushless Motor Calculator Heat Racing 2014-11-18.pdf

[PowerDemon]

Thats awesome! Thanks for the info. Congrats on the WR!

[Kaotic]

Thanks Tyler, I always wondered when people are referring to RPMs are they referring to loaded or unloaded. So loaded sounds like the universal way.

[Fluid]

Wrong, not universal on the boards. Too many newbies (and others) refer to unloaded rpm - Kv times nominal voltage which for Neu, Leopard, TP etc. is not realistic. You have to ask to be certain.




.

[Kaotic]

Got it thanks Fluid.