LLRCFlyer

One of my club members was practicing rolling harriers with his Flex Mamba 60 when he experienced 4 slung magnets in the Potenza 65-3D motor. It is 550KV and the full model number is FPZM10653D. Flex is replacing the motor under warranty, but we are wondering if there is a better motor alternative in case the warranty replacement motor also slings its magnets. The trouble is we can't get enough information on the Potenza 65-3D to make any comparisons. Does anyone have data on this motor such as maximum continuous allowable amps or watts and max voltage? Unlike the Lepoard or SunnySky brands, Flex does not list any physical or performance data on their website for the Potenza motors. One would think that if it really is a quality motor, then they should be proud to post the performance specifications for it on their website. Is anyone else experiencing slung magnets with this motor? Thanks for your input.

ron_van_sommeren

Conservative rule of thumb for max. continuous motor power: 4watt per gram motor mass.
A safe starting point.

You already have the velocity_konstant_Kv
Note that Kv says nothing about a motor's maximum power, both the motor in your toothbrush and the motor in e.g. a 1:1 train can have the same Kv.

However, Kv has a massive effect on actual current and power drawn, both are proportional to Kv cubed.
E.g. doubling Kv, would 2³=eight fold current and power.
Some expensive realistic and some extremely silly examples, hopefully instructive as well.
Therefore always check/measure currentdraw in a new/changed setup.

Motors can any voltage in RC land, as long as current, power and rpm don't get too high.
The wire insulation/lacquer/resin/coating can withstand several hundred volt.

Method for securing the magnets afterwards, as an extra precaution. Also describes a method for epoxy heat treatment to increase glue maximum temperature:
old.torcman.de/motoren/manuals/manuals_e.htm
→ Assembly Procedure TM280, 350, 430
→ 3.2 Filling the magnet spaces

Lucien Miller knows powersystems, they test their motors themselves, you can take their numbers to the bank, excellent propcharts. Not the usual nonsensical heap of voltages and propsizes.
www.innov8tivedesigns.com and www.badasspower.com


Prettig weekend Ron
• Without a watt-meter you're in the dark ... until something starts to glow •
• E-flight calculators • watt-meters • diy motor tips&tricks • Cumulus MFC •

LLRCFlyer

Ron,

Thanks for the input. The assembly manual for the Torcman motors was most interesting. Besides voiding the warranty, I wonder how much rotor imbalance would be caused by the epoxy-micro balloons fill between the magnets? Currently, my friend is without a motor for a few days until the replacement motor arrives under warranty. When it arrives, we will weigh it, measure the can diameter and depth, measure the voltage/amps/watts with my watt meter and also take an rpm reading to determine the percentage of KV "slip" with the recommended propeller. From this, we should be able to "reverse engineer" that data into something we can compare to other motor specs. I just thought it would be so much easier if someone had the actual Potenza 65-3D motor data to share. The original motor had been running very cool for several dozen flights... barely warm to the touch after 3 minutes of fairly aggressive 3-D flying. It worked very well until is slung its magnets. At $95 (US), the Potenza 65-3D is not cheap and should not be throwing magnets. If the replacement motor also shucks its magnets, then we will be looking for something else.

LLRCFlyer

The Flex Mamba 60 is a 3-D airplane designed to do some rather violent maneuvers. Since the propeller hub bolts directly onto the rotor, all the propeller gyroscopic bending loads must be transmitted back to the airframe through the rotor can. If the propeller is slightly heavy (i.e. plastic instead of wood), could the gyroscopic forces generated during tumbling maneuvers be apt to distort the rotor sufficiently to pop the magnets from the rotor shell? If this occurs, is it common? Or, is it just an indication of a cheaply made motor with a rotor that is too weak?