paper: 4 CIM versus 6 CIM theoretical calculations

[InFlight]

Originally Posted by Richard Wallace

This is not correct. Check the data, which I can vouch for. It was measured correctly by people who know their motor physics, and their FRC design.

The Mini CIM has about 2/3 the active material (armature core length, permanent magnets) compared to the CIM, and it has the same commutator.

This is why the Mini CIM performs well during prolonged heavy loading -- it does not heat up as fast internally as a CIM under the same load proportional to its size. Look at the test results provided by VexPro; after 60 seconds at peak load, the Mini CIM is still providing 200 Watts shaft output (87% of what it developed starting at with room-temperature innards), while the CIM is down to 230 Watts shaft output, only 70% of what it developed cold. Pound for pound in the heat of combat, the Mini CIM outperforms its big brother.

The Mini-CIM has 58% of the rated stall torque at 68% Amps of the CIM. A tank drive with 3 Mini-CIMs provides 87% of the initial performance compared to 2 CIMS.

When hot if we just use the 87%/70% = 1.24 performance ratio. The three Mini-CIM drive would now be 1.08% of the performance of a two CIM drive. The three CIM drive would be heavier, and need extra motor controllers.