I'm designing a series of small drones for use in a swarm configuration in combination with terrestrial / marine / submarine robots. As part of the process, I've designed a test rig to measure the thrust performance of various motor / propeller combinations. The general layout of the rig is shown in the Sketchup diagram below:
The motor mount is attached to a plate, which is bolted to a MGN12C linear bearing block mounted on a 100mm rail. (If anyone is interested, the details of the MG series linear bearings can be downloaded here). This particular bearing was just one I happened to have available.
At the other end of the plate, a load cell protrudes through a slot, and this is used to measure the thrust force generated by the motor / propeller combination. The mount is designed to allow the load cell to be easily changed (I have quite a few 1kg, 3kg, 5kg, and 10kg load cells).
The data, together with temperature and vibration measurements from an accelerometer, will be gathered using an Arduino (or possibly a Raspberry Pi if I decide to integrate the rig with other test gear).
The length of the plate means there is ample room to mount the ESC between the motor mount and the load cell.
It occurs to me that it would be fairly straightforward to modify the rig to allow the twisting force, or torque, generated by the motor / propeller combination to be measured. Probably the simplest way with the parts I have available now would be a pair of load cells fitted between a modified motor mount and the plate attached to the linear bearing as shown here:
Minimal modification to the electronics would be required to add this to the design, and I have more than enough load cells available to add this to the rig.
We had to re-design arms in a previous model when we found the forces generated by the motors caused them to deform while testing the unit on a static rig, which is why this modification appeals to me. However, I wonder whether anyone else has any experience of using this kind of data in drone design.
So, how useful is it to know the torque generated by a motor prop combination when designing multi-rotor drones?