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I am interested in finding out the RPM of the motors on my drone with certain amounts of load and without load. Is there some way to measure the RPM of a drone motor using BetaFlight? If not, is there another way?
Not sure if it matters, but I am using the SucceX-E 45A 2-6S BLHeli_S Dshot600 4-in-1 ESC and some Xing-E 2207 2750kv motors.
Bi-directional DShot can help you here. After updating the BLHeli firmware on your BLHeli_32 ESCs to the latest version (support was added only recently) and the firmware on your flight controller to Betaflight >4.0 (PR on Github), you can go into the Betaflight Configurator app and enable Bi-directional DShot under the Configuration tab.
It must be said that the easy BLHeli ESC firmware upgrade is only available for BLHeli_32 ESCs. There are ways to get support for bi-directional DShot on BLHeli_S ESCs, but they're more complicated. Instructions are linked to on the Betaflight Wiki page.
The ESC-reported motor RPM values will then be displayed under the R label next to each motor in the Motors tab.
There is also an OSD widget for viewing motor RPMs, called OSD_ESC_RPM in the code, which can be enabled under the OSD tab.
As @BenWilson points out in his comment on this answer, you can also set the BlackBox debug mode to DSHOT_RPM_TELEMETRY and get motor RPM values recorded in your BlackBox log The implementation is described on the Betaflight Wiki here.
