Features

On an RC plane, propeller performance depends on pitch, diameter, profile, and material.

Testing your propellers will allow you to measure and improve their efficiency.

This motor + propeller test equipment will measure:

• Thrust
• RPM
• Current
• Voltage
• Electrical power
• Temperature

This project is an improved version of https://hackaday.io/project/202213-rc-motor-propeller-test-bench

Compared to V1 version we can now access to :

• torque
• mecanical power
• motor efficiency
• propeller efficiency

It can be controlled either manually via a servo tester or your radio transmitter/receiver or automatically via your Android phone.

Schematics

• The heart of the system is based on a Lolin32 lite ESP32 microcontroler.
• Then a bunch of sensors are added to measure all the parameters.
• An Oled dispaly is (optionnaly) there to help debug or usage without smartphone

Bill of material can be found here : RC motor tester V2 BoM

This schematics is pretty much identical to the V1, simply 2 more load cells have been added . One is for torque measurement and the other one is for spare !

PCB

I have designed a nice and compact PCB allowing to fit the ESP32 and to connect all the sensors

The PCB was kindly sponsored by PCBWay and is as usual of excellent quality.

You can order it here: PCBWay shared project. It's cheap, delivered very fast and so professional looking!

And if you are new to PCBWay please use this affiliated link : https://pcbway.com/g/o35z4O

Soldering this board was easy and result is a "mezzanine board" at three floors !

Power considerations

5V can be delivered either by the DC/DC converter (prefered solution) or directly by the ESC of your plane  

power with DC/DC converter : 

• first tune the trim pot value in order to get less than 5V (4.8V) output (do not power anything else before...)
• when this 5V is achieved, you can paint the trim pot with a drop of nail varnish to fix the potentiometer
• then (and only then) solder the SJ solder pad on the bottom side of the PCB. The 5V will now flow to the DFPlayer and the ESP32 (via the battery connector)
• Do not solder the SJ1 solder pad

using the DC/DC will insure a stable 5V supply which is used by the current sensor. Zero current is half the 5V supply. So this value ("5V") must be stable. If powered by the ESC, the "5V" could be as well 4.8V of 5.2V... this would induce a biais into the idle current measurement from ESC to ESC... So it's better to have a consistant "5V" which will allow to calibrate properly the current sensor.

Power with the ESC :

If your ESC is equiped with a strong enough BEC (1A for the ESP32) you can power the board and the ESP32 directly with the ESC connector :

• do not solder the SJ solder pad (nor the DCDC module if you want)
• solder the SJ1 solder pad
• connect the ESC servo pin header to the ESC connector on the board and power your ESC

I however do not recommand this second option (power with the ESC) as the 5V delivered by the ESC would change form ESC to ESC... see above...

Power with the USB plug :

It is safe but not reliable for exactly the same reason as above.

However you can power the device by the DC/DC converter (or the ESC) AND plug safely your USB to the PC for debugging purposes.

sensors

Six sensors are there to measure the parameters of your motor and propeller:

• ADC to measure battery voltage
• current sensor to measure  current flowing into the motor
• IR sensor to measure rotation speed of the propeller
• temperature sensor to prevent over heating of the controller
• load cell sensor to measure the "weight" of the propeller (converted to thrust !)

Links for these sensors are provided into the bill of material

ADC

Voltage of the battery is directly measured by one of the ESP32 ADCs

R1/R2 are a voltage divider needed to decrease the battery voltage to the ESP32 range (3V)

V_IN = R1 x Vbat / (R1 +R2)

So you have to...