My friend and I are building a small direct drive helicopter. We both have a background in mechanical engineering and we found it very difficult to obtain good specs on brushless motors and propellers. Some websites provide a results database, but these databases are frequently for a combination of both motor and airplane propeller, which makes building something different very difficult. When we started rewinding motors, we built a system to measure torque, current, rpm, voltage and temperature. With torque, we can actually completely decouple the motor and propeller in the results, which really speeds up the development and allows calculating ideal gear ratios or find the correct propeller, in order to maximize efficiency.
The code is based on a modified MultiWii system with a series of connected sensors. Currently, the tests are entirely automated to test different pitch and torque combinations. There are safeguards in the code to stop the tests based on measured temperature, rpm and current. The code automatically generates graphs of the results.
That got us thinking. Would people be interested in a community-based website with motor and propeller specs? Our code is already open source and we could make our test rig available for purchase. The rig could be sold on kickstarter for approximately 150-250$ if we sell 40-100 copies. We don't expect this project to generate money really, but the goal is to help the community obtain better motor and prop tests. The system would include torque, thrust, current, voltage, rpm and temperature sensors. The instrument would include a mount for most standard motors. People with test rigs could upload the motor and propeller results on the website and specify the brand, spec or custom winding, etc.
Below are a few more images of our tests. The helicopter is a modified FBL100 and we tested quite a few motors and propellers. Our tests demonstrated that it is very difficult to make a small and efficient direct drive helicopter. It flies though.
If you are interested, please reply to this survey!