9 Hidden Costs of Building a Thrust Stand

1. Electromagnetic Considerations

Motors generate a significant amount of electromagnetic interference (EMI), which can introduce noise into measurements and even cause USB dataloggers to crash. Identifying and resolving these issues can be challenging, emphasizing the importance of careful design and simulation of electrical connections from the outset. It's essential to allocate time for diagnosing EMI problems, and consulting with an electronics engineer skilled in power electronics, EMI mitigation, and grounding is highly recommended.

2. Finding the Right Load Cells

Our research indicates that sourcing a commercial multi-axis load cell capable of simultaneously measuring torque and thrust with the appropriate ratio of thrust to torque is challenging. Typically, one of the two measurements may not utilize the load cell's full scale of measurement, leading to reduced accuracy. Additionally, our load cells are engineered to minimize airflow restrictions while ensuring a minimum thickness, allowing for testing of coaxial systems.

3. Calibration and Verification

After acquiring suitable load cells, the process continues with designing a calibration method and verifying its accuracy. In powertrain testing, thrust and torque are seldom isolated, highlighting the need to calibrate the load cells under conditions that closely resemble actual operation. This entails calibrating both thrust and torque simultaneously and addressing crosstalk when generating the polynomial. Without a dedicated calibration apparatus, recalibration becomes impractical after prolonged use.

4. Software Development

In our endeavor to create the next iteration of test equipment, we found that revamping the software was as time-consuming as upgrading the hardware. The intricacy of the software varies depending on the desired features, but at the very least, it must encompass functionalities for controlling the test stand and performing data logging.

5. Data Processing

Beyond mere data recording, the processing of data significantly affects your workload. To simplify data handling and analysis, we've incorporated several data processing features into our software:

1. Integration of a low-pass filter option to enhance data smoothness.

2. Data resampling at varying frequencies to cater to diverse analysis needs.

3. Implementation of powertrain mapping functionality.

While programming these features requires time and effort, they ultimately save users time and prove highly practical.

6. Safety and Mechanical Tests

Designing a test stand can present unexpected challenges, such as identifying the stand’s resonance frequencies and mitigating vibration. Without knowledge of these frequencies, there's a higher risk of damaging both the stand and the propulsion system. Balancing stability and measurement accuracy amid vibration poses a challenge, requiring a delicate equilibrium to be struck.

7. Coaxial Testing Configurations

Once you've mastered a single-rotor testing setup, you may wish to test dual motors in a coaxial or offset configuration. While face-to-face propeller configurations are relatively straightforward, back-to-back configurations, common in many quadcopters, pose a greater challenge. Achieving optimal rotor proximity demands meticulous design and planning.

8. Designing a Compact Solution for Minimal Airflow Disturbance 

Developing a compact test solution poses a significant challenge. If the test stand interferes too much with the airflow from the propellers, it can affect the accuracy of the readings. Creating a compact design that maintains stability without compromising airflow requires extensive development time.

One of our primary objectives in redesigning our test stands was to ensure a compact design that minimally interfered with airflow, ideally less than or only slightly more than the motor itself.

9. Imprecise Measurement Leading to Underperformance

Experiencing imprecise measurements that result in underperformance is a nightmare scenario for drone builders. Relying on data presumed to be reliable, only to find that your prototype's actual performance falls short of expectations, can be frustrating and challenging to rectify.

Conclusion

While our test stands may not always align perfectly with your project requirements, we trust that this article has equipped you with the knowledge to make an informed decision on whether building your own test stand or purchasing one is the best choice for your project.

If you seek a reliable, professional test stand to ensure results you can trust, we welcome you to explore our range of products further.