Vibration

​1​. Applicable products

  • Series 1520 Thrust Stand
  • Series 1580 Thrust Stand and Dynamometer
  • Series 1585 Thrust Stand and Dynamometer
  • Series 1780 Thrust Stand and Dynamometer

2.​ What describes your problem?

Please find within the following table which describes your problem. Once selected, mark down the troubleshooting points to follow.

table scope
3.
 Problem specific troubleshooting

3.1​ I had a vibration cut-off on my thrust stand Series 1580/1585.

Please take note that only the Series 1580/1585 is equipped with an accelerometer that can quantify the overall vibration on the main circuit. Please take note that the measured vibration is for reference only. Other products such as Series 1520 and Series 1780 do not have the capacity to measure the vibration. This guideline 3.1 is only applicable to the Series 1580/1585.

  • Open the RCbenchmark GUI and go to the Safety Cutoff tab
  • Please first verify the safety cut-off setting of the vibration value

  • In a normal circumstance, we recommend setting the maximum vibration up to 3 g.
  • If you prefer setting safety cut-off to a higher value, that means you allow a higher vibration on the stand. Please bear in mind that severe vibration may damage the load cell or loosen the fasteners. Please follow section 3.2 for the guideline regarding how to handle severe vibration.
  • If you have already set the vibration safety cut-off to the maximum 8 g but it still comes with a cut-off, depending on your physical observation towards the stand:
  • If the stand does appear to be under severe vibration, please understand that this is the limit of the stand and it can be extremely dangerous when exceeding the safety limit. We recommend following section 3.2 to better improve the propeller, the setup or check fasteners.
  • If the stand does NOT appear to be under any vibration, there can be an issue with the accelerometer on the circuit. In this case, please send your case to support@rcbenchmark.com and indicate the following info:
  • Subject: Vibration cut-off but no physical vibration
  • Send us the troubleshoot that you run
  • Make an CSV file of the manual control and let the stand cut-off by recording the data itself
  • Send us a video of the stand whether it is under vibration

​3.2​ I observed a severe vibration on my stand. What shall I do?

Vibration is very common on the turning motor and propeller. However, severe vibration can potentially damage the load cells and the structure, and it may also loosen the fasteners thus fail the structure, where it may cause motor or propeller flying out.

First to understand the nature of the vibration or the resonance:

  • All propulsion systems generate vibration and it is a matter of severeness.
  • Propeller shall be properly balanced before using on the stand.
  • Motor, propeller and also the prop adaptor shall be perfectly symmetrical and well aligned.
  • The stand has a natural frequency but it also depends on the size and the weight of the propeller.
  • Resonance will only occur at a certain range of RPM, when the speed goes higher or lower, the vibration may potentially disappear.

Please also understand the limit of our thrust stand:

  • This is not a tool used for dynamic characterization (acceleration, vibration, etc.)
  • This is not a tool designed to test unbalanced propellers, motors or adaptors.
  • The tool will break when extreme vibration occurs.
  • Fasteners can get loose due to the vibration.

When you observe severe vibration, follow this procedure:

  • USE CAUTION and stop the test immediately.
  • Disconnect the thrust stand from the power source.
  • Once the voltage drops below 15 V, approach the stand and check the propeller. If you have a propeller balancer at the correct size, remove the prop and try to balance the prop by adding a small counter-balancing weight on different sides.
  • Check if the propeller adapter is properly balanced as well: you shall not have set screw on one side but not another.
  • Check the tightness of ALL the fasteners: screws, nuts and standoffs. If you are using the optical RPM probe, also check the fasteners fixing the probe on the motor mount.
  • Make sure that all fasteners are properly tightened, if you have a torque wrench, you may use it to properly gauge the fasteners.
  • Once confirmed with the fasteners, connect the power.
  • Use manual control to quickly increase the throttle, and mark down the throttle A% (PWM μs input) then continue going up until the vibration ends, mark down again the throttle B% when this resonance disappears.
  • Stop the test and shut off the power, then check the fasteners again once the voltage drops below 15 V.
  • At any test, you shall always QUICKLY bypass the throttle A% to B%. For example, when you are writing a script for automatic control, you may need to avoid staying at A% of throttle at all and quickly move to B% in order to avoid any damage. If you are running manual control, move quickly to B%.

Please also take note that:

  • The A%, B% throttle may differ based on the motor and the propeller
  • On the Series 1580/1585, you may choose to use the L-bracket instead of the hinge, this may avoid certain resonance:

https://www.rcbenchmark.com/products/series-1580-1585-replacement-l-bracket

When your thrust stand is damaged by the vibration, please send your request of RMA to support@rcbenchmark.com and include the following info:

  • Subject: Vibration/Resonance caused damage
  • Photos of the broken components
  • If possible, video of the accident
  • If you have an output CSV file, please also include it

We will suggest the necessary replacement parts according to the damage.

4.​ Problems persist?

We support all issues related to the measurement tools itself, and we can provide limited support regarding your test setup and power-train selection. If you need extended support for your specific tests, manufacturing facility or UAV, contact us at sales@rcbenchmark.com. We offer extended support contracts including phone and video conference at affordable rates.

To obtain a solution to your problem faster, please indicate which troubleshooting steps you have already done. Also, include the debug log from the software. If relevant, please also include screenshot or pictures of the issue.

​4.1​ Cross-reference to other types of problem

  • S15CNT - vibration may cause loose cable connection on the Series 15

​4.2​ Cross-reference from other types of problem

  • SITMDG - measurement discrepancies may also due to the vibration, thrust and torque sensor may not be able to measure the correct value
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