Roll Oscillations on New Alta X Model

Date First Published	May 25th 2023
Date Last Updated	Nov 9 2023
Status	Active Issue

Introduction

This Service Bulletin is being issued to advise customers on an issue discovered when using the XM2 Labs SLG-20-AX Retractable Landing Gear on Freefly Alta X Drones which use the newer X9 Motors. Refer to this page to determine which motors your Alta X is using https://freefly.gitbook.io/freefly-public/products/alta-x/untitled-3/alta-x-motor-change-june-2022

Background

XM2 Labs has determined through feedback from customers that the SLG-20-AX landing gear is inducing roll oscillations on newer Alta X aircraft. Upon investigation and analysis of log files, we have determined that the newer Alta X aircraft have a wider control bandwidth (due to more responsive motors) which is causing a feedback loop with the natural frequency of the SLG-20-AX legs.

Recommendations

If the landing gear exhibits visible roll oscillations in flight, cease operation - we do not advise flying the aircraft while visible oscillations are present.

You may try the following measures which may eliminate the issue for some customers:

• Use 600mm Legs rather than 700mm legs - the shorter length will mitigate oscillations

• Check spring tension is correct - refer to this guide for details XM2 Labs | Installation Guide: SLG-20 Retractable Landing Gear For Alta X

While the above measures will help some customers avoid the issue, it may not be sufficient in all cases, we are actively working on a solution that will resolve the issue for all customers with newer Alta X drones.

All customers who experience this issue should contact customer support so we can track the issue and provide a solution as soon as possible. Further communication will be released to update customers as we work to resolve the issue.

Resolution

We have tested and found a solution to this issue which involves increasing the stiffness of the connection between the legs and the aircraft, and reducing the weight on the legs. This involves three things

• Removal of the plastic spacer between mounting plate and the aircraft

• Use of lighter weight rubber feet on the end of the bottom tubes

• Providing 650mm down tubes instead of 700mm down tubes.

  • Note that we used to provide 700mm tubes for customers using the DJI Ronin 2 gimbal which is taller. For using the R2 gimbal, we now recommend 650mm legs and the use of our Alta X Standoff which is shorter than the normal standoff to provide extra clearance.

All new SLG-20-AX kits will use the new parts mentioned above.

For customers who purchased SLG-20's during or after June 2022, please contact us and we can provide these parts free of charge. All other customers can contact us to purchase these parts for a small fee.