Roll Oscillations on New Alta X Model

Date First Published	May 25th 2023
Date Last Updated	Jan 9th 2025
Status	Resolved

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.

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 any customers who purchased their SLG-20 landing gear after June 2022 but before we started shipping the updated parts in late 2023, we can provide the shorter 650mm tubes and lighter weight feet free of charge to resolve the issue. (The replacement of the carbon plate to remove the plastic spacer has a smaller effect and is difficult to change)