@Maya-Boker , please see a discussion regarding flight time vs added payload to Starling 2 Max. https://forum.modalai.com/topic/3732/starling-2-max-payload-capacity-and-flight-time-impact
Considering that you would be increasing the mass by 50% in your case (quite substantial), I imagine some flight controller tuning would be required (no ESC tuning needed).
Any new mass should be mounted as close as possible to the geometrical center of the drone in order to reduce the added moment of inertia. Off-center mass will not only have greater impact on the moment of inertia, it will also make the vehicle imbalanced at hover and even more so during accelerations.
You will probably need to perform or at least check the Attitude Controller tuning, and Height Controller tuning (due to increased mass). Please consult the PX4 tuning guide(s) for this, as we do not offer any additional information on that topic. You should be able to use a stock Starling 2 Max tune and make adjustments. If adding 250g does not work well, try a smaller weight increase with a dummy weight and see what tuning parameters you need to change to make it work well again (and then go from there).
Alex
