# 3.3. CoG calibration

3.3.1. Put the batteries into the battery compartment.

<figure><img src="https://1851866520-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FIWx9bMxy88NRLPUcOemU%2Fuploads%2FEZ5R4sLYWHwy8gu4oFUQ%2Fimage.png?alt=media&#x26;token=69701868-b9a1-4f26-a192-1d2d695a0bf1" alt=""><figcaption></figcaption></figure>

3.3.2. Check the aircraft center of gravity.

<figure><img src="https://1851866520-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FIWx9bMxy88NRLPUcOemU%2Fuploads%2FI0QGCwz1sbFaShMehqHb%2Fimage.png?alt=media&#x26;token=858b353c-7770-4a40-984d-1516d3171a25" alt=""><figcaption></figcaption></figure>

3.3.3.Tight the batteries.