# Balancing a copter with just gyro data [duplicate]

It seems like pitch angle could be computed from just gyro data, which uses 2 gyros.

However, isn't pitch computed from acceleration rather than gyro data?

pitch = 180 * arctan (accelerationX/sqrt(accelerationY*accelerationY + accelerationZ*accelerationZ))/PI


where no gyro data is needed. So how could a copter be balanced with just gyro data?