is futaba gy401 gyro ok for an airplane
There's no reason why you cannot use your Futaba FY401 in an airplane model.
The reason the servo may not move much would be due to how much gain you may have set. The more gain, the more servo movement when the gyro tells the it to move. Moving the tail slowly would give you a small response, but a rapid movement of the tail should give you more response from the servo.