A mid-body which a cylindrical housing which defines a longitudinal axis and has an interior compartment. A guidance controller is housed within the mid-body for controlling flight. A plurality of wings are connected to the housing and each of the wings is movable into a deployed position to provide guidance during flight. The mid-body has an access window which facilitates communication between the interior compartment of the housing and an external environment. A normally door covers the access window, but when the door is moved, relative to the access window, into an open position, communication between the interior compartment and the external environment is established. An optical sensor is accommodated within the interior compartment and the optical sensor, once the door is moved relative to the access window, can view the external environment and supply data to the guidance controller for controlling operation of the plurality of wings during flight.