Long and slender cylinder gradually tapering about half-way up the rocket to the smaller diameter second stage followed by the larger diameter third, fourth, and payload sections contained in a heat shield fairing. Four fixed triangular aerodynamic fins at base of first stage; fins with moveable outer tips to assist directional control and provide stability. This specimen is cutaway on top to reveal the dual payloads of a backup of the Injun V (Explorer 40) and Explorer 39 satellites. A Scout D launched the original payloads on 8 August 1968.