This picture comes from a demonstration of how hard it is for a fighter aircraft to shoot down a Piper Cub - so long as the Cub can see the fighter coming. Cubs were used as artillery spotters (among other jobs), and proved difficult for fighters to destroy. The Harvard played the part of a fighter, and tried to get a line on the Cub. But every time it tried, the Cub could get out of the line of fire. You can see in this image the Cub dodging out of the way.