The pilot reported that, while participating in a slow flight competition, he was over the target area for the radar speed check about 30ft. above the ground, at 17 mph ground speed, when the left wing stalled. He added, that he did not have sufficient altitude to recover. Subsequently, the airplane impacted the ground.

The airplane sustained substantial damage to both wings.

The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.