According to the flight instructor in the tailwheel-equipped airplane, the purpose of flight was to provide a "proficiency check" for the pilot in the front seat. The pilot was on the controls and landed the airplane after accomplishing one pattern. During the subsequent takeoff, about 5 ft above ground level, the airplane's right wing "went down," and the pilot applied left stick, but the airplane struck the ground. During an interview with the National Transportation Safety Board investigator-in-charge, the instructor reported that he believed that the airspeed was too slow during the takeoff climb and that the airplane stalled. The airplane sustained substantial damage to the right-wing lift struts. The METAR at the airport reported that, about the time of the accident, the wind was from 20° at 4 knots. The pilots used runway 15. The pilot and instructor reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation.