The pilot intended to perform a short-field takeoff in the tailwheel equipped airplane for both practice, and as a demonstration to the passenger. His intention was to climbout at the airplane's best angle of climb airspeed (48 mph). He stated that the airspeed indicator was not accurate at low airspeeds, and that an indicated airspeed of 40 mph was actually 50 mph true. He selected 20 degrees of flaps, and observed the angle of wind vary during both the run-up, and while lining the airplane up on the runway. As he began the takeoff roll, the wind moved to a direct headwind, and he initiated rotation at an indicated airspeed of 40 mph. He maintained that airspeed, and once they reached an altitude of 150 feet agl, the airframe began to shudder. The airplane began to descend, and he applied forward elevator control in an effort to regain control. After doing so, the runway came into view, and concerned that they might collide with the ground, he released elevator pressure. The airplane subsequently settled just left of the runway and ground looped, coming to rest on its nose. The pilot stated that the accident could have been avoided if he increased the takeoff airspeed to counter for the wind conditions, and applied more down elevator pressure during the subsequent recovery. The airplane sustained substantial damage to both wings, and the pilot reported no preimpact mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation.