On October 28, 1993, about 1320 eastern daylight time, a Piper J3-C65, N24524, piloted by Mr. Richard G. Robinson, nosed over after landing at a private airstrip near Greenland, New Hampshire. The airplane was substantially damaged. The 2 pilots were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight was being conducted under 14 CFR 91. The pilot had landed the airplane on a grass runway and touched down hard on the main landing gear. The gear collapsed, and the airplane nosed over. According to the pilot's statement on the NTSB Form 6120.1/2: Just before the flare point I felt the loss of lift and increase in sink rate. Adding power and other control in-puts had no effect. The main gear contacted the ground, broke and spread...[the airplane] skidded on [the ground] for 20 or 30 feet then flipped over.