On August 10, 2005, at 1230 eastern daylight time, a Cessna R172E, N7880N, was substantially damaged during a hard landing at the Patuxent River Naval Air Station (NHK), Patuxent River, Maryland. The student pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the flight which originated at the Walter Francis Duke Regional Airport (2W6), Leonardtown, Maryland. The solo instructional flight was conducted under 14 CFR Part 91. According to the pilot, during landing at NHK, he "porpoised" the airplane, and did not recover until the third touchdown. He realized after parking the airplane, that the propeller had struck the ground during the landing. The pilot reported 322 hours of total flight experience, 311 of which were in make and model. He additionally reported no mechanical deficiencies with the airplane. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed substantial damage to the firewall.