On May 7, 2007, at 1230 central daylight time, a Cessna 172R, N51827, operated by Skyline Aeronautics LLC as a rental/instructional airplane, received substantial damage on impact with terrain during a hard landing on runway 8L (5,000 feet by 75 feet, asphalt) at Spirit of St. Louis Airport (SUS), Chesterfield, Missouri. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 solo instructional flight was not operating on a flight plan. The student pilot was uninjured. The local flight originated from SUS. The student pilot stated that he performed 10 touch and go landings at a nearby airport prior to returning to SUS. He was instructed and complied with air traffic control (ATC) instructions to fly a straight-in approach. He stated that the airplane was probably high and too fast, which was usually not a problem for him and elected to land anyway. He stated that he knew he was high based upon the visual approach slope indicator and could of performed a go-around but elected to continue the landing. He felt pressure to land by air traffic control to fly a straight-in approach. During the flare, he "probably dropped the yoke forward slightly," which dropped the nose resulting in the airplane bouncing. The airplane began to porpoise from which he landed after the third bounce. He wasn't sure what was happening, but he did keep the yoke back and that seemed to help. He stated that he didn't know what a porpoise was at the time and how to correct from it. He also stated that there is pressure to follow ATC directions and to clear the airspace as quickly as possible. The airplane sustained firewall damage.