On July 23, 1995, at 1200 mountain daylight time, a homebuilt Steinke Early Bird homebuilt (2/3 scale Jenny), N593JN, landed hard following a partial power loss on takeoff from Akron, Colorado. The pilot was not injured and the aircraft sustained substantial damage. Visual meteorological conditions prevailed and no flight plan was filed for this personal flight to Oshkosh, Wisconsin. According to the pilot, the aircraft was sluggish after takeoff and in an interview said the "engine was not developing sufficient power to remain airborne." The pilot stated that he made a hard landing, bounced, and allowed the aircraft to drift off the runway where it touched down breaking off the main landing gear and nosed over. The engine was removed and sent to Northland Recreational Products, Phillips, Wisconsin, for examination. According to the attached examination report provided by that facility, there were several problems noted with the engine which would account for the partial power loss. Item number 2 reported a PTO side rave valve possibly being stuck shut. This may have caused maximum rpm to be limited. Item number 3 reported a problem with an overly rich mixture. This problem would be exacerbated by density altitude which was approximately 7,200 feet above mean sea level at the Akron Airport.