On August 22, 2009, at 1303 mountain daylight time, a Cessna 182H, N1921X, registered to Lincoln Sport Parachute Club, Inc., impacted terrain during departure from Browns Airport (NE69), Weeping Water, Nebraska. Neither the airline transport pilot nor the four sky divers on board were injured. The airplane was substantially damaged. The flight was operated under provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed. The local flight was originating at the time of the accident.The pilot stated that he used a short/soft field take off procedure when departing the soft, dry, 2,200 foot turf airfield. After becoming airborne, the airplane briefly settled back onto the runway. The airplane became airborne and settled back onto the runway a second time after losing "ground effect" due to down sloping terrain; the right main wheel separating from the landing gear strut allowing the strut to dig into the ground. The airplane spun around and came to rest upright resulting in bent left and right wing spars, a bent fuselage aft of the passenger compartment, and a bent firewall. An examination of the airplane by a Federal Aviation Administration Airworthiness Inspector revealed no pre-existing mechanical anomalies. A review of the pilot's operating handbook (POH) for the Cessna 182 showed that soft field take-offs are to be "performed with 20 degrees of flaps by lifting the airplane off the ground as soon as practical in a slightly tail-low attitude" and the airplane accelerated in ground effect if no obstacles are present in the flight path. Consulting the performance charts found in the POH, at maximum gross weight, the calculated ground roll for this type aircraft was 730 feet with 1350 feet needed to clear a 50 foot obstacle. A 15 percent increase in ground roll distance is assessed for operation from a dry, grass runway. Density altitude at the time of the accident calculates to approximately 2,195 feet. The accident aircraft was upgraded with Short take-off and landing (STOL) equipment in the form of ART R1582 wing extensions, and an engine conversion that allow for an increased take-off gross weight limit. Information contained in the NTSB Form 6120.1, as completed by the accident pilot, indicated that the airplane was five pounds under maximum gross weight at 2945 pounds.