On September 15, 2018, about 1540 mountain standard time, Cessna 172N airplane, N734FT was substantially damaged shortly after takeoff from St Johns Industrial Airpark (SJN), St Johns, Arizona. The commercial pilot, pilot rated passenger and one passenger were seriously injured. The airplane was registered to R2D2 LLC and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed for the cross-country flight, and a flight plan was not filed. The flight was originating at the time of the accident, with a reported destination as Phoenix Goodyear Airport (GYR), Goodyear, Arizona. In a report submitted to the National Transportation Safety Board investigator-in-charge, left seat pilot-in-command reported that he initially attempted takeoff from runway 21, but when he noticed that the airplane was not accelerating [fast enough] he elected to abort the takeoff. He then decided to take off from runway 14, which had a longer runway. The pilot stated that after he took off from runway 14, the airplane ascended to about 100 ft above ground level, but then observed that the airplane was not continuing to climb. At this time the right-seat occupant, who was a rated pilot and owner of the airplane, advised the pilot to turn left, as the terrain was lower in that direction. The pilot opined that the airplane then began to sink before the airplane collided with a stand of trees in his flight path. The pilot mentioned that there were no mechanical anomalies with either the airframe or the engine which would have precluded normal operation. The pilot reported that the airplane's weight at the time of the takeoff was 50 pounds less than its maximum gross takeoff weight. In a postaccident telephone interview with the pilot-rated owner of the airplane, he reported that during the initial climb from runway 14, and at a low altitude, the stall warning horn sounded. At this time the left seat pilot-in-command said to the right seat pilot/owner, "You better take it," which was almost immediately followed by the airplane colliding with a stand of cottonwood trees. The airplane subsequently came to rest inverted with substantial damage to both wings, the forward fuselage, and empennage. The owner stated that they had just "topped off" both fuel tanks prior to departing. The owner also stated that he thought the accident was the result of the high density altitude condition. At 1554, the automated weather observation system located at SJN reported wind from 180° at 5 knots, sky clear, visibility 10 miles, temperature 31°C, dew point 3°C, and an altimeter setting of 30.10 inches of mercury. The SJN airport elevation is 5,737 ft. The calculated density altitude was about 8,600 ft at the time of the accident. According to the Federal Aviation Administration Koch Chart, considering the surrounding temperature and field elevation, the airplane would have likely experienced a 68% decrease in the normal climb rate.