The pilot was making the first of a series of test flights for the new airplane. After engine run-ups and a high speed taxi run, the first takeoff was attempted. The airplane became airborne after a takeoff roll of 1,000 feet. At 30 feet AGL, the airplane would not climb higher or accelerate above 50 knots. Insufficient runway remained to land and the airplane impacted trees in a fully-stalled condition. The pilot reported there was no mechanical malfunction and the ground adjustable propeller was not set to allow the airplane to accelerate.