The pilot of the experimental amateur-built airplane was flight testing a newly installed propeller. During ground static testing, the pilot found the propeller rpm to be acceptable. After liftoff, the engine rpm increased to a non-acceptable range. The pilot responded by reducing the throttle and retracting the flaps. He also described that the airplane’s flight controls felt like a “…mushy precursor to a stall.” The pilot then increased the engine power to full and lowered the nose of the airplane to increase airspeed. The airport was surrounded by housing developments, and the pilot turned left in an attempt to return to the airport, but the airplane would not maintain altitude. He then guided the airplane toward trees in order to avoid impacting the houses. During the accident sequence, the airplane sustained substantial damage to the wings, tailboom, and cabin structure. Following the accident, the pilot stated that he had, “inadequately adjusted” the propeller’s pitch before the accident flight, which resulted in the airplane’s inability to maintain thrust and lift.