The Budd RB-1 Conestoga cargo plane was undergoing trial flights at the Patuxent River Naval Air Station. Takeoff was started using full flaps and standard takeoff power for the plane. It was airborne after a run of about 3000 feet and the wheels were immediately retracted, but take-off power was maintained in an effort to gain altitude. The crew then attempted to raise the flaps in stages but the flap indicator remained in the full flap position and the trim of the did not change. The flap switch was then put alternately in the neutral and up position, but the flaps still did not retract. The climb at full throttle was not sufficient to clear the trees and upsloping terrain ahead and therefore a crash landing was made in the trees. Distance from the point of takeoff to the scene of the crash is about 9,130 feet and the tree tops in the vicinity of the crash were 85 feet higher above sea level than the runway.