The aircraft and instructors from an aero club were based at Eulan Downs to train a group of five students to the general flying progress test (GFPT) standard. The instructor and student had planned to carry out an upper air sequence prior to returning to Fairfield to commence circuit training. After the completion of the upper air flying the instructor decided to demonstrate a practice forced landing. The forced landing was commenced at 2500 feet above mean sea level (the elevation of the airstrip is 600 feet amsl). During the descent the instructor found it necessary to adjust his circuit, to ensure a landing on the airstrip, such that a base turn was commenced approximately abeam the threshold and the aircraft aligned on final at about 20 feet above the ground. The instructor reported that the indicated airspeed was 60 knots and the flaps were still selected up when the aircraft was aligned on final. The aircraft stalled at this point and landed heavily on the airstrip. All three legs of the landing gear were torn off and the aircraft slid for about 20 metres before coming to rest.