The pilot reported that, after commencing the take-off with flaps up, he selected 10 degrees of flap and rotated at 60 knots. Although the aircraft became airborne it did not climb normally. The aircraft struck a telephone line near the end of the strip and then landed in a paddock before passing under a power line. With full power still applied, the pilot attempted to clear a fence but the wing leading edges struck fenceposts. The aircraft landed heavily and came to rest 478 metres from the strip end. The take-off performance had been degraded by a loss of engine power resulting from unserviceable piston rings in two cylinders. The aircraft was being operated at some 120 Kilograms in excess of the weight extracted from the performance charts as being the maximum allowable for the strip length.