I share the experience of an older wiser former instructor regarding power loss and return to field attempts. My friend (in addition to his bonanza and aerobatic biplane) flys ultralights. He was trying at altitude to determine the safe amount of excess altitude necessary to attempt a     full 180 degree turn to return to airport. After numerous high altitude practices, he determined that 300 feet was minimum altitude for safe turn around. eventually he tried it in the pattern and ended up stalling and spinning it into the ground. Luckily escaped without life threatening injurys. In his evaluation of why he was unable to replicated the 300 feet was that when doing it at such a low altitude ones perspective of the nearness of the ground does alter your thinking and makes you fly the plane incorrectly. that urge to bcreak the law of physics must be irresistable.