Man-powered aircraft have been built in which a man generating between 0·5 and 0·6 horse-power has remained airborne in straight flight for upwards of 3 minutes. Noone has yet succeeded in demonstrating sustained turning flight nor can sufficient endurance be expected in order to achieve the difficult Kremer prize course.

It seems probable that refining the current design of aircraft is unlikely to bring the required horse-power down by a factor approaching two and therefore a radically new approach is required if the Kremer course is to be successfully completed.