Father of Flight - Vertical Flying Machine

In this design, the pilot stands erect in the middle of an enormous machine. The pilot must use their arms, legs and head to move the sliding mechanisms up and down to get the vessel off the ground. Leonardo was using all parts of the human body to try to maximise the energy source.
The machine, as envisaged by Leonardo, is 12 metres (40 feet) long with a wing span of 24 metres (80 feet), with a 12 metre (40 foot) retractable ladder complete with shock absorbers.
Leonardo decided it was necessary to have two pairs of wings, beating 'crisscross, the way a horse moves!