Nature's helicopters.

The flowers on my sycamore tree have now set fruit in their usual ultra-prolific way. The paired, winged seeds ripen in autumn; their spiralling descent increases the time it takes for them to fall to the ground, and so maximises the chance that they will be dispersed further away from the parent tree in the wind. Here in Britain children, and children who have never really grown up, enjoy flying the fruits as miniature 'helicopters'.

Our aeronautical engineers must have enjoyed playing with sycamore seeds in their youth as they named the first British-designed helicopter to fly and serve with the Royal Air Force, the Bristol Type 171 Sycamore. Created by the Bristol Aeroplane Company, the first flight took place in 1947. It was used for search and rescue and anti-submarine warfare.