When I first started flying gliders as a kid in Benalla (North East Victoria, Oz) we had an ES52B Kookaburra sitting beside the strip and noticed a willy willy coming across the field in a straight line for the Kooka. The Duty Pilot yelled a warning and a couple of us threw ourselves onto the a/c, one guy across the fuselage at the tail and me across the downward wing tip. The willy willy arrived amongst lot of dust and I had a sensation of flying through the air and came down rather solidly with the wind completely knocked out of me on the ground on THE OTHER SIDE OF THE GLIDER. The a/c had a wingspan of 15 metres so I was thrown at least 20 metres and an observer said I achieved an altitude of at least 5 metres!
I have had a healthy respect for the lifting power of aerofoils ever since.