i think the flying machine had the biggest impact because people probably thought he was crazy. and a number of years later people invented airplanes. i think he designed one because it would be very convenient and people could save alot of time traveling.  
my three inventions are
1. a fold up never snap skateboard. a skateboard that never snaps in half and folds up so you can put it in your back pack and sneek it to school
2. interactive touchscreen tv . a tv that you can go behind and your are in the picture
3. never rip shoelaces. shoelaces that never rip or wear down when your are skateboarding.