I've made videos of my best solutions for each level and uploaded them on Youtube.
My Times are:
Level 1: 5.0
Level 2: 3.7
Level 3: 14.3
Level 4: 12.5
Level 5: 3.8
Level 6: 45.0
Level 7: 8.6
Level 8: 58.3
Level 9: 3.14.5
Level 10: 28.1
Level 11: 8.7
Level 12: 33.2
Level 13: 2.35.3
Level 14: 1.17.5
Level 15: 29.6
Level 16: 1.29.3
Level 17: 1.30.0
Level 18: 8.4
Score: 207,020. Search for Air Transporter on Youtube, or username notthat3 (there's a playlist), or follow the link (Hopefully kongregate allows links)
www.youtube.com/user/NotThat3#p/c/E60FB9D9D7DA0AEA
If you want a competitive highscores board, the scores should more accurately reflect the completion times. Sometimes I shave multiple seconds of a level with no change in score.
In fact I suspect that in some levels there is a maximum bonus score which is set to an achievable time frame, which is not what you want to do in a competitive game.
BaruMonkey, I've been stuck on it for a long time myself. You have to light the explosive on fire using the trees before throwing it. (BTW, don't bother with the catapult. throw it manually.)
Woohoo completed the game on hard. It has 11 levels, so don't despair thinking it has 50 hard levels.
The graphic is terrible, not because it's ugly but because it bothers the eyes. There's no reason to make a game with such graphics. I liked the difficulty though, just right. 4/5 because of the graphics.