What goes up

I came home from work to find the girls playing with these catapult helicopter things their gran brought back from her holiday. You know the things, fire it up in the air with the elastic band launcher and it whirls it's way back to earth. Even better in the dark as they have a blue LED.

So I say "be careful you don't lose it into nextdoors garden".
Then Emma has a go and I say "that's not very high, let me show you how it's done........"