Awhile ago my fellow during one of our weekly LabChats the topic of conversation we discussed the possibility of using an air cannon as the first stage of a model rocket. Here's a video from a creator who is exploring that possibility. He's using microcontroller to determine when the vehicle reachers the highest point in it trajectory. I think we could do much better, but I'd like to share this and see what everyone thinks. Enjoy!

Here's a very interesting physics demo, or perhaps a cheap practical solution for pumping water where efficiency isn't important. No moving parts, but some of the water is pumped above the head waters of the system. A good technique ore mad scientists it keep filed in the back of their minds for a rainy day. Enjoy