Rocket Science

Every year at Whitsun me and a couple of friends leave Leipzig for a weekend out in the nature. Like last year, we've chosen my family's house in Obergeißendorf as this year's destination. Packed with a proper Hi-Fi setup consisting of Robert's turntables, a ton of vinyl, loudspeakers, my amp and heaps of cables accompanied by other DJing gadgets some of us arrived on Thursday. The rest of our 14 people strong party came the day after. It's been six days of relaxing, music, lot's of air-dried sausages, barbecue and draught – mostly outside in the chill winds of Thuringia.

More pictures can be found over at Gunnar's site.

The most fun part was the "rockets" we built based on a rocket game set for kids Christiane gave Marci and me last Christmas. It contained a book with instructions for making rockets in order to fulfill three missions. The First Mission was pretty lame (conceivably not for kids), i.e. you had to put two pieces of cardboard together and weight the rocket's nose with a bit of modelling clay. Then fire off the whole thing with a slingshot-like device.

Marci and Robert, both filled with the engineer's spirit, didn't stop there and tried to accomplish Mission Two. You need some more stuff, here's a quick list:

An empty PET bottle, size doesn't matter
The cork from a bottle of wine, it should fit tightly in the bottle's opening
Air pump with a ball valve
Water
Gaffer tape (Tappe™), depending on how sophisticated your rocket should look
Something to use as the launching pad (we used stones)

We took the following steps to build and start the rocket:

Prepare the PET bottle rocket as you wish, for example you may add stands and an aerodynamic nose – see below for our construction.
Pour water into the bottle until one quarter is filled. You can experiment with how much water you put into your rocket later.
Stick a thin hole through the cork so that the ball valve gets through it.
Put the cork into the bottle's opening.
Put up the bottle upside down on your launch pad.
Pump until the pressure inside the bottle forces the cork to shoot out of the bottle and the rocket starts.

I wish I had one of those alluring Tablet PCs to illustrate the building process better. You may have a look at various web sites that describe the issue and the physics behind it.

We had so much fun starting the rocket over and over again. Unbelievable! :-)