Hydroaeropropulsion Rocket Research Labs

24 april 2002

Connecting the bicycle hose to the cork

A 5 litre bottle comes in handy to refuel rockets

The launcher ready for filling the rocket with air. Our launcher basically is a plank with a hole in it; the bicycle hose fits through that hole. We connect the cork to the hose, press it against the plank so that the cork fits snugly inside the bottle opening, move the little metal plates in place ,...

and start pumping!

The rocket is pressurized and pushes upwards, but the two metal plates keep it in place. The only thing needed now ...

is a gentle tug to the rope!

The Hilde I being prepared for launch: we press the cork in the bottle by pushing it against the plank.

And push :-) The metal plates are not yet in place.

The metal plates are again holding the bottle in place. You can see clearly see the function of the rope.

The result of all our work ...

When the bottles come down, they are filled with a very fine water vapour, almost looking like white smoke.

A bigger one this time! 1.5l instead of 0.5.

Pumped up and good to go!

Another succesful one ...

I think this is Hilde I again.

During the evening, we did some more launches. We made a simple goniometer and used it to measure the maximal height of the rocket, giving us about 10m. This seemed lower than our earlier launches, and indeed: launching manually (i.e., by pushing the bottle against the plank by hand and not with the metal plates) gave much greater heights! The reason seems to be that using the launcher, the metal plates cannot fully keep the bottle in place when pressurized: it lifts for a few millimeters, while the cork stays in place (since the cork is pushed downwards by the water and the buttle upwards!). This causes a few millimeters of cork to be exposed and expanded by the pressure, causing much wear and tear on the cork and allowing water to leak. Launching manually, we can push the bottle hard enough against the plank to keep the cork fully inside the bottle and no water at all leaking.