Of course you can pressurize your rockets with a bicycle pump. But I can assure you that filling a 10L rocket with air up to 10 bar
is quite an exercise!, especially if you want to launch your rocket a couple of times. I think it is a lot more fun when this job is
done by a portable compressor.
Thats why I made my pumping station, see the picture below. Its easy to carry, water supply in bottles are included. The station has two pumps, one (the yellow one)
is for filling the rocket remotely with water and to pressurize the rockets up to about 3 bar, this pump can deliver quite a high volume but is limited in pressure.
The other pump (the black one) is for the higher bar regions, it is capable to pressurize rockets up to 17 bar. This is far above the pressure my rockets can handle at the moment
The power comes from a car starting aid, which contains a sealed lead-acid battery from 12V / 17Ah, sufficient energy for a couple of launches on high pressure.
See the schematic drawing for the working principle, it is self explaining. The valves are put in place to separate the two pumps, the low pressure pump cant handle the high pressures
that are generated by the high pressure pump and to prevent that water is pumped into the high pressure pump, during water fill.
A drawing of the working principle of the pumping station.
Low pressure pump for water fill and pre-pressurization.
High pressure pump for final pressurization.
Two valves prevent water flow to high pressure pump and high pressure on water bottle.
The valves
The valves section is made from valves you find on bicycle tires. Best are the ones with an internal piece of soft plastic that stops the reverse flow
(as opposed to the older types with an external rubber tube).
Remove the (black) plastic sealing ring and PL (polyurethane) glue it in a 6mm brass pipe (0.5 mm wall thickness). Before gluing "stretch" the brass pipe
a little so that the bicycle valve easily fits in the brass tube this to give the PL a chance to creep between both surfaces.
For my pumping station I made a T-pipe with two valves in the top part of the pipe and soldered (before gluing the valves) a pipe perpendicular and in the middel on to it.
See pictures for a visual explanation.
