Abandoned project

under contruction water rockets

Water rocket apogee home page


Abandoned project

Expired overview on my abandoned 20L project.
Final goal was a 380 cm long rocket with a pressure vessel of 20 liter.
Reason for abandoning it was the long rockets had to high drag and limitations on maximum pressure.
For reference this page is kept.
Feel free to learn from it or to comment see link on index page.
If successful it must be able to reach an altitude of 500 meter, my personal goal.

Project status ->abandoned
Design: finished, for pressures up to 14 bar.
Pressure vessel: construction now at 14 liter / length 260 cm.
Fins: 4: ready.
Release mechanism: mechanical timer, tested once at 30 January on 3.8L rocket.


Plan:
1: Do some more test launches with mechanical timer on 3.8L rocket, to better determine the reliability of the mechanical timer release mechanism.
2: Do test launches with 14L @ max. 14 bar, to see stability of rocket, deployment and recovery.
3: Add altimeter to have my first logged altitude measurements, for better judgment on chances for success of the 20L concept.
4: Increase volume to 20 liter, goal is +400 m apogee @ 14 bar.
5: Then redesign / reinforce pressure vessel so it will hold 18 bar -> ++500 m???.


A chain is just as strong as its weakest link. This is a fact of live and it is used for the construction of the 20 liter pressure vessel. The approach I use is first to join two bottle halves with a sleeve and pressure test it. Then make a same pressure vessel and test this if it can hold the pressure.

If both pressure vessels are tested ok i join them. In this way you find the weaker joints / bottles before pressure testing the whole assembly. With the size of rocket i'm trying to build this looks the only reasonable approach to me. You can't build the 20 liter vessel without pressure testing it in between. The chance that one of the 20 bottles or 15 glued joints is weak is to high.
body halves
Picture on the right shows three bottle halves joined. Tested to 220 psi.
 body halves
On Feb. 3 the pressure vessel has grown to 260 cm in length and a volume of 14 liter. Ready for pressure testing. On the picture to the right the body looks as if it is curved a little but this is an distortion effect of my little digital camera.
Pressure vessel is now ready for final pressure testing.
Next construction step is to assemble the rocket (add fins / release mechanism and chute-bay.) 		14l pressure vessel on the floor
Pressure vessel without fins / release mechanism on the launcher.
Launcher footprint is to small, has te be increased for more stability.
 14l pres vessel and me


After the pressure test, wheather permitting, some test launches to see if the 20 liter concept is going to work.
What i have in mind is launches at increasing pressures up to 14 bar / 200 psi, apogee according to simulator 332 meter. For the release timer i will use the mechanical timer as described on the construction pages. The maiden test flight of the mechanical timer was on 30 jan. 2005 and went ok (see 190 psi launch).