8L Rocket
This was my first rocket made by joining 4x2L bottles together.
It only ever achieved two flights due to poor recovery system implementation. The first flight was launched at a low pressure of about 50 psi because the poorly constructed launcher was wobbling about.
Because of the wobbling a friend was holding the rocket, unfortunately he didn’t quite move his hand out of the way in time and the fins hit his hand on the way up, knocking the rocket off course.
The nose of at apogee parachute mechanism also deployed after only a few meters off the ground. I don’t know whether the hand knocking incident caused this or whether it was just poorly designed, I would expect the latter. This caused the parachute cords to rip off under the high speed and then as the rocket veered ever more off course, it plummeted into the ground. Since a low height had only been achieved, damage was minimal.
For the second launch it was decided to launch without the parachute since it was obviously not working and we wanted to get an idea of the height we could get out of the rocket. During pressurising the rocket, the launcher started to make a hissing noise at about 70 psi, suddenly the rocket just shot up into the air, with half the launcher still attached! The rocket flew off at an angle, over a bunch of trees and then crash landed in the middle of a pond. The rocket had quite severely buckled on impact. After retrieving it a few days later after it had drifted to the side, it was decided to retire it.
To join the bottles together I used 21mm PVC pipe and hot glue to make a seal. Below you can see one of the joints between the base of two bottles.
And another picture showing the joint between two bottle necks.
And a final picture looking down inside the rocket.
The rocket seemed to pressure test well up to around 80 psi, but with only a small foot pump at the time, I never managed to take it any further. I would in the future like to see how these types of joins standup to robinson couplings as they let a lot more air flow through them.