Water rockets are loads of fun to experiment with.
The following instructable shows the construction and use of a zip tie based release mechanism.
Length of fluorescent tube protector (source TAP plastics)
Zip ties, enough for the circumference of the launcher
The photos should make the construction steps clear.
This is my first instructable. All work creating this instructable was done on my Android device.
Step 1: Water Rocket Launcher, Rocket,
Step 2: Rocket Detail
sticker from my favorite record store
Step 3: Sheath, Release Mechanism
holds the zip ties in lock position
Step 4: Zip Tie Based Release Mechanism Detail
Detail of release mechanism. The zip ties are attached to the pvc launcher tube with duct tape
Step 5: Zip Tie Mechanism With Sheath
The sheath is what holds the zip ties in place.
Step 6: Zip Tie Mechanism Detail
Step 7: Rocket And Launcher
Rocket loaded on the launcher before securing
Step 8: Rocket And Launcher Detail
Step 9: Rocket View From Nose
Step 10: Rocket Loaded Detail
Step 11: Rocket Loaded Detail
another detail view
Step 12: Close Up Rocket Loaded Before Securing
note how the sheath is not fully covering the zip ties
Step 13: Close Up Rocket Secure
note how the sheath covers all of the zip ties.
Step 14: Video Of Launch
The video shows usage of the launcher with the release mechanism.