Yet Another Water Rocket Parachute Fail

If you have been reading my blog or website you might have noticed that I do not give up real easy when faced with an engineering challenge. Getting reliable parachute deployment has been an issue for many people that experiment with water rockets. I would like to find a simpler method than using a windup mechanism but I do not know what it would be. Some people have gone to electronic devices but I sure would like a simpler and cheaper solution.

Large Plunger on Rocket to Push Nose Off

After some success with my first rocket that used the windup mechanism that held back a compression spring and pushed a rod upwards to push the nose off, I thought that idea could still work with modification. My thought was if the push upwards of the nose cone had a longer stroke and more force behind it the nose would have to come off.

Two Tension Springs Pull Pushrod Upwards 

To accomplish this I used two springs under tension that pulled a rod up from inside the cottage cheese container that was part of my rocket. To make sure this great thrust upwards would always be pushing on the nose cone I created a round disk and then four dowels attached to the disk pushed against a ring inside the nose cone. The windup mechanism pulled a short string connected to a catch mechanism that held back the springs. Worked great on the ground.

Disk Removed to Show Mechanics

My theory of why it did not work in a real launch is; I believe that even though the nose cone was forced off, the force of the air at such high speed was pushing the nose back down. It almost impossible to know because everything happens so fast and the rocket is so far away at apogee. Examing the rocket after it crashed was of little help because it was broken so badly.

Four Dowels Push Against Ring

After three prototypes of the push off nose I decided it was time for a whole new approach which started my experiments with the side deploy parachute. To me this is rather ugly but it has been reliable after several test launches.

Bill Kuhl
http://www.ideas-inspire.com