Most likely if you have ever experimented with getting a
parachute to deploy with a water rocket you have discovered the challenge in
getting completely reliable operation. Compounding to the problem is that when
the parachute fails to deploy properly the rocket is so smashed up when it hits
the ground that any mechanism is broke so that you cannot see what state it was
in before it should have deployed.
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| Parachute Deployed Perfect This Time |
The first water rockets I built with parachutes I just set
the nose loose on the rocket hoping it would stay on until the top of the
launch. This did work some of the time maybe half the time but failing even
once can break the rocket. I tried to
design some type of shock absorbing nose tip that would hopefully save the
rocket from destruction when it hit full speed with no parachute. One of the
first rockets of this type I used part of a foam small football on the end of
the nose. There would be some launches
the parachute would come out too soon and it would never get very high.
I had read somewhere about people using the wind up
mechanism that comes in some toys that walk commonly referred to as the “Tomy Timer”. This mechanism can also be used in free
flight model airplanes and that is where I found a source for some of the
wind-up mechanisms. My first rocket to utilize appeared to work fine on the
ground but launch testing it is a whole different situation. First launch worked perfect and luckily I
took pictures because the rocket would be destroyed soon afterwards.
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| Pin was pulled out by string attached to plastic arm |
My idea on the first rocket was to have the timer mechanism
hold down one side of a compression spring. When the timer mechanism was
released to turn it would pull out a small pin that would let the compression
spring push a rod that would push off the nose of the rocket letting the
parachute deploy. After breaking the first rocket I would even try a second
rocket like this with the same results.
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| Rod seen on side of nose pushed nose off |
My theory to what was happening is that the rod did push the
nose off the rest of the rocket but the air pushing against the nose was pushing
the nose back down again before the parachute could deploy. These were rockets
based on 2-liter bottles and like the saying goes, “the bigger they are, the
harder they fall”.
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| Next idea of pushing the nose off picture C is broken timer after crash |
All though frustrating, I find that failure can be a good
teacher and forces one to think of the challenge before you in greater detail.
Bill Kuhl
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