Good weather, light wind, sunny, Had several launches that day. Mostly succesful. Below a few video’s:
Setting up:
You see me fiddeling around with a stick with a white end at some point, pushing that in through the nose cone and afterwards putting on the bottlecap again. That is the stick I use to push the magnet downwards in the tumbler canal. Thus setting the trigger for use.
Here the onboard video’s:
My second rocket was launched for it’s maidenflight, the airhose couldn’t stand the heat of the pumping and got so hot we had a meltdown... So half way I needed to fix the hose and get a bottle of water to cool the hose for more pumping, my Dad assisted me:
In retrospect I forgot something in the eject mechanism. The tumbler-tube which contains the tumbler magnet is open on the top side, this permits me to push down the magnet down the tube with a stick. Thus setting the trigger ready for use. The bottom of the tube is sealed with a small piece of styrofoam so the magnet doesn’t fall out of the bottom and renders the whole mechanism useless. The plug in the bottom however neds to be really tight because of the downward forces while the rocket is accelerating upwards. The magnet is about 8 grams and it’s mass is so slow that it wants to stay in place while launching, thus putting pressure on the plug. In my case I forgot to tape the plug down with ducktape. The plug fell out and the magnet too! And that was it! The results are below.
Looking at the onboard video’s it seems that the tumbler kicks in right after burnout (after acceleration comes decelleration) so the rocket hits the (air)brake and the tumbler, being an inert mass flies upward trough the tube (hit the brakes in your car hard with your dog on the backseat and see what happens to the dog, despite not being an inert mass).
To give the rocket some time to fly upwards after burnout we need a slower trigger. The suggestion from the group was: put the magnet in a pipe full of water and it will be slower due to visc(i)ous (couldn’t let that pass by) slowness. But I have a problem with that, I need to reset the magnet with a prodding stick, so I can’t close the tube tot hold the water, and I can’t lose the water in the cargobay because of the camera. And I want to be sure the magnet is in place in time, so the rocket doesn’t drop without the parachute.
The burnout time is different every time because I use a handpump to pressurize the rocket, so basically the tube itself is Ok, that goes whenever ready. After the tumbler is in it’s place to pull in the trigger, I’m sure the chute will go out. So my idea is to slow down the trigger. We know Ikea sells everything, they sell triggers too! These are used to dampen the closing of cupboard doors, you throw the door closed and the damper catches it and slowly releases either air, or a liquid goes through (I believe air, thats more easy (= cheap) to make) and the door closes gently after half a second or a second orso. I’ll get these dampers this week and see If I can modify for rocket use.
