This blog covers the day to day progress of water rocket development by the Air Command Water Rockets team. It is also a facility for people to provide feedback and ask questions.

Thursday, January 07, 2010

Flight MicroLab - Mercury Switch Experiment

One of the things we want to fly this weekend at Doonside is a small science experiment. The main intention is to demonstrate how mercury switches behave during flight. It is a very common question we get asked all the time. "Why not use a mercury switch to detect when the rocket tips over at apogee?" ... it's a reasonable question since the system works well on the ground.

I thought video taping what they actually do in flight should give people a better understanding why they don't work the way they think they should.

Experiment setup:

There is a small digital video camera looking through a lens at a set of three mercury switches. Two are mounted the way people would typically mount them and the other is mounted upside down. They are wired to an LED each so you can see when in flight they actually activate. There is also a light source (white LED) above them so the mercury can be clearly seen. There is also a barometric recording altimeter mounted on the side to correlate the activation timing of the switches vs altitude/speed.

The parachute will be set to deploy later than normal so we can see what happens through apogee and somewhat beyond. After we have flown it I'll post the results to our regular website again.

Here is the MicroLab before being installed in the rocket. The rocket will be a Polaron style rocket of around 9.5L. capacity. The rocket is made up of the old Acceleron V bottles so we will be launching it at only about 110psi.

Front view

Back view with power turned on

View from inside the experiment


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