This week the items that we ordered last week arrived. This allowed us to do more pretests, namely the thrust of our propellers and the drop speed of a weight with a parachute. On Thursday we prepared these tests at the lab. First, we filled a tupperware container with water to weigh about 1kg, since this is the expected upper bound for our device weight. We then attached the two 54-inch parachutes to the container and secured it with the duct tape.
We walked these items over the Pausch Bridge, and tossed them off, while one of us recorded a video of the drop from a distance. The video indicates a time from release to landing of about 3.8 seconds. This is approximately the amount of time during which the device can operate, and it is very close to the amount of time we anticipated. Video.
Meanwhile, we also began creating an apparatus to measure the thrust of the motors and propellers. The apparatus consists mainly of a motor and propeller mounted to some wood, placed on a scale, with a battery and PWM generator. An image of the full setup is attached below. With the propeller at full speed, the change in weight indicated by the scale provided us with a verifiable measurement of the thrust: 400g. Our test was not ideal, and it appears that some of the thrust was exerted onto the scale, because the arm may have acted as a moment arm. To remain on schedule we are accepting these results and moving on. As a form of early risk mitigation, we are researching thermal cameras as an alternative to antennas.