Propulsion

Initially assumed to be negligible, the torque produced by one propeller was enough to cause a major path deviation. Thus, we soldered an additional counter-rotating motor to the ESC to counter the torque. Additionally, since the propellers now have to control pitching as well, another servo motor must be attached to the yawing servo motor such that when the propellers are pitched, the yawing motor pitches along with them. It operates in a similar way to a pan-tilt system.

Avionics

 

To secure both propellers on to the yawing servo motor, a propeller holder was printed and the motors’ casings were hot glued to the holders. The yawing servo was secured to the arm of the pitching servo using a hot glue gun.

Payload

For this prototype, we finally included our payload: the speaker! It has a hefty weight of close to 90g. In order to attach it to the balloon, we did not want to stick it on directly as we feared that it might tear the Mylar due to its sheer mass. Instead, we opted to punch holes in the seams – 2 on each side – with one pair being closer to the front and the other pair closer to the CG. Strings were tied to connect each pair and were hanging below the balloon. The speaker was then hung on the strings.

Flight

Post-Flight Review

As the propulsion system was mostly secured to the balloon by tape, there were major perturbations whenever we moved the joysticks to control the servos. Hence, we decided to redesign a more stable and rigid system.

Sadly, path deviation was still observed. However, minute corrections by trial and error has allowed for a ~6m straight flight. This appeared to be the furthest it can fly straight without any manual steering. Once steering is introduced, we were able to fly at a straight line with no issue provided small yawing adjustments were made.

In addition, the new pitching mechanism was ineffective when the speaker was introduced. This made us questioned if it was worth to add the speaker since it would compromise the pitching ability of the blimp.

Balloon

The same balloon in Version 2 was used. No further modifications would be made since it has a sufficiently large lift.