One alternative we looked into is solar power. However, after some research, we found that solar cells are very inefficient and quite heavy, hence not suitable for flight. Also, lightweight thin solar films, though available on the market, are very expensive.
Another alternative we considered was helium. Upthrust from helium can offset some of the thrust provided by the drone battery, allowing the drone to expend less power to stay in air and hence fly longer.
However, helium balloons cannot be directly attached to the drone because the strings will get tangled up in the propellors and cause the drone to stall. We need to attach balloons to a rigid structure before it can be incorporated with the drone.
As drones fly in a similar fashion as helicopters – in that they tilt forward before flying in the desired direction – placing a structure on the drone will cause the entire system to overturn due to the moment caused by the forward tilt. This is undesirable and must be avoided at all costs.
Hence, we thought of building a gyroscope with two free-rotating axes so the drone can move freely with reduced unbalance to the entire system.
As a proof-of-concept, we made a cardboard gyroscope with one rotating axis and a mount to attach the drone. It turns out that cardboard was too heavy, even though it is stable and rigid. We decided to source and create prototypes with light but sturdy materials.
Our circular foam gyroscope was much lighter, but was too flimsy. It is too weak to withstand the strong thrust from the drone and loses its shape very quickly. Sadly, another unsuccessful attempt.
To confer rigidity to the gyroscope, we changed the shape of the gyroscope from concentric circles to squares. This greatly increased the hardiness of the gyroscope as the structure was less likely to bend or lose shape when a force is applied to it. A square shape also makes it easier to attach balloons during the later stages.