Flying unmanned aircrafts in winter conditions requires more caution than during other seasons since the cold has a significant impact on the functioning of electronic components and thus the device’s behaviour while flying.
The LiPo batteries, which can be found in most unmanned aircrafts, are especially sensitive to cold as their capacity and power change drastically when temperatures drop. The diminished capacity of batteries results in shorter flight time, which is something that needs to be taken into account when planning the length of the flight. It is therefore important to always check whether the batteries are really full before the flight. Taking a full spare battery along when setting out on the field is highly recommendable so as to prolong the time of using the aircraft. Furthermore, the aircraft and the batteries should be kept in a warm place (in the car, in a warm casing etc.) for as long as possible prior to take-off. It is also important not to fill cold batteries until they reach the room temperature as this extends their useful life. Despite all these measures, we should expect shorter flight time and save some of the battery power to ensure safe landing in the event of unfavourable weather conditions (wind, fog etc.).
Once the aircraft is brought from a warm place and into the cold, it should be left for a few minutes so that is can acclimate before being activated. During this time, the sensors stabilise and adapt to the surrounding situation. Ideally, the aircraft should be calibrated and adapted outside, so that it can adjust to the actual situation. Great temperature changes (i.e. inside vs. outside temperature) can cause the aircraft’s camera lenses to fog up, and although moisture can start condensing on the cold electronic components, this problem usually disappears once the aircraft acclimates.
If there is a great deal of moisture in the air and the temperatures are close to the freezing point, parts of the aircraft can start freezing. The ice on the propeller diminishes the aircraft’s capabilities, increases the battery power consumption and can even result in defects. The possibility of freezing can be ascertained by conducting a brief test flight.
Checking the visibility of the surroundings is also part of flight preparations as fog can greatly reduce visibility and the ability to identify objects in the environment. For the flight to be safe, it is essential to always keep the aircraft within one’s field of vision.
When flying over areas covered in snow, one should bear in mind that great white expanses and dispersed light can create an optical illusion that the ground is flat and the relief is not raised. This can confuse the aircraft’s landing sensors, causing the aircraft to land with great force. A softer landing can be achieved if the landing area is “improved” by artificially breaking up the monotonous white snowy surface (e.g. with tyre tracks, footprints, sand etc.).
After the landing, the snow should be removed from the aircraft and the accumulated moisture wiped off, and the device should be stored somewhere dry and warm.
The senseFly eBee used by Geavis is tried and tested for work within the temperature range from -15 °C to +35 °C, and its electronic components are constructed for operation in the range from -20 °C to 50 °C. The aircraft’s housing is made of flexible expanded polypropylene (EPP) foam, which does not react to the cold by becoming hard and fragile. All this enables a safe use of the aircraft even in the harshest climate conditions.
