Low battery RTH and flight time

Return to home can be triggered automatically due to low battery. This article describes the parameters considered for triggering RTH and provides recommendations on optimizing the battery consumption.

In optimal conditions, the time to trigger low battery RTH is computed and it should happen after approximately 45 min with the RX1RII camera and the PPK module and 50 min with the QX1 camera. However, RTH can be triggered earlier so that a safe landing is always ensured. 

During the flight, it is estimated the amount of battery that the WingtraOne needs to safely return to the home point. For the battery estimation, the following parameters are taken into account. 

Absolute altitude (above mean sea level) of the home point

Increasing the absolute flight altitude, the density of the air decreases. In those conditions, the motors need more power to generate the thrust required for the flight, so the battery consumption increases. For more details about this parameter and what to do in order to ensure longer flight time, check this article.

Distance to home position

For mapping large areas, the drone flies far away from the home point. As the distance between the drone and the home point increases, the drone needs more battery for a safe return; therefore the RTH will be triggered at a higher level of remaining battery. To delay the low-battery RTH try the following:

  • if the terrain allows you, keep the home point closer to the mapping area
  • move the home point closer to the remaining part of the area after resuming a mission

For more details on how to map large areas, check this article.

The wind speed and direction

In windy conditions, the drone consumes more energy. Consequently, the battery consumption is increased. More energy is required so that the drone flies safely to home, so RTH is triggered at a higher battery percentage. For recommendations about flying in windy conditions see this article

Transition height

By increasing the transition height, the drone spends more time hovering up or down and it consumes more energy therefore, to achieve a safe landing the RTH will be triggered earlier. For more details about the transition height, how does it influence the RTH and what to do in order to delay it, check this article.

The biggest impact on battery consumption has the transition height. To extend the flight time, we suggest reducing this parameter, taking always into account all obstacles near the home point. Reducing the time that WingtraOne will spend in hover during takeoff and landing leads to an increase in the total flight time.

Minimum RTH height

This safety parameter has a similar impact on the flight time as the transition height. Loitering up and down for a longer period increases the required battery level. The impact of the transition altitude is clearly stronger than the RTH altitude. 

Flight time

The following tables present the flight time expectations and the percentage of low-battery RTH at different altitude levels for different environmental conditions.

Maximum flight time in optimal conditions (transition altitude: 20m, wind speed < 1m/s, furthest distance from home: 1.2 km, air temperature: 15 °C)

 

Payload Take-off altitude AMSL Low battery RTH % Post-landing battery % Max. flight time
QX1 20mm, no PPK 0-500 m  15-25% 5-15% 59 min
QX1 20mm, no PPK 2000 m 30-40% 20-30% 47 min
RX1RII - PPK 0-500 m 15-25% 5-15% 52 min
RX1RII - PPK 2000 m 30-40% 20-30% 40 min

 

Maximum flight time in default conditions (transition altitude: 50m, wind speed < 3m/s, furthest distance from home: 1.2 km, air temperature: 20 °C)

Payload Take-off altitude AMSL Low battery RTH % Post-landing battery % Max. flight time
QX1 20mm, no PPK 0-500 m  15-25% 5-15% 54 min
QX1 20mm, no PPK 2000 m 30-40% 20-30% 42 min
RX1RII - PPK 0-500 m 15-25% 5-15% 47 min
RX1RII - PPK 2000 m 30-40% 20-30% 35 min

 

Flights performed at high altitudes (above 2500 m AMSL) are only possible with high altitude propellers and they are shorter than flights performed at lower altitudes.