VTOL aircraft including a reconfigurable battery thermal regulation system

1. A vertical take-off and landing (VTOL) aircraft having a propulsion system reconfigurable between a horizontal flight configuration and a vertical flight configuration, the VTOL aircraft comprising:

an aircraft air inlet and an aircraft air outlet;

a battery pack comprising battery cells;

a reconfigurable battery thermal regulation system comprising (i) a first air channel, a surface of which is in thermal communication with the battery cells so that air flowing through the first air channel exchanges heat with the cells through the surface, (ii) a second air channel, (iii) an airflow device arranged in the second air channel, and (iv) actuating means; and,

a controller configured to control the actuating means so as to cause the reconfigurable battery thermal regulation system to switch between a first mode of operation for horizontal flight of the VTOL aircraft and a second mode operation for vertical take-off and landing of the VTOL aircraft, wherein:

in the first mode of operation, the controller controls the actuating means so that the first air channel is fluidly connected with the aircraft air inlet and the aircraft air outlet whereby, during horizontal flight of the VTOL aircraft, air can enter the aircraft through the air inlet, flow through the first air channel and exit the aircraft through the air outlet; and

in the second mode of operation during vertical take-off and landing of the VTOL aircraft, the controller controls the actuating means to disconnect the first air channel from the aircraft air inlet and the aircraft air outlet and connect the first air channel to the second air channel to form a closed loop in which the first and second air channels are in fluid communication so that the airflow device drives an airflow through the first and second air channels.

2. The VTOL aircraft of claim 1 , wherein the airflow device is reversible, whereby a direction of the airflow driven through the first air channel by the airflow device is reversible.

3. The VTOL aircraft of claim 2 , wherein the controller is configured to control the reversible airflow device so that, in the second mode of operation, the direction of the airflow through the first air channel is periodically reversed.

4. The VTOL aircraft of claim 1 , wherein the reconfigurable battery thermal regulation system further comprises a cooler for cooling the airflow driven by the airflow device through the first channel.

5. The VTOL aircraft of claim 1 , wherein the reconfigurable battery thermal regulation system further comprises a heater for heating the airflow driven by the airflow device through the first channel.

6. The VTOL aircraft of claim 1 , further comprising an adjustable airflow regulator for regulating the airflow through the first air channel.

7. The VTOL aircraft of claim 1 , wherein the first air channel comprises a plurality of parallel air channels.

8. The VTOL aircraft of claim 7 , further comprising one or more additional channels arranged to carry a flow of liquid in a closed loop, wherein a portion of the loop is in thermal communication with the battery cells so that liquid flowing through the one or more additional channels exchanges heat with the cells.

9. The VTOL aircraft of claim 8 , wherein a portion of the loop of the one or more additional channels follows a serpentine path.

10. The VTOL aircraft of claim 8 , wherein the one or more additional channels are arranged so that the one or more additional channels form a non-zero angle with the horizontal.

11. The VTOL aircraft of claim 8 , wherein the first air channel, or each of the plurality of parallel air channels, has a larger cross-sectional area than each of the one or more additional channels.

12. The VTOL aircraft of claim 8 , further comprising means for draining the one or more additional channels of liquid.

13. The VTOL aircraft of claim 1 , wherein the first air channel is an integral part of the battery pack.

14. A method of controlling a vertical take-off and landing (VTOL) aircraft having a propulsion system reconfigurable between a horizontal flight configuration and a vertical flight configuration,

the VTOL aircraft comprising:

an aircraft air inlet and an aircraft air outlet;

a battery pack comprising battery cells; and

a reconfigurable battery thermal regulation system comprising (i) a first air channel, a surface of which is in thermal communication with the battery cells so that air flowing through the first air channel exchanges heat with the cells through the surface, (ii) a second air channel, (iii) an airflow device arranged in the second air channel, and (iv) actuating means,

wherein the reconfigurable battery thermal regulation system has a first mode of operation for horizontal flight of the VTOL aircraft and a second mode operation for vertical take-off and landing of the VTOL aircraft; and

the method comprising:

in the first mode of operation, controlling the actuating means so that the first air channel is fluidly connected with the aircraft air inlet and the aircraft air outlet whereby, during horizontal flight of the VTOL aircraft, air can enter the aircraft through the air inlet, flow through the first air channel and exit the aircraft through the air outlet; and

in the second mode of operation during vertical take-off and landing of the VTOL aircraft, controlling the actuating means to disconnect the first air channel from the aircraft air inlet and the aircraft air outlet and connect the first air channel to the second air channel to form a closed loop in which the first and second air channels are in fluid communication so that the airflow device drives an airflow through the first and second air channels.