Methods of taking a measurement

A method of taking a measurement using a sensor mounted on an aerial vehicle, wherein said aerial vehicle is a fixed-wing aerial vehicle, and wherein said sensor is operable to take a measurement of an object other than the aerial vehicle, the aerial vehicle having one or more propellers and one or more motors which are selectively operable to spin the one or more propellers to rotate to cause the vehicle to fly, and a sensor mounted on the aerial vehicle, wherein the aerial vehicle further comprises a controller which is operably connected to the one or more propellers and the sensor, the method comprising the steps of,

• operating the one or more motors to rotate the one or more propellers at a speed that is sufficient to cause the vehicle to fly;
• detecting when a predefined condition is fulfilled, and/or, receiving a command at the controller;
• at a first time instant, the controller effects slowing down said one or more motors so as to reduce the speed at which said one or more propellers rotate, in response to detection that the predefined condition is fulfilled and/or in response to receiving a command at the controller;
• at a second time instant maintaining the aerial vehicle at a substantially constant altitude using lift force provided by the fixed-wing, for a time duration;
• while the aerial vehicle is maintained at said substantially constant altitude, the controller effects the sensor to take a measurement of an object other than the aerial vehicle, during said time duration;
• detecting at the controller when the sensor has taken said measurement, and at a third time instant, which is after the measurement has been taken by the sensor, the controller effects operating the one or more motors again to rotate the one or more propellers at a speed that is sufficient to cause the vehicle to fly, in response to detecting that the sensor has taken said measurement.