A method for measuring a windspeed vector is described. A true airspeed vector of a flying machine is measured while the machine is in flight using one or more nanowires on the flying machine. Each nanowire is configured to measure a value of local air velocity relative to the flying machine. A velocity of the flying machine relative to the ground is measured while the machine is in flight, and then (a) the true airspeed vector is subtracted from (b) the velocity of the flying machine relative to the ground. Other applications are also described.