iFlight XING 8108 87KV

The iFlight XING 8108 87KV is a flat outrunner with 36 slots and 42 poles (36N42P) for heavy-lift drones and multicopters with long flight times. iFlight is a Chinese maker of FPV and multicopter drives. The case measures 87.2 mm in diameter and only 25 mm in height, the mass is 260 g, and the stator has a diameter of 81 mm and a height of 8 mm.

At 87 KV the motor turns very slowly: on 12S (44.4 V nominal) that is roughly 3,900 rpm unloaded, on 6S roughly 1,900. The high pole count gives high torque at low speed and suits large propellers. Permitted cell counts are 6 to 12S. The maker quotes 1,050 W and 21.7 A over 180 s; together they correspond to a voltage of about 48 V, which is the 12S range.

180 s is the longest time basis makers use for power figures and so the closest to continuous running; these values cannot be compared with peak values over 3 or 10 s. The span of 6 to 12S is a factor of two in voltage: the same power needs twice the current on 6S as on 12S, so controller (ESC) and cables must be sized accordingly. Anyone flying heavy loads must check whether the drone stays in the open category (up to 25 kg take-off mass) or moves into the specific category; the class depends on the weight of the whole drone.

With a flat, large-diameter rotor even slight bearing play has a strong effect: the bell tilts, the air gap to the stator varies and the magnets can rub. When buying second-hand, play, true running and roughness of the bearings are the main checks, followed by the phase resistances and the condition of the mounting. Because of the long flight times the winding insulation ages from sustained heat; discolouration or a burnt smell means overload.