HOBBYWING XRotor 1408 Race Pro 2400KV

The HOBBYWING XRotor 1408 Race Pro 2400KV is a small FPV outrunner with 9 slots and 12 poles (9N12P) for 3-inch builds in the 130 mm class. Hobbywing is a Chinese maker of drives and speed controllers. At 15.8 g without cable, the motor is among the light drives for small, fast quadcopters.

The stator is 14 mm in diameter and 8 mm in height, and the case measures 19 x 16.3 mm; the dimension gives rotor diameter and case length. At 2,400 KV the motor turns up to roughly 53,300 rpm unloaded on 6S (22.2 V nominal). As values over 30 s the maker quotes 9.31 A and 223.6 W; the values at full throttle are higher, at 12.97 A and 311.5 W. The thrust of 637 g was measured with the Azure 3060 propeller at 24 V.

Time basis and test condition have to be read along with the figures: 223.6 W holds for 30 s, and 637 g of thrust only with this propeller and this voltage; a different propeller shifts both. Motor, speed controller (ESC) and battery must carry the same cell count, here 6S. For the rules, the weight of the whole drone decides: a quadcopter of this class with a 6S battery and a camera, ready to fly, sits only just below or above 250 g; with a camera, operator registration is due regardless of weight, and class C0 covers masses below 250 g.

In a 15.8 g motor the shaft is more delicate than in a 5-inch motor. Small bearings suffer from sand and dust, and because the bell has little mass it tolerates hard impacts only to a limited degree. The checks are the turn by hand (quiet, even), shaft wobble at the propeller seat, the winding resistance of the three phases and the condition of the cables where they leave the motor. Thin cables break at the bend.