T-MOTOR U5 KV400 (U Power)

The U5 KV400 from the U-Power series by T-MOTOR, a Chinese maker, is a UAV motor for mid-size multicopters with propellers of 14 to 16 inches. The layout has 12 slots and 14 poles, and the housing measures 42.5 x 37.5 mm.

The motor weighs 195 g including the cable, 156 g without. At KV 400 and 22.2 V that works out to about 8,900 rpm at no load. It is rated for 3 to 8S, with 6S recommended. The continuous current of 30 A applies for 180 s. The maximum thrust of 2,850 g is a test-stand value with the 16x5.4 carbon propeller at 22.2 V, almost 15 times the motor's own weight; the P15x5 and P16x5.4 are recommended.

Four motors weigh 780 g with cable and 624 g without, with frame, ESC, battery and payload still to come. With every EU class limit the obligations change: C0 lies below 250 g, C1 below 900 g, C2 below 4 kg, C3 and C4 below 25 kg. Remote ID is mandatory for C1 to C3, and operator registration applies from 250 g take-off mass. A 6S battery at 22.2 V stays below 100 Wh up to about 4.5 Ah and then travels freely in hand baggage.

Because 3 to 8S are permitted, cell count and propeller together set the load; 6S is the recommended middle. For the weight budget it matters whether the cable is included. A propeller larger than recommended overloads motor and ESC. Check the bearing run, the winding insulation, the bell's concentricity and the magnet retention after impacts.