SunnySky V2806 KV400

The V2806 KV400 from SunnySky, a Chinese maker, is a light outrunner for small to mid-size multicopters with long flight times. The type code gives a stator of 28 mm diameter and 6 mm height; the motor measures 35 mm across and 18 mm in height on the outside.

It weighs 47 g and its KV is 400. It is rated for 4 to 6S, and the recommended propellers run from EOLO CN11x4.5 to CN15x5.5. With the CN13x5 at 25 V it delivers 1,260 g of thrust, about 27 times its own weight. The continuous current of 10 A applies for 180 s, and the maximum power of 250 W corresponds to those 10 A at 25 V. Both values depend on this time base and on the voltage; they cannot be compared with figures resting on 10 s or 30 s.

Aircraft designed for long flight times carry large batteries. For air transport the rule is: up to 100 Wh, lithium batteries travel freely in hand baggage; from 100 to 160 Wh only with the airline's approval; above that they may not travel as passenger baggage. For EU classification the take-off mass of the whole aircraft counts: C0 below 250 g, C1 below 900 g, C2 below 4 kg.

Anyone designing for endurance picks large propellers with moderate pitch and flies near the hover point, not at peak thrust. Bearing play and out-of-round bells cause vibration that reaches the flight controller's sensors. Also check the magnet retention and the winding insulation after an overload.