EMAX ECO II 2807 1300KV

The EMAX ECO II 2807 1300KV is an FPV outrunner for propellers from 6 to 7 inches, intended for long-range and cinematic builds and permitted on 3 to 6S. EMAX is a Chinese maker of model-flying and FPV drive components. The magnets are N52SH arc magnets.

The 2807 stator is 28 mm in diameter and 7 mm in height, and the case measures 33.9 x 33.8 mm. The motor weighs 47.6 g without cables. At 1,300 KV it turns roughly 28,900 rpm unloaded on 6S (22.2 V nominal) and roughly 14,400 on 3S. The maker quotes a maximum thrust of 2,640 g on 6S; thrust only means something with a propeller and a voltage, and this figure is the peak thrust of a single motor, not a continuous thrust.

Thrust decides what a multicopter can carry: four motors give 10,560 g of peak thrust, and as a rule of thumb thrust should be at least twice the take-off weight, leaving reserve for gusts and climbing. That points to a take-off weight of about 5 kg as the upper limit for a four-motor build, and a 7-inch long-range machine in practice sits far below it. For long-distance flights the EU open category requires sight of the aircraft by the pilot or an observer, and from class C1 remote identification (Remote ID) is part of the equipment; the class depends on the weight of the whole drone.

Long-range drives run for long periods at an even load in cruise, so winding and bearings are the wear parts: the insulating varnish ages under lasting heat, and the bearings take in dust and moisture. When buying second-hand, turn the bell by hand: it should run smoothly, quietly and without notches, and the shaft must show no wobble. The SH magnet grade tolerates higher temperatures than the standard grade.