KDE Direct KDE2306XF-2550

The KDE Direct KDE2306XF-2550 is a small outrunner with a high KV value (12N14P) for 5 to 6-inch racing and FPV multicopters. KDE Direct is a US manufacturer of drone drives. The type has been discontinued. The stator class 2306 stands for 23 mm diameter and 6 mm height; the motor weighs 29 g (42 g with cables) and measures 28.3 x 18 mm.

At 2,550 KV the motor turns roughly 37,700 rpm unloaded on 4S (14.8 V nominal) and roughly 47,200 on 5S. Permitted cell counts are 2 to 5S. KDE quotes 34 A continuous current over 180 s, the longest time basis makers use and so close to continuous running. The thrust of 1,460 g was measured with an HQ 6x4.5-inch propeller on 4S, which is about 50 times the motor mass. Propellers up to 8 inches are permitted, up to 6 inches on 4S.

The propeller limit depends on cell count: a larger propeller draws more current, and on 4S the maker limits it to 6 inches. The current and thrust figures hold only with a propeller and a voltage, and the 34 A over 180 s only with enough airflow over the winding. Motor, speed controller (ESC) and battery must carry the chosen cell count. For the rules the weight of the whole drone counts; a 5 to 6-inch racing quad normally sits above the 250 g of class C0.

Because the type has been discontinued, a replacement should have the same 2306 stator class, the same hole pattern and a suitable shaft size. On used units the bearings (roughness, play), the shaft (wobble) and the magnets in the bell should be checked; overload of the winding shows as dark varnish. The combination of 12 slots and 14 poles is the common pattern for 5-inch motors.