Electromagnetic scattering from propellers of smallsized Unmanned Aerial Vehicles (UAVs) is studied in this work. Previous works have shown that rotating propeller blades produce significant fluctuations of the Radar Cross Section (RCS) in the case when the propeller length is about half a wavelength of the illuminating wave. To some extent, this facilitates both the measurement of the RCS in anechoic chamber and the detection of small-sized UAVs. In the present contribution, these studies are extended to the case of multiple propellers, between which an electromagnetic coupling is expected. The scattered field and the RCS is calculated by means of electromagnetic simulation using an integral equation formulation, and the theory is validated against anechoic chamber measurements.