Analysis and study of the influence of the geometrical parameters of mini unmanned quad-rotor helicopters to optimise energy savingPenkov, Igor; Aleksandrov, DmitriInternational journal of automotive and mechanical engineering2017 / p. 4730-4746 : ill https://doi.org/10.15282/ijame.14.4.2017.11.0372 Journal metrics at Scopus Article at Scopus