Parallel dual-engine coaxial unmanned helicopter

The invention relates to a parallel dual-engine coaxial unmanned helicopter, belongs to the technical field of aircraft and aims to solve the problems that the prior aircraft is poor in carrying capacity and low in reliability. Two engines are symmetrically arranged and fixedly connected to the lower portion of a connection frame; a power coupler is fixedly connected to the middle of the connection frame; a reducer is fixedly connected to the upper portion of the connection frame; four belt drive sets are symmetrically arranged; each belt drive set is connected with an engine output shaft, a power coupler input shaft, a power coupler output shaft and a reducer input shaft on one side of the belt drive set; power of the two engines is decelerated by the belt drive sets, is collected and outputted by the power coupler, is transmitted to the reducer through the belt drive sets, and is transmitted to upper and lower rotors through two coaxial hollow spindles. Variable pitches of the upper and lower rotors are controlled through two independent pitch varying sets respectively. Power is centrally output after the power of the two engines is coupled; the parallel dual-engine coaxial unmanned helicopter is high in reliability, simple to control and reloadable.