[docs]defmass_gas_engine(max_power):""" Estimates the mass of a small piston-driven motor. Source: https://docs.google.com/spreadsheets/d/103VPDwbQ5PfIE3oQl4CXxM5AP6Ueha-zbw7urElkQBM/edit#gid=0 :param max_power: Maximum power output [W] :return: Estimated motor mass [kg] """max_power_hp=max_power/745.7mass_lbm=6.12*max_power_hp**0.588mass=mass_lbm*0.453592# to kilogramsreturnmass