Unmanned aerial vehicles are expected to complete their missions even in adverse weather conditions. Overheating in the engine area may occur, particularly at high speeds due to using the full engine throttle. Another design factor that affects endurance duration and maximum take-off weight is the weight of the unmanned aerial vehicle heat exchanger. In this paper, a new type of air-cooled fuel cooler heat exchanger is proposed to reduce the total weight of the heat exchanger by increasing cooling performance through the design flexibility offered by additive manufacturing. The printed circuit heat exchanger has a circular cross-section to prevent dead bends in the heat transfer surfaces and feed coolant air directly onto the fins and circulation pipes. Twisted fins and piping structure were adjusted so they could be produced without any support, generate turbulence, and reduce total weight. The fluid flow and heat transfer characteristics of novel and conventional heat exchangers were simulated in 3-D. The flow physics of both exchangers were studied to determine how the new design enhances heat transfer. Numerical results showed that the new heat exchanger has 55.6% more cooling capacity than the conventional one. The heat exchanger weight was decreased from 774g to 263g.