Optimization of thrust and fuel efficiency in low-altitude UAV engines through experimental design and statistical analysis

Abstract

With advancements in UAV technology, their applications in both defense and civilian sectors have expanded rapidly. These vehicles are powered by engines with diverse cylinder configurations, fuel capacities, and material characteristics. For low-altitude, small-scale UAVs, two-stroke engines are commonly preferred due to their high payload capacity and extended flight durations of 3-6 h, generally outperforming electric motors. The performance of gasoline-powered UAVs is influenced by critical factors such as engine temperature, thrust generation, and fuel consumption. This study focuses on a typical engine used in medium-sized, low-altitude UAVs, widely adopted across the globe. Researchers developed a prototype engine by increasing the fuel intake volume and enhancing cooling mechanisms to improve overall performance. The performance of both the original and modified engines was thoroughly evaluated under varying operational conditions, including different propeller types, sizes (23-8 inch and 24-10 inch), and rotations per minute (3000-5000 RPM). Key metrics such as thrust, fuel consumption, engine temperature, and RPM were systematically measured using a specially designed test setup equipped with advanced sensors and real-time data acquisition systems. To maximize flight endurance with minimal fuel consumption, response surface methodology and analysis of variance (ANOVA) were employed. The study identified an optimal operating speed of 4000 RPM, which resulted in a 47% performance improvement. At this speed, fuel consumption for a standard 4-h low-altitude flight was reduced from 2.51 to 1.86 L, demonstrating significant efficiency gains. ANOVA results revealed that propeller type significantly impacts engine performance, with propeller variations accounting for 86% of engine temperature changes. Additionally, optimized propeller designs achieved a 7% reduction in fuel consumption. This research underscores the potential of targeted engine and propeller modifications to significantly enhance UAV efficiency, providing valuable insights for future UAV development and operational strategies.