Abstract
Small hobby engines with masses less than 1 kg are attractive for use in low-cost unmanned air vehicles, because they are mass-produced and inexpensive. However, very little information about their performance is available in the scientific literature. This paper describes the development of a dynamometer system suitable for measuring the power output and efficiency of these small engines and presents detailed performance measurements for a particular engine with a mass of 150 gm that could be suitable for powering a low-cost unmanned air vehicle. When the mixture setting is adjusted according to the manufacturer's instructions, the peak power of this engine is 112 W at 9450 rpm with a brake specific fuel consumption of 3.0 kg/k Wh. The performance can be improved to 159 W at 12,000 rpm and brake specific fuel consumption of approximately 2.1 kg/kWh by controlling the mixture.