Increasing Reliability of a Two-Stroke Internal Combustion Engine for Dynamically Changing Altitudes

Steven C. Crosbie, Marc D. Polanka, Paul J. Litke, John L. Hoke
2014 Journal of Propulsion and Power  
Remotely Piloted Aircraft (RPA) typically utilize commercial internal combustion engines (ICE) as their power sources. These engines are designed to run at sea level, but these aircraft are often pressed into service at higher altitudes where the performance characteristics deteriorate. A Brison 95cc two-stroke engine's performance characteristics at altitude are investigated using a test facility that can measure these characteristics over a range of pressures and temperatures. With its stock
more » ... arburetor at sea level static (SLS) conditions, the engine makes 5.5 peak hp and brake specific fuel consumption (BSFC) ranged from 1.2-4.0 lb/(hp-hr). At 10,000 ft conditions, the peak hp drops 40% while off peak power conditions can see a drop of over 90%. As well, the carburetor makes operating at high altitudes unreliable and unpredictable. In order to increase reliability, a throttle body fuel injection (TBI) system was installed on the engine. The fuel injection system matched carburetor peak power at SLS conditions while increasing power by as much as 90% at low RPM and high altitude operating conditions. BSFC is decreased to a consistent 1.0 to 1.2 lb/(hp-hr) across all operating conditions. Lastly both reliability at high altitude and startup reliability are increased with the TBI system while eliminating the need for the tuning by the end user. v Acknowledgements I would like to thank my research advisor, Dr. Marc Polanka, and the research sponsor, Dr. Fred Schauer, for allowing me the opportunity to work on this research with them. Thank you Dr. Polanka for the weekly meetings spending hours discussing the direction of the research, my understanding of how to conduct research, and how to best present the research. Thank you Fred for having the confidence in me from the start and letting me work in your facility. None of this research would be possible without the continued support of the key players that work in 5-Stand and D-Bay. Dr. John Hoke was instrumental helping me understand key concepts for the research as well as advising me on the appropriate direction to take the research. Thank you Paul Litke for taking the time to look at my data and help me understand the trends we were seeing. Dave Burris, thank you for all of your help troubleshooting LabVIEW code and your timeliness in fixing the areas we highlighted. To the guys in 5-Stand, thank you Adam Brown, Jacob Baranski, and Dr. Eric Anderson for showing me how things work in 5-Stand and helping me fit into the 5-Stand operating cycle. Thank you Captain Cary Wilson and JR Groenewegen for showing me the ropes with small engine research and allowing me to share the lab when operating schedules were tight this summer. Thank you Ben Naguy for helping me machine the parts I needed, often last minute, and teaching me how to use most of the equipment in the machine shop. Thank you Rich Ryman for always being available to answer questions regarding how to install hardware, which hardware to select, and where to find the hardware I needed. vi
doi:10.2514/1.b34753 fatcat:ez3wrqqvjjbhrjhixd4a7gfu2a