Helicopters as a theme in a machine design course

Abstract

The idea proposed here is to study helicopters and their components throughout a machine design course as a theme to teach students about different mechanical elements. A helicopter is an ideal system to exemplify the concepts taught in the course since all aspects of machine design are encapsulated in its design. Furthermore, a helicopter deeply pushes the limits of safety; the price of failure of one or more components or of the overall system is high (human fatality). This suggests large factors of safety in the design, but there is an inherent tradeoff. If factors of safety are too large, component designs do not satisfy weight constraints for flight. For each topic of the course, the connection to helicopters is presented and helicopter design challenges are posed. For example, the shafts and gearboxes that transfer power from the highspeed turbine engines to the lower speed rotors can be used to teach students about shaft sizing (bending, safety, etc.), bearing sizing and placement, and principles of gearbox design. (In the standard helicopter configuration, two turbine jet engines drive a main rotor and a tail rotor, and the pilot controls are linked to both rotors for handling of the aircraft.) Students quickly discover that due to size constraints planetary gears are used in the gearbox to achieve the speed reduction between the engines and the main rotor. In this paper, we describe the connection between the topics of a typical machine design course and helicopters and their components. The motivation for selecting a theme system in teaching machine design is to enhance learning and bring more excitement to the topics in a course that is generally considered very challenging. Most students are not familiar with the design and components of helicopters, yet are fascinated with their operation making it an attractive topic. The approach of using helicopters as a theme in a machine design course is being implemented and evaluated. © American Society for Engineering Education, 2014.