Helicopter engine-in-the-loop test setup

During the development process of new systems computer-based simulations are often used today. Depending on the system a point is sometimes reached where only computer-based simulations are not sufficient anymore. Beyond this point, the required testing of the system prior to product launch can be furthered by using hardware-in-the-loop (HIL) systems. This paper describes a HIL system consisting of a real helicopter turboshaft engine and a helicopter flight dynamics simulation. As the term HIL is usually used for describing controller testing, the whole system is renamed by the term engine-in-the-loop (EIL). Nevertheless, it can also be used for evaluating new engine controller concepts. Another application is analysis of the differences in dynamic behavior of a virtual and real engine in real time and using the EIL for educational purposes. For the realization of the EIL the existing institute's test bed of the Allison 250-C20B engine is used. An electric dynamometer simulates the loads of the helicopter rotors. The engine controller consists of a controller model running on a real-time computer and a fuel control unit. For the helicopter flight dynamics simulation a non-linear flight dynamics model of the BO 105 helicopter is implemented. For verification and validation of the EIL system simple flight missions were performed and the test data were evaluated.