Stability and Handling Qualities of a Helicopter Carrying a Slung Load

Kobi Enciu
Work toward a Ph.D. degree under the supervision of Prof. Aviv Rosen
Faculty of Aerospace Engineering
Technion – Israel Institute of Technology

External carriage of underslung loads by rotorcraft is frequently airspeed limited by instabilities of the combined helicopter-load system. Loads prone to such instabilities include box-like loads, plate-like loads, different types of military loads and more.

Due to modeling difficulties, the study of slung loads stability and development of means for their stabilization has been performed in recent years experimentally, based on combining wind tunnel tests and flight tests. These tests also showed that the pilot can unintentionally lead to the excursion of load’s oscillations due to the creation of pilot induced oscillations (PIO).

Nonlinear simulations that were performed previously included only partial and limited descriptions of the system, while utilizing degenerate models.

During the course of the present research a nonlinear simulation model representing a cargo container stabilized by two rear mounted fins was developed. The model was first used for the investigation of the isolated load’s dynamics and stability, using Dynamical Systems Theory (DST). The model’s accuracy was validated by comparisons with detailed wind tunnel test results that were obtained during the first stage of the research.

Next, an extended MATLAB simulation was developed, for the simulation of a UH-60 Black Hawk helicopter carrying the fins stabilized underslung load. A human pilot model was also included in the simulation. The results were validated based on comparisons with flight test data. The combined system’s dynamics and stability for two different piloting techniques was studied using DST methods.

The isolated load’s dynamical characteristics, as well as those of the combined helicopter-slung load system will be presented. The strong influence of piloting technique on the resulting system’s stability will be demonstrated and discussed.

The talk will be given in Hebrew

Wed, 28-05-2014, 16:30 (Gathering at 16:00)

Classroom, ground floor, Library, Aerospace Eng.

Light refreshments will be served before the lecture

Stability and Handling Qualities of a Helicopter Carrying a Slung Load