Using Wind Tunnel Tests for Slung-Load Clearance, Part 1: The CONEX Cargo Container

Abstract

Previously, the authors showed that dynamic wind tunnel tests of a suspended CONEX cargo container model exhibited encouraging levels of success in predicting the stability characteristics and speed envelope of the full-scale load. The present study includes further use of the UH-60/CONEX system to investigate effects that were observed previously, but not fully addressed. These effects include the influence of pilot inputs and helicopter motions on the coupled pilot/helicopter/slungload dynamics, the influence of center of gravity offset of the slung load, and the behavior of a load when a yaw swivel is not used in the suspension. It is shown that all three effects are important and affect the slung-load dynamics. The capability of wind tunnel tests to predict the behavior of slung loads in flight is shown for these effects. NomenclatureA () amplitudes of () cg center of gravity D aerodynamic drag force, N PF principal frequency, rad/s SPF simple pendulum frequency, rad/s W weight, N Y aerodynamic lateral force, N φ c , θ c roll (lateral) and pitch (longitudinal) cable angles, deg. ω ψ yaw oscillation angular frequency, rad/s * Corresponding author;

Using Wind Tunnel Tests for Slung-Load Clearance, Part 2: Other Loads

“…The differences and similarities between wind tunnel, PIL, and SF flight-test results are in agreement with the results for the CONEX in Ref. 1. If the pilot uses the PIL technique, stabilizing the aircraft roll attitude makes the system behave more like a simple pendulum, again like the wind tunnel.…”

“…1) confirmed further what had been presented in previous papers (see literature survey in Ref. 1) that carefully designed wind tunnel tests of scaled-down models of slung loads exhibit good agreement with flight tests of the same full-scale loads.…”

“…1) confirmed further what had been presented in previous papers (see literature survey in Ref. 1) that carefully designed wind tunnel tests of scaled-down models of slung loads exhibit good agreement with flight tests of the same full-scale loads. It was shown that the above-mentioned effects, as well as other ones, may have important influence on the coupled system slung-load/helicopter/pilot dynamics and stability.…”