BACKGROUND
Helicopter slung load operations are common in both military and civil contexts. The addition of the load can degrade the system stability and reduce the operating envelope of the combined system below that of the helicopter alone. A utility helicopter will carry a wide variety of loads using a variety of slings during its operational life, each with different dynamic characteristics. A result is that such operations are subject to incidents and accidents in which the dynamic limits of the helicopter and load are unknowingly exceeded. Military helicopters and loads are often qualified for these operations in flight tests which can be expensive, time consuming, and sometimes risky.
In this context, a capability for flight-time analysis allows quantitative assessment of helicopter flying qualities and load pendulum stability during flight tests after each test airspeed and before going on to the next test point, thus reducing the cost, time, and risks of qualification tests. Further, the ability to make reliable predictions of load-helicopter stability from analytical models will reduce the requirement for flight test qualifications to a few loads, provide knowledge of critical points in advance of flight testing, and allow assessment of loads for which flight test evaluations are not available.
FY97 ACCOMPLISHED
Flight tests were conducted at Ames with an instrumented UH-60A Blackhawk helicopter and 8x6x6 foot standard military cargo container. Data was telemetered to the Ames ground station where it was analyzed, using a system of 3 work stations interfaced with the real-time telemetry system. The computations took 4-8 minutes to complete before clearing to the next test point.
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