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The U.S. Army-s Aeronautical Design Standard-
33 (ADS-33D-PRF) is a rotorcraft handling-qualities
specification that was developed at Ames. Because
this specification was initially applied in the RAH-66
Comanche helicopter program, the requirements
generally related more to scout and attack rotorcraft.
Recently, Ames expanded its handling-qualities
research work to include utility rotorcraft, with and
without externally slung loads. As part of this
research, an 80-hour flight-test assessment of ADS-33D-
PRF was conducted at Ames using an instrumented
UH-60A Black Hawk, the Army's primary
utility helicopter. The trial was performed
(1) to assess the required compliance testing and to
evaluate the requirements in a good visual environment;
(2) to tailor the existing flight-test maneuvers
and develop new maneuvers specifically designed to
adequately evaluate the handling-qualities of utility
helicopters, with and without externally slung loads;
(3) to correlate the results from the quantitative
testing with those from the qualitative evaluations;
and (4) to establish a handling-qualities baseline of
the UH-60A in terms of ADS-33 against which the
effects of future modifications to the aircraft may be
better quantified.
The 80-hour flight test was performed in three
phases. Six pilots participated in Phase 1, the purpose
of which was to tailor the existing ADS-33D-PRF
flight-test maneuvers and to develop new ones. As
shown in figure 1, course cueing for these flight-test
maneuvers was constructed and refined to provide
sufficient cues such that the evaluation pilots could
determine "Desired" and "Adequate" maneuver
performance standards. Eight experimental test pilots
participated in the Phase 2 formal handling-qualities
evaluations of the Black Hawk for these maneuvers
and for three aircraft configurations: empty (approximate
average weight = 13,500 pounds); with an
internal ballast (17,300 pounds); and empty but with
a 6,000-pound externally slung load (total operating
weight 19,300 pounds). Data were collected in calm
(<5 knots) and light wind conditions (7-15 knots).
During Phase 3, the empty and internal ballast
configurations were used to assess the compliance
testing and criteria from the quantitative requirements
in ADS-33D-PRF at hover and in forward flight.
Selected flight-test maneuvers from ADS-33D-PRF
and from a CH-47D cargo helicopter assessment
were refined for the utility mission. The maneuver
performance standards were generally aligned with
those developed in the cargo helicopter flight test.
The addition of light winds (7-15 knots) tended to
degrade the handling-qualities for some maneuvers
more so than others. From the internal ballast configuration,
the qualitative results for calm conditions
(shown in figure 2) suggest that except for the Hover
Turn and the Pirouette maneuvers, the average
Handling Quality Rating (HQR) for the UH-60A, as
tested, is close to the Level 1-2 boundary. The
Phase 3 results showed that with real-time monitoring
of the control inputs and aircraft response, the
frequency-sweep testing and the steps, doublets, and
pulse control inputs were performed in a routine and
efficient manner. The initial lessons learned and
results from this flight-test assessment of ADS-33D-PRF
using a UH-60A Black Hawk helicopter will be
instrumental in expanding the D-version of ADS-33
into an E-version that includes a first-cut at criteria
suitable for utility rotorcraft, with and without
externally slung loads.
Point of Contact: C. L. Blanken
(650) 604-5836
cblanken@mail.arc.nasa.gov
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Fig. 1. UH-60A Black Hawk with externally slung
load performing maneuver assessment.
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Fig. 2. Handling-quality results from internal ballast configuration in calm winds.
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