Details:

Creators:
McFarland, R.E. ; Duisenberg, Ken
McFarland, R.E. ; Duisenberg, Ken Less -
Corporate Creators:
Ames Research Center
Corporate Contributors:
United States. National Aeronautics and Space Administration
Subject/TRT Terms:
[+]
Helicopter Rotors Rotor Blades Rotorcraft Simulation Turbulence Turbulence Modeling
DOI:
https://doi.org/10.21949/1403609
Resource Type:
Tech Report
NTL Classification:
NTL-AVIATION-AVIATION
Abstract:
A piloted, motion-based simulation of Sikorsky's Black Hawk helicopter was

used as a platform for the investigation of rotorcraft responses to vertical

turbulence. By using an innovative temporal and geometrical distribution

algorithm that preserved the statistical characteristics of the turbulence over

the rotor disc, stochastic velocity components were applied at each of twenty

blade-element stations. This model was implemented on NASA Ames' Vertical

Motion Simulator (VMS), and ten test pilots were used to establish that the

model created realistic cues.

The objectives of this research included the establishment of simulation-

technology basis for future investigations into real-time turbulence modeling.

This goal was achieved; our extensive additions to the rotor model added less

than a 10 percent computational overhead. Using a VAX9000 computer the entire

simulation required a cycle time of less than 12 msec.

Pilot opinion during this simulation was generally quite favorable. For

low speed flight the consensus was that SORBET (acronym for title) was better

than the conventional body-fixed model, which was used for comparison purposes,

and was determined to be too violent (like a washboard). For high speed flight

the pilots could not identify differences between these models. These opinions

were something of a surprise because only the vertical turbulence component on

the rotor system was implemented in SORBET. Because of the finite-element

distribution of the inputs, induced outputs were observed in all translational

and rotational axes. Extensive post-simulation spectral analyses of the SORBET

model suggest that proper rotorcraft turbulence modeling requires that vertical

atmospheric disturbances not be superimposed at the vehicle center of gravity

but, rather, be input into the rotor system, where the rotor-to-body transfer

function severely attenuates high frequency rotorcraft responses.


Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:810baaf28b3cf5f1d62a9a8322b67421aeb318c38a91cb2793a75f1cea2cf406
Download URL:
https://rosap.ntl.bts.gov/view/dot/12951/dot_12951_DS1.pdf
File Type:

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