Performance, vibrations, and survivability of a compound helicopter with control redundancy

Reddinger, Jean-Paul Francis
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Other Contributors
Gandhi, Farhan
Julius, Anak Agung
Hicken, Jason
Mishra, Sandipan
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Aeronautical engineering
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This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.
Full Citation
A fully compounded helicopter includes the full set of controls present on a conventional helicopter (collective, longitudinal cyclic, lateral cyclic, and tail rotor pitch) in addition to fixed-system control surfaces (stabilator pitch and differential ailerons) and compound-specific auxiliary controls (propeller thrust and main rotor speed). The control redundancy allows an infinite number of potential steady-state trimmed flight conditions, over which the controls can be optimized to achieve a target such as low power. Using a rigid blade analysis with linear inflow, parametrically varied trim states are examined in detail to extract the relevant physical phenomena and corresponding rotor aeromechanics of the minimum power trim states at 225 kts. An elastic blade model with prescribed wake inflow modeling is developed to examine blade loads and rotor vibrational characteristics. Important design considerations such as blade twist are considered by comparing -8° linearly twisted blades and untwisted blades. The minimum power and vibration states corresponded to different redundant control settings and main rotor behavior for the twisted blade, but for the untwisted blade, the settings for minimum power and vibrations are similar.
August 2017
School of Engineering
Dept. of Mechanical, Aerospace, and Nuclear Engineering
Rensselaer Polytechnic Institute, Troy, NY
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