Impedance tailored fluidic pitch links for passive hub vibration control and improved rotor efficiency

Lloyd H. Scarborough, Christopher D. Rahn, Edward Smith, Kevin L. Koudela, Mark R. Jolly

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

Replacing rigid pitch links on rotorcraft with fluidic pitch links changes the blade torsional impedance. At low frequency, the blade must have high impedance to pass through the pilot's collective and cyclic commands to control the aircraft. At higher frequencies, however, the pitch link impedance can be tuned to change the blade pitching response to higher-harmonic loads. Active blade control to produce higher-harmonic pitch motions has been shown to reduce hub loads and increase rotor efficiency. This paper investigates whether fluidic pitch links can passively provide these benefits. An analytical model of a fluidic pitch link is derived and incorporated into a rotor aeroelastic simulation for a rotor similar to that of the UH-60. Eighty-one simulations with varied fluidic pitch link parameters demonstrate that their impedance can be tailored to reduce rotor power and all six hub forces and moments. While no impedance was found that simultaneously reduced all components, the results include cases with reductions in the lateral 4/rev hub force of up to 91% and 4/rev hub pitching moment of up to 67%, and main-rotor power of up to 5%.

Original languageEnglish (US)
Title of host publicationAmerican Helicopter Society International - 5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics
PublisherAmerican Helicopter Society International
Pages273-281
Number of pages9
ISBN (Electronic)9781634391788
StatePublished - 2014
Event5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics - San Francisco, United States
Duration: Jan 22 2014Jan 24 2014

Other

Other5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics
CountryUnited States
CitySan Francisco
Period1/22/141/24/14

Fingerprint

Fluidics
Vibration control
Rotors
Analytical models
Aircraft

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering

Cite this

Scarborough, L. H., Rahn, C. D., Smith, E., Koudela, K. L., & Jolly, M. R. (2014). Impedance tailored fluidic pitch links for passive hub vibration control and improved rotor efficiency. In American Helicopter Society International - 5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics (pp. 273-281). American Helicopter Society International.
Scarborough, Lloyd H. ; Rahn, Christopher D. ; Smith, Edward ; Koudela, Kevin L. ; Jolly, Mark R. / Impedance tailored fluidic pitch links for passive hub vibration control and improved rotor efficiency. American Helicopter Society International - 5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics. American Helicopter Society International, 2014. pp. 273-281
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abstract = "Replacing rigid pitch links on rotorcraft with fluidic pitch links changes the blade torsional impedance. At low frequency, the blade must have high impedance to pass through the pilot's collective and cyclic commands to control the aircraft. At higher frequencies, however, the pitch link impedance can be tuned to change the blade pitching response to higher-harmonic loads. Active blade control to produce higher-harmonic pitch motions has been shown to reduce hub loads and increase rotor efficiency. This paper investigates whether fluidic pitch links can passively provide these benefits. An analytical model of a fluidic pitch link is derived and incorporated into a rotor aeroelastic simulation for a rotor similar to that of the UH-60. Eighty-one simulations with varied fluidic pitch link parameters demonstrate that their impedance can be tailored to reduce rotor power and all six hub forces and moments. While no impedance was found that simultaneously reduced all components, the results include cases with reductions in the lateral 4/rev hub force of up to 91{\%} and 4/rev hub pitching moment of up to 67{\%}, and main-rotor power of up to 5{\%}.",
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Scarborough, LH, Rahn, CD, Smith, E, Koudela, KL & Jolly, MR 2014, Impedance tailored fluidic pitch links for passive hub vibration control and improved rotor efficiency. in American Helicopter Society International - 5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics. American Helicopter Society International, pp. 273-281, 5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics, San Francisco, United States, 1/22/14.

Impedance tailored fluidic pitch links for passive hub vibration control and improved rotor efficiency. / Scarborough, Lloyd H.; Rahn, Christopher D.; Smith, Edward; Koudela, Kevin L.; Jolly, Mark R.

American Helicopter Society International - 5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics. American Helicopter Society International, 2014. p. 273-281.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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PY - 2014

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N2 - Replacing rigid pitch links on rotorcraft with fluidic pitch links changes the blade torsional impedance. At low frequency, the blade must have high impedance to pass through the pilot's collective and cyclic commands to control the aircraft. At higher frequencies, however, the pitch link impedance can be tuned to change the blade pitching response to higher-harmonic loads. Active blade control to produce higher-harmonic pitch motions has been shown to reduce hub loads and increase rotor efficiency. This paper investigates whether fluidic pitch links can passively provide these benefits. An analytical model of a fluidic pitch link is derived and incorporated into a rotor aeroelastic simulation for a rotor similar to that of the UH-60. Eighty-one simulations with varied fluidic pitch link parameters demonstrate that their impedance can be tailored to reduce rotor power and all six hub forces and moments. While no impedance was found that simultaneously reduced all components, the results include cases with reductions in the lateral 4/rev hub force of up to 91% and 4/rev hub pitching moment of up to 67%, and main-rotor power of up to 5%.

AB - Replacing rigid pitch links on rotorcraft with fluidic pitch links changes the blade torsional impedance. At low frequency, the blade must have high impedance to pass through the pilot's collective and cyclic commands to control the aircraft. At higher frequencies, however, the pitch link impedance can be tuned to change the blade pitching response to higher-harmonic loads. Active blade control to produce higher-harmonic pitch motions has been shown to reduce hub loads and increase rotor efficiency. This paper investigates whether fluidic pitch links can passively provide these benefits. An analytical model of a fluidic pitch link is derived and incorporated into a rotor aeroelastic simulation for a rotor similar to that of the UH-60. Eighty-one simulations with varied fluidic pitch link parameters demonstrate that their impedance can be tailored to reduce rotor power and all six hub forces and moments. While no impedance was found that simultaneously reduced all components, the results include cases with reductions in the lateral 4/rev hub force of up to 91% and 4/rev hub pitching moment of up to 67%, and main-rotor power of up to 5%.

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Scarborough LH, Rahn CD, Smith E, Koudela KL, Jolly MR. Impedance tailored fluidic pitch links for passive hub vibration control and improved rotor efficiency. In American Helicopter Society International - 5th Decennial AHS Aeromechanics Specialists' Conference 2014: Current Challenges and Future Directions in Rotorcraft Aeromechanics. American Helicopter Society International. 2014. p. 273-281