Helicopter vibration reduction in forward flight using blade integral twist actuation

2007 ◽  
Vol 21 (2) ◽  
pp. 251-263 ◽  
Author(s):  
Sang Joon Shin ◽  
Carlos E. S. Cesnik
Keyword(s):  
Vibration Reduction ◽  
Forward Flight ◽  
Twist Actuation ◽  
Helicopter Vibration

Terfenol-D driven flaps for helicopter vibration reduction

1996 ◽  
Vol 5 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Ralph C Fenn ◽  
James R Downer ◽  
Dariusz A Bushko ◽  
Vijay Gondhalekar ◽  
Norman D Ham
Keyword(s):  
Vibration Reduction ◽  
Helicopter Vibration

Helicopter Vibration Reduction Using Discrete Controllable-Stiffness Devices at the Rotor Hub

2002 ◽  
Vol 39 (4) ◽  
pp. 668-677 ◽  
Author(s):  
Farhan Gandhi ◽  
Phuriwat Anusonti-Inthra
Keyword(s):  
Vibration Reduction ◽  
Helicopter Vibration

Relative rotor phasing for multicopter vibratory load minimisation

2021 ◽  
pp. 1-20
Author(s):  
R. Niemiec ◽  
F. Gandhi ◽  
N. Kopyt
Keyword(s):  
Pareto Front ◽  
Vibration Reduction ◽  
Complete Elimination ◽  
Forward Flight ◽  
Harmonic Phase ◽  
Multiple Phase ◽  
Vibratory Load ◽  
Parametric Studies ◽  
Left And Right ◽  
Higher Harmonic

Abstract This study focuses on vibration reduction for quadcopters and octocopters with elastic, two-bladed, fixed-speed, variable-pitch rotors through the use of relative rotor phasing. The study defines phase modes such as a pitch phase mode with relative phasing between the front and aft rotors, a roll phase mode with relative phasing between the left and right rotors, and a differential phase mode with relative phasing between the clockwise and counter-clockwise spinning rotors for both the quadcopter and the octocopter, as well as additional higher harmonic phase modes for the octocopter. Parametric studies on individual phase modes indicate that, for the quadcopter in forward flight, the pitch and roll phase modes can almost entirely eliminate the 2/rev vibratory forces (at the aircraft level), but the 2/rev vibratory moments cannot be minimised at the same time. By simultaneously using multiple phase modes, a Pareto front can be generated and a solution selected based on the relative emphasis on force or moment vibration reduction. For the octocopter, it was observed that individual higher harmonic modes (specifically the 2c or 2s modes) could almost entirely eliminate both the 2/rev vibratory forces and moments, simultaneously. Compared with vibration levels in forward flight that might, on average, be expected if the rotors were randomly phased, a 62% reduction of a composite vibration index can be achieved on a quadcopter, and complete elimination of vibration was achievable on an octocopter, with appropriate rotor phasing.

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