Reducing Trailing Edge Flap Deflection Requirements in Primary Control with a Movable Horizontal Tail

Bluman, James E.; Gandhi, Farhan

doi:10.4050/jahs.56.032005

Cited by 9 publications

(16 citation statements)

References 7 publications

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“…A model similar to the one in this study was used in Ref. 15, and good correlation of power and trim predictions with experimental data was reported for the baseline UH-60A aircraft. A soft torsional spring is introduced at the torsion bearing with a stiffness that results in a nominal torsion frequency of 2•1/rev, soft enough to allow the TEFs to effect rotor collective and cyclic pitch change.…”

Section: Discussionmentioning

confidence: 74%

“…More details on the model as well key aircraft properties are given in Ref. 15. Sectional aerodynamic loads are calculated using Blade Element Theory, coupled to a prescribed wake analysis to calculate the induced velocitiy, and using C81 aerofoil tables to obtain the aerodynamic coefficients of the base aerofoil for the local Mach number and angle-of-attack, augmented by CFD-based increments due to TEF deflections.…”

Section: Discussionmentioning

confidence: 99%

“…In a recent study Gandhi and Sekula (14) reported that rotor cyclic pitch requirements in cruise could be reduced through horizontal tail control, and Bluman and Gandhi (15) extended this idea and showed that TEF deflection requirements for swashplateless primary control on a torsionally softened UH-60A Blackhawk could similarly be reduced significantly through the use of the horizontal stabilator. Yoshizaki, Gandhi and Sekula (16) also showed that for a light rotary-wing UAV, RPM variation was a viable approach for rotor collective control.…”

Section: Introductionmentioning

confidence: 99%

“…Yoshizaki, Gandhi and Sekula (16) also showed that for a light rotary-wing UAV, RPM variation was a viable approach for rotor collective control. Thus, after the first generation studies showed that swashplateless primary control was possible using TEFs on torsionally softened rotors, the studies by Gandhi and co-workers (15,16) laid out some strategies that could significantly reduce the TEF deflection requirements. However, to realise swashplateless primary control based on the use of TEFs, many questions still remain unanswered.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On power and actuation requirement in swashplateless primary control of helicopters using trailing-edge flaps

Gandhi¹,

Duling²,

Straub³

2014

Aeronaut. j. (1968)

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This paper examines three specific aspects pertaining to the trailing-edge flap (TEF) enabled swashplateless primary control of a helicopter. The study is based on a utility helicopter very similar to the UH-60A Blackhawk helicopter, with rotor torsion frequency reduced to 2•1/rev, and 20% chord TEFs extending from 70-90% span. The questions addressed in the paper are the power penalty due to aerodynamic drag associated with TEF control, the pitch-index required to limit the range of TEF deflections over variations in aircraft gross-weight and airspeed, and the influence of rotor RPM variation on swashplateless primary control. Results indicate that the power penalty associated with TEF enabled primary control at high speeds is in the range of 6-7%, due to increased drag on the advancing side in the region of the TEFs and at the blade tips. At low to moderate speeds the increase in power is 2-4% on average, more dependent on the pitch-index, and due to drag increase over most of the azimuth in the region of the TEFs. A variation in pitch-index from 16° for lower speeds and gross weights, to 20-22° for higher speeds and gross weights, would reduce the steady level flight TEF deflection requirements to under ±3°, leaving sufficient control margin. Increase in rotor RPM does not increase directly increase thrust (as with a stiff-torsion rotor) but reduces the rotating torsion frequency, and together with the increased dynamic pressures increases the sensitivity to TEF control. At low to moderate speeds a 9% increase in RPM reduces the maximum TEF deflections required by about 1°, but is accompanied by a large increase in rotor power. Conversely, a 9% RPM reduction decreases rotor power required, but the TEF deflections required increase by 1-1•5°.

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Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On power and actuation requirement in swashplateless primary control of helicopters using trailing-edge flaps

Gandhi¹,

Duling²,

Straub³

2014

Aeronaut. j. (1968)

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“…Some of these methods include moving the tail using collective and differential pitch angle variations of the left and right side of the horizontal tail and the forward and backward motion of the tail in longitudinal axis (e.g., see [1,2]). Other methods include redesigning some of the helicopter main rotor parameters (e.g., radius, chord length, and flapping spring stiffness) before flight (i.e., passive morphing) and continuously changing some of the helicopter main rotor parameters (e.g., radius and chord length) during flight (i.e., active morphing).…”

Section: Introductionmentioning

confidence: 99%

Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort

Oktay

Sal

2017

International Journal of Aerospace Engineering

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In this study, the effect of simultaneous variation in blade root chord length and blade taper on the control effort of helicopter flight control system (i.e., FCS) of a helicopter is investigated. Therefore, helicopter models (i.e., complex, control-oriented, and physicsbased models) including the main physics and essential dynamics are used. The effect of simultaneous variation in the blade root chord length and blade taper (i.e., in both chordwise and lengthwise directions dependently) on the control effort of an FCS of a helicopter and also on the closed-loop responses is studied. Comparisons in terms of the control effort and peak values with and without variations in the blade root chord and blade taper changes are carried out. For helicopter FCS variance-constrained controllers, specific output variance-constrained controllers are beneficial.

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Simultaneous swept anhedral helicopter blade tip shape and control-system design

Sal

2022

AEAT

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Purpose This paper aims to offer a simultaneous design approach for helicopter having swept anhedral blade tip shape and helicopter flight control system (HFCS) to minimize controller cost. Design/methodology/approach By considering previously stated offer, control-oriented models and a stochastic optimization method are applied to minimize controller cost of the HFCS. Findings Using simultaneous design approach for helicopters having blade tip swept and blade tip anhedral causes considerably less control effort than the helicopters not benefiting this related design approach. Practical implications Simultaneous design approach for helicopters having blade tip swept and blade tip anhedral is applicable to consider fuel economy. Originality/value One important novelty of this paper is using simultaneous approach for determining optimum shape of blade tip swept and anhedral. Another considerable novelty of this paper is also using a stochastic optimization method called simultaneous perturbation stochastic approximation for previously mentioned purpose. In this paper, it is also reached that using simultaneous design approach for swept anhedral helicopter blade tip shape and HFCS causes less control effort than the helicopters not using this approach. This leads to less fuel consumption and green environment.

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Reducing Trailing Edge Flap Deflection Requirements in Primary Control with a Movable Horizontal Tail

Cited by 9 publications

References 7 publications

On power and actuation requirement in swashplateless primary control of helicopters using trailing-edge flaps

On power and actuation requirement in swashplateless primary control of helicopters using trailing-edge flaps

Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort

Simultaneous swept anhedral helicopter blade tip shape and control-system design

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