Launch and Recovery Systems

Sadraey, Mohammad H.

doi:10.1007/978-3-031-79582-4_9

Cited by 3 publications

(17 citation statements)

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“…Importantly, the vortex behavior of the gapped wing clarifies why gapped wing control effectiveness varies over angle of attack (figure 5) [12]. The vortices overall decrease the lift produced by the gapped semi-span [19,20], thus causing roll due to the asymmetric lift distribution relative to the baseline semispan. The strength of the vortices increases at higher lift coefficients, which is proportional to the angle of attack for the gapped wings.…”

Section: Aerodynamic Effects Of the Gaps On The Flow Over The Wingmentioning

confidence: 94%

“…All data were reported in the wind axes [18]. According to sign conventions, a negative aileron deflection angle was upwards and a positive aileron hinge moment was downwards towards the neutral position [18,20]. Positive rolling moments were produced by an upwards aileron deflection and open gaps.…”

Section: Methodsmentioning

confidence: 99%

“…We assumed standard atmospheric conditions. We simulated a single aileron on the right semi-span, with a chord of 25% of wing chord and a span 24.2% of the semispan starting at 72.6% of the half span [14] because this is the same configuration used in [12] and these dimensions are within the typical range for an aileron [20]. We calculated the aileron hinge moment about the hinge axis at 75% of wing chord and normalized it by aileron area and aileron chord.…”

Section: Jh-aileron Wing Experimental Validationmentioning

confidence: 99%

“…Vortices affect the lift distribution of a wing. In turn, the distribution of induced drag is a function of lift distribution, and is responsible for the roll-yaw coupling traditionally seen with deflected ailerons [20]. A yawing moment in the opposite direction from roll is referred to as adverse yaw, since it results in an uncoordinated and inefficient turn [20].…”

Section: Aerodynamic Effects Of the Gaps On The Flow Over The Wingmentioning

confidence: 99%

“…In turn, the distribution of induced drag is a function of lift distribution, and is responsible for the roll-yaw coupling traditionally seen with deflected ailerons [20]. A yawing moment in the opposite direction from roll is referred to as adverse yaw, since it results in an uncoordinated and inefficient turn [20]. Gapped wings were previously found to produce comparable rolling moment coefficients to an aileron, and ultimately a greater maximum rolling moment coefficient [12].…”

Section: Aerodynamic Effects Of the Gaps On The Flow Over The Wingmentioning

confidence: 99%

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Energy considerations and flow fields over whiffling-inspired wings

Sigrest

Inman

2023

Bioinspir. Biomim.

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Some bird species fly inverted, or whiffle, to lose altitude. Inverted flight twists the primary flight feathers, creating gaps along the wing’s trailing edge and decreasing lift. It is speculated that feather rotation-inspired gaps could be used as control surfaces on uncrewed aerial vehicles (UAVs). When implemented on one semi-span of a UAV wing, the gaps produce roll due to the asymmetric lift distribution. However, the understanding of the fluid mechanics and actuation requirements of this novel gapped wing were rudimentary. Here, we use a commercial computational fluid dynamics solver to model a gapped wing, compare its analytically estimated work requirements to an aileron, and identify the impacts of key aerodynamic mechanisms. An experimental validation shows that the results agree well with previous findings. We also find that the gaps re-energize the boundary layer over the suction side of the trailing edge, delaying stall of the gapped wing. Further, the gaps produce vortices distributed along the wingspan. This vortex behavior creates a beneficial lift distribution that produces comparable roll and less yaw than the aileron. The gap vortices also inform the change in the control surface’s roll effectiveness across angle of attack. Finally, the flow within a gap recirculates and creates negative pressure coefficients on the majority of the gap face. The result is a suction force on the gap face that increases with angle of attack and requires work to hold the gaps open. Overall, the gapped wing requires higher actuation work than the aileron at low rolling moment coefficients. However, above rolling moment coefficients of 0.0182, the gapped wing requires less work and ultimately produces a higher maximum rolling moment coefficient. Despite the variable control effectiveness, the data suggest that the gapped wing could be a useful roll control surface for energy-constrained UAVs at high lift coefficients.

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Section: Aerodynamic Effects Of the Gaps On The Flow Over The Wingmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Section: Jh-aileron Wing Experimental Validationmentioning

confidence: 99%

Section: Aerodynamic Effects Of the Gaps On The Flow Over The Wingmentioning

confidence: 99%

Section: Aerodynamic Effects Of the Gaps On The Flow Over The Wingmentioning

confidence: 99%

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Energy considerations and flow fields over whiffling-inspired wings

Sigrest

Inman

2023

Bioinspir. Biomim.

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Avian whiffling-inspired gaps provide an alternative method for roll control

Sigrest

Inman

2022

Bioinspir. Biomim.

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Some bird species exhibit a flight behavior known as whiffling, in which the bird flies upside-down during landing, predator evasion, or courtship displays. Flying inverted causes the flight feathers to twist, creating gaps in the wing’s trailing edge. It has been suggested that these gaps decrease lift at a potentially lower energy cost, enabling the bird to maneuver and rapidly descend. Thus, avian whiffling has parallels to an uncrewed aerial vehicle (UAV) using spoilers for rapid descent and ailerons for roll control. However, while whiffling has been previously described in the biological literature, it has yet to directly inspire aerodynamic design. In the current research, we investigated if gaps in a wing’s trailing edge, similar to those caused by feather rotation during whiffling, could provide an effective mechanism for UAV control, particularly rapid descent and banking. To address this question, we performed a wind tunnel test of 3D printed wings with a varying amount of trailing edge gaps and compared the lift and rolling moment coefficients generated by the gapped wings to a traditional spoiler and aileron. Next, we used an analytical analysis to estimate the force and work required to actuate gaps, spoiler, and aileron. Our results showed that gapped wings did not reduce lift as much as a spoiler and required more work. However, we found that at high angles of attack, the gapped wings produced rolling moment coefficients equivalent to upwards aileron deflections of up to 32.7° while requiring substantially less actuation force and work. Thus, while the gapped wings did not provide a noticeable benefit over spoilers for rapid descent, a whiffling-inspired control surface could provide an effective alternative to ailerons for roll control. These findings suggest a novel control mechanism that may be advantageous for small fixed-wing UAVs, particularly energy-constrained aircraft.

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Investigations on the Potentials of Novel Technologies for Aircraft Fuel Burn Reduction through Aerostructural Optimisation

Mosca

Elham

2022

Aerospace

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A physics-based optimisation framework is developed to investigate the potential advantages of novel technologies on the energy efficiency of a midrange passenger aircraft. In particular, the coupled-adjoint aerostructural analysis and optimisation tool FEMWET is modified to study the effects of active flow control at different load cases for conventional and unconventional wing configurations. This multidisciplinary design optimisation (MDO) framework presents the opportunity to optimise the wing considering static aeroelastic effect and, by its gradient-based method, save substantial computational time compared to high-fidelity tools, keeping a satisfying level of accuracy. Two different configurations are analysed: a forward- and backward-swept wing aircraft, developed inside the Cluster of Excellence SE2A (Sustainable and Energy-Efficient Aviation). The forward-swept configuration is sensitive to the aeroelastic stability effect, and the backward configuration is influenced by the aileron constraint. They may lead to a weight increment. Sensitivity studies show the possible role of key parameters on the optimisation results. The highest fuel weight reduction achievable for the two configurations is 5.6% for the forward-swept wing and 9.8% for the backward configuration. Finally, both optimised wings show higher flexibility.

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Launch and Recovery Systems

Cited by 3 publications

References 0 publications

Energy considerations and flow fields over whiffling-inspired wings

Energy considerations and flow fields over whiffling-inspired wings

Avian whiffling-inspired gaps provide an alternative method for roll control

Investigations on the Potentials of Novel Technologies for Aircraft Fuel Burn Reduction through Aerostructural Optimisation

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