#### Journal of Aircraft

Journal Information
ISSN / EISSN : 0021-8669 / 1533-3868
Total articles ≅ 10,616
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#### Latest articles in this journal

Hector D. Ortiz-Melendez, James G. Coder, Arvin Shmilovich
Published: 22 November 2021
Journal of Aircraft pp 1-15; https://doi.org/10.2514/1.c036550

Abstract:
This work uses a computational fluid dynamics approach to evaluate the ability of the aft element of a slotted, natural-laminar-flow airfoil, designed for transonic applications, to function as a high-lift device. The analysis is based on the Reynolds-averaged Navier–Stokes equations with a laminar–turbulent transition model for subsonic flow at representative flight conditions and a fully turbulent model for the aft-element optimization. Results obtained at angles of attack near maximum lift contribute to the understanding of stall characteristics and show that maximum aerodynamic efficiency is obtained with a constant slot width between the flap and main element. Results indicate that the microflap can augment the effectiveness of the aft element. Drag calculations when compared with angle of attack and lift show insight on the aerodynamic efficiency of the microflap system in landing as a lift effector, as well as a drag device. Pitching-moment data are also presented for completeness. Results obtained with Fowler flaps are consistent with other studies of extended-flap configurations; more specifically, the aforementioned velocity ratio decreases toward the aft-element trailing edge, indicating that the multi-element high-lift system is operating as intended.
Nando van Arnhem, Reynard de Vries, , Roelof Vos, Leo L. M. Veldhuis
Published: 15 November 2021
Journal of Aircraft pp 1-18; https://doi.org/10.2514/1.c036338

Abstract:
In this combined experimental and numerical study, the propeller–airframe aerodynamic interaction is characterized for an aircraft configuration with propellers mounted to the horizontal tailplane. The contributions of the propeller and airframe to the overall loading are distinguished in the experimental analyses by using a combination of external balance and internal load cell data. Validated computational fluid dynamics simulations are then employed to quantify the interaction at a component level. The results show that the propeller installation shifts the neutral point aft with increasing propeller thrust. For the configuration considered herein, the yawing moment due to sideslip is increased by approximately 10%, independent of the propeller thrust coefficient. The changes in propeller loading due to the airframe-induced flowfield are the dominant factor to change the airframe stability and performance. The prominent installation effects occur at high angle of attack, because in that condition the propeller experiences a significant nonuniform inflow that affects the propeller and tailplane. The relatively large propeller diameter compared with tailplane span leads to a change of the tailplane root vortex that causes the tailplane effectiveness to reduce with an inboard-up rotating propeller.
Soonho Shon, Yu-Eop Kang, Yoonpyo Hong, Kwanjung Yee, R. S. Myong
Published: 15 November 2021
Journal of Aircraft pp 1-14; https://doi.org/10.2514/1.c036435

Abstract:
A hybrid airfoil is a scaled model for generating a full-scale ice shape for icing wind tunnel tests. This is possible by matching full-scale properties such as the distributions of collection efficiency and heat transfer coefficient. Previous studies have used indirect methods using full-scale stagnation point location or tangent droplet trajectories. Therefore, these methods can cause a discrepancy between the full-scale and hybrid airfoil ice shapes under glaze ice conditions. To cope with the issue, this paper proposes a new approach to match the distributions of the full-scale collection efficiency and heat transfer coefficient on the leading edge, using a viscous turbulent computational fluid dynamics icing simulation. For computational efficiency, reduced-order modeling based optimization was used to match the distributions. The optimization process was applied to the glaze ice condition with a high liquid water content and temperature. The results indicate that matching the distribution of the heat transfer coefficient is recommended to minimize the error between full-scale and hybrid airfoil ice shapes for the glaze ice condition. Finally, a hybrid airfoil flap geometry, which can be applied to various angles of attack, was designed using the optimization design process.
Palash Jain, , Christopher Cameron
Published: 15 November 2021
Journal of Aircraft pp 1-6; https://doi.org/10.2514/1.c036509

Published: 11 November 2021
Journal of Aircraft pp 1-14; https://doi.org/10.2514/1.c036339

Abstract:
Formation flying techniques, demonstrated by migratory birds, have the potential to significantly save energy when two or more transport aircraft fly the same route at the same time. In fuel-saving formations, aircraft are flying straight trajectories for most of the time. For proof of concept, however, how vertical and lateral maneuvers can be flown has to be investigated. Those investigations require a flight simulator that is equipped with adequate flight mechanical models. Not much research exists on maneuvers of formation. The paper addresses the components that are needed to perform this research with real-time flight simulations. They are, first, a method to model wake vortices on curved trajectories; second, a formation flight control system, which comprises a method for the relative position determination, the design of control laws, and suitable cockpit displays; and third, techniques that allow vertical and lateral flight maneuvers. Two different strategies to position the following aircraft relative to the wake vortex during turns are described, and simulation results show their differences in terms of fuel savings and passenger comfort. Piloted flight simulator tests confirmed the usability of the proposed flight techniques for formation maneuvers, and the participating airline pilots indicated general consent to the concept.
Monami Sasamori, Seigo Koga, Mitsuru Kurita
Published: 11 November 2021
Journal of Aircraft pp 1-11; https://doi.org/10.2514/1.c036409

Abstract:
A method for estimating the drag reduction performance of riblets installed on the surfaces of an aircraft was extended to take the effect of the pressure gradient over the aircraft into account. This method simply and roughly estimates the effectiveness of riblets applied to arbitrary surfaces of any aircraft by fusing wind tunnel test data and computational fluid dynamics analysis. The drag reduction rate is calculated from the relationships between friction drag reduction $DR$ , wall-normalized riblet spacing $s+$ , and Clauser pressure gradient parameter $β$ . To obtain this relationship, a wind tunnel test with straight riblets in an adverse pressure gradient was carried out. The resulting shift in the value in the intercept of the log-law region of the mean velocity profile for riblet cases indicates that the drag reduction effect decreases as the Clauser parameter $β$ increases. Based on these results, an approximate surface for the relationship between $DR$ , $s+$ , and $β$ was proposed, and the drag reduction performance of riblets installed on the surfaces of a conceptual aircraft was estimated. The total drag reduction rates estimated by the extended method considering pressure gradient effects and the original method case were both about 2%, which indicates that the effects of the pressure gradient on the aircraft on overall riblet performance are small.
Yasser M. Meddaikar, Johannes K. S. Dillinger, Gustavo H. C. Silva,
Published: 5 November 2021
Journal of Aircraft pp 1-14; https://doi.org/10.2514/1.c036551

Abstract:
This paper presents an approach for optimizing practical commercial-scale aircraft wings using sandwich composites in a preliminary design stage. The approach uses lamination parameters as design variables in a continuous optimization step. Structural constraints for classic composite laminate design such as material failure and buckling, and for sandwich design such as crimping, wrinkling, dimpling, and core shear failure are accounted for using industrial-standard and empirical methods driven by finite element analyses. As an application case, optimization studies are performed at a skin panel level on the open-source Common Research Model wing. Optimization trends show areas of the wingbox where sandwich composites offer superior structural performance, as well as potential cost savings by requiring lesser number of stringers. The aim and novelty of this work is to present performance gains that can be achieved using sandwich composites in primary load-carrying aircraft structures when compared with monolithic composite designs and, through this, to provide a motivation for further research and development in sandwich composites and their applications.
Khalid Khalil, Salvatore Asaro, André Bauknecht
Published: 5 November 2021
Journal of Aircraft pp 1-17; https://doi.org/10.2514/1.c036426

Abstract: