Maximum Aerodynamic Efficiency Research Articles

Numerical Analysis of Bioinspired Tails in a Fixed-Wing Micro Air Vehicle

Bird tails play a key role in aerodynamics and flight stability. They produce extra lift for takeoff and landing maneuvers, enhance wing functions and maintain stability during flight (keeping the bird from yawing, rolling and pitching, or otherwise losing control). This paper investigates the use of bioinspired horizontal stabilizers for Micro Air Vehicles (MAVs) involving a Zimmerman wing-body geometry. A selection of five tail shapes of the main types existing in nature is presented, and a parametric analysis is conducted looking into the influence of the most relevant tail geometric parameters to increase the longitudinal static stability of the vehicle. Based on the parametric study, a smaller subset of candidate tail designs are shortlisted to perform a detailed aerodynamic analysis. Then, steady RANS CFD simulations are conducted for a higher-fidelity study of these candidate tail designs to obtain an optimum of each tail type. The criterion for selection of the optimum tail configuration is the maximum aerodynamic efficiency, CLCD , as well as a high longitudinal static stability. The squared-fan tail provides the highest aerodynamic efficiency while maintaining a high longitudinal stability of the vehicle. In conclusion, this paper provides an innovative study of improving longitudinal stability and aerodynamics through the implementation of bioinspired horizontal stabilizers in vehicles with these characteristics.

Axial turbine flow path design for concentrated solar power plants operating with CO2 blends

The utilisation of certain blends based on supercritical CO2 (sCO2), namely CO2/TiCl4, CO2/C6F6 and CO2/SO2, have been found to be promising for enhancing the performance of power cycles for Concentrated Solar Power (CSP) applications; allowing for up to a 6% enhancement in cycle efficiency with respect to a simple recuperated CO2 cycle, depending upon the nature of the used blend and the cycle configuration of choice. This paper presents an investigation of the impact of adopting these sCO2-based blends on the flow path design for a multi-stage axial turbine whilst accounting for aerodynamic, mechanical and rotordynamic considerations. This includes assessing the sensitivity of the turbine design to selected working fluid and imposed optimal cycle conditions. Ultimately, this study aims to provide the first indication that a high-efficiency turbine can be achieved for a large-scale axial turbine operating with these non-conventional working fluids and producing power in excess of 120 MW. To achieve this aim, mean-line aerodynamic design is integrated with mechanical and rotordynamic constraints, specified based on industrial experience, to ensure technically feasible solutions with maximum aerodynamic efficiency. Different turbine flow path designs have been produced for three sCO2 blends under different cycle boundary conditions. Specifically, flow paths have been obtained for optimal cycle configurations at five different molar fractions and two different turbine inlet pressure and temperature levels of 250 & 350 bar and 550 & 700 °C respectively. A total-to-total turbine efficiency in excess of 92% was achieved, which is considered promising for the future of CO2 plants. The highest efficiencies are achieved for designs with a large number of stages, corresponding to reduced hub diameters due to the need for a fixed synchronous rotational speed. The large number of stages is contrary to existing sCO2 turbine designs, but it is found that an increase from 4 to 14 stages can increase the efficiency by around 5%. Ultimately, based on the preliminary cost analysis results, the designs with a large number of stages were found to be financially feasible compared to the designs with a small number of stages.

Application of wavy leading edge to enhance winglet aerodynamic performance

AbstractThe wavy leading edge (WLE, also known as leading edge protuberances) is a passive flow control device inspired by the humpback whale pectoral flippers. It reduces the flow of three-dimensional effects on wings and increases their aerodynamic performance at high angles of attack. Despite the numerous studies on its aerodynamic benefits, research on its possible applications is still incipient. Therefore, this article addresses an evaluation of the WLE effects on the aerodynamic performance of a winglet. A rectangular wing, a base smooth leading edge winglet, and a winglet with WLE were designed and manufactured for CFD simulations and wind tunnel measurements. The winglet with WLE increased the maximum aerodynamic efficiency, i.e. this configuration reduced the induced drag by increasing wingtip vortex dissipation at a given angle-of-attack. Such results were used in re-evaluations of the aerodynamic performance of an original agricultural aircraft initially configured with a multi-winglet device. The winglet with WLE showed to be effective at increasing the aircraft operational time and range under a simulated actual condition.

Investigations on Aerodynamic Performance of Fixed Wing Micro Air Vehicle with Different Planforms

Lots of large aircrafts have been developed with various designs for different purposes like commercial, combat and cargo. Presently, for small inaccessible regions, due to security and inspection, there is a need for small sized aircraft. With the development in technology, lots of research is being conducted for small sized unmanned aircrafts. So, under fixed wing type small sized aircrafts, various designs can be generated for the wing with better aerodynamic performance. In this present study, the aerodynamic characteristics of the micro air vehicle fixed wing with different planforms are investigated using Fluent Solver with standard k- turbulence model. The planforms taken up for study are Zimmerman, Inverse Zimmerman, Modified Trapezoid, Plaster 2. The airfoils chosen to design the wing are Selig-4083 and Epple-61. All the wing designs have same chord length, wingspan, and analysed with same air speed for different angle of attacks ranging from 0 to 40. Numerical data of two wings with Zimmerman and Inverse Zimmerman results are validated with the experimental values of CSIR - NAL. All the wing planforms results are compared with the Zimmerman and Inverse Zimmerman. Based on the study, Plaster2 and Modified Trapezoid gives the optimum value in terms of aerodynamic coefficients. But Inverse Zimmerman has the maximum aerodynamic efficiency among all planforms while Plaster2 has the maximum value of coefficient of lift.

Flow-field alternation and wave drag reduction under repetitive laser energy deposition

In situ laser energy deposition ahead of supersonic/hypersonic vehicles controls the surface force and reduces drag dramatically. In the present study, the effects of repetitive laser pulse deposition on the flow-field alteration and wave drag reduction over a blunt body travelling at supersonic speed are investigated. The simulation is performed by solving the Navier-Stokes equation accompanied by the species conservation equations in two dimensions by assuming chemical non-equilibrium and thermal equilibrium. The interaction of the low-density area (of the breakdown induced by blast-wave) and the bow shock in front of the body, results in modification in the flow-field, thereby reducing the wave drag. The maximum drag reduction occurs when the repetition rate is kept below 100 kHz for all the positions of energy deposition considered in the present study. Higher frequencies of energy deposition result in higher wave drag on the body. For 300 kHz and the farthest location considered in the present study, the drag reduction is found as low as 18% of drag without energy deposition with 6.8% aerodynamic efficiency. The maximum wave drag reduction was observed at 50 kHz with a maximum aerodynamic efficiency of 78.7% at the farthest position of energy deposition considered in the present study.

High-Lift Computational Strategy for Slotted, Natural-Laminar-Flow Airfoils

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.

Computational investigation of the aerodynamic performance of reversible airfoils for a bidirectional tidal turbine

A reversible airfoil is an airfoil that has equal performance when the flow is reversed. Such airfoils are relevant for many different applications, including use in ventilation fans, helicopter rotors, wind turbines and tidal turbines. Compared to traditional airfoils, reversible airfoils have different performance characteristics and have been less explored in the scientific literature. This work investigates the aerodynamic performance of some selected reversible airfoils using computational fluid dynamics. The selected airfoils are based on existing NACA 6 profiles and a profile using B-spline parameterization. The results show reduced performance for the reversible airfoils compared to a unidirectional airfoil. Of the investigated airfoils, the B-spline airfoil has the highest performance, with a maximum aerodynamic efficiency which is 87 % of the unidirectional design.

Effect of Airfoil-Preserved Undulation Placement on Wing Performance and Wingtip Vortex

The effect of undulation placement (leading edge, trailing edge, or leading and trailing edges) on the wing performance and the wingtip vortex was investigated. Experiments were performed at the University of Dayton Low-Speed Wind Tunnel on undulated wings where the NACA 0012 airfoil cross section is preserved along the wingspan. Sensitivity studies were done on the undulation wavelength along the span (, 0.21, and 0.15) and undulation placement (leading edge, trailing edge, and both leading and trailing edges). The leading-edge undulations delayed stall until higher angles of attack; however, the maximum aerodynamic efficiency was reduced. The trailing-edge undulated wing, on the other hand, increased the maximum aerodynamic efficiency but was not successful in stall mitigation. Wings with both leading- and trailing-edge undulations showed improvement in aerodynamic efficiency as well as delayed stall. The effect of the undulations on the wingtip vortex was also investigated through Particle Image Velocimetry. For the same coefficient of lift, the undulated wing cases reduced the wingtip vortex circulation by 25%. Investigations into the wingtip vortex core RMS and aerodynamic efficiency revealed a direct relationship where a higher vortex core rms resulted in a higher aerodynamic efficiency, and vice versa.

Aerodynamic Performances of Paper Planes

Paper plane has a high potential to be upgraded as a Micro Air Vehicle (MAV). Due to its simplicity, paper plane offers easier design option compared to the biological inspired designs as shown in recent MAV development. However, researchers have underestimate and overlook the basic aerodynamic performance induced by these paper planes. This is due to its common usage as toys and wide range of paper plane design. Thus, the objective for current work is to analyse and compare the aerodynamics forces and its performance for selected paper plane design known as Glider, Wide Stunt Glider Plane and Stunt plane. A series of CFD simulations on each paper plane was executed by using ANSYS-CFX module. A steady state, incompressible flow Navier-Stokes equation (RANS) combined with Shear Stress Turbulence (SST) model were used in this works to solve flow problem over the paper planes. The analysis is mainly conducted to study and compare the lift coefficient (), drag coefficient ()and aerodynamic efficiency () performances for each paper planes. The results show that the Glider paper plane has managed to produce better performances in terms overall magnitude, stall angle, wider angle of attack (?) envelope and higher maximum lift coefficient magnitude compared to the other paper plane design. However, Glider paper plane has the least distributions by producing at least 14.3% larger magnitude compared to the other plane design at certain ? region. Instead, The Wide Stunt has promisingly produced better distribution by producing lower value compared to the other plane design. Based on performance, the Wide Stunt paper plane has produced better and maximum aerodynamic efficiency () magnitudes compared to the other design. Wide Stunt paper plane induced at least 6.4% better magnitude compared to the other paper plane design. Based on these results, it can be concluded that Wide Stunt paper plane has promising advantages which are very crucial for the paper plane especially during hovering operation, take-off and landing manoeuvre.

A Novel Control Allocation Method for Yaw Control of Tailless Aircraft

Tailless aircraft without vertical stabilisers typically use drag effectors in the form of spoilers or split flaps to generate control moments in yaw. This paper introduces a novel control allocation method by which full three-axis control authority can be achieved by the use of conventional lift effectors only, which reduces system complexity and control deflection required to achieve a given yawing moment. The proposed method is based on synthesis of control allocation modes that generate asymmetric profile and lift induced drag whilst maintaining the lift, pitching moment and rolling moment at the trim state. The method uses low order models for aerodynamic behaviour characterisation based on thin aerofoil theory, lifting surface methodology and ESDU datasheets and is applied to trapezoidal wings of varying sweep and taper. Control allocation modes are derived using the zero-sets of surrogate models for the characterised aerodynamic behaviours. Results are presented in the form of control allocations for a range of trimmed sideslip angles up to 10 degrees optimised for either maximum aerodynamic efficiency (minimum drag for a specific yawing moment) or minimum aggregate control deflection (as a surrogate observability metric). Outcomes for the two optimisation objectives are correlated in that minimum deflection solutions are always consistent with efficient ones. A configuration with conventional drag effector is used as a reference baseline. It is shown that, through appropriate allocation of lift based control effectors, a given yawing moment can be produced with up to a factor of eight less aggregate control deflection and up to 30% less overall drag compared to use of a conventional drag effector.

On the aerodynamic fog collection efficiency of fog water collectors via three-dimensional numerical simulations

Fog water collection gained interest in recent years as an emerging solution for water scarcity in arid and semi-arid areas. During a fog event, a porous mesh screen of plastic polymer retains the water through droplet impaction, where the droplets coalesce and trickle into a gutter for collection. This type of collecting system has existed since the 1960s; however, a substantial lack of understanding remains as to the aerodynamics that dominates the collection phenomena. The Aerodynamic Collection Efficiency (ηa) is the determining factor in the overall performance of such systems. This paper aims to further the fundamental knowledge on the aerodynamic behavior during fog collection. For this, a three-dimensional computational fluid dynamics model was developed, where the collector's mesh was modeled as a porous medium, which simulates a conventional two-dimensional double layer mesh. A parametric study was carried out varying the mesh's geometric characteristics (flat and concave), mesh-to-ground distance, and wind speed. The effect of wind speed on aerodynamic collection efficiency is mainly determined by the relative relationship between the viscous and inertial pressure drop in the porous medium. A greater curvature reduces the mesh's airflow impedance, leading to a significant improvement of the aerodynamic collection efficiency. Within the parameter range of our study, we found a maximum aerodynamic collection efficiency of 35% for the largest curvature (1.1 m), the highest mesh-to-ground distance (2 m), and the maximum wind speed (5 to 7 m s−1).

Aerodynamic Performance of a Flapping Wing Inspired by Bats

Bio-inspiration is a design method where natural observation was used to solve a mechanical problem. In this study, a bio-inspiration meth-od was used to design a flapping wing for a Micro Air Vehicle (MAV) that is inspired by bat wings. The objective of this study is to study the aerodynamic performance of a flapping wing based on bat wings at different angles of attack. This is done using Computational Fluid Dynamics (CFD) simulation where the aerodynamic performance a wing derived from a natural bat wing shape was studied. The wing was generated by tracing the wing shape of a bat wing and the shape was generalized to produce the wing shape. In the simulation, a 2-way Fluid Structure Interaction (FSI) method was used where a Finite Element Analysis (FEA) solver was coupled with a CFD solver to simulate the wing during flapping flight. The flight condition was set at 1 m/s flight speed at a flapping frequency of 2.5Hz. From the results, it was shown that the wing has a zero-lift angle at 0o and a stall angle at 16o. It is also shown that the wing has a minimum drag angle at 3o and a maximum aerodynamic efficiency at angle of attack 12o.

ANÁLISIS AERODINÁMICO DE LA AERONAVE USB AERO MEDIANTE DINÁMICA DE FLUIDOS COMPUTACIONAL

The present research study presents the results of the aerodynamic analysis of a USB AERO aircraft using computational fluid dynamics (CFD) in operational conditions of cruise flight at an angle of attack of 3.5 degrees. The ANSYS FLUENT computational tool was used, with which the lift, drag and longitudinal momentum coefficients were determined. Additionally, the aircraft was analyzed at different angles of attack in order to determine aerodynamic characteristics such as the highest lift coefficient and the loss angle, in addition to establishing the maximum aerodynamic efficiency.

Wind Turbine Blade Optimal Design Considering Multi-Parameters and Response Surface Method

Within the framework of blade aerodynamic design, the maximum aerodynamic efficiency, power production, and minimum thrust force are the targets to obtain. This paper describes an improved optimization framework for blade aerodynamic design under realistic conditions, while considering multiple design parameters. The relationship between the objective function and the design parameters, such as the chord length, maximum chord, and twist angle, were obtained by using the second-order response surface methodology (RSM). Moreover, the identified parameters were organized to optimize the aerodynamic design of the blades. Furthermore, the initial and optimized blade geometries were compared and showed that the performance of the optimized blade improved significantly. In fact, the efficiency was increased by approximately 10%, although its thrust was not varied. In addition, to demonstrate the improvement in the resulting optimized blades, the annual energy production (AEP) was estimated when installed in a specific regional location. The result showed a significant improvement when compared to the baseline blades. This result will be extended to a new perspective approach for a more robust optimal design of a wind turbine blade.

Blade shape optimization of an aircraft propeller using space mapping surrogates

Propeller performance greatly influences the overall efficiency of the turboprop engines. The aim of this study is to perform a propeller blade shape optimization for maximum aerodynamic efficiency with a minimal number of high-fidelity model evaluations. A physics-based surrogate approach exploiting space mapping is employed for the design process. A space mapping algorithm is utilized, for the first time in the field of propeller design, to link two of the most common propeller analysis models: the classical blade-element momentum theory to be the coarse model; and the high-fidelity computational fluid dynamics tool as the fine model. The numerical computational fluid dynamics simulations are performed using the finite-volume discretization of the Reynolds-averaged Navier–Stokes equations on an adaptive unstructured grid. The optimum design is obtained after few iterations with only 56 computationally expensive computational fluid dynamics simulations. Furthermore, an optimization method based on design of experiments and kriging response surface is used to validate the results and compare the computational efficiency of the two techniques. The results show that space mapping is more computationally efficient.

Performance evaluation of multiphase induction generator in stand‐alone and grid‐connected wind energy conversion system

This study presents a detailed performance analysis of multi-phase (six-phase) induction generator in conjunction with different types of wind energy conversion systems (WECS). It targets to emphasise the advantages of considering an asymmetrical six-phase induction generator (ASIG) in stand-alone, grid-connected fixed speed and grid-connected variable speed operation. Various aspects such as efficiency, reliability and productivity are considered while performing the analysis. In stand-alone mode, reliability and efficiency of the self-excited ASIG are ascertained by disconnecting one of the two three-phase sets connected to a resistive load. In grid-connected fixed speed mode, two different scenarios are implemented to pursue the applicability of ASIG. In the first scenario, only one three-phase winding set is connected to the grid and another set is connected to a local resistive load. In the second scenario, both three-phase windings are connected to the grid via Y− Δ /Y three-winding transformer. Variable speed operation in grid-connected mode is accomplished by employing back-to-back pulse-width modulation converters between the generator and grid. In this configuration, ASIG is operated with indirect field oriented control to obtain maximum aerodynamic efficiency. Transmission of active and reactive power is monitored with vector-oriented control. Experimental results of considered scenarios are presented to verify the viability of ASIG in various configurations of WECS.

Aerodynamics of Discrete Location Camber Morphing Airfoils in Low Reynolds Number Flows

Objectives: This paper focuses on morphing the base airfoil similar into that of the target airfoil for the application of small unmanned aerial vehicle in low Reynolds number regime. Methods/Statistical Analysis: In this study, discrete location camber morphing approach was used to achieve the morphing configurations of base airfoil. Discrete location camber morphing method was classified into single, two and three location morphing configuration based on the number of morphing locations. The aerodynamic performance of morphed airfoil configurations were studied at the low Reynolds numbers of 2.5 × 10 5 and 3.9 × 10 5 using XFLR5 - e N method. Findings: The base airfoil for this study was selected as NACA0012. The E 207 airfoil which has better aerodynamic performance in low Reynolds number regime was selected as the target airfoil. Eleven different morphing configurations of base airfoil were developed for this study, which falls under these three classifications. Two out of eleven morphed configurations have similar geometric features and equivalent performance as that of E 207 for different range of angles of attack. These two morphed configurations showed a rise of about 3% in maximum aerodynamic efficiency compared to the target airfoil for the tested Reynolds number. Out of these two morphed configurations, one belongs to two location morphing method and another belongs to three location morphing method. This study also reveals that atleast one morphing location has to be closer to maximum camber position of the target airfoil to achieve an effective morphing. There is a possibility for switching between these two morphed configurations as they have two common morphing locations during the flight. Application/Improvements: This type of camber morphing can be positively applied in small unmanned aerial vehicles to achieve better aerodynamic performance over the entire flight mission.

Optimizing a Two-Element Wing Model with Morphing Flap by Means of the Response Surface Method

In designing the wings of UAVs, some factors such as the lift coefficient and lift-to-drag ratio (aerodynamic efficiency) play important roles in meeting the required fuel consumption, flight endurance, speed, reliability, maneuverability and runway length. One of the schemes presented for achieving the above objectives is the use of multi-element wings, in which high-lift mechanisms such as flaps and slats help the main airfoil. The recent advancements in the design of these mechanisms have made it possible to present a variety of morphing flap models that can perform adequately under different flight conditions. In the present research, a two-element wing model of a drone with medium-altitude and long-endurance capabilities and a morphing flap is numerically analyzed and the obtained results are compared with and validated by the empirical data obtained from wind tunnel tests. For optimizing the flap shape to achieve the maximum aerodynamic efficiency of the wing, the response surface method is used as a design of experiments technique. In this approach, several geometrical parameters that indicate the position and curvature of a flap were defined and different arrangements of these parameters are presented as experiment designs, then the aerodynamic efficiency of the wing for each design of experiment is determined numerically and the optimum design is proposed. The results show that the factors of flap curvature and vertical distance of flap to the main airfoil have a significant effect on the aerodynamic efficiency of the considered wing.

The PELskin project-part V: towards the control of the flow around aerofoils at high angle of attack using a self-activated deployable flap

During the flight of birds, it is often possible to notice that some of the primaries and covert feathers on the upper side of the wing pop-up under critical flight conditions, such as the landing approach or when stalking their prey (see Fig. 1) . It is often conjectured that the feathers pop up plays an aerodynamic role by limiting the spread of flow separation . A combined experimental and numerical study was conducted to shed some light on the physical mechanism determining the feathers self actuation and their effective role in controlling the flow field in nominally stalled conditions. In particular, we have considered a NACA0020 aerofoil, equipped with a flexible flap at low chord Reynolds numbers. A parametric study has been conducted on the effects of the length, natural frequency, and position of the flap. A configuration with a single flap hinged on the suction side at 70 % of the chord size c (from the leading edge), with a length of L=0.2c matching the shedding frequency of vortices at stall condition has been found to be optimum in delivering maximum aerodynamic efficiency and lift gains. Flow evolution both during a ramp-up motion (incidence angle from alpha _0=0 to alpha _s=20^circ with a reduced frequency of k= 0.12, U_{infty }/c, U_{infty } being the free stream velocity magnitude), and at a static stalled condition (alpha =20^circ) were analysed with and without the flap. A significant increase of the mean lift after a ramp-up manoeuvre is observed in presence of the flap. Stall dynamics (i.e., lift overshoot and oscillations) are altered and the simulations reveal a periodic re-generation cycle composed of a leading edge vortex that lift the flap during his passage, and an ejection generated by the relaxing of the flap in its equilibrium position. The flap movement in turns avoid the interaction between leading and trailing edge vortices when lift up and push the trailing edge vortex downstream when relaxing back. This cyclic behaviour is clearly shown by the periodic variation of the lift about the average value, and also from the periodic motion of the flap. A comparison with the experiments shows a similar but somewhat higher non-dimensional frequency of the flap oscillation. By assuming that the cycle frequency scales inversely with the boundary layer thickness, one can explain the higher frequencies observed in the experiments which were run at a Reynolds number about one order of magnitude higher than in the simulations. In addition, in experiments the periodic re-generation cycle decays after 3–4 periods ultimately leading to the full stall of the aerofoil. In contrast, the 2D simulations show that the cycle can become self-sustained without any decay when the flap parameters are accurately tuned.

Estimation of Performance Airspeeds for High-Bypass Turbofans Equipped Transport-Category Airplanes

Conventional Mach-independent subsonic drag polar does not replicate the real airplane drag characteristics exactly and especially not in the drag-divergence region due to shock-induced transonic wave drag. High-bypass turbofan thrust is a complicated function of many parameters that eludes accurate predictions for the entire operating envelope and must be experimentally verified. Fuel laws are also complicated functions of many parameters which make optimization and economic analysis difficult and uncertain in the conceptual design phase. Nevertheless, mathematical models and predictions have its important place in aircraft development, design, and optimization. In this work, airspeed-dependent turbofan thrust and the new fuel-law model were used in combination with an airplane polynomial drag model to estimate important performance speeds. Except for the airframe-only dependent control airspeeds, all performance speeds are airframepowerplant dependent. In all analytical considerations one ends up with polynomials of the 4 order that have no closed-form solutions. A real positive-root seeking numerical procedure based on the family of Newton-Raphson methods was used to extract performance airspeeds for variable in-flight weights and altitudes in the ISA troposphere. Extensive testing of the accuracy and convergence of the Newton-Raphson nonlinear equation solvers was conducted before performance speed calculations. A fictitious long-range wide-body transport-category airplane was modeled in combination with a pair of high-bypass and ultra-high bypass ratio flat-rated turbofans. Procedure employed here can be easily extended to cases when fitted, measured drag and thrust data is given in arbitrary polynomial forms. Sensitivity analysis is performed on minimum-drag airspeed and maximum aerodynamic efficiency. Transonic wave drag considerations are introduced.