This Paper explores the development of a novel hybrid air vehicle for package delivery called the quadrotor biplane tail-sitter. This vehicle uses differential thrust to effect body attitude changes like a traditional quadrotor, ensuring full transitional control between hover and forward flight modes. This method of control also allows the vehicle to remain mechanically simple. A vehicle was designed

Longitudinal vortices are a common flow phenomenon in the flow around aircraft. They emerge wherever sharp edges are encountered and affect the stability of the boundary layers with which they interact. Hence, for an optimal aircraft design, it is necessary to accurately predict not only the formation of these vortices, but also their downstream evolution. This paper presents a numerical simulation

In the context of conceptual design there are low-fidelity lifting line models capable of predicting the maximum lift coefficient of trapezoidal twisted wings. However, more complex geometries like that of the blended-wing–body (BWB) require the introduction of additional geometrical hypotheses. This paper introduces a compound-wing lifting line model that predicts the maximum lift coefficient of geometries

The low-sweep transonic natural laminar flow wing with shock control bumps, namely, LS-NLF-SCB wing, has a promising potential to be applied to future narrow-body commercial aircraft due to its advanced natural laminar wing design combined with shock control. This paper aims to assess the benefits of LS-NLF-SCB wing application from the viewpoint at the aircraft level. Based on the previous published

High-altitude scientific balloons are often prohibited from flying due to the risk associated with flying over populated areas. One solution to this problem is the use of a trajectory control system to control the ground track of the balloon. To assess the performance of one such trajectory control system in a real wind field, a small-scale sail was designed and built to fly beneath a moored balloon

Active flow control (AFC) is conventionally used to reduce flow separation at high angles of attack. A novel alternative form of AFC for controlling rotor blade loads in attached flow is examined. The AFC system employs pulsed fluidic jets near the trailing edge of a VR-12 airfoil on the pressure side and suction side. Each jet has two operating modes: tangential blowing and normal blowing. Unsteady

A flight test with a simplified hybrid laminar flow control (HLFC) system on the vertical tail plane (VTP) of an A320 aircraft was performed in April/May 2018. This HLFC system was a prototype for a simplified system that might be attractive for drag reduction of commercial long-range aircraft. The paper presents the design principles of a simplified HLFC system, including passive suction, and shows

Ice accretion on a helicopter’s aerodynamic surfaces during flight can lead to incidents and fatal accidents. An iced helicopter blade results in a decrease in stall angle, an increase in required torque, as well as potential damage from shed ice. While the high centrifugal forces on a rotor may serve as a natural deicing mechanism, they can also lead to uneven ice shedding, causing rotor imbalances

In an effort to evaluate the accuracy of the finite-state dynamic inflow of Peters and He (“Finite State Induced Flow Models Part II: Three-Dimensional Rotor Disk,” Journal of Aircraft, Vol. 32, No. 2, 1995, pp. 323–333) for use in rotor design, comparisons between dynamic inflow-based calculations and measured test data are presented for a wide variety of single rotor configurations and operating

This paper presents a theoretical investigation into the potential use of structural power composites in regional aircraft passenger cabins and the corresponding challenges to widespread use, including fire resistance, long-term cycling performance, and cost. This study focuses on adapting sandwich floor panels with structural power composite face sheets, designed to power the in-flight entertainment

The modeling and assessment of the community noise impacts of a representative hybrid-electric aircraft implementing windmilling motors as drag generators on approach is presented. An increasing desire to reduce emissions caused by aviation has motivated the development of hybrid-electric aircraft that have some degree of their traditional gas-turbine propulsion replaced with electric propulsion. Turboelectric

Structural optimization technology, as advanced as it has become, is still not used to fully automate the design of airframe components at a level of analysis detail that would be acceptable for certification by regulatory agencies. It is part of the development of certifiable structures but is still just a part, requiring significant manual labor invested by stress engineers working with empirical

Various characteristics of small surface-normal jets (microjets) located on a flap’s pressure-side near the trailing edge are investigated as an active aerodynamic load control technology for multi-element high-lift systems. Two-dimensional computational studies are carried out to investigate the sensitivity of microjet aerodynamic effectiveness to configuration. Initially, the effects of microjet

Mechanical instabilities and elastic nonlinearities are emerging means for designing deployable and shape adaptive structures. Dynamic snap-through buckling is investigated here as a means to tailor the deployment and retraction of a slat-cove filler (SCF), a morphing component used to reduce airframe noise. Upon deployment, leading-edge slats create a cove between themselves and the main wing, producing

In this Paper, the mechanic properties and sealing performance of the aircraft fabric rubber seal during flight are studied. First, the mechanic parameters, geometric structure, loading method of different aircraft cabin door fabric rubber seals, and gas conditions are analyzed. Second, the modified gas leakage rate formula of fabric rubber seal within wide ranges of temperature and gas pressure is

Journal of Aircraft, Ahead of Print.

Many electric vertical takeoff and landing concepts are characterized by nontraditional vehicle layouts with distributed propellers. Two propeller interaction types were distinguished in this Paper, which investigates how propeller interaction in side-by-side and one-after-another configuration affects performance, in terms of thrust, power, in-plane forces, and out-of-plane moments, and how those

The present study numerically explored the hydrodynamic characteristics of a helicopter model experiencing guided ditching on wavy water. The air–water two-phase flow was computed by solving unsteady incompressible Reynolds-averaged Navier–Stokes equations enclosed by the k-ω shear stress transport turbulence model. The effect of water-entry position of the wave, viz., crest, falling, rising and trough

A recent consideration in aircraft design is the use of folding wingtips, with the aim of enabling higher-aspect-ratio wings with less induced drag but also meeting airport gate limitations. A formulation is introduced to account for finite rotations of rigid folding wingtips attached through hinges on a flexible airframe structure including also aerodynamic follower forces for the folding wingtip

A wind tunnel test was performed in the 0.3-Meter Cryogenic Transonic Tunnel at the NASA Langley Research Center to investigate the impact of various boundary layer thickeners on the height and shape of the boundary layer on the aft portion of a half-fuselage model. The present paper discusses USM3D analyses that were performed in support of the wind tunnel test. The results consisted of comparisons

The influence of the lift-share ratio between a rotor and a wing on the aerodynamic performance of a winged compound helicopter in high advance ratio flight is investigated through numerical simulations in this paper. A simplified model constructed with only a rotor and a winged body is considered to focus on the aerodynamic interactions between the rotor and the wing. The effect of the interaction

Journal of Aircraft, Ahead of Print.

Balancing accurate and efficient estimation of aerothermodynamic loads is a significant challenge for multidisciplinary modeling and analysis of high-speed vehicles. This study focuses on this issue by studying the impact of analytical and data-driven model reductions over a broad operational space. Reduced models are compared with Reynolds-averaged Navier–Stokes predictions for steady-state aerodynamic

In conventional aircraft design, engine loads are transferred directly from the engine core and fan case to the pylon via engine mounts. Literature is available on the modeling of individual powerplant components, but limited work is available on the whole assembled system (engine, pylon, and nacelle). The influence of the structural connections between the components on overall system performance

Icing on three-dimensional lifting surfaces has been shown to produce highly complex flowfields. However, there is a lack of experimental and computational information in the public domain regarding three-dimensional aerodynamics for iced commercial aircraft wing geometries. Recent work completed at NASA Glenn Research Center’s Icing Research Tunnel has developed realistic ice shapes for the leading

The recent growth of interest in hybrid-electric and fully electric aircraft has led to a renewed focus on the design and optimization of propeller aircraft. Considering propeller–wing interaction provides the opportunity to design aircraft that take advantage of aerodynamic benefits through propulsion integration. In this paper, the cruise drag of a wing with an inboard-mounted tractor propeller is

The commercial aircraft development program is generally confronted with huge risks from various aspects. To improve the economic benefits of the aircraft program and increase the competitiveness of aircraft manufacturers, the risk analysis and economic evaluation of the aircraft program are studied in this paper, within which the qualitative risk assessment index system of the aircraft program is

The effect of aircraft performance, quantity, and schedule on aircraft cost has been analyzed in order to create a method for making informed decisions about aircraft optimization. Operations analysis and parametric costing were used to compare the operational value of increased aircraft performance to the cost of increasing aircraft performance. In addition to the direct cost of performance, this

In this paper the application of a wing fence on an unmanned aerial vehicle (UAV) is examined. The UAV under consideration is characterized by flow separation initiating at the tip, leading to a loss of lift and controllability and the appearance of a nose-up pitching moment. A possible solution to this problem is the use of wing fences: plates placed on top of the wing aligned with the flow and developed

Accurate modeling of aircraft fuel consumption, emissions, and noise is crucial in evaluating new air transportation operational procedures and policies to abate negative environmental impacts. The Aviation Environmental Design Tool (AEDT) is a comprehensive software package developed to address this requirement. Although the modeling of departure operations around airports is of great interest to

A high-fidelity coupled computational fluid dynamics and comprehensive analysis solver is developed for helicopter flight on Mars. The objectives are accurate prediction of flight loads and fundamental understanding of Martian aeromechanics. Performance, structural loads, pitch link loads, rotor wake, and interrotor blade separation are studied for hingeless and flap articulated coaxial rotors. In

Unlike a single-body approach, modeling based on a two-body approach has been employed to prepare the required system dynamic model as a time update equation in the applied filtering technology and measurement data for the estimation process. This more precise mathematical model enabled better understanding about the dynamics of the change in the aircraft mass properties during the airdropping operation

Low technology readiness level (TRL) technologies are attractive to the aerospace industry because their maturation cycles can happen simultaneously with the development lifecycle of the aircraft. However, due to the limited knowledge about a new technology in system evaluation, a low TRL technology’s high potential is counterbalanced by its inherent high risk and high uncertainty. As a result, the

In this paper, the validity of the thin-airfoil-theory-based source term modeling, Bender–Anderson–Yagle (BAY) model, for predicting the flows induced by a range of different vane-type vortex generators (VGs) is analyzed. By directly comparing the BAY model computations with the body-fitted VG computations using the same grids, the modeling errors involved in the BAY model are elucidated. The results

The unsteady flows produced over the stern of a Simple Frigate Shape 2 ship model are studied in a low-speed wind tunnel. Time-resolved particle image velocimetry (TR-PIV) measurements were performed in several streamwise and cross planes. Two grids of Cowdrey rods were used to simulate the basic characteristics of an atmospheric boundary layer in terms of upstream velocity profile and turbulence intensity

This paper details the successful takeoff and landing of a wing-tip-connected meta aircraft prototype. The aircraft consisted of two commercial off-the-shelf high wing trainers connected wing tip to wing tip with three neodymium magnets. The flight controller on board each aircraft was a Raspberry Pi 3B complete with Navio2 flight controller. The software running on the aircraft was built using Emlid

In this paper, a computationally efficient multifidelity local search algorithm for aerodynamic design optimization is presented. In this paper’s approach, direct optimization of a computationally expensive model is replaced by an iterative updating and reoptimization of a fast multifidelity model constructed using a low-fidelity model adapted locally using manifold mapping (MM) to become a reliable

Application of the aeroelastic analysis and design framework developed at Delft University of Technology to a design of two aeroelastically tailored composite wings for a flying demonstrator is presented. The objective of the design process is to minimize structural mass of the wing while maintaining a target cruise shape. For this purpose, the jig shape of the wing is parameterized and becomes an

A classical flow-vane approach for reconstructing translational gust velocities from air data and inertial sensor measurements was improved and implemented for real-time computation. The reconstructed turbulence measurements were then included in a system identification analysis to estimate nondimensional stability and control derivatives in a longitudinal short period model using the maximum likelihood

Waveriders have a high lift-to-drag ratio in hypersonic states, while the flexibility of design methods must still be improved because of some deficiencies such as unsatisfactory off-design performance and stability. In this paper, a geometric relationship in the osculating-cone method is derived and expressed by a differential equation set including five equations. Then the equation set is simplified

Journal of Aircraft, Ahead of Print.

Journal of Aircraft, Ahead of Print.

The Aircraft Noise Simulation Working Group (ANSWr) was established by DLR, ONERA, and NASA to compare simulation tools, establish guidelines for noise prediction, and assess uncertainties associated with the simulation. A benchmark test was initiated, and initial results for a reference and a low-noise vehicle are discussed. The reference aircraft is a conventional tube-and-wing configuration with

A computational study is conducted on thin flat plates to simulate flows of Reynolds numbers at 104 to provide understanding and guidance for micro air vehicles and other low-Reynolds-number airfoil designs. A synergistic effort between experiments and validated and computational fluid dynamics (CFD) tools were used as part of this study. The CFD tool used in this study is an established Reynolds-averaged

The second generation of supersonic civil transport has to match ambitious targets in terms of efficiency to be economically and environmentally viable. Computational fluid dynamics-based design optimization offers a powerful approach to address the complex tradeoffs intrinsic to this novel configuration. This approach is applied to the design of airfoils and wings at both supersonic cruise conditions

This research focused on furthering the current understanding of the flowfield inside a cavity under typical flight conditions. The flight envelope included altitudes of up to 40,000 ft and maximum Mach number of 1.28 and included several test points between Mach 0.9 and 1.1, which are challenging to isolate in wind tunnel testing due to tunnel wall interference. The pod was instrumented to collect

Air vehicle sizing requires the ability to estimate the propulsive power and energy requirements of a flight vehicle as well as its weight. Existing tools and methods for aircraft sizing typically focus on a specific air vehicle category, generally assume a conventional fuel-burning propulsion system architecture, and employ a point-mass performance model. These shortcomings limit or preclude their

A low-order method is presented for aerodynamic prediction of wings operating at near-stall and post-stall flight conditions. The method is intended for use in design, modeling, and simulation. In this method, the flow separation due to stall is modeled in a vortex lattice framework as an effective reduction in the camber, or “decambering.” For each section of the wing, a parabolic decambering flap

Hover performance and prediction for tiltrotor-like vehicles lack experimental data and computational models for rotor–wing interaction at low disk loading and low Reynolds number. An experimental investigation of rotor–wing interaction in hover near the small unmanned-air-vehicle scale (disk loading < 100 N/m2 and Re<100,000) is conducted to determine how changes in rotor–wing geometry influence rotor–wing

This paper presents an investigation of the effects of tip sweep on highly twisted composite rotor blades by acquiring strain data in vacuum. Three parametric test cases were designed for strain measurements, and predictions from a special three-dimensional (3-D) finite element method were used for assessment of data. A set of rotating aluminum beams was also tested as a rudimentary baseline. Three

Implementations of lifting-line theory predict the lift of a finite wing using a sheet of semi-infinite vortices extending from a vortex filament placed along the locus of aerodynamic centers of the wing. Prandtl’s classical implementation is restricted to straight wings in flows without side slip. In this Paper, it is shown that lifting-line theory can be extended to swept wings if, at the control

A self-adaptive dissipation method based on a fifth-order dissipative compact scheme is proposed to reduce the numerical dissipation in separated flow. The method involves a self-adaptive operating parameter to adjust the weight of upwind part, which is a major source of numerical dissipation. Cooperated with delayed detached eddy simulation, the method can perform with less numerical dissipation in

The paper presents an aerodynamic investigation of 70 different streamlined bodies with fineness ratios ranging from 2 to 10. The bodies are chosen to idealize both unmanned and small manned aircraft fuselages and feature cross-sectional shapes that vary from circular to quadratic. The study focuses on friction and pressure drag in dependency of the individual body’s fineness ratio and cross section

Formation flight has the potential to significantly reduce aircraft fuel consumption by allowing “follower” aircraft to fly in the aerodynamic wake of “leader” aircraft. However, this requirement for aircraft to be in close proximity for large parts of their journey raises questions about the suitability of flying in formation given the diverse range of existing flights and geographical regions. This

Hybrid wing body is a fuel-efficient aircraft configuration where the pressurized center section is confined by almost-flat panels jointed at right angles. The combination of internal pressure and in-plane loads imparts cyclic large out-of-plane deformations to the noncircular fuselage. These repeated pressure loads would lead to separation between the skin and flanges and delaminations in traditional

Airfoils tested at low speeds generally produce surface pressure distributions that differ substantially from those measured at transonic conditions, which in turn results in very different boundary-layer characteristics even for the same Reynolds number. A methodology is presented for mapping transonic pressure gradients to an equivalent low-speed airfoil. It is applied to the design of a low-speed

The aerodynamic data of winged and lifting space vehicles are considered. Recently, there was an investigation with respect to the longitudinal aerodynamics of these vehicles in the supersonic and hypersonic Mach number regimes with the astonishing result that for the lift and drag coefficients a similarity with regard to the geometrical configuration could be observed. It was shown that by introducing

Uncertainty based multidisciplinary analysis (UMDA) is a methodology to quantify uncertainty on the system-level quantity of interest by propagating uncertainty within and among multiple disciplines of a system. In an industrial setting, the design of complex systems involves the collaboration of multiple and diverse teams involving high-fidelity disciplinary tools and experts. Under such scenarios

An experimental study is conducted on a NACA 0012 airfoil with a control surface to investigate the influence of a propeller slipstream under a low-Reynolds-number condition. To investigate the influence of the propeller slipstream on a wing surface, the flowfield on the wing surface is visualized using a temperature-sensitive paint when the chord-based Reynolds number is equal to 3.0×104. The control

Flying animals exploit highly nonlinear dynamics to achieve efficient and robust flight control. It appears that the distributed flow and force sensor arrays found in flying animals are instrumental in enabling this performance. Using a wind-tunnel wing model instrumented with distributed arrays of strain and pressure sensors, we characterized the relationship between the distributed sensor signals