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Unconventional configuration aircrafts are not often designed because of many problems, mainly with stability and trim. However, they could be very promising. The problems can be compensated by extraordinary performance and some flying characteristics. The three-surface aircraft, presented in the paper, is such a configuration – problems and profits are both present, but advantages seem to be more prevalent. This paper aims to present main assumptions for a new, three-surfaces aircraft design, its evaluation according to flying quality requirements and the discussion on selected performance characteristics. The paper completes with the first experimental results of flight tests of a 40 per cent scaled model.

Aerodynamic computations were made using panel method code (KK-AERO, PANUKL). Stability analysis was done using SDSA package, developed within the SimSAC project.

Initial design assumptions and numerical analysis results were proven during flight tests.

The paper contains results of numerical analysis, which were crucial in designing the layout of the new, three-surface aircraft.

This paper presents an original approach to design a new, unconventional aircraft. The approach and results could be useful in other projects.

The present study aimed to demonstrate different computational models, data and stability results obtained in a wide number of projects of various aircrafts such as unmanned aerial vehicles (UAVs), general aviation and big passenger flying airliners in blended wing body (BWB) configurations. Many details of modeling and computing are shown for unconventional configurations, namely, for a BWB aircraft and for tailless UAVs.

Mathematical models for analysis of static and dynamic stability were built and investigated based on equations of motion in the linearized form using the so-called state variable model for a steady-state disturbed, generally asymmetric, flight.

Flight dynamics models and associated computational procedures appeared to be useful, both in a preliminary design phase and during the final assessment of the configuration at flight tests. It was also found that the difference between thresholds for static and dynamic stability conditions was equal to 9 per cent of mean aerodynamic chord (MAC) in the case of BWB and 3 per cent of MAC in the case of tailless UAVs.

Many useful information about aircraft dynamics can be easily obtained from computational analyses including time to half/double and periods of oscillation, undamped frequencies, damping ratio and many others. Stability analysis of different unconventional configurations will be easier and faster if an access to such configurations is available.

This paper presents a very efficient method of assessment of the designing parameters, especially in an early stage of the design process. In open literature, there are a great number of datasets for classical configurations, but it is hard to find anything for passenger BWB and tailless UAVs. Stability computations are performed based on equations of motion derived in the stability frame of the reference fixed with one-quarter of MAC. It can be considered as an original, not typical but a very practical approach because values of stability and control derivatives do not change even if the centre of gravity is travelling.

This paper aims to present the results of aerodynamic calculation of the aircraft in tandem wing configuration called VTOL. A presented vehicle combines the capabilities of the classic aircraft and helicopters. The aircraft is equipped with two pairs of tilt-rotors mounted on the tips of the front and the rear wing. The main goal of the presented research was to find the aerodynamic impact of both pairs of tilt-rotors on aerodynamic coefficients of the aircraft. Moreover, the rotors impact on the static stability of the aircraft was investigated too.

The CFD analysis was made for the complete aircraft in the tandem wing configuration. The computation was performed for the model of aircraft which was equipped with the four sub-models of the front and rear rotors. They were modeled as the actuator discs. This method allows for computing the aerodynamic impact of rotating components on the aircraft body. All aerodynamic analysis was made by the MGAERO software. The numerical code of the software was based on the Euler flow model. The used numerical method allows for the quick computation of very complex model of aircraft with a satisfied accuracy.

The result obtained by computation includes the aerodynamic coefficients which described the impact of the tilt rotors on the aircraft aerodynamic. The influence of the angle of attack, sideslip angle and the change of rotor tilt angle was investigated. Evaluation of the influence was made by the stability margin analysis and the selected stability derivatives computation.

Presented results could be very useful in the computation of dynamic stability of unconventional aircraft. Moreover, results could be helpful during designing the aircraft in the tandem wing configuration.

This paper presents the aerodynamic analysis of the unconventional configuration of the aircraft which combines the tandem wing feature with the tilt-rotor advantages. The impact of disturbance generated by the front and rear rotors on the flow around the aircraft was investigated. Moreover, the impact of rotors configuration on the aircraft static stability was found too.

This paper presents first sight on the longitudinal control strategy for an aircraft in the tandem wing configuration. It is an aerodynamic strongly coupled configuration that needs a lot of detailed aerodynamic analysis which describes the mutual impact of the main parts of the aircraft. The purpose of this paper is to build the numerical model that allows to make an analysis of necessary flaps (front and rear) deflection and prepare the control strategy for this kind of aircraft.

Aircrafts’ aerodynamic characteristics were obtained using the MGAERO software which is a commercial computing fluid dynamics tool created by Analytical Methods, Inc. This software uses the Euler flow model. Results from this software were used in the static stability evaluation and trim condition analysis. The trim conditions are the outcome of the optimisation process whose goal was to find the best front and rear flap deflection to achieve the best lift to drag (L/D) ratio.

The main outcome of this investigation is the proposal of strategy for the front and rear flap deflection which ensured the maximum L/D ratio and satisfied the trim condition. Moreover, the analysis of the mutual impact of the front and rear wings and the analysis of the control surface impact on the aerodynamic characteristic of the aircraft are presented.

In terms of aerodynamic computation, MGAERO software uses an inviscid flow model. However, this research is for the conceptual stage of the design and the MGAERO software grantee satisfied accurate respect to relatively low time of computations.

The ultimate goal is to build an aircraft in a tandem wing configuration and to conduct flying tests or wind tunnel tests. The presented result is one of the milestones to achieve this goal.

The aircraft in the tandem wing configuration is an aerodynamic-coupled configuration that needs detailed analysis to find the mutual interaction between the front and rear wings. Moreover, the mutual impact of the front and rear flaps is necessary too. Obtaining these results allowed this study to build the numerical model of the aircraft in the tandem wing configuration. It allows to find the best strategy of flap deflection, which allows to obtain the maximum L/D ratio and satisfy the trim condition.

Tandem wing aircrafts belong to an unconventional configurations group, and this type of design is characterised by a strong aerodynamic coupling, which results in lower induced drag. The purpose of this paper is to determine whether a certain trend in the wingspan impact on aircraft dynamic stability can be identified. The secondary goal was to compare the response to control of flaps placed on a front and rear wing.

The aerodynamic data and control derivatives were obtained from the computational fluid dynamics computations performed by the MGAERO software. The equations of aircraft longitudinal motion in a state space form were used. The equations were built based on the aerodynamic coefficients, stability and control derivatives. The analysis of the dynamic stability was done in the MATLAB by solving the eigenvalue problem. The response to control was computed by the step response method using MATLAB.

The results of this study showed that because of a strong aerodynamic coupling, a nonlinear relation between the wing size and aircraft dynamic stability proprieties was observed. In the case of the flap deflection, stronger oscillation was observed for the front flap.

Results of dynamic stability of aircraft in the tandem wing configuration can be found in the literature, but those studies show outcomes of a single configuration, while this paper presents a comprehensive investigation into the impact of wingspan on aircraft dynamic stability. The results reveal that because of a strong aerodynamic coupling, the relation between the span factor and dynamic stability is nonlinear. Also, it has been demonstrated that the configuration of two wings with the same span is not the optimal one from the aerodynamic point of view.

A review is attempted with the objective to indicate the most promising aeronautical technology for application to future subsonic civil transport aircraft.

A methodology is put forward, according to which direct operating costs (DOC) are examined in order to identify those that can be reduced, and, then, specific technology is assessed in relation to its efficiency in reducing these DOC, operational feasibility and cost‐effectiveness.

This assessment suggests the selection of propfan and powered lift as the leading future aeronautical technology. These findings are supported by a comparison of a number of advanced technology designs.

Provides a starting point for further investigation of advanced aeronautical technology and unconventional configurations for large subsonic civil transport aircraft.

This study aims to analyse slender thin-walled anisotropic box-beams. Fiber-reinforced laminated composites could play an important role in the design of current and future generations of innovative civil aircrafts and unconventional unmanned configurations. The tailoring characteristics of these composites not only improve the structural performance, and thus reduce the structural weight, but also allow possible material couplings to be made. Static and dynamic aeroelastic stability can be altered by these couplings. It is, therefore, necessary to use an accurate and computationally efficient beam model during the preliminary design phase.

A proper structural beam scheme, which is a modification of a previous first-level approximation scheme, has been adopted. The effect of local laminate stiffness has been investigated to check the possibility of extending the analytical approximation to different structural configurations. The equivalent stiffness has been evaluated for both the case of an isotropic configuration and for simple thin-walled laminated or stiffened sections by introducing classical thin-walled assumptions and the classical beam theory for an equivalent system. Coupling effects have also been included. The equivalent analytical and finite element beam behaviour has been determined and compared to validate the considered analytical stiffness relations that are useful in the preliminary design phase.

The work has analyzed different configurations and highlighted the effect of flexural/torsion couplings and a local stiffness effect on the global behaviour of the structure. Three types of configurations have been considered, namely, a composite wing box configuration, with and without coupling effects; a wing box configuration with sandwich and cellular constructions; and a wing box with stiffened panels in a coupled or an uncoupled configuration. An advanced aluminium experimental test sample has also been described in detail. Good agreement has been found between the theoretical and numerical analyses and the experimental tests, thus confirming the validity of the analytical relations.

The equivalent beam behaviour that has been determined and the stiffness calculation procedure that has been derived could be useful for future dynamic and aeroelastic analyses.

The article presents an original derivation of the sectional characteristics of a thin-walled composite beam and a numerical/experimental validation.

The purpose of this paper is to define reliability requirements to be imposed on electric engines to assure similar or higher value of mean time between failures (MTBF) for mixed piston-electric propulsion configurations when compared to classic and unconventional piston engine configurations.

Reliability estimation was done using mathematical model of safety of light aircraft commercial operations. The model was developed on the basis of Federal Aviation Administration and National Transport Safety Board data. The analysis was conducted for numerous piston and electric configurations. It allowed comparison of selected solutions and definition of relation between electric engine MTBF and MTBF calculated for entire mixed piston-electric propulsion system.

It was found that, from reliability point of view, mixed piston-electric engine propulsion is attractive alternative for classic single- and twin-piston configuration. It would allow to at least doubling of MTBF for propulsion without increase of operational cost.

Rationale behind exploiting electric propulsion in aviation is provided. Relation between electric engine reliability and entire propulsion reliability was identified and defined. Minimum requirements concerning MTBF value for electric engine application in aviation was assessed. Conclusions from this study can be used for definition of requirements for new aircraft and by the regulatory authorities.

Originality consists in use of real accident statistics included in mathematical model of safety for assessment of MTBF for various classic and novel piston and piston-electric engine configurations of light aircraft. Output from the study can be exploited by the industry.

The purpose of this paper is to study the conceptual design and optimisation of a compound gyroplane. A study of a compound gyroplane configuration and its characteristics was performed to develop a sizing program.

The vertical takeoff and landing capabilities of a helicopter are particularly important. The need for efficient hover and the effectiveness of forward flight in the helicopter can cause conflicts within the design process. The designers usually wish to increase the helicopter's maximum forward speed. Recently, the compound aircraft is one of the concepts considered for the purpose of expanding the flight envelope of rotorcraft. The study of the compound gyroplane showed its advance capabilities for this purpose. Understanding its characteristics, a number of calculations are conducted to implement a sizing program for compound gyroplanes based on the conventional helicopter sizing process.

The results of the sizing program were validated using existing aircraft data such as the Challis Heliplane, Carter Copter, FB‐1 Gyrodyne, and Jet Gyrodyne. The program is appropriate to size a compound gyroplane at the conceptual design phase. An optimisation study was also performed to enhance sizing results. The compromise between the rotor lift sharing factor and the ratio of the wing span (Bw) to rotor diameter (D) was solved by choosing the total gross weight (TOGW) as the objective function, while the design variables are compromising factors. The optimum results showed that the TOGW of all four kinds of compound gyroplanes was considerably reduced.

A conceptual sizing program for unconventional compound aircraft was developed. The study showed that an optimum design process is necessary to enhance the sizing results.

This paper aims to present a preliminary study on a disruptive vertical take-off and landing (VTOL) configuration based on the best wing system concept by L. Prandtl.

A preliminary design has been addressed from several points of views: a conceptual design has been carried out thanks to in-house optimization tool; aerodynamic performances, propulsion design and mechanical design have been addressed to make the first prototype for preliminary vertical flight tests.

The study shows the feasibility of box-wing configuration for VTOL aircraft.

The work shows a general design procedure for box-wing unmanned air vehicle (UAV) configuration. The study of this configuration can be easily adopted in wider range, from UAV to general aviation. In the last category, it can be a promising configuration for the future of urban air mobility.

This work lays the foundation for studying and testing box-wing configuration for unmanned VTOL aircraft. The design procedure can be scaled to manned aircraft belonging to general aviation aircraft.