Stability, Flying Qualities and Parameter Estimation of a Twin-Engine CS23/FAR23 Certified Light Aircraft

This paper presents some results of the flight test campaign conducted on the Tecnam P2006T aircraft, on the occasion of its certification process. This twin-engine propeller airplane is certified in the category CS23/FAR23. Many preliminary flight tests on a prototype of this light aircraft were aimed at optimizing performances and flight qualities. These experiences led to the application of two winglets to the original wing. The final configuration was extensively tested for the purpose of CS23 certification achievement. At the same time the airplane model, through a dedicated set of flight maneuvers, has been characterized by means of parameter estimation studies. The longitudinal and lateral-directional response mode were assessed and quantified. All the aircraft stability derivatives have been estimated from the acquired flight data using the well-known Maximum Likelihood Method (MLM). Some estimated stability derivatives have been also compared with the corresponding values extracted from leveled flight tests and from wind-tunnel tests performed on a scaled model of the aircraft

Numerical aerodynamic analysis on a trapezoidal wing with high lift devices: a comparison with experimental data

The aerodynamic analysis on the DLR-F11 high lift configuration model has been performed on the supercomputing grid infrastructure SCoPE of the University of Naples ???Federico II???. The model geometry is representative of a wide-body commercial aircraft, which experimental investigations at high Reynolds number have been performed at the European Transonic Wind-tunnel (ETW) for the 2nd AIAA High Lift Prediction Workshop. The commercial CAE package Star-CCM+ has been used to solve the Reynolds-averaged Navier-Stokes equations. Inviscid, viscous incompressible, and compressible analyses have been performed with mesh refinement. The inviscid calculations have been used to assess how far is the eulerian prediction from experimental data. Viscous and compressible calculations have been realized using the Spalart-Allmaras turbulence model at 0.175 Mach number and 15.1 million Reynolds number. Results show that the simple Spalart-Allmaras turbulence model can predict quite accurately the stall and post-stall behaviour, getting the angle of stall and underestimating the maximum lift coefficient by less than 5%. Comparisons among numerical and experimental pressure coefficients at several sections are also shown. Finally, the stall path is described

An Investigation on Vertical Tailplane Design

The paper presents a deep investigation on the methodologies to design a vertical tailplane. Nowadays the most used methodologies in preliminary design to estimate the contribution of vertical tailplane on aircraft directional stability and control are: the classical method proposed by USAF DATCOM (also presented in several aeronautics textbooks) and the method presented in ESDU reports. Both methodologies derive from NACA world war II reports of the first half of the ’900, based on obsolete geometries, and give quite different results for certain configurations, e. g. in the case of horizontal stabilizer mounted in fuselage. As shown in literature, the main effects on the side force coefficient of the vertical tail are due to the interactions among the aircraft components: the fuselage acts like a cylinder increasing the local sideslip angle, the wing position and aspect ratio have an influence on the airflow near the tail zone and the horizontal tail, depending on position and size, can act as an endplate increasing the side force. In order to better highlight these effects, a different approach using the RANS equations has been adopted. Several CFD calculations have been performed on some test cases (used as experimental database) described in NACA reports and used in the past to obtain the semi‐empirical methodology reported in USAF DATCOM, to verify the compliance of CFD results with available experimental data. The CFD calculations (performed through the use of a parallel supercomputing platform) have shown a good agreement between numerical and experimental data. Subsequently the abovementioned effects have been deeply investigated on a new set of propeller transport aircraft configurations. The different configurations that have been prepared differs for wing aspect ratio, wing‐fuselage relative position (high‐wing/low‐wing), vertical tailplane aspect ratio (vertical tail span versus fuselage radius) and horizontal tailplane position respect to the vertical tailplane (in particular investigation the effect of fin‐mounted T configuration, typical of regional turboprop transport aircraft). For all configurations the computational mesh has been carefully analyzed and prepared. All the CFD analyses will be useful to obtain new curves to predict the above-mentioned effects and to have a more accurate estimation of vertical tailplane contribution to aircraft directional stability and control

Design and aerodynamic analysis of a twin-engine commuter aircraft

The present paper deals with the preliminary design of a new general aviation Commuter 11 seat aircraft. The commuteraircraft market is today characterized by very few new models and the majority of aircraft in operation belonging to this category are older than 35 years. Tecnam Aircraft Industries and the Department of Industrial Engineering (DII) of the University of Naples "Federico II" have been deeply involved in the design of a new commuter aircraft that should be introduced in the market with very good opportunities of success. This paper aims to provide some guidelines on the conceptual design of this new twin-engine commuter aircraft. Aircraft configuration and cabin layoutchoices are shown and compared to similar solutions adopted by main competitors. The aerodynamic analyses are focused on some particular effects such as the wing-fuselage interference and the nacelle lift contribution and their effect on wing span loading. The aerodynamic analyses have been also essential to validate the preliminary estimation of aircraft stability and control derivatives (both longitudinal and lateral-directional) and to lead to a right sizing of tail surfaces. These analyses have been carried out through the use of a 3-D panel code. Finally some preliminary wind tunnel test results are presented

Aerodynamic analysis and design of a twin engine commuter aircraft

The present paper deals with the preliminary design of a general aviation Commuter 11 seat aircraft. The Commuter aircraft market is today characterized by very few new models and the majority of aircraft in operation belonging to this category are older than 35 years. Tecnam Aircraft Industries and the Department of Aerospace Engineering (DIAS) of the University of Naples "Federico II" are deeply involved in the design of a new commuter aircraft that should be introduced in this market with very good opportunities of success. This paper aims to provide some guidelines on the conception of a new twin-engine commuter aircraft with eleven passengers. Aircraft configuration and cabin layouts choices are shown, also compared to the main competitors. The research activity also deals with the aerodynamic design that has been performed at DIAS during 2011 and it was focused on a general aerodynamic analysis and a deep investigation on some particular effects (such as the wing-fuselage interference or the nacelle lift contribution and their effect on wing span loading). The aerodynamic analysis was also essential to have an accurate estimation of aircraft stability and control derivatives (both longitudinal and lateral-directional) and to lead to a right sizing of tail surfaces. The aerodynamic analysis have been carried out through the use of a 3-D panel code internally developed and the aerodynamic analysis performed through 3-D panel code calculations have been also supported by semi-empirical estimation methodologies. Design of winglets to improve climb performance will be presented

Development of new preliminary design methodologies for regional turboprop aircraft by CFD analyses

Since 2011 the aerodynamic research group of the Dept. of Industrial Engineering of the University of Naples "Federico II" makes use of the University's computing grid infrastructure SCoPE to perform parallel computing simulations with the commercial CAE package Star-CCM+. This infrastructure allows Navier-Stokes calculations on complete aircraft configurations in a relative short amount of time. Therefore, the software and the above mentioned infrastructure allow the parametric analysis of several configurations that are extremely useful to the correct estimation of aerodynamic interference among aircraft components and to highlight some useful trends that could indicate how a specific aerodynamic characteristic (i.e. the drag of a component, the wing downwash or the directional stability contribution of the vertical tail) is linked to aircraft geometrical parameters. Thus, with the choice of a specific set of test-cases it is possible to make a deep investigation on some aerodynamic features and, from the analyses of results, it is possible to extract and develop ad-hoc semi-empirical methodologies that could be used in preliminary design activities. In this paper, two investigations are presented: the aerodynamic interference among aircraft components in sideslip and the aerodynamic characteristics of a fuselage, focusing on typical large turbopropeller aircraft category

Aerodynamic analysis and optimization of a regional transport aircraft

The geometry of a typical regional transport aircraft is modified to reduce drag and improve performances, in particular cruise speed. Once performed a preliminary aerodynamic analysis on the original geometry, in order to detect those portions of the body shape whose modification mostly influences drag variation, an automatic procedure, manageable trough MATLAB, allows to modify those parts using interpolating curves and surfaces, espectively NURBS and NURBCOONS. Within the modification loop, each new geometry is analyzed trough a panel code solver until optimized shapes are found. Finally, the optimized body is exported into a CAD format (IGES) suitable for design and production. The optimization process has guaranteed a reduction of 3 percent of the total drag and an increase of 2 percent of cruise speed respect to the original configuration

Development of a Java-Based Framework for Aircraft Preliminary Design and Optimization

The paper deals with the description of a software tool to be used for aircraft preliminary design and optimization. The software tool, called ADOpT (Aircraft Design and Optimization Tool) has been developed in order to have a fast, reliable and user friendly framework to be used in preliminary/conceptual design phase. The software platform is made to perform fast multi-disciplinary analysis of an established aircraft configuration and search for an optimized configuration in a domain whose boundaries are defined by the user. The software has been conceived to be used in an industrial environment across conceptual and preliminary design phases. The software is still in development at the Department of Industrial Engineering of University of Naples

CFD sensitivity analysis on bumped airfoil characteristics for inflatable winglet

The new aerospace technological milestone is aimed to reducing direct operating costs and pol- lution. In order to obtain pollution reductions via high aerodynamic efficiency, a performance anal- ysis for bumped airfoil based winglet has been pro- posed. Most conventional aircrafts are equipped with fixed winglets to decrease the induced drag; thus, saving more fuel. New projects point to- wards advanced smart materials and telescopic wing tip devices to obtain an adaptive morphing shape that gives, through performance improve- ment, a fuel consumption reduction resulting in less pollutants. The focus of this paper is to evalu- ate the aerodynamic performance, in terms of lift, drag and moment coefficient for a bumped airfoil in climb/descent flight condition at 5000 meters altitude. The performance analysis has been con- ducted via a numerical investigation of the effects of bumps number, height and width for inflatable winglet airfoil, a system that would guarantee a more comfortable arrangement of extraction sys- tem and just minor surplus of weight compared to classical winglet solutions, with all the subsequent advantages

A comprehensive review of vertical tail design

This work aims to deal with a comprehensive review of design methods for aircraft directional stability and vertical tail sizing. The focus on aircraft directional stability is due to the significant discrepancies that classical semi-empirical methods, as USAF DATCOM and ESDU, provide for some configurations because they are based on NACA wind tunnel (WT) tests about models not representative of an actual transport airplane. Design/methodology/approach: The authors performed viscous numerical simulations to calculate the aerodynamic interference among aircraft parts on hundreds configurations of a generic regional turboprop aircraft, providing useful results that have been collected in a new vertical tail preliminary design method, named VeDSC. Findings: The reviewed methods have been applied on a regional turboprop aircraft. The VeDSC method shows the closest agreement with numerical results. A WT test campaign involving more than 180 configurations has validated the numerical approach. Practical implications: The investigation has covered both the linear and the non-linear range of the aerodynamic coefficients, including the mutual aerodynamic interference between the fuselage and the vertical stabilizer. Also, a preliminary investigation about rudder effectiveness, related to aircraft directional control, is presented. Originality/value: In the final part of the paper, critical issues in vertical tail design are reviewed, highlighting the significance of a good estimation of aircraft directional stability and control derivatives