This paper presents a detailed analysis of the Blade Element Theory (BET) as applied to the aerodynamic performance of propellers and rotor systems. BET, a low-fidelity but widely used method, models the rotor blade as a series of independent elements along its span, allowing local aerodynamic forces to be calculated based on flow conditions. The approach combines the Blade Element Theory with Momentum Theory, implemented in a MATLAB program for a forward flight helicopter, facilitating the computation of thrust, torque and power coefficients. To account for inflow distribution and induced velocity effects, actuator disk theory is applied at the rotor disk level, providing a consistent estimation of the induced velocity required for accurate flow velocity values. The rotor solidity is used to compare lifting rotor system to an ideal actuator disk. Results demonstrate that the coupled method of BET and Momentum Theory provides accurate and consistent aerodynamic predictions for use in rotor design, optimization and validation against experimental measurements or CFD simulations.

The paper contains recent work of the authors regarding the quality of layers deposited with the laser cladding technique. In the field of additive manufacturing, directed energy deposition (DED) in laser cladding presents both opportunities and challenges, especially in adapting to complex geometries while maintaining consistent material properties. Traditional laser cladding systems operate with fixed parameters, making it hard to balance precision and deposition efficiency. Smaller laser spot sizes offer high accuracy but lower deposition rates, while larger spots enable faster cladding at the expense of fine detail. This paper investigates an approach to adjusting parameters like laser power to achieve uniform material characteristics in 316L stainless steel claddings on 304 stainless steel substrates. The deposition parameters were adapted to the type of the materials that were used. Custom parameters are necessary in order for both the substrate and the alloy deposited, including laser power, laser spot size, advance speed, and degree of overlap between deposited layers.

This paper contains personal contributions discussed in a collaborative working group ICAO-IFAR DiTAC Action “Digital Transformation in Aircraft Certification” in order to highlight that the certification requirements are satisfied in a structural analysis process. Compliance with CS-25 when using FEM is demonstrated through engineering justification, correlation with test results (when available), application of appropriate safety margins, and documentation of all modelling assumptions and boundary conditions. Each analysis must provide evidence that the structural behavior meets the regulatory criteria under all applicable loading conditions. Performed structural analyses are verified for compliance with applicable EASA certification requirements, in this case, CS-25. It is described that there is no direct correspondence between CS-25 certification requirements and the FEM modelling process, since the regulation defines safety objectives, not recommending specific analysis methodologies.

Oblique shock wave - boundary layer interactions (OSBLIs) at transitional Reynolds numbers are known to generate low-frequency unsteadiness that can impact aerodynamic efficiency, structural integrity, and system reliability in high-speed aerospace components. The present research examines how variations in Mach number, Reynolds number, and inviscid pressure jump influence the dynamics of these transitional interactions. Experimental campaigns were conducted in the TST-27 transonic–supersonic wind tunnel at TU Delft, utilizing high-speed and spark-light Schlieren imaging to capture flow behavior, followed by digital and spectral post-processing. The results reveal that transitional OSBLIs exhibit low-frequency shock oscillations strongly correlated with the periodic formation and disappearance of a Mach stem, a mechanism referred to as the “dual-domain” phenomenon. Systematic parameter variations showed that even small changes in Mach or Reynolds number substantially altered the presence of this dual domain as well as the amplitude and frequency of the oscillations. Furthermore, the Reynolds number regime previously identified as transitional for flat-plate boundary layers was experimentally validated in the present configuration. A secondary focus of the study was the application of passive flow control by introducing thin two-dimensional steps (≈60 μm) to trip the boundary layer. These perturbations were found to effectively suppress shock oscillations and modify the overall interaction dynamics, with frequency analyses confirming the disappearance of oscillation peaks observed in the baseline cases. A nondimensional analysis demonstrated a consistent Strouhal number convergence around St ≈ 0.33 for cases with strong unsteadiness. Increasing Reynolds number led to reduced laminar separation lengths and higher oscillation frequencies, consistent with expected transition dynamics. Overall, this research identifies the primary parameters governing unsteadiness in transitional OSBLIs, highlights effective suppression through minimal boundary-layer tripping, and provides nondimensional scaling to support predictive modeling. These insights contribute to improved understanding and design of aerospace components subject to shock-induced boundary-layer interactions.

This research introduces a simulation framework for aircraft ground roll, integrating a dynamic model developed in Simcenter Amesim with a control system implemented in MATLAB/Simulink through the Functional Mock-up Interface (FMI). The study aims to provide a robust environment for analysing and validating advanced ground control strategies under realistic runway roll conditions. The aircraft model, based on a 6DOF tricycle configuration, includes steering and differential braking features adapted from a validated Amesim taxi model, using representative data of a commercial turboprop aircraft. The framework enables bidirectional communication between Amesim and MATLAB through FMI and Co-Simulation, allowing performance evaluation of the control system. The controller employs a structured H-Infinity approach combined with a control allocator to coordinate rudder, nose wheel, and differential braking actions, ensuring runway centerline tracking and stability even in the presence of crosswind and for different runway conditions. The FMI integration process includes interface remapping, FMI export from Simulink, and closed-loop coupling with the Amesim model. Additional simulations were performed using a reverse configuration, with Amesim running as a co-simulation module within MATLAB via an S-function interface, to validate interoperability and numerical consistency. Comparative analysis between FMI and Co-Simulation confirm consistent data exchange and equivalent dynamic responses across platforms. The developed framework demonstrates the feasibility, flexibility, and accuracy of hybrid Amesim–MATLAB environments for studying complex aircraft ground dynamics configurations and provides a foundation for future work.

While aerodynamic optimization of wing geometry in cruise flight has been widely investigated, such modifications inevitably alter the aerodynamic characteristics of high-lift devices, which remain essential during take-off and landing regimes. In this context, the present study addresses the influence of flap slot geometry on the aerodynamic characteristics of single-slotted flap configurations. For this reason, a parametrization method is introduced, combining cubic Bézier curves for flap definition with local curvature parameters for the cove region of the airfoil. This approach ensures geometric continuity in the retracted configuration while enabling rigorous control of the deployed flap geometry. The parametrization was integrated into an automated CFD and gradient-based optimization framework, enabling the efficient exploration of six geometric parameters across multiple configurations. The analysis revealed that lip length and the curvature of the flap’s upper surface have the most significant impact on aerodynamic performance, influencing lift generation, flow attachment, and drag reduction. Optimized configurations achieved up to a 7% increase in maximum lift coefficient and a 5% reduction in drag relative to the baseline geometry. These results highlight the potential of precise geometric control of flap slots to enhance aerodynamic efficiency, particularly in low-speed regimes relevant to take-off and landing. The proposed methodology establishes a foundation for advanced parametrization and optimization strategies for multi-element airfoil configurations and next-generation high-lift systems.

This paper presents a novel approach to address the challenge of self-localization of flying vehicles. It utilizes visual cues provided by the map imagery fed to a map-recognition convolution neural-network (CNN). This approach is invaluable during the navigation of flying vehicles in scenarios where the Global Positioning System (GPS) signal is unavailable. The proposed approach leverages the power of convolutional neural networks (CNNs) to imitate the visual perception and navigation abilities of homing pigeons, enabling the vehicle to navigate using solely real- time visual data with limited or no GPS information. Two pre-trained CNN’s (SqueezeNet and GoogLeNet) are selected and re-trained with Google Maps imagery, enabling them to efficiently learn and generalize from the diverse visual attributes present in the map. Extensive experimentation and evaluation have demonstrated the efficacy and resilience of the vision-based GPS-free navigation system. The resulting system predicts position accurately achieving an accuracy of 89.9% and 96.4% for SqueezeNet and GoogLeNet, respectively, for images with a resolution of (one km x one km) and reaching an accuracy of 94.7 for GoogLeNet for images with a resolution of (374 m x 374 m). Results underscore the potential of this approach for overcoming the challenge of GPS unavailability in aerial navigation.

INCAS BULLETIN is a scientific quartely journal published by INCAS – National Institute for Aerospace Research “Elie Carafoli” (under the aegis of The Romanian Academy). Its current focus is the aerospace field, covering fluid mechanics, aerodynamics, flight theory, aeroelasticity, structures, applied control, mechatronics, experimental aerodynamics, computational methods. All submitted papers are peer-reviewed. The journal will publish reports and short research original papers of substance.

After creating a new Finite Elements Model (FEM) of the aircraft IAR-99 HAWK using special elements, the team decided to validate the results by performing a free-free vibrations analysis on this model. In this presentation we have described the finite elements used and their peculiarities, the finite elements model obtained for the aircraft IAR-99 HAWK and the results of the free-free vibrations analysis obtained in the empty equipped configuration. The results of the theoretical free-free vibrations obtained for the IAR-99 HAWK in the empty equipped configuration are presented and compared to those obtained from ground tests, thus confirming the accuracy of the new Finite Element Model (FEM). The aerodynamic idealization of the IAR-99 aircraft was made using the DLM method for subsonic flow, also considering the load-bearing surface/fuselage interference and aims to determine the generalized aerodynamic forces that occur on one mode of vibration due to the influence of another mode of vibration. The flutter calculation for the IAR-99 HAWK empty equipped configuration aircraft was made using the p-K methodology presented in the MSC.Nastran program, using the vibration modes obtained on the basis of the new finite element model and the matrix of generalized aerodynamic forces in subsonic flow.

This study presents light metal alloys used in the aeronautical industry, specifically focusing on their suitability for Friction Stir Welding (FSW) and Friction Stir Processing (FSP). These innovative techniques play an important role in improving the mechanical properties and performance of aluminum, magnesium, and titanium alloys, which are extensively utilized in aerospace applications due to their superior strength-to-weight ratios. FSW and FSP offer significant advantages in joining and processing materials, including enhanced weld integrity, defect reduction, and refined microstructural properties. The integration of light metal alloys by these methods within the aeronautical sector fosters the production of lighter and stronger structures, contributing to reduced fuel consumption and improved overall performance in aeronautical engineering.