Search Results (45)

Runway microtexture is a key parameter governing pavement friction. In recent years, several microtexture assessment methods have been developed; however, understanding of microtexture evolution under operational conditions, as well as the effects of maintenance techniques, remains limited. In this study, a runway at an Australian airport was investigated using laser profilometry. Measurements were conducted across multiple transverse sections, including aircraft touchdown and mid-runway zones. Microtexture deterioration rates were evaluated based on the estimated number of tire–pavement contacts, and aggregate polishing was assessed at different locations. Measurements were also performed after rubber contamination removal and rejuvenation treatments. The results indicate that approximately 25% of total microtexture reduction can be attributed to surface polishing, with a lower contribution in touchdown zones due to the protective effect of rubber deposits. A non-linear degradation trend was observed in touchdown zones, where approximately 1100 tire contacts reduced average microtexture roughness from 18 μm to 11 μm. Rubber removal effectively restored microtexture close to its original levels across the runway width. A rejuvenation treatment with a covering of fine sand initially improved microtexture; however, rapid deterioration occurred due to loss of the sand coating. These findings improve the understanding of microtexture evolution under operational runway conditions, albeit only at a case study level, and support more effective runway maintenance planning and intervention strategies. Full article

In response to the bottleneck issue of natural rubber selection in aircraft tire formulation design, this study proposes a data-driven screening methodology that integrates a simulated performance database with grey system theory. A multidimensional performance simulation database was constructed, encompassing representative NR brands from six major global producing regions: Malaysia, Indonesia, Thailand, Vietnam, Hainan (China), and Yunnan (China). This repository encompasses critical metrics, including raw rubber constitution, molecular characteristics, and the static/dynamic mechanical behaviors of vulcanizates. Utilizing this foundation, a novel material selection protocol was formulated, grounded in a multi-objective weighted intelligent grey target decision framework. The Analytic Hierarchy Process (AHP) was applied to ascertain differentiated performance criteria and assign corresponding weights, specifically tailored to the functional necessities of distinct aircraft tire sections. To substantiate the model’s efficacy, the primary tire of the ubiquitous Boeing 737-800 served as a validation case. The optimal Natural Rubber (NR) grade identified by the algorithm was cross-referenced with the empirical expertise and engineering practices of premier global tire manufacturers, thereby confirming the framework’s robustness and predictive accuracy. Consequently, this investigation establishes a comprehensive intelligent decision-making architecture, spanning data construction to engineering deployment, offering a quantitative and referential pathway for NR material screening in aviation applications. Full article

This paper develops new empirical relationships to estimate FAA/EASA- and MIL-3013B-rules-compliant landing-field performance of multi-engine transport aircraft. Widely cited textbooks date from an era when inferior tire and braking capability limited aircraft performance. Today, the use of overly pessimistic conceptual design-level performance estimates may lead concept-design teams to advocate for unnecessary engineering solutions (for example, more complex flaps) to solve “problems” which do not actually exist. Moreover, today’s aircraft designer is likely to face customer-imposed wet and/or contaminated runway performance requirements, where the classic books only discussed dry-weather operations. Taken together, the design community needs a collection of revised empirical equations to estimate landing distances for dry and wet runways. The empirical relationships published here are based upon modern flight-manual data augmented by a calibrated physics-based numerical simulation applied to a wide range of possible vehicle configurations. They offer improved accuracy, compared to earlier methods. The new method, when applied to FAA rules for aircraft operating on dry runways, predicts the substantially shorter “real-world” certified landing distances attainable by modern aircraft. Full article

To clarify the wear degradation of airport cement concrete pavements under combined environmental and traffic actions, this study established an environment-tire-pavement multi-physics finite element model incorporating surface texture, freeze–thaw deterioration, temperature gradients, and aircraft lift during taxiing. Indoor rapid freeze–thaw tests, accelerated wear tests, and 3D texture scanning were further conducted to calibrate and validate the model. The results show that temperature gradients significantly amplify pavement wear. At 180 km/h and 1.2 million wear cycles, increasing the temperature gradient from 0 to 60 °C/m increased wear depth and wear mass by about 40% and 96%, respectively. Taxiing speed was negatively correlated with wear, mainly because higher speed reduced tire-pavement contact duration and effective vertical load. Freeze–thaw deterioration was the dominant factor affecting wear, and the coupled freeze–thaw–temperature–load condition produced the most severe damage. The experimental and simulation results agreed well, with R² values above 0.98. Based on the combined experimental-simulation dataset, an interpretable CNN-BiLSTM model was developed for wear-depth prediction, achieving RMSE values of 0.019 and 0.035 for the training and test sets, respectively. SHAP analysis further confirmed that freeze–thaw cycles contributed most to wear prediction. This study can provide a quantitative basis for the wear resistance evaluation, life prediction, and maintenance decision-making of airport pavements. Full article

Aircraft functions under extreme environmental circumstances, encompassing both elevated and diminished temperatures, influence the material characteristics and inflation pressure of aircraft tires. This results in modifications to the tire’s cornering, affecting the shock absorption efficacy of the landing gear and maneuvering stability during cornering. This study examines the cornering characteristics of aircraft tires at four ambient temperatures: −60 °C, −40 °C, 25 °C, and 50 °C. The analysis of stress–strain findings of rubber materials at varying temperatures assessed the impact of ambient temperature on rubber properties. Based on this, a numerical model for tire cornering was constructed using ABAQUS to examine the impact of ambient temperature on the tire’s cornering characteristics. The model considers the intricate friction dynamics between the tire and road surface and the convergence tolerance parameter of ABAQUS. The precision of this model and methodology was confirmed through experimental testing. The findings demonstrate that ambient temperature significantly affects the lateral force and self-aligning torque of aircraft tires, hence impacting cornering stiffness considerably. The influence of radial force and rolling speed on cornering differs with varying ambient temperatures. These results offer significant insights into the design of aircraft tire environmental adaptability and aircraft ground handling systems. Full article

The seemingly endless expanse of the sky might suggest that it could support a large volume of aerial traffic with minimal risk of collisions. However, mid-air collisions do occur and are a significant concern for aviation safety. Pilots are trained in scanning the sky for other aircraft and maneuvering to avoid such accidents, which is known as the basic see-and-avoid principle. While this method has proven effective, it is not infallible because human vision has limitations, and pilot performance can be affected by fatigue or distraction. Despite progress in electronic conspicuity (EC) systems, which effectively increases the visibility of aircraft to other airspace users, their utility as collision avoidance systems remains limited. This is because they are recommended but not mandatory in uncontrolled airspace, where most mid-air accidents occur, so other aircraft may not mount a compatible device or have it inactive. In addition, their use carries some risks, such as causing pilots to over-focus on them. In response to these concerns, this paper presents evidence on the utility of using an optical flow-based obstacle detection system that can complement the pilot and electronic visibility in collision avoidance, but that, unlike pilots, neither gets tired like the pilot does nor depends on whether other aircraft have mounted devices, such as EC devices. The current investigation demonstrates that the proposed optical flow-based obstacle detection system meets or exceeds the critical minimum time required for pilots to detect and react to flying obstacles (12.5 s) using a mid-air collision simulator in various test environments. Full article

The transfer of aircraft on deck relies on the traction system, which is easily affected by the offshore environment. Violent ship motion in the complex marine environment poses a great threat to the aircraft traction process, such as the tire sideslip, off-ground phenomena, the aircraft overturning, traction rod fatigue fracture, and so on. Therefore, it has merits in both academia and engineering practice to study the dynamic behaviors of the ship-borne aircraft towing system under high sea states. Considering the intricate coupling motions of the hull roll, pitch, and heave, the dynamic analysis of the towing system with rod are carried out based on the multibody dynamics theory. The influence of the sea state level and the traction speed on the dynamic characteristics of the towing system is investigated. The results indicate that noticeable tire sideslip occurs under sea state 3, with the peak lateral tire force increasing by approximately 250% compared with sea state 2. Under sea state 4, intermittent off-ground phenomena are observed, accompanied by a further increase of about 22% in lateral tire force. These findings provide quantitative insights into the dynamic characteristics and operational limits of rod-traction systems for ship-borne aircraft in rough marine environments. Full article

Aiming to address the problems of the violent fluctuation of winch traction rope and tire forces and the high safety risk caused by coupling ship motions (rolling, pitching, and heaving), wind loads, and deck space limitations in carrier-based aircraft, this paper focuses on a multi-winch traction system on a small deck. A fully coupled dynamic model of an aircraft landing gear–tire–rope–winch system is constructed, ADAMS2020 and MATLAB/Simulink (MATLAB R2021b) co-simulations are used to develop the three-winch and five-winch traction system models, and a Fiala tire model and a telescopic landing gear model are adopted to build a precise mechanical model of the aircraft. The PID control strategy is proposed, based on the Bessel curve, to control the driving trajectory of the aircraft, and the quantitative influence of ship motion, winch number, and preset trajectory on traction dynamic characteristics is systematically studied. Compared to without trajectory control, the peak force of the winch rope before the start-up phase of the three-winch system is reduced by 54.9%, and the five-winch system is reduced by 57.6%. The fluctuation amplitude of the lateral force of the rear wheel is greater than that of the front wheel, up to a maximum of 215% of the front wheel. The correlation coefficient between the theoretical model and the simulation results is 0.91~0.97, and the error is less than 12%. The PID control strategy based on the Bessel trajectory can significantly improve the steadiness and security of the carrier-based aircraft winch traction system on a small deck. The study delivers the requisite theory and engineering means for the optimized design of carrier-based aircraft traction systems. Full article

Runway friction is a critical factor in aircraft safety, affecting braking performance during landing and take-off. This study evaluates friction measurement variability and runway life-cycle dynamics at four typical Australian airports, using GripTester data from calibration strips and operational runways. The results show that friction measurements are influenced by seasonal effects, random errors, and testing equipment tire wear, with greater variability at lower speed (65 km/h) than at higher speed (95 km/h). Analysis of runway friction decay indicates that friction reduction rates are higher in touchdown zones and decelerating rate gradually decrease as friction declines, while regular rubber removal significantly restores friction, sometimes exceeding post-construction levels. Current internationally recommended friction testing intervals may not adequately ensure safety, with a sufficient probability of friction dropping below maintenance planning levels between tests. Based on observed reduction rates, updated intervals of approximately 3000 to 4000 landings are proposed to achieve 90% confidence in maintaining safe friction levels. The findings provide practical guidance for friction management and maintenance scheduling as part of an optimized airport pavement management system. Full article

To optimize and improve the nose landing gear shock absorber of a fixed-wing carrier-based aircraft, the cross-sectional area of the oil needle in the main oil orifice and the cross-sectional area of the oil return orifice shall be reconfigured. Firstly, a dynamic analysis of a single landing shock absorber system is conducted, with a focus on explaining the calculation methods for air spring force and oil damping force. Secondly, the shock absorber is modeled and its typical working processes are simulated, including calculations of shipboard landing buffering results under different sinking speeds and catapult extension results under different terminal drag speeds. Phenomena such as wheel transition oscillation and shock absorber hysteresis compression are interpreted. Finally, an orifice area configuration optimization scheme based on the work-energy diagram of the shock absorber system is proposed, with principles and necessary explanations for key steps in the scheme provided. The optimized scheme, which comprehensively considers buffering and extension performance, is applied to a single shock absorber system model for verification. The results show that the main orifice area should exhibit a slight increase near the critical stroke of the high and low pressure chambers. After optimizing the orifice area, under the ultimate sinking speed, the peak load of the shock absorber is reduced by 12.92%, the compression stroke is decreased by 2.91%, and the energy absorption efficiency is increased by 19.90%; the peak load of the tire is reduced by 12.17%, the compression stroke is decreased by 5.92%, and the energy absorption efficiency is increased by 12.28%. Full article

This study developed a natural rubber composite reinforced with selenol-functionalized carbon nanotubes, demonstrating significant mechanical enhancement. The composite exhibited remarkable improvements in elastic modulus, with 300% and 500% modulus increasing by 2.23 MPa and 2.68 MPa, respectively, along with a 1.22 MPa boost in tensile strength compared to conventional counterparts. Material characterization was successfully performed using a polynomial hyperelastic constitutive model. The optimized composite was applied to the tread of a Bridgestone 1270 × 455 R aircraft tire for performance evaluation. Finite element analysis in ABAQUS revealed that under 2.5 MPa inflation pressure, the tire achieved specified dimensional requirements with a cross-sectional width of 459.55 mm and a diameter of 1270.50 mm. Three-dimensional static load simulations showed characteristic elliptical contact patches that expanded with increasing load, while maintaining rectangular normal contact stress distribution. Critical performance evaluation demonstrated excellent radial stiffness stability of 22.9 kN/mm within the operational pressure range of 1.5–2.0 MPa under rated load conditions. These findings validate the composite’s potential for enhancing aircraft tire performance. Full article

This paper develops empirical relationships to estimate FAA/EASA and MIL-3013B rules-compliant take-off field performance for single and multi-engine aircraft. Recent experience with modern aircraft flight manuals revealed that popular empirical legacy methods are no longer accurate; improvements in tires and brakes lead to significantly shorter certified distances. This work relies upon a survey of current operational aircraft and extensive numerical simulations of generic configurations to support the development of a collection of new equations to estimate take-off performance for single and multi-engine aircraft under dry and wet conditions. These relationships are individually tailored for civilian and U.S. Military rules; they account for the superior capability of modern braking systems and the implications of minimum-control speed on the certified distance. Full article

The winch traction system for shipboard aircraft, when operating in a marine environment, is subjected to additional forces and moments due to the complex motion of the hull. These loads pose significant threats to the safety of the aircraft during the traction process. To address the safety issues under complex sea conditions, this paper adopts harmonic functions to describe the rolling, pitching, and heaving motions of the hull. A theoretical analytical model of the three-winch traction system, considering the intricate coupling motions of the ship, is established. Unlike previous studies that often simplify ship motion or focus on single-component modeling, this work develops a complete, whole-system dynamic model integrating the winch system, rope, aircraft structure, and ship interaction. The dynamic characteristics of the small-deck winch traction system are investigated, with particular focus on the influence of the rear winch position, driving trajectory, and ship motion on the system’s dynamics and safety. This research is innovative in systematically exploring the dynamic safety behavior of a three-winch traction system operating under small-deck conditions and complex sea states. The results show that as the distance between the two rear winches increases, the lateral force on the tire decreases. Additionally, as the aircraft’s turning angle increases, the front winch rope force also increases. Moreover, with higher sea condition levels and wind scales, the maximum lateral force on the tires increases, leading to a significant reduction in the stability and safety of the winch traction system. This is particularly critical when the sea condition level exceeds 3 and the wind scale exceeds 6, as it increases the risk of tire sideslip or off-ground events. This research has substantial value for enhancing the safety and stability of winch traction systems on small decks, and also provides a theoretical basis for traction path design, winch position optimization, and the extension of the service life of key system components, demonstrating strong engineering applicability. Full article

When the winch traction system of a carrier-based aircraft works under complex sea conditions, the rope and the tire forces are greatly changed compared with under simple sea conditions, and it poses a potential threat to the safety and stability of the aircraft’s traction system. The accurate calculation of the rope and tire forces of a carrier-based aircraft’s winch traction under complex sea conditions is an arduous problem. A novel method of dynamic analysis of the aircraft-winch-ship whole system under complex sea conditions is proposed. A multiple-frequency excitation is adopted to describe the complex sea conditions and the influences of pitching amplitude, and the rolling frequency on the traction dynamics of a carrier-based aircraft along the setting trajectory under complex sea conditions are studied. The advantages and disadvantages of a winch traction system with trajectory control and without trajectory control in complex sea conditions are analyzed. For realizing the trajectory control of the aircraft, the vector difference between the center of mass for the carrier-based aircraft and the position on the predetermined Bessel curve is calculated, so as to obtain the azimuth vector in the aircraft coordinate system. This research is innovative in the modeling of the whole system and the trajectory control of a carrier-based aircraft’s winch traction system under the complicated sea condition of the multi-frequency excitation. ADAMS (Automatic Dynamic Analysis of Mechanical System) is used to verify the correctness of the theoretical calculation for the winch traction. The results show that the complex sea environment has a certain influence on the winch traction safety of the aircraft; in the range of 10–15 s for the traction, the rope force amplitude of complex sea conditions under the multi-frequency excitation is 29.5% larger than that of the single-frequency amplitude, while the vertical force amplitude of the tire is 201.1% larger than that of the single-frequency amplitude. This research has important guiding significance for the selection of rope and tire models for a carrier-borne aircraft’s winch traction in complex sea conditions. Full article

Most airports rate and publish the strength of their runway pavement using the international system known as Aircraft Classification Number–Pavement Classification Number (ACN–PCN). The ACN–PCN system has been in place since 1981 and includes many simplifications that were necessary at the time of its development, primarily due to the general absence of computer power to support more sophisticated analysis. However, airport pavement thickness determination has evolved since that time and now includes much more sophisticated analysis methods. To bring the strength rating system into line with contemporary pavement thickness determination methods, a new system has been developed, known as Aircraft Classification Rating–Pavement Classification Rating (ACR–PCR). This critical review found that ACR–PCR provides many improvements over ACN–PCN, including minimizing anomalies between pavement thickness design and subsequent pavement strength rating, the use of more representative aircraft traffic loadings and pavement structures, and the alignment of rigid and flexible subgrade support categories. However, ACR–PCR could be improved with regard to the representative subgrade characteristic values, the retention of an overly simple tire pressure category limit approach for surface protection, the provisions for single-wheeled light aircraft pavements, and the absence of a rational approach to strength rating that is substantially better than a usage-based approach but does not necessarily follow the formalized technical rating protocol. Despite these limitations, the current ACN–PCN system has been in place for over 40 years without significant change, so it is expected that ACR–PCR will be in place for many years as well. Consequently, airports should prepare for its imminent introduction, regardless of the associated limitations. Full article