Large Commercial Airplane Research Articles

Least Risk Bomb Location Explosives Identification, Detection and Mitigation

This paper investigates the still evolving strategic trajectories and the context adopted for the procedures for inducting a Least Risk Bomb Location (LRBL) that began with discretionary participation by various aircraft manufacturers approximately in the year 1972, where the use of a specific procedure has been designed to decrease the effects of an explosion significantly in the aircraft’s passenger cabins of large commercial airplanes. Additionally, the International Civil Aviation Organization (ICAO) has provided the information on the location of the LRBL and guidance to various operators (National/International)on the procedures to use when a suspected threat item is found on-board an airplane. The designation of LRBL for aero planes is intended to be used solely for the transport of cargo, where an aero plane must include a designated location where a bomb or other explosive device could be designated to protect integrity of the structure and flight-critical systems from damage in the case of detonation occurs.

Design and prototyping of a novel composite architecture for a widebody landing gear bay

Composite materials may reduce the final weight of the aircraft structural components, in addition to improve fatigue performance and corrosion resistance. In order to achieve the optimization of air transport systems, making them increasingly sustainable, the structural design must be surely reviewed, starting to follow the “composite thinking” philosophy. The present research provides some relevant outcomes concerning the design of a composite sample for the main landing gear bay of a large commercial airplane (EASA CS25 category), within ITEMB (InTEgrated Full Composite Main landing gear Bay Concept) project, a program of Clean Sky 2 EU research framework. The most ambitious goal is to develop a new generation of Lower Center Fuselage (LCF) with an innovative integrated landing system in the fuselage, which is considered the next frontier in the development of landing systems for medium-haul aircraft, such as the Airbus A320 aircraft family. The development of a different architecture, with the landing gear integrated within the related fuselage bay, could lead to a simplification of the whole sub-assembly with potential advantage in terms of construction and assembly times. Final target of the project is the manufacturing of an innovative monolithic composite structure that will replace the actual configuration (a mixed structure of metal and composite sub-assemblies) reducing or actually removing all the cost of assembly and increasing the production rate. This paper presents the main results of the work, introducing the main processing steps and prototype results; in the last part of the work, also some experimental test on significant element are introduced as first assessment of the technology readiness level that has been achieved.

Manufacturing and Validation of a Novel Composite Component for Aircraft Main Landing Gear Bay

Composite materials may reduce the final weight of the aircraft structural components, in addition to improve fatigue performance and corrosion resistance. In order to achieve the optimization of air transport systems, making them increasingly sustainable, the structural design must be surely reviewed, starting to follow the “composite thinking” philosophy. The present research provides some relevant outcomes concerning the design of a composite sample for the main landing gear bay of a large commercial airplane (EASA CS25 category), within ITEMB (integrated full composite main landing gear bay concept) project, a program of Clean Sky 2 EU research framework. The most ambitious goal is to develop a new generation of lower center fuselage (LCF) with an innovative integrated landing system in the fuselage, which is considered the next frontier in the development of landing systems for medium-haul aircraft, such as the Airbus A320 aircraft family. The development of a different architecture, with the landing gear integrated within the related fuselage bay, could lead to a simplification of the whole subassembly with potential advantage in terms of construction and assembly times. Final target of the project is the manufacturing of an innovative monolithic composite structure that will replace the actual configuration (a mixed structure of metal and composite subassemblies) reducing or actually removing all the cost of assembly and increasing the production rate. This paper presents the main results of the work, introducing the main processing steps and prototype results; in the last part of the work, also some experimental tests on significant element are introduced as the first assessment of the technology readiness level that has been achieved.

Research and simulation on key technologies of airliner’s flight management system under next-generation navigation system

This paper focuses on the requirements of flight management system (FMS), such as trajectory based operations (TBO) and required navigation performance (RNP), for large commercial airplanes under next-generation navigation system. systematic research has been carried on the architecture of FMS, the required accurate 4D trajectory prediction function, flight guidance function and integrated navigation functions. Aimed at FMS of large commercial airplanes, the research effort has been mainly on design and develop the 4D trajectory prediction algorithms based on navigation database, performance database, and the energy model of aircrafts. 4D flight guidance law is designed based on performance database. Integrated navigation system promotes navigation accuracy to satisfy the requirement of RNP and autonomous integrity monitoring (AIM) based on various navigation sensors. Based on our independently built flight deck verification platform, the simulation and verification are conducted by using real models of large commercial airplane and flight plans. As a result, the architecture of FMS and its key technologies have been proved to be feasible, reasonable, and applicable for engineering implementation on large commercial airplanes.

Influence of aeroelastic control reversal problem in the airplane lateral stability modes

At high-cruising speeds, airplane wing structures shall experience air loads of significant magnitudes from different directions. The flexible wing structure with an elevated aspect ratio produces the bend-twist coupling that often exceeds the control limits. The popular aeroelastic control reversal issue occurs because of the unsystematic changes in the aerodynamic quantities. This article presents a detailed investigation on the airplane lateral stability that is subjected to a variety of aerodynamic forces at cruising flight. A novel idea is proposed to find the dynamic stability characteristics of an airplane against the aeroelastic reversal problem. Initially, the pitching moment relating to the change in lift at various angles of attack with longitudinal static stability condition is verified by using computer simulation. Then the slope of wing lift curve, aileron lift curve and the moment coefficient concerning to aileron deflection are computed using computational as well as experimental methods. The changes in pressure distributions about the aileron deflection revealed several facts to enhance the reversal speed. The wind tunnel testing results are perfectly concur with the computational fluid dynamics plots. The outcome of experimental analysis is confirming that aeroelastic control reversal speed enhancement without any major structural optimization is possible. The aeroelastic behaviour of large commercial airplanes and subsonic bombers are the primary interest in the view of application about this analysis.

Thermal-hydraulic Modeling and Simulation of the Hydraulic System based on the Electro-hydrostatic Actuator

Electro-hydrostatic actuator (EHA) was a typical power-by-wire (PBW) actuator, which was widely-used in large commercial aircrafts, such as Airbus A380. The electro-hydrostatic actuator(EHA) had the advantages of small sizes, light weight, high power density, high reliability and maintainability. With the application of EHA in large commercial airplanes, the airworthiness certification of EHA became an new problem. The precondition of the airworthiness certification of EHA was to understand its operating principle and characteristic. Because of no centralized hydraulic oil tank and short cycle oil circuit, the temperature-rise of the hydraulic system in EHA always kept high during operation. Therefore, it was important to build the thermal-hydraulic models of the hydraulic system in EHA, and to do the thermal analysis of the EHA by this model. In this paper, a lumped-parameter thermal-hydraulic model of the hydraulic part in EHA was proposed. The model was built based on the detailed analysis of the heat transfer of the hydraulic part in EHA. By the simulation of a practical system and the comparison with the traditional hydraulic system, the accuracy and practicality of this model was verified.

Aerodynamics Analysis on Unsymmetrical Fuselage Models

The large commercial passengers airplanes are mostly designed to have symmetrical body with respect to the longitudinal axis. However for small passengers airplanes or for the airplane designed as UAV plat form is normally having an unsymmetrical fuselage. The aerodynamics characteristics fuselage may give a strong influence to the overall aerodynamics characteristics of the airplane. The present work investigates the aerodynamics characteristics of the unsymmetrical fuselage with respect to the longitudinal axis. The fuselage assumed to have circular cross section and the coordinate of the fuselage are created by using the same equation which had been used in defining the coordinate of cambered airfoil NACA series four digits. The fuselage had been set to have the same maximum thickness 15 % of the fuselage length and different fuselage models are obtained through varying the position as well as the value of the maximum camber line. The semi empirical aerodynamic method for estimating the fuselage lift coefficient CL, drag coefficient CDand the fuselage pitching moment coefficient CMsuch as given by DATCOM are well established. However when it came to the unsymmetrical fuselage, this approach can not be adopted easily. The required of angle attack at zero lift of the corresponding unsymmetrical fuselage is difficult to define. The result for particular cambered fuselage indicates that the aerodynamics characteristics strongly influenced by how the fuselages camber lines look likes.

The politics of airplane production: The emergence of two technological frames in the competition between Boeing and Airbus

Economic models of technological innovation, as well as modern sociological approaches to the study of organizations, predict that two-actor markets will eventually evolve into one dominant technological logic. Why is it, then, that the only two global manufacturers of large commercial airplanes have developed diametrically opposed technological philosophies? Based on secondary historical sources, this article employs a theory of two-party democracies from political science and the theory of sociotechnical frames to explain why Boeing pilots are allowed ultimate command of their aircraft whereas Airbus confers this authority to the flight computer.

Two types of a passive safety containment for a near future BWR with active and passive safety systems

The paper presents two types of a passive safety containment for a near future BWR. They are named Mark S and Mark X containment. One of their common merits is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. The PCV pressure can be moderated within the design pressure. Another merit is the capability to submerge the PCV and the RPV above the core level. The third merit is robustness against external events such as a large commercial airplane crash. Both the containments have a passive cooling core catcher that has radial cooling channels. The Mark S containment is made of reinforced concrete and applicable to a large power BWR up to 1830 MWe. The Mark X containment has the steel secondary containment and can be cooled by natural circulation of outside air. It can accommodate a medium power BWR up to 1380 MWe. In both cases the plants have active and passive safety systems constituting in-depth hybrid safety (IDHS). The IDHS provides not only hardware diversity between active and passive safety systems but also more importantly diversity of the ultimate heat sinks between the atmosphere and the sea water. Although the plant concept discussed in the paper uses well-established technology, plant performance including economy is innovatively and evolutionally improved. Nothing is new in the hardware but everything is new in the performance.

Variations of a passive safety containment for a BWR with active and passive safety systems

The paper presents variations of a certain passive safety containment for a near future BWR. It is tentatively named Mark S containment in the paper. It uses the operating dome as the upper secondary containment vessel (USCV) to where the pressure of the primary containment vessel (PCV) can be released through the upper vent pipes. One of the merits of the Mark S containment is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. Another merit is the capability to submerge the PCV and the reactor pressure vessel (RPV) above the core level by flooding water from the gravity-driven cooling system (GDCS) pool and the upper pool. The third merit is robustness against external events such as a large commercial airplane crash owing to the reinforced concrete USCV. The Mark S containment is applicable to a large reactor that generates 1830 MW electric power. The paper presents several examples of BWRs that use the Mark S containment. In those examples active safety systems and passive safety systems function independently and constitute in-depth hybrid safety (IDHS). The concept of the IDHS is also presented in the paper.

BOEING VS. AIRBUS: COMPETING FOR THE FUTURE

Boeing Company has been the world's leading producer of large commercial airplanes for several decades. However, in the late 1990s, Europe‐based Airbus Industrie competed with Boeing aggressively and captured almost fifty percent of the over‐100‐seat airplane market. This paper examines the battle between Boeing and Airbus, including a concise report on Airbus' launch of its A380 superjumbo project. The paper also contains the authors' recommendations to Boeing and the U.S. government.

SEA modeling and analysis of stowage bin noise isolation and reduction

The statistical energy analysis method is applied to the noise prediction and analysis of large passenger airplane stowage bin isolation. The purpose is to reduce the cabin noise generated from the external turbulent boundary layer and transmitted from the stowage bins via their supports. AutoSEATM is adopted for the modeling and analysis of the coupled structural-acoustic problem where the connection between the structural fuselage and the stowage bins is represented and implemented by a coupling loss factor (CLF). A significant amount of noise level reduction can be achieved by using elastomeric rod ends to replace the metallic rigid connection between the structural fuselage and the stowage bins. It is also possible to obtain a significant amount of weight reduction using the stowage bin isolators instead of the blanket applied to the cabin crown. Some analysis results have shown good agreement with flight test data. This modeling and analysis provides an effective way of reducing cabin noise for large commercial airplanes without any weight penalty. Economic gains will be obtained from both noise reduction and weight saving. [Support for this effort from B. Cimerman of Vibro-Acoustics Sciences, Inc. and Evan B. Davis of Boeing is gratefully acknowledged.]

Mixed H/H8 Method Suitable for Gain Scheduled Aircraft Control

The formulations of mixed H2/H1 gain scheduling control of aircraft in longitudinal motion aredeveloped. The coefe cients of a linear model of aircraft are estimated from the aircraft geometry. Based on e ight Mach number, gain scheduling is applied with the mixed H2/H1 . It is shown that the state equation of aircraft can be mathematically simplie ed to the standard mixed H2/H1 problem. The advantage of decoupling the aircraft system based on phugoid (slow) and short period (fast) modes is to allow the slow model with its disturbance to be controlled by the H2 method, whereas the fast system with the fast disturbance is to be stabilized by the H1 technique. A comparison of this method with the standard H1 control is made using aircraft coefe cients derived for a large commercial airplane. It is shown that the current method will provide better performance for the given aircraft while the condition on the disturbance attenuation is also satise ed. The actual model controlled by the estimated controller and by the real controller is also discussed. It is shown that the estimated controller performs as well as the controller derived from the actual model.

Structural analysis and design of a nuclear power plant building for aircraft crash effects

The object of this investigation is to assess the effect of a large commercial airplane crashing perpendicularly on to the surface of a spherical reactor building dome. This investigation is related to a project currently in execution. Practical solutions of the postulated case, which vary in the degree of engineering effort used, are shown. Based on safety consideration the various solutions are discussed from the viewpoint of penetration, cracking and collapse modes of failure, where, primarily, the carrying capacity of the structure under an equivalent statical load is considered. The performed investigations include: 1. (a) Calculation of the failure load following the yield line theory; 2. (b) Calculation of the sectional forces using the linear-elastic shell theory and subsequent design by the ultimate strength method; 3. (c) Calculation of the failure load, establishing of the failure mechanism and distribution of sectional forces using the plastic shell theory; 4. (d) Calculation using a three-dimensional FEM program with plastic capabilities; this includes the collapse load, the failure mechanism and the distribution of sectional forces. A discussion of the resultant forces and the configutation of the critical section is given for the various methods used. The evaluation of the carrying capacity of the structure with respect to load is based on energy considerations. It is attempted to compare such results, to evaluate possible simplifications in the used solutions, and to give some recommendations for the practical design and for the development of structural details.