Showing papers by "Vaughn College of Aeronautics and Technology published in 1997"

The Cranfield tests on index language devices

Abstract: The investigation dealt with the effect which different devices have on the performance of index languages It appeared that the most important consideration was the specificity of the index terms; within the context of the conditions existing in this test, single‐word terms were more effective than concept terms or a controlled vocabulary

The constrained torsional characteristics of some carbon fibre composite box-beams

Abstract: A simple analytical procedure for determining the constrained torsional response of a specific class of carbon fibre composite box-beams is detailed in this paper. The analysis approach essentially makes use of the existing theories of torsion appropriate to isotropic construction and these are then suitably modified to account for the non-isotropic nature of typical carbon fibre composite material. The composite box-beams are devoid of overall elastic couplings through the use of constituent laminates which are symmetrically laid-up about their own mid-planes and which possess in-plane orthotropy. The thin walls of the box-sections can have different lay-up configurations provided the stiffness distribution around the sections is of a symmetrically disposed nature. The flanges of a box-section can thus have a different lay-up configuration to that of the section webs. The constrained condition considered in the paper is that of the cantilevered box-beam with torque applied at the free end and the torsional and warping rigidities of the composite box-sections are determined through the use of the appropriate equivalent engineering elastic constants of the individual thin composite walls. Comparisons between theory and finite element solutions are given in the paper and these are shown to give close agreement. It is also clear that the use of the appropriate equivalent engineering elastic material constants in the theory is able to closely predict actual behaviour.

Implications of NOy emissions from subsonic aircraft at cruise altitude

Abstract: The exhaust emissions from civil subsonic aircraft at cruise altitude are important man-made sources that pollute the upper troposphere and the lower stratosphere (8-12 km). The formation of NOy species from NOx, both before and after the exit nozzle, have created increasing environmental concerns. Flight histories of Boeing 747-400 aircraft during the cruise stage between selected city pairs have been simulated using a computer program developed at Cranfield University. The passive distribution of NOx and HNO3 is calculated using the UGAMP three-dimensional chemical transport model. The sink of NOx, which is HNO3, is parameterized using an exponential decay process with an altitude-dependent lifetime. The model also includes transport by advection, vertical diffusion and convection. These simulations for January and July are analysed in terms of the resulting mean volume mixing ratios for both NOx and HNO3.

Pilots' knowledge of the relationship between alcohol consumption and levels of blood alcohol concentration

Abstract: The U.K. Civil Aviation Authority is currently proposing that a maximum BAC (Blood Alcohol Concentration) limit of just 0.02% should be imposed on United Kingdom pilots. In this survey of 477 pilots, it was found that a large proportion could not determine when their BAC was likely to fall below this level after drinking alcohol and could, therefore, potentially inadvertently infringe the proposed regulation. Another large proportion of pilots felt that they were safe to fly before their BAC had dropped below 0.02%, which may be indicative of a willingness to infringe the regulations. Estimates of when it was safe to fly also became more inaccurate as the amount drunk increased and varied with the type of alcoholic beverage consumed. It was also found that the conclusions drawn were heavily dependent upon the formula used to estimate BAC. This methodological problem identified has considerable implications for the study of alcohol consumption when flying.

Knowledge-based geometric modelling of aircraft structures:

Abstract: Aerospace engineering offers a challenging test environment for advanced design systems and methods. Focusing particularly on knowledge-based engineering (KBE) systems, this paper demonstrates their application in automating the solid modelling of aircraft structures. The principles are illustrated through a case study example in which a description is given of the knowledge-based geometric modelling of light alloy fuselage frame sectors. The business benefits of using KBE systems in an aerospace engineering programme are quantified. Recommendations for the extended application of the technology to achieve strategic market advantage are also given.

Visualization of non-equilibrium dissociating flows

Abstract: A Mach-Zehnder interferometer has been used for both flow-field visualization and quantitative assessment of aerodynamic parameters in a shock tube environment. Of special interest are the high- temperature effects in the post-shock region of bodies travelling at hypervelocity. Infinite-fringe interferograms give the density contours of the flow field and, in combination with an equilibrium real gas code, they can be used to provide information on the non-equilibrium state of the dissociating flow.

Avionics cooling-rate trade-off modelling for ultra-high capacity aircraft

Abstract: A computer aided conceptual aircraft design methodology (CACAD) has been developed to size ultra-high capacity jet transport aircraft. Modules were also developed for predicting maintenance costs of each airframe and avionics system and these were incorporated into CACAD. A methodology was developed to enhance the reliability of avionics systems, based on experimentally-proven engineering design solutions. A number of avionics cooling techniques were investigated, and reliability and maintainability models of thermal management were developed and linked to an avionics maintenance cost module. Further models were produced to investigate the impact of proposed changes on the environmental control systems, engine-provided bleeds and power off-takes. It was found that increased flowrates above the normally recommended values for the avionics bay, and to the flight deck instruments, may increase the reliability of the avionics systems, and also increase aircraft dispatch reliability. They may not, however, gre...

Advanced short take‐off vertical landing combat aircraft: part 2 ‐ the powerplant installation

Abstract: Reports on the MSc group design project of students at the College of Aeronautics aerospace vehicle design in 1995. The students worked on advanced short take‐off and vertical landing of a combat aircraft. Part 2 reports on powerplant installation and associated systems.

Systems design for an advanced short take‐off vertical landing combat aircraft ‐ Part 3

Abstract: Reports on the MSc group design project of students at the College of Aeronautics, Cranfield University. Details the design of the aircraft systems and their reliability and maintainability.