CoA. Reports

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Now showing 1 - 9 of 9

Open Access
Aerodynamic characteristics of a swept wing with spanwise blowing.
(Cranfield University, 1956-09) Ayers, R. F.; Wilde, M. R.
This report is the first of a series of studies to investigate the effectiveness of a spanwise blowing on the aerodynamic characteristics of low aspect ratio wings and bodies. The model used in this investigation was an untapered half-wing aspect ratio 1.39,50 degree sweep back, and mounted on a reflective plate.
Open Access
Debris removal from low earth orbit (DR LEO)
(Cranfield University, 2010-09-13) Hobbs, Stephen
Students of the MSc course in Astronautics and Space Engineering 2009/10 at Cranfield University studied a low Earth orbit (LEO) debris removal mission for their group project. The mission's name was DR LEO (Debris Removal from LEO) and its aim was to develop a credible mission baseline using conventional technology to perform active debris removal from LEO. This report summarises the students' work and their findings. The report consists of an overview and discussion of the technical work of the project and a compilation of the executive summaries which describe the specific contributions of each student. The baseline mission design developed is broadly credible and provides a useful benchmark against which other missions can be compared to evaluate the potential of alternative technologies. The mission costing from this first design iteration sets a benchmark cost per unit mass de-orbited of approximately € 20-30k kg - 1 using conventional chemical propulsion.
Open Access
Effects of nonlinear flight control system elements on aircraft
(Cranfield University, 2011-09) Lone, Mudassir M.; Cooke, Alastair K.
This report presents the experimental method and results from a series of desktop simulation tests designed to investigate manual control characteristics of young and relatively inexperienced civil pilots (24 years average age and 66 hours flight experience). Subjects were asked to perform tasks during which they had to establish longitudinal control through pitch attitude shown on a primary flight display. A linear aircraft model coupled with nonlinear flight control system was used to produce realistic vehicle dynamics. Increased encroachment into nonlinear command gearing was found to make aggressive subjects resort to high levels of crossover regression. The combined effects of rate-limiting and nonlinear command gearing was observed only for demanding tasks during which over-control was a typical feature. The classical precision and bimodal models were used for an in-depth study of pilot dynamics observed during compensatory tasks. Model parameters were found through the definition of a constrained nonlinear optimisation problem. A single feedforward equalisation element was used for tracking tasks. It was found that subjects developed similar low frequency feedforward equalisations, whilst large inter-subject variations exist for high frequency equalisations. The resulting models also provided some insight into the Neal-Smith and Bandwidth handling qualities criteria. Actuator rate-limiting could not be directly correlated to any of the pilot model parameters.
Open Access
Formulation and System Identification of the Equations of Motion for a Dynamic Wind Tunnel Facility.
(Cranfield University, 2008-03) Carnduff, S. D.; Cooke, A. K.
This document describes the equations of motion of an aircraft model tested in Cranfield’s 4 degreeof- freedom (DoF) wind tunnel facility. In previous research, the equations have been derived assuming that the model’s centre of gravity (cg) is coincident with the gimbal mechanism about which the model rotates on the rig. However, in this report a general approach is taken with the cg assumed to be located away from the gimbal. The equations are developed from first principles and reduced to a linearised form where motion can be represented as small perturbations about trim. The equations are also decoupled into longitudinal and lateral/direction expressions and converted into state space form. It had been found in practice that models tested in the facility are very responsive in heave and can only be operated open-loop if movement is restricted to purely rotational motion. Therefore, the equations for this 3DoF case are also developed. Having obtained theoretical expressions, a series of wind tunnel tests were conducted on a 1/12 scale BAe Hawk model in order to establish if the theoretical relations were valid in practice. The particular technique used in testing the model was dynamic simulation and the analysis of the experimental data was performed using system identification. An established model structure determination procedure is used to determine which stability and control derivatives should be included in the equations of motion. Frequency domain, equation error parameter estimation is then employed to obtain numerical values for the stability and control derivatives. For both the longitudinal and lateral/directional examples described, the final model structure obtained from experiment matches that derived from theory. Derivatives values obtained from parameter estimation and empirical analysis are also in good agreement.
Open Access
Generic regional aircraft flying qualities for the approach and landing task
(Cranfield University, 1997-08) Gautrey, Jim
Many changes have occurred in the past 20 years in aircraft manufacture and development. New technologies have appeared, spanning the entire aircraft design environment, such as new production methods, new materials and new avionics systems. These new methods have been developed for two reasons. For military aircraft, they have arisen through the need to improve performance. However, for civil aircraft they have arisen through the need to reduce the overall cost. This report considers one aspect of these technologies for civil aircraft: fly-by-wire. This technology uses electrical signalling in place of conventional heavy mechanical control runs. In addition, flyby- wire generally permits improvements to be made in aircraft flying and handling qualities. This requirement has originated from two main sources; a need to make improvements in the light of an increasing amount of experience, and a requirement to cope with aerodynamic modifications which have been implemented to improve aerodynamic efficiency, but which have a deleterious effect on the aircraft's flying and handling qualities. Both of these adverse effects have come about from a desire to reduce costs for the end aircraft user, i.e. the airlines. The aircraft used for these evaluations is a Generic Regional Aircraft, of about 100 seats and a weight of 90,000 lbs. Only a limited portion of the flight envelope was considered since these evaluations primarily concentrate on the approach and landing flight phase. These evaluations are being carried out as part of a joint Avro International Aerospace — Cranfield University Engineering Doctorate programme researching advanced flight control system design for a Generic Regional Aircraft. The overall aim of this programme is to produce a control law design which gives aircraft in question excellent handling qualities. The evaluations described here comprise the first in a series of three planned studies, and consider solely the approach and landing flight phase.
Open Access
GeoSAR Feasibility Study: Summary of the Group Design Project. MSc in Astronautics and Space Engineering 2012/13
(Cranfield University, 2013-06-28) Hobbs, Stephen
Students of the MSc course in Astronautics and Space Engineering 2012–13 at Cranfield University performed a feasibility study of a geosynchronous radar mission for their group project. This report summarises the students’ work and their findings. The report consists of an overview and discussion of the technical work of the project and a compilation of the executive summaries which describe the specific contributions of each student. The mission studied is a Ku-band monostatic SAR in a small inclination (80 km relative orbit diameter) geosynchronous orbit. The total launch mass is 2 tonnes, and images with resolution 40 m to monitor land subsidence in urban areas are produced. The mission appears to be feasible within the scope of an ESA Earth Explorer proposal.
Open Access
Laplace plane GeoSAR feasibility study: summary of the group design project MSc in astronautics and space engineering 2014-15, Cranfield University
(Cranfield University, 2015-10-07) Hobbs, Stephen
Students of the MSc course in Astronautics and Space Engineering 2014-15 at Cranfield University performed a feasibility study of a geosynchronous radar mission for their group project. This report summarises the students' work and their findings. The report consists of an overview and discussion of the technical work of the project and a compilation of the executive summaries which describe the special contributions of each student. The mission studied is a geosynchronous synthetic aperture radar Earth observation mission using the Laplace orbit plane to reduce station-keeping propulsion demand. User applications are drawn from a wide range of sectors (agriculture, meteorology, geohazards, etc.) and are translated into system design requirements. The proposed mission design uses satellites with 13 m diameter antennas and a total electrical power demand of 6 kW. The mission seems feasible, although further study is recommended especially for the areas of _ orbit selection with respect to user requirements, imaging performance and orbit maintenance, _ mass budget (driven largely by the propulsion system), _ user requirements, imaging performance and operational imaging modes, _ opportunities for improved imaging with a constellation.
Open Access
Multi-objective Tabu Search 2: first technical report
(Cranfield University, 2015-06) Tsotskas, Christos; Kipouros, Timoleon; Savill, Mark A.
The purpose of this document is to describe Multi-Objective Tabu Search 2 (MOTS2), which is a native mutli-objective optimiser. It has been developed to tackle a variety of real-world problems of engineering interest. The design and implementation are presented, followed by verification, validation and user instructions. At a glance, it involves introduction to the algorithm, explains configuration settings and structure, and results interpretation. Then, the optimiser is tested against a series of mathematical test functions in order to verify its functionality. The main goal is to demonstrate and assess the performance and applicability of the optimiser. The next step is to use MOTS2 on a real-world case, where the performance of optimising a 2D airfoil is validated and illustrated.
Open Access
Space weather warning system
(Cranfield University, 2012-09-27) Hobbs, Stephen
Students of the MSc course in Astronautics and Space Engineering 2011–12 at Cranfield University studied a space weather warning mission for their group project. The mission was inspired by the Space Weather Diamond mission proposed by St. Cyr et al. in 2001. This report summarises the students’ work and their findings. The report consists of an overview and discussion of the technical work of the project and a compilation of the executive summaries which describe the specific contributions of each student. Two mission concepts are developed to provide at least 2 hours’ warning of severe space weather events. These are an augmented Space Weather Diamond mission and a Circular Heliocentric Constellation: both missions have advantages which justify further work.

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