Pub Date : 1989-07-01DOI: 10.1017/S000192400001705X
A. Simpson
A comparison is presented of three methods for the generation of numerical, modal approximating functions for use in modal Lagrangian analysis of rotating flexible blades. The methods considered are those based on the use of uniform beam/bar eigenfunctions, smooth bending moment or torque modes, and modes generated by recourse to one stage of the Stodola method. For blades which are highly non-uniform in their specific stiffness and inertial properties, and where the objective is to use a small number of approximating functions, consistent with accurate determination of eigen-solutions in the fundamental spectrum, it is demonstrated (as is well known) that direct use of uniform system eigenfunctions is unsatisfactory. On the other hand, it is demonstrated that the use of smooth bending moment modes, even in cases where the variations in sectional inertia properties are very large, can produce excellent results. The use of ‘Stodola modes', however, is shown to offer the all-important advantage of enhanced convergence rate in all cases considered.
{"title":"On the generation of a set of accurate numerical modal functions for use in the aeroelastic analysis of flexible rotor blades","authors":"A. Simpson","doi":"10.1017/S000192400001705X","DOIUrl":"https://doi.org/10.1017/S000192400001705X","url":null,"abstract":"A comparison is presented of three methods for the generation of numerical, modal approximating functions for use in modal Lagrangian analysis of rotating flexible blades. The methods considered are those based on the use of uniform beam/bar eigenfunctions, smooth bending moment or torque modes, and modes generated by recourse to one stage of the Stodola method. For blades which are highly non-uniform in their specific stiffness and inertial properties, and where the objective is to use a small number of approximating functions, consistent with accurate determination of eigen-solutions in the fundamental spectrum, it is demonstrated (as is well known) that direct use of uniform system eigenfunctions is unsatisfactory. On the other hand, it is demonstrated that the use of smooth bending moment modes, even in cases where the variations in sectional inertia properties are very large, can produce excellent results. The use of ‘Stodola modes', however, is shown to offer the all-important advantage of enhanced convergence rate in all cases considered.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1989-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1988-03-01DOI: 10.1017/S000192400002203X
L. Crabtree
{"title":"Aerodynamics: the science of air in motion — Third edition. Edited by J. E. Allen. Allen Brothers a Father, Blythburgh, 1986. 205 pp. Illustrated. £15.00.","authors":"L. Crabtree","doi":"10.1017/S000192400002203X","DOIUrl":"https://doi.org/10.1017/S000192400002203X","url":null,"abstract":"","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1988-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S000192400002203X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1987-11-01DOI: 10.1017/S0001924000021667
B. Nageswara Rao, G. Venkateswara Rao
Summary Large deflection problem of a spring loaded hinged nonuniform cantilever beam subjected to a rotational distributed loading is formulated by means of a second-order non-linear integro-differential equation. The problem is examined by considering the beam of rectangular cross-section with linear depth taper subjected to a uniform rotational distributed load. The elastic curves of a beam for this special case are presented.
{"title":"Large deflections of a spring-hinged tapered cantilever beam with a rotational distributed loading","authors":"B. Nageswara Rao, G. Venkateswara Rao","doi":"10.1017/S0001924000021667","DOIUrl":"https://doi.org/10.1017/S0001924000021667","url":null,"abstract":"Summary Large deflection problem of a spring loaded hinged nonuniform cantilever beam subjected to a rotational distributed loading is formulated by means of a second-order non-linear integro-differential equation. The problem is examined by considering the beam of rectangular cross-section with linear depth taper subjected to a uniform rotational distributed load. The elastic curves of a beam for this special case are presented.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1987-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000021667","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-04-01DOI: 10.1017/S0001924000030682
R. Le Claire
The integration of a system—or a group of systems — into a modern fixed-wing aircraft can only be satisfactorily achieved if the fuel penalty incurred by the aircraft is minimised, i.e. if the amount of fuel needed to restore the initial aircraft performance is kept to a minimum. Over the years, aircraft systems have had to meet more and more stringent requirements which reflect not only on the increasing performance of aircraft, but also on the greater demands made by systems on the aircraft, a somewhat extreme example being that of the Mach 2 + Rockwell International B-l bomber on which the cooling requirements for the avionic equipment were to exceed several hundred kilowatts. As such trends are likely to continue in the foreseeable future, the current deteriorating situation regarding fuel supplies and the ever rising costs involved, stresses the need for ensuring that systems on the next generation aircraft are designed for the least penalty and most efficient use of the available fuel.
{"title":"Energy Conservation Designing systems for the least fuel penalty on the aircraft","authors":"R. Le Claire","doi":"10.1017/S0001924000030682","DOIUrl":"https://doi.org/10.1017/S0001924000030682","url":null,"abstract":"The integration of a system—or a group of systems — into a modern fixed-wing aircraft can only be satisfactorily achieved if the fuel penalty incurred by the aircraft is minimised, i.e. if the amount of fuel needed to restore the initial aircraft performance is kept to a minimum. Over the years, aircraft systems have had to meet more and more stringent requirements which reflect not only on the increasing performance of aircraft, but also on the greater demands made by systems on the aircraft, a somewhat extreme example being that of the Mach 2 + Rockwell International B-l bomber on which the cooling requirements for the avionic equipment were to exceed several hundred kilowatts. As such trends are likely to continue in the foreseeable future, the current deteriorating situation regarding fuel supplies and the ever rising costs involved, stresses the need for ensuring that systems on the next generation aircraft are designed for the least penalty and most efficient use of the available fuel.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1980-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1980-04-01DOI: 10.1017/s0001924000030700
J. H. Sims Williams
{"title":"Applied Optimal Design. E. J. Haug and J. A. Arora. John Wiley & Sons Ltd, Chichester. 1979. 520 pp. Illustrated. £17.40.","authors":"J. H. Sims Williams","doi":"10.1017/s0001924000030700","DOIUrl":"https://doi.org/10.1017/s0001924000030700","url":null,"abstract":"","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1980-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1978-10-01DOI: 10.1017/S0001924000095051
H. E. Le Sueur
In considering the necessity for requirements to establish the airworthiness of helicopters it is essential to take into account the capabilities of the vehicle itself, the environment in which the vehicle is likely to be used and the abilities of the people most likely to be involved with the vehicle. As envisaged by the inventors the helicopter is a vehicle which is capable of both vertical and translational flight. Unfortunately if the helicopter enters a cloud whilst engaged in vertical flight all visual reference is lost and the pilot is unable to correct any disturbance due to gustiness in the surrounding air. Conversely, if descending in vertical flight a situation can arise where the rotor develops a vortex ring and without forward speed the descent rate cannot be reduced until the helicopter hits the ground. It is therefore apparent that in flying the helicopter the pilot has to know its limitations and must be trained to handle the aircraft properly. Again in the course of flying the helicopter there is a probability that something will fail and if that probability is too high then such failures must be taken into account in assessing the airworthiness.
{"title":"Airworthiness of helicopters","authors":"H. E. Le Sueur","doi":"10.1017/S0001924000095051","DOIUrl":"https://doi.org/10.1017/S0001924000095051","url":null,"abstract":"In considering the necessity for requirements to establish the airworthiness of helicopters it is essential to take into account the capabilities of the vehicle itself, the environment in which the vehicle is likely to be used and the abilities of the people most likely to be involved with the vehicle. As envisaged by the inventors the helicopter is a vehicle which is capable of both vertical and translational flight. Unfortunately if the helicopter enters a cloud whilst engaged in vertical flight all visual reference is lost and the pilot is unable to correct any disturbance due to gustiness in the surrounding air. Conversely, if descending in vertical flight a situation can arise where the rotor develops a vortex ring and without forward speed the descent rate cannot be reduced until the helicopter hits the ground. It is therefore apparent that in flying the helicopter the pilot has to know its limitations and must be trained to handle the aircraft properly. Again in the course of flying the helicopter there is a probability that something will fail and if that probability is too high then such failures must be taken into account in assessing the airworthiness.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1978-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000095051","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57256323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1978-07-01DOI: 10.1017/s0001924000090953
J. H. Sims Williams
{"title":"Linear Estimation and Stochastic Control. M. H. A. Davis. Chapman and Hall, London. 1977. 224 pp. Illustrated. £8.00.","authors":"J. H. Sims Williams","doi":"10.1017/s0001924000090953","DOIUrl":"https://doi.org/10.1017/s0001924000090953","url":null,"abstract":"","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1978-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57255682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1978-01-01DOI: 10.1017/S0001924000094847
R. Yates
As you could all imagine I am sure, the title of this lecture embraces a subject which is very close to the airline operator's heart. One of the prime objectives of any airline is to operate on time all the time. The word ‘delay’ of course can encompass a wide range of problems. As the second oldest airline in the world—after KLM—and the operator of the world's longest average passenger journey length we do not mind admitting that we have had our share of delays over the years. I know this is a very serious subject but I could not resist having a brief look through our records recently to pluck out a few of the more extreme reasons for delays that you run into in the airline business.
{"title":"Factors influencing schedule reliability in international operations","authors":"R. Yates","doi":"10.1017/S0001924000094847","DOIUrl":"https://doi.org/10.1017/S0001924000094847","url":null,"abstract":"As you could all imagine I am sure, the title of this lecture embraces a subject which is very close to the airline operator's heart. One of the prime objectives of any airline is to operate on time all the time. The word ‘delay’ of course can encompass a wide range of problems. As the second oldest airline in the world—after KLM—and the operator of the world's longest average passenger journey length we do not mind admitting that we have had our share of delays over the years. I know this is a very serious subject but I could not resist having a brief look through our records recently to pluck out a few of the more extreme reasons for delays that you run into in the airline business.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1978-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57256086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-12-01DOI: 10.1017/S0001924000049502
J. H. Sims Williams
The book is a teaching text in which the author has used problems of types (i) and (ii) to help the student understand the ideas needed in the solution of the control problem, which is clearly his principal interest. The Calculus of Variations, the Pontryagin Maximum Principle and first and second order gradient methods are derived in turn and each is applied to a simple problem from the aerospace field. Finally, the author introduces the basic algorithm of dynamic programming and from the Dynamic Programming Functional Equation derives the HamiltonJacobi Differential Equation. The book is a good introductory test for engineering and mathematical students of Optimal Control. A set of worked examples are provided at the end; although the problems are all from the aerospace field they are accessible to all students. J . H. SIMS WILLIAMS Engineering Anthropometry Methods
{"title":"Optimisation Methods. Henning Tolle. Springer-Verlag, Berlin. 1975. 226 pp. Illustrated. Dm 57.70; $24.80.","authors":"J. H. Sims Williams","doi":"10.1017/S0001924000049502","DOIUrl":"https://doi.org/10.1017/S0001924000049502","url":null,"abstract":"The book is a teaching text in which the author has used problems of types (i) and (ii) to help the student understand the ideas needed in the solution of the control problem, which is clearly his principal interest. The Calculus of Variations, the Pontryagin Maximum Principle and first and second order gradient methods are derived in turn and each is applied to a simple problem from the aerospace field. Finally, the author introduces the basic algorithm of dynamic programming and from the Dynamic Programming Functional Equation derives the HamiltonJacobi Differential Equation. The book is a good introductory test for engineering and mathematical students of Optimal Control. A set of worked examples are provided at the end; although the problems are all from the aerospace field they are accessible to all students. J . H. SIMS WILLIAMS Engineering Anthropometry Methods","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1975-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57254299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-05-01DOI: 10.1017/S0001924000035314
R. Le Claire
The purpose of this note is: (a) to provide a method for evaluating the fuel mass penalty incurred in flight after fitment of a system to an aircraft. The method relies only on a limited number of parameters and should prove particularly useful in the early design stages of a new project. (b) to show the relative importance of the parameters involved, in particular the relationship between the fuel penalty due to system basic mass and that due to system drag (other than mass drag) which, depending on the flight conditions, could be significant or even greater.
{"title":"Evaluation of the overall fuel mass penalty of an aircraft system","authors":"R. Le Claire","doi":"10.1017/S0001924000035314","DOIUrl":"https://doi.org/10.1017/S0001924000035314","url":null,"abstract":"The purpose of this note is: (a) to provide a method for evaluating the fuel mass penalty incurred in flight after fitment of a system to an aircraft. The method relies only on a limited number of parameters and should prove particularly useful in the early design stages of a new project. (b) to show the relative importance of the parameters involved, in particular the relationship between the fuel penalty due to system basic mass and that due to system drag (other than mass drag) which, depending on the flight conditions, could be significant or even greater.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1975-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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