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THE importance of achieving a low structural weight is illustrated by simple estimates of the large decreases in aircraft gross weight and size made possible by conscientious weight saving in structural design. A brief review is then made of the many variables in aircraft design which affect the weight of the structure. The review is made chiefly to emphasize the close interplay in project work between the structural and aerodynamic effects of changes of layout. Finally some remarks are made about comparative structural design efficiency. It is concluded that good weight prediction formulae are at present the best means by which the structural design efficiencies of different aircraft may be readily compared.

This paper suggests a means of estimating wing weight using formulae based on the theoretical ideal wing. The predicted wing weight is attained by multiplying the weight of the ideal wing by a correction factor derived from a statistical analysis of actual wing weights. The method has the advantage that it provides the designer with a yardstick by which to compare alternative designs and indicates where improvement might be effected.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.

IT was an open secret for a considerable time—before the fact became, as it has been now for some months, common knowledge —that the BRISTOL AEROPLANE COMPANY was concerning itself with the development of the helicopter. It is, therefore, with particular interest that we publish this month an article on the performance of rotors by MR TOMS, who is a member of the staff of this firm's helicopter department. It follows an American article, which appeared in Aircraft Engineering last October, on the power requirements of this type of aircraft, from MR AUTRY, of the BOEING AIRCRAFT COMPANY. Our regular readers will, of course, also remember the ‘classic’ series on ‘Rotary Wing Aircraft’ by DR BENNETT, then with the AUTOGIRO COMPANY, and now with the FAIREY AVIATION COMPANY, which originally appeared in our January to August 1940 issues, and the recurrent demand for which necessitated our recently having to make available photostat reprints for those who missed it at the time and now want to make a study of the basic principles of the subject.

Abstracts of the Reports and Memoranda of the Aeronautical Research Council are usually published on the pages specially reserved for ‘Research Reports and Memoranda’. The Editor feels that an exception should be made for this report because of its importance not only to those directly associated with accident investigation, but to all concerned with aeronautical research and development.

The purpose of this paper is to examine contagion among the major world markets during the last 25 years and propose a new way to analyze contagion with wavelet methods.

The analysis uses a novel way to study contagion using wavelet methods. The comparison is made between co‐movements at different time scales. Co‐movement methods of the discrete wavelet transform and the continuous wavelet transform are applied.

Clear signs of contagion among the major markets are found. Short time scale co‐movements increase during the major crisis while long time scale co‐movements remain approximately at the same level. In addition, gradually increasing interdependence between markets is found.

Because of the chosen method, the approach is limited to large data sets.

The research has practical implications to portfolio managers etc. who wish to have better view of the dynamics of the international equity markets.

The research uses novel wavelet methods to analyze world equity markets. These methods allow the markets to be analyzed in the whole state space.

The studies on international housing markets have not modeled frequency domain and focused only on the time domain. The purpose of the present research is to fill this gap by using the state-of-the-art econometric technique of wavelets to understand how differences in the horizon of analysis across time impact international housing markets’ relationship with some of the key macroeconomic variables. The purpose is to also analyze the direction of causation in the relationships.

The author uses the novel time–frequency analysis of international housing markets’ linkages to the macroeconomic drivers. Unlike conventional approaches that do not distinguish between time and frequency domain, the author uses wavelets to study house prices’ relationship with its drivers in the time–frequency space. The novelty of the approach also allows gaining insights into the debates that deal with the direction of causation between house price changes and macroeconomic variables.

Results show that the relationship between house prices and key macroeconomic indicators varies significantly across countries, time, frequencies and the direction of causation. House prices are most related to interest rates at the higher frequencies (short-run) and per capita income growth at the lower frequencies (long-run). The role of industrial production and income growth has switched over time at lower frequencies, particularly, in Finland, France, Sweden and Japan. The stock market’s nexus with the housing market is significant mainly at high to medium frequencies around the recent financial crisis.

The present research implies that in contrast to the existing approaches that are limited to the only time domain, the frequency considerations are equally, if not more, important.

Results show that interested researchers and analysts of international housing markets need to account for the both horizon and time under consideration. Because the factors that drive high-frequency movements in housing market are very different from low-frequency movements. Furthermore, these roles vary over time.

The insights from the present study suggest policymakers interested in bringing social change in the housing markets need to account for the time–frequency dynamics found in this study.

The paper is novel on at least two dimensions. First, to the best of the author’s knowledge, this study is the first to propose the use of a time–frequency approach in modeling international housing market dynamics. Second, unlike present studies, it is the first to uncover the direction of causation between house prices and economic variables for each frequency at every point of time.

This study seeks to examine the relationship between macroeconomic shock indicators, namely geopolitical risk (GPR), global economic policy uncertainty (GEPU) and financial stress (FS), and returns as well as volatilities on seven carefully selected stock markets in Africa. Specifically, the study intends to unravel the co-movement and interdependence between the respective macroeconomic shock indicators and each of the stock markets under consideration across time and frequency.

This study employed wavelet coherence approach to examine the strength and stability of the relationships across different time scales and frequency components, thereby providing valuable insights into specific periods and frequency ranges where the relationships are particularly pronounced.

The study found that GEPU, Financial Stress (FS) and GPR failed to induce significant influence on African stock market returns in the short term (0–4 months band), but tend to intensify in the long-term band (after 6th month). On the contrary, stock market volatilities exhibited strong coherence and interdependence with GEPU, FSI and GPR in the short-term band.

This study happens to be the first of its kind to comprehensively consider how the aforementioned macro-economic shock indicators impact stock markets returns and volatilities over time and frequency. Further, none of the earlier studies has attempted to examine the relationship between macro-economic shocks, stock returns and volatilities in different crisis periods. This study is the first of its kind in to employ data spanning from May 2007 to April 2023, thereby covering notable crisis periods such as global financial crisis (GFC) and the COVID-19 pandemic episodes.