An outline is given of the uses of flutter models as an aid to the designer in the avoidance of flutter. Details are given of the different types and methods of construction that…
Abstract
An outline is given of the uses of flutter models as an aid to the designer in the avoidance of flutter. Details are given of the different types and methods of construction that are used for flutter models and of the various test facilities that are available for high speed and low speed tests. The procedure followed in the U.K. for flutter clearance of the full scale aircraft is described, and the value of the electronic flutter simulator in this field is discussed.
The current trend in ground resonance testing is aimed at providing aircraft modes of vibration appropriate to the free‐free condition. To achieve this objective the rigid body…
Abstract
The current trend in ground resonance testing is aimed at providing aircraft modes of vibration appropriate to the free‐free condition. To achieve this objective the rigid body frequencies of the aircraft on its supports must be low by comparison with the frequency of any mode of distortion. A minimum frequency ratio of 1:3 is specified. The various types of support in current use are considered in relation to the minimum frequency they are likely to provide. It appears that none are capable of frequencies lower than about 0·5 cycles/sec. For the forthcoming generation of large thin‐wing aircraft with fundamental frequencies below 1 cycle/sec. some further development in methods of support seems necessary. A non‐linear spring system appears to hold great promise in this respect, and one such system is described capable of frequencies less than 0·25 cycles/sec. for a limited range of movement.
On the basis of certain simplifying assumptions a general equation can be developed that provides an estimate of the flutter speed of a binary system. The equation includes…
Abstract
On the basis of certain simplifying assumptions a general equation can be developed that provides an estimate of the flutter speed of a binary system. The equation includes aerodynamic stiffness derivatives, and in the absence of reliable derivatives for oscillatory motion it is suggested that derivatives derived from steady flow measurements can be used. The equation is applied to derive specific formulae for main surface flexure‐torsion flutter. The effects of compressibility on the derivatives for this particular case is deduced, and the derivatives are then used to estimate certain general effects of compressibility on flutter. It appears that many of the generally accepted features of flutter in the transonic region can be established by this approach, but the application of the formula is limited by the lack of reliable data for aerodynamic stiffness derivatives. A concentrated effort to establish these derivative values is likely to be more rewarding in the long run than flutter tests on innumerable models to establish overall flutter trends of limited application.
AT the present time it is a general practice to make extensive investigations of the flutter and oscillatory stability characteristics of all prototype aircraft at an early stage…
Abstract
AT the present time it is a general practice to make extensive investigations of the flutter and oscillatory stability characteristics of all prototype aircraft at an early stage in the design. So far as theoretical investigations of these characteristics are concerned there is often considerable uncertainty as to the values of the aerodynamic coefficients to be used, for there is evidence that measured and theoretical coefficients may differ considerably. Measured values of the coefficients are therefore required both for direct use in calculations and as a check on the theoretical coefficients, and also to provide a guide in the development of more precise theories. Unfortunately the wide variations in wing plan forms and the rapid increase in flight speeds which have occurred in recent years have meant that experimental work in this particular field has not kept pace with development and the designer is faced with the problem of ensuring the safety and operational efficiency of his aircraft using theoretical coefficients whose values may be unreliable.
Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Technical Reports and Translations of the United States…
Abstract
Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Technical Reports and Translations of the United States National Aeronautics and Space Administration and publications of other similar Research Bodies as issued.
AIRCRAFT ENGINEERING was born in March 1929 of the belief that the emerging technology from which it took its title would become a fundamental element of engineering progress. The…
Abstract
AIRCRAFT ENGINEERING was born in March 1929 of the belief that the emerging technology from which it took its title would become a fundamental element of engineering progress. The keystone of its policy was that it would attempt to meet the needs of engineers and students working in this field and that its contents should be ‘written by engineers — for engineers’. That this venture was fully justified has been amply vindicated by the achievements of the industry during the ensuing 41 years — as recorded in the first 500 issues of this Journal, the major milestone celebrated this month. This is a propitious occasion on which to review the record to date because, although aviation has always been about looking forward, history is instructive and it is the impressive performance of the aerospace industry to date that inspires and motivates confidence in its future.
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…
Abstract
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…
Abstract
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…
Abstract
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…
Abstract
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.