Aircraft Engineering and Aerospace Technology

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032432

THROUGH the courtesy of the American Society of Mechanical Engineers we are enabled to publish in this issue two papers on pressforging which were read at a meeting of the Society eleven months ago.

Argyris, John H.

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032433

FAILURE of panels under static compression, or for that matter under any loads, involves a vast array of problems ranging from properties of material to initial instability and postbuckling phenomena as occurring in various types of panels. It is not intended here to do justice to all these aspects of the subject but to select a singlebut at the same time very importanttopic, develop its analysis as fully as possible, and present the results in a readily applicable form. The structure investigated is the single skin stiffened panel under compression and the mode of failure considered, denoted by flexural cum torsional failure, involves predominantly flexure and torsion of the stringer with a wavelength of greater order of magnitude than stringer height and pitch. By torsional deformation of the stringer we understand a rotation of its undistorted crosssection about a longitudinal axis R in the plane of the plate, the position of which will be selected later on see FIG. 1b. The panel may, of course, also fail in a local mode of stringer and plate with a short wavelength of the order of magnitude of stringer height and pitch, but the analysis of this case is not included here see, however, Argyris and Dunne. Note that a local mode of deformation of a stringer formed by straight walls is commonly defined as a distortion of the crosssection in which the longitudinal edges where two adjacent walls meet remain straight see FIG. 1c.

Andrews, C.W.

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032434

THE contribution to higher performance can be accomplished by the structural designer in the development of greater efficiency in structure 1 By the selection and distribution of material giving the maximum possible strengthweight ratios 2 by the elimination of joints and their inherent inefficiencies and eccentricities 3 by greater refinement of analysis 4 by the maximum utilization of testing to obtain efficiency in components which are difficult to analyse 5 by the design of multipurpose instead of singlepurpose elements 6 by proper consideration of the importance of external structure design to aerodynamic efficiency and 7 by considering the importance of rigidity in the basic structure to dynamic efficiency.

Broad bent, E.G.

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032435

IN Parts I, II and III of this series we have discussed the physical nature of divergence, control reversal and various forms of flutter, and have seen how these phenomena can be predicted by theory. The flutter problem is so complicated, however, that the aircraft designer needs the assistance of certain guiding principles otherwise he may find when the aircraft is ready to fly that the flutter calculations which are just completed show that drastic modifications to the aircraft are necessary. These principles form the basis of this concluding part of the series and have two main objects first to avoid large changes in design on flutter grounds and secondly to obtain a high efficiency from the flutter calculations.

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032436

THE thirtyeighth annual Exhibition of the Physical Society was held at the Imperial College, South Kensington, on April 813, and the account which follows describes a few of the items shown, which have been selected because of their more direct interest for the aeronautical engineering profession.

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032437

Under this beading 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

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032438

A chaindrive transmission is made in two separate portions mounted one on each of two separable components, such as a detachable or folding wing structure, or a removable engine installation, and so arranged that the drive is automatically broken when the components are separated and reengaged when they are reassembled. As shown applied to a detachable wing 10 which is secured to the body 11 of the machine by the engagement of pins 14, 15 in hooks 12, 13, the aileron and flap controls consist of chainandsprocket circuits 16, 17 and 18, 19 on the wing and body respectively, normally slack portions 23 of the chains 20 of circuits 18, 19 being engaged by sprockets 27, integral with the sprockets 25 of circuits 16, 17, when the wing is attached to the body. If desired a change of gear ratio may be introduced by making the sprockets 25, 27 of different sizes.

1954 Aircraft Engineering and Aerospace Technology

doi: 10.1108/eb032439

The method of increasing the efficiency and output horsepower of a gas turbine which comprises introducing the motive gas to the turbine at a temperature substantially in excess of a safe operating temperature for the stator and rotor blades of said turbine and simultaneously spraying water into the gas stream adjacent the turbine inlet to form a water film on the rotor and stator blades, said water being in a finely dispersed condition having an approximate size of 60 to 100 microns when it leaves the spray nozzle and sprayed in amounts insufficient to materially lower the gas temperature in the time the gas passes to the blades, and in amounts great enough to keep the outside of the blades wet, whereby the sensible temperature of the blades is at least several hundred degrees Fahrenheit lower than the entering gas temperature.