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PROGRESS in most branches of engineering has been dependent upon model tests, and in no branch has the testing of models been of greater importance than in that of aeronautics. The earliest flights were made on models; and after the first successful flight of the full‐sized aeroplane, the development of aircraft to their present state of efficiency has been bound up, at every step, with the information obtained from model tests.

THROUGH the courtesy of the Chief of the Division of Aeronautics, Council for Scientific and Industrial Research, Commonwealth of Australia, we are enabled to publish in this issue the official report describing the 9 ft. by 7 ft. wind‐tunnel recently put into operation at Fishermen's Bend. This is, in fact, the first news we have had of the activities of the Division since its inauguration in 1939, though in a covering letter Mr. L. P. COOMBES—late of Farnborough, which he left to take up the post of Chief of the Division—informs us that practically all the equipment originally planned has now been installed.

It is usual when carrying out tank tests on seaplane models to include measurements of the change in attitude when pitching moments of different amounts are applied. The measurements are generally made over a range of speeds in the neighbourhood of three‐quarters of the take‐off speed, in the neighbourhood of one‐third of the take‐off speed, and also with the hull or floats at rest. Curves of attitude against speed, with different applied moments, are shown in Fig. 11, for a twin‐float seaplane, and may be regarded as typical.

THE period from 1884 to 1937 (the events of which are summarized on earlier pages of the pamphlet) may be said to have been exploratory as regards aeronautical science in Australia. Many beginnings had been made in research, in teaching and in manufacture, but, no generally organized growth had occurred. The visible beginnings of the present developed state of the industry and of research may be traced from two sources.

THE design of a flying boat hull is a compromise between the usually conflicting requirements of good performance on the water and in flight. For example, from aerodynamic considerations the hull should be without discontinuities, while for low water resistance when planing, discontinuities are necessary in the form of steps and chines, the former to localise the wetted area to that portion providing lift, and the latter to keep the spray as low as possible. Again, though the minimum air drag results from symmetry about the longitudinal axis, it is usual to curve the tail of a hull upwards to give the tail plane sufficient water clearance.

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

IT is probable that the earliest recorded results of model experiments conducted for the express purpose of determining the water resistance of a body relate to the tests made by Beaufoy in the Greenland Dock during the years 1793 to 1798. The results of these tests were made public in 1834, and in the same year Scott Russell commenced a series of model experiments upon ship forms, these tests being conducted in a canal. Based on the results of these tests, Scott Russell formulated his theory of ship resistance, and in his paper to the British Association in 1869 he drew particular attention to the important effect of depth of water upon the wave formation. In 1869 the committee of the British Association recommended that experiments should be carried out on a steamer of known form by towing her at various speeds by means of an apparatus which would register the towing force. To this Mr. Froude, who was a member of the committee, added that so great a variety of forms ought to be tried that it would be impossible, alike on the score of time and expenditure, to perform the experiments with full‐sized ships. The Admiralty, when asked to carry out the proposal, declined to do so, but agreed to carry out Mr. Froude's proposal to try models.

AERONAUTICAL research is now firmly established in Australia. Nevertheless, many people, including a large proportion of Australians, may well wonder why a country which derives the major part of its wealth from primary products should expend large sums on an activity apparently unrelated to its economy. Thus it will not be out of place to begin with some of the relevant background.

The third term has been expressed as but in wind tunnel work it is often more convenient to measure were the omission of the dash signifies that the moment is now measured about a wind axis. The two quantities are very closely related and the measurement of one tells us almost as much as if the two were known. The latter, however, tells us either directly or indirectly what effect the addition of fin and rudder will have on the autorotation properties of the wings alone. The damping of fin and rudder being due essentially to the air flow meeting them at an angle on account of the rotation it should theoretically be possible to deduce this dynamic quantity from a simple static test of moment due to yaw angle. An experiment to test this was carried out several years ago but the static test did not give any approximation to the truth. This was ascribed at the time to the shielding of fin and rudder by the tail plane in the rotative experiment and subsequent work has amply confirmed this view. It is now known that shielding by the tail plane is by far the most important factor in determining the efficiency of the vertical surfaces at high angles of attack.

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