The loss in efficiency which arises in connection with present aircraft designs has been dealt with very fully during recent years. It has been shown that the perfect streamline aeroplane would only have a drag of one-third that of a conventional machine. While it is improbable that this ideal design will ever be attained, considerable improvements can be made by refinements in design and careful revision of those items which are the cause of comparatively big losses.

Many attempts are being made to reduce parasitic drag and interference effects, for the importance of obtaining increased performance by aerodynamic cleanliness rather than by increased power is apparent.

Referring more particularly to the undercarriage component, it can be fairly stated that until quite recently the aeronautical engineer has been more concerned with the provision of a satisfactory undercarriage mechanism than the more difficult problem of providing a low resistance unit.

Tests on certain aircraft having disclosed discrepancies between the characteristics estimated from the figures for the individual components and those observed for the complete model, the present investigation was undertaken to determine the nature and magnitude of the effects of interference between the body and wings of aircraft and to ascertain the factors influencing the interference.

The models were made up of standard 3in. x 18in. duralumin aerofoils and fuselages of wood.

The aerofoils employed in the investigation were:–

1. (a) R.A.F.-15–a thin section.

2. (b) U.S.A.-27–a section of medium thickness.

3. (c) Gottingen-387–a thick section.

The fuselages used were:–

1. a. Fuselage A–of streamline form.

2. b. Fuselage B–of cabin form.

3. c. Fuselage C–of usual open cockpit form.

A number of typical monoplane and biplane combinations Of wings and fuselages were tested, and in some cases the effect of fairing between wings and fuselage was studied.

The results of the investigation indicate that the interference effects are dependent on the shape of the fuselage, the aerofoil section and the relative position of the fuselage and aerofoil. The better the aerodynamic form of the fuselage, and the thicker the aerofoil section, the greater are the interference effects and the more marked the influence of the relative vertical position of the wings and body on the interference.

Interference between wings and body tends, in general, to lower the critical angle and increase the drag of the combination as compared with the individual components. It may increase or decrease the lift.

From an aerodynamic standpoint, the best position for the wing is at the top of the fuselage, and the worst that at the bottom.

Fillets and fairing may improve a combination having poor characteristics, but have little effect if the arrangement already possesses good characteristics.

An explanation of the cause of the observed interference effects is advanced.

The site of the Flying School was selected on a gentle eastward slope about midway between the southern slope of the “ Wasserkuppe ” and the western slope of the “ Weltensegler,” a ridge running at right angles to the former, the slopes of which are most used for training glides. The hangar, 60m. by 12m., was built of timber, with a cantilever roof requiring few supports and with drop doors at each end. The pupils are boarded at the school for convenience and for better supervision and direction of their spare time activities. It was also necessary to provide workshops and offices, and quarters for the mechanics and instructors and for the head of the school. A single building, also 60m. by 12m., adjacent to the hangar contains living quarters below, and a workshop above; a long central passage leads to a hall, on the south side, off which are the quarters of the Director of Research and of the Head of the School, and the kitchen premises; on the north side a woodworking shop equipped with a combined plane and shaping machine, a combined circular saw milling and slotting machine, and a hand saw.

Three years ago I had the pleasure of speaking before the Royal Aeronautical Society, and I feel highly honoured that I have again been requested to say a few words about the German commercial air services. From this request I draw the conclusion that Great Britain is as much as ever interested in the progress of German commercial flying. The essential basis of good relationship between the nations, namely, that in order to understand each other they must know each other, applies also to the realm of commercial aviation. The present developments in commercial flying demand that the nations interested shall work with one another and not against one another. This, however, will only be possible if there is a mutual understanding and knowledge of air activities on both sides.

Air Photography and its serious application to map-making may be traced to the Great War. It was at this period that grave consideration had to be given to Air Photography as a method of producing maps.

In all the theatres of war, which included France, Palestine, Salonica, and Mesopotamia (or Iraq as this country is now known), extensive operations were carried out in Air Photography, and the photographs used for the amplification of existing maps, and in many cases to the compilation of new maps.

The first of the 1929 team to be posted for High Speed Flying was Greig, who towards the end of 1928 was sent to Calshot to make another attempt on the Speed Record. He achieved 319 miles an hour, which was the fastest speed on record, but did not exceed the Italian speed by a sufficiently large margin to count as a new record. While at Calshot, Atcherley and Stainforth joined him to start training, but very little flying was done during the winter months. Squadron Leader Orlebar took charge of the Flight when it was formed early in February, 1928, and I came a few weeks later. We had Moon as an engine officer, who had been with the 1927 team in the same capacity.

Recent developments in the design of rigid airships, as commercial air liners in England and Germany, and for military purposes in America, show a demand for greater lifting capacity, cruising range and speed. The increase in size is mainly responsible for radical changes in the structural arrangement of the transverse frames, introduced by the designers of the British airships, R.100 and R.101.

The lecturer opened with a brief and general description of R. 100, which has an overall length of 709 ft. and a diameter of 133 ft., with a cubic capacity of 5,250,000 cu. ft. There are three power cars, each with two engines. These cars are situated at a considerable distance fore and aft from the passenger accommodation, and there was therefore a minimum of noise and vibration in the latter. The ship contained some 11 miles of special spiral seam tubing. Her displacement was 156 tons. In the Graf Zeppelin the cross sectional area of the girders equalled some 12 sq. ins., whereas in the British ship the cross sectional area amounted to 3 sq. ft.

The scope of the paper is not so wide as the title may suggest. The primary object is to put forward a graphical method of determining the shape of the cross-section of the airship, and the loads in the envelope and rigging wires, in the plane of the cross-section, for different loading conditions.

Various secondary matters, such as a brief review of other methods of dealing with the subject, and the effect of different schemes of rigging on “ breathing,” are included in the paper as points of interest.

The field covered by the title of this paper is a very comprehensive one, and is too large to be dealt with in a single lecture. Only certain aspects of the subject, therefore, will be dealt with, and very brief reference made to such tests as have been described in other papers.

The subject naturally falls into three divisions:—Ground tests, tests on the water, and aerial tests, and it will be convenient to deal with them in this order. The methods of test described are those in use at the Marine Aircraft Experimental Establishment, Felixstowe, the official seaplane testing station, and, as far as is known, these methods are as up to date as those in use in other countries.

If it is felt that gaps exist on which information is desired, the inquirer is referred to Squadron Leader England's lecture on “ The Practical Side of Performance Testing of Aircraft,” which was published in the Aeronautical Society's Journal of January 1928, and to other papers which are mentioned.