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This paper aims to present the results of calculations that checked how the longerons and frames arrangement affects the stiffness of a conventional structure. The paper focuses only on first stage of research – analysis of small displacement. Main goal was to compare different structures under static loads. These results are also compared with the results obtained for a geodetic structure fuselage model of the same dimensions subjected to the same internal and external loads.

The finite element method analysis was carried out for a section of the fuselage with a diameter of 6.3 m and a length equal to 10 m. A conventional and lattice structure – known as geodetic – was used.

Finite element analyses of the fuselage model with conventional and geodetic structures showed that with comparable stiffness, the weight of the geodetic fuselage is almost 20 per cent lower than that of the conventional one.

This analysis is limited to small displacements, as the linear version of finite element method was used. Research and articles planned for the future will focus on nonlinear finite element method (FEM) analysis such as buckling, structure stability and limit cycles.

The increasing maturity of composite structures manufacturing technology offers great opportunities for aircraft designers. The use of carbon fibers with advanced resin systems and application of the geodetic fuselage concept gives the opportunity to obtain advanced structures with excellent mechanical properties and low weight.

This paper presents very efficient method of assessing and comparison of the stiffness and weight of geodetic and conventional fuselage structure. Geodetic fuselage design in combination with advanced composite materials yields an additional fuselage weight reduction of approximately 10 per cent. The additional weight reduction is achieved by reducing the number of rivets needed for joining the elements. A fuselage with a geodetic structure compared to the classic fuselage with the same outer diameter has a larger inner diameter, which gives a larger usable space in the cabin. The approach applied in this paper consisting in analyzing of main parameters of geodetic structure (hoop ribs, helical ribs and angle between the helical ribs) on fuselage stiffness and weight is original.

II—FUSELAGE JIGS (cont.) Girder Fuselages The girder fuselage has, in the last few years, fallen into desuetude, save for some training and light types, yet it has many very decided advantages for rapid production. Perhaps paramount among its virtues is the simplicity of the “plumbing” installations. Chief among the disadvantages is the unsuitability of fabric covering for modern high speeds, yet this can be overcome by careful attention to the method of attachment for the fabric, as may be seen from the success of the Hawker Hurricane and the Morane‐Saulnier MS 406‐C1. In the lower speed ranges the advantages should easily outweigh other considerations, particularly for training aeroplanes where rapid repair on the spot is essential. Again, the success of the de Havilland Tiger Moth, North American Harvard and the Westland Lysander, not to mention the many American light aeroplanes with tubular fuselages speak well in favour of the system.

The purpose of this paper is to present the result of calculations that were performed to estimate the structural weight of the passenger aircraft using novel technological solution. Mass penalty resulting from the installation of the fuselage boundary layer ingestion device was needed in the CENTRELINE project to be able to estimate the real benefits of the applied technology.

This paper focusses on the finite element analysis (FEA) of the fuselage and wing primary load-carrying structures. Masses obtained in these analyses were used as an input for the total structural mass calculation based on semi-empirical equations.

Combining FEA with semi-empirical equations makes it possible to estimate the mass of structures at an early technology readiness level and gives the possibility of obtaining more accurate results than those obtained using only empirical formulas. The applied methodology allows estimating the mass in case of using unusual structural solutions, which are not covered by formulas available in the literature.

Accurate structural mass estimation is possible at an earlier design stage of the project based on the presented methodology, which allows for easier and less costly changes in designed aircrafts.

The presented methodology is an original method of mass estimation based on a two-track approach. The analytical formulas available in the literature have worked well for aeroplanes of conventional design, but thanks to the connection with FEA presented in this paper, it is possible to estimate the structure mass of aeroplanes using unconventional technological solutions.

The Henschel standard section jig as used for tail surfaces is in its simplest form. Unfortunately no details of its application to other parts have been published, but the Heinkel jigs shown in Figs. 148 and 149 appear to have been built on this principle. This fact is of particular interest as, although the Henschel Flugzeugwerke A.G. had been used as a “shadow” factory for a number of designs, it had had no published connexion with the Heinkel works at the time (1939) that these photographs were taken. The He 111k fuselage frame jig shown in Fig. 148 has a basic structure of square tubes and gusset plates which closely resembles the Henschel type. The frame, an important spar‐locating bulkhead, is held by a profile plate fitted within the basic structure. The second Heinkel jig (Fig. 149) is for the nose portion of the He 111k and is undoubtedly designed on similar lines, if the Henschel patents have not actually been used. (The uniformed official in the foreground is Dr Ley, the photograph having been taken at a propaganda inspection of the Oranienburg factory.)

An aerofoil including an oval spar composed of continuous intersecting oppositely pitched geodetic bracing members extending unbrokenly in both directions for more than one complete pitch turn, said geodetic members being passed at their intersections by halving each member oppositely, said geodetic members formed with holes aligned from end to end of the spar and a longitudinal stiffening member extending through said holes from end to end of said spar and rigidly connected to the said bracing members where it passes through said holes, and a nose forming fairing secured at one edge and a trailing edge forming fairing secured to the opposite edge of said spar, said fairings merging into the sides of said spar, and together therewith forming an aerofoil section.

THE Warwick is the third type to be built entirely on the Wallis principle of geodetic construction and is palpably an enlarged version of the ubiquitous Wellington. In addition to the increased dimensions and engine power the fuselage lines have been slightly refined.

THE Liberator is one of the most distinctive four‐engined aeroplanes yet built. It has been designed round the Davis aerofoil, which was patented in the United States some years ago. This aerofoil does not appear to be unduly thin, although designed for high‐speed operation, but is claimed to provide an almost perfect co‐ordination of the airflow across upper and lower surfaces. The main plane of the Liberator is of exceedingly high aspect ratio, greater even than that of the Vickers geodetic aeroplanes, so that some special structural design must have been evolved. Extensive Fowler flaps are fitted, but it is not certain if the built‐in slots have been retained on the British version.

II—FUSELAGE JIGS THE type of jig required for the erection of a main component depends primarily upon the machine's construction (stressed‐skin or girder) and secondarily upon the type of assembly adopted (one‐piece or unit). With a fuselage the former is by far the more important factor, as upon it rests not only the form of the building of the actual structure, but also all the installation problems of the more advanced stages of assembly.

A supporting surface I for aircraft is provided with a control surface II adjustable on the surface I and an auxiliary surface III adjustable on the lower side of the surface II and adapted to participate in the adjustment of the surface II and also throughout at least part of its movement to be adjusted independently of the surface II; the surface II is adjustable so that it is given a motion compounded of a rotation and a fore‐and‐aft displacement. In one form, an auxiliary surface III is nested normally on a control surface II and is connected thereto by links 2, 3 and a tension spring. The surfaces II, III are simultaneously operated from a crank 4 through a link 6 and the surface III is adjustable independently of the surface II from a crank 7 through a link 9. In a modification, the surface II is connected by links to out‐riggers on the wing I so that the surfaces II, III are adjustable together and are moved rearwardly and downwardly. In a further modification, the abutting surfaces of the wing 1 and the surface II are so shaped as to leave a slot when the surface II is moved. The surface III may be arranged so that when in its extreme adjusted position it closes the slot formed at its leading edge during its initial movement. In another form, the surfaces II, III are operated by means concentric with the axis of articulation of the control surface II and in a modification the surface III is operable by cam means and only after a predetermined adjustment of the surface II. In a further form, the surfaces II, III are housed normally in a recess 23 at the rear of a wing. The surface III is again connected to the surface II on outriggers connected thereto by links 3, 2. The surfaces are adjustable as one by a rack 19 and a pinion 22. After the surfaces have been fully adjusted towards the rear, the surface III is independently adjustable through a rack and pinion. The leading edge of the surface III is shaped so that on adjustment of the surface III a slot between the surface II and the wing is uncovered. In a modification, the link 2 is replaced by a pin‐and‐slot and the rack for adjusting the surface III only engages with its pinion when the rack 19 has been disengaged, due to rearward adjustment of the surfaces. In a further modification, the surface III is adjusted by an endless band connected to the pin moving in the slot. In a further modification, the surface II comprises two portions separated by a slot and the surfaces II, III are nested normally in the underside of a wing. In a still further modification, the recess 23 is closed when the surfaces have been adjusted rearwardly by a surface IV and a slot forming slat 47 is adjusted concurrently with the surface III, this is effected by a rope 50 carrying a pin 56 which engages in a slot 55 in discs 57 connected to the slat 47 by a link 59 when the surface III is in position prior to adjustment, In a still further form, the surface II is connected to outriggers 63 by links 66, 64 and 69, 67 connected and operated from a link 71 as shown. The surface III is adjusted by rotation of the pivot axis 76 or through links from a rod rotatable in the surface II. In a still further form, the adjusting mechanism is carried by the leading edge of the surface II.