• Aircraft Influence on the Road Vehicle of the Future
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THERE is a world of difference between the powerful war plane of the present, with its cargo of armament and destructive explosive, and the everyday commercial vehicle with its load of constructive materials or passengers, but many of the problems of both remain fundamentally the same. In both cases; we see the attempt to obtain the lowest possible structure. weight and the greatest. disposable capacity, combined with the necessity of economy in man-hours and largescale production.
Under war conditions, of course, the problem of low cost must give place to the more pressing ones of efficiency and striking power, and developmett is unrestricted by the question of economy. The aircraft designer, therefore, has brought into being production methods and machinery which were forbidden to the pre-war motor-vehicle manufacturer, but, with the coming of peace, large plants and new materials will be at the disposal of the latter.
Widespread use of aluminium and the great accumulated store of experience in its manufacture and working offer new scope for the vehicle designer, Whilst .the many factories engaged on its production give promise of an unprecedented economy which will lead to aluminium alloys rivalling, or even surpassing in low cost, the structural steel now in use.
Many aircraft builders use extrudetl light-alloy spars for structural members, and these would_ seem to offer great possibilities for the automobile designer. Previously frame sidemembers have been almost limited to rolled or pressed-steel girder or channel sections. Sometimes, in the search for greater rigidity, boi membersformed by overlapping channels have been used, but this construction does not permit an easy assembly.
The extrusion system permits of an
almost infinite variety of forms, and enables sections giving maximum strength with minimum weight to, be used. Shapes which suggest themselves are theelliptical, rectangular. Z and channel. Cross-members can also be extruded, although requirements are more complex, and arrangements must be made for engioe and gearbox mountings. Castings or stampings can simplify the problems arising.
These sections could also• be utilized for body frames for buses, lorries -and vans, whilst offering scope for the elimination of the fraine proper by the distribution of stresses over a suitable fabricated structure.
There is probably much to be learnt from aircraft riveting methods, and there is little doubt that the explosivefilled rivet will overcome many intricate automobile assembly problems.
The German Messerschmitt fighter is constructed in a manner that may well be used as a basis for a tank wagon, bus or coach. The fuselage plates are curved by rolling, an theends are joggled and flanged so that a unit which is stiff without the addition of separate ribs or other strengthenings results. These are spaced apart by 'plain curved plates, and thus is • produced what is in effect a long -curved plate with integral internal ribs. It is not a considerable step to gdd end plates to form a tank of cylindrical or elliptical section, or to incorporate window openings, thereby forming a body component. Front and rear-ax‘le housings offer scope for the use of light-alloy stampings, and aluminium' cylinder blocks with inserted liners afford a material weight reduction. Cast wheels of light alloy have been used in the past, and would have been more widely employed but for their high cost when compared with ferrous materials—a consideration which will not in the future be so marked.
Plastics are now much used on aircraft, and possess attractive possibilities for road vehicles. Whilst it is improbable that stress-carrying members will be made of synthetics, there are many non-stressed components. such as panels for application to a lightalloy framework, for which, owing to its lightness, durability and economy, plastic material is inherently suitable.
Much has been said about the finish of plasacs and about their imperviousness to damage in respect of appearance, due to the fact that the colour goes right through as it were. This, however, is not justified by experience, as a scratch on a polished plastic is equally unsightly as on painted metal. A body congtructed on this principle would also possess extremely good sound and heat insulating properties, besides its intrinsic economy of price and weight.
Another possible application would be to non-stressed engine components. For instance, valve and timing-gear covers, inspection doors and sumps, which are often made of unnecessarily heavy metals, because of the cost of lighter ones.
The cellulose acetates now being used in gun turrets, etc., could be ,employed to supersede glass. The consequent saving in weight on a double-decker, for instance, would be considerable, and this material is, of course, unsplin tera ble. Furthermore, production would be simplified by the possibility of purchasing large sheets to be sawn to shape as required. It is readily formed to three-dimensional shapes, thereby lending itself to flowing body lines. A transparent area covering possibly the whole driver's compartment would give unparalleled visibility with ensuing lack of driving fatigue and added safety. The ,whole upper part of a coach could be of transparent cellulose acetate, and thus would be an attractive proposition for touring purposes., One well-known motor company has taken out a patent for an hydraulic spare-wheel carrier which may well have been influenced by aircraft undercarriage design. Rams are used to lift the heavy wheel on to the chaois frame, enabling the driver to perform with ease in a matter of seconds a duty which otherwise would be arduous if not impossible.
Supercharging, which can ascribe to aircraft a good measure of its development, has definite possibilities in connection with commercial vehicles. • By its means, size and weight of power unit can perhaps be reduced, with greater disposable space and load as a consequence. Operating for lengthy periods in temperatures which are considerably below freezing point, aircraft require heating systems which must be highly efficient to ensure the comfort of the crews, and the study of these systems should enable the bus-body builder to remedy the lack of warmth which has been a .fault of some otherwise fine vehicles, for -there are few things less likely to make a contented passenger than a chilly atmosphere.
The service department would appredate the wider application of the " power egg " principle, namely, the whole of the prime-mover arranged so 'that it can be detached from the aeroplane or -vehicle as a unit for major overhauls. This department's satisfaction would be reflected in the operator, for the period in dock would be consequently reduced.
It will thus be seen that an intelligent interest by the designer in aircraft construction may be amply repaid by the satisfaction of builder, owner and user alike, and has possibilities of the opening of a new era in vehicle manufacture.