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Aviation History
1943
1943 - 0513.PDF
•FEBRUARY 25*11, 1943 FLIGHT 207 HIGH-ALTITUDE FLIGHT of attachment for the supporting struts between pressure cabin and main fuselage. The stiffeners for the lateral metal skin of the cabin also act as a support for the outer aerodynamic failing. One advantage of this system is that aircraft could be designed to be readily adapted for high- altitude service by removing the front portion of the fuse- lage and substituting the pressure cabin which, as the illus- tration shows, is hung from the airframe by a structure similar in principle to a radial engine mounting. In addi- tion the power plants could be readily interchanged by a standard installation design which permitted the substitu- tion of engines supercharged for high altitude. Such a scheme might have practical value in wartime. Another design by the Henschel Co. shows a pressure cabin with,a sealed-off tubular passage through which structural members of the wing may pass. The sealed tunnel forms part of the supporting frame of the cabin and encloses either the top or bottom flange of the wing spar, according to the position of the wing, i.e., high or low. Not only does the flange pass through the cabin but, in addition, it is elasticaily supported, the top boom of the. d II •; ; \|\ ' \ Henschelpres s u r e cabin, com-prising box beam con-struct ion. Mounted a laradial engi ne. spar being constructed with the sealed tube integral with the cabin. External attachments for the outer spar boom are provided. In a third design (not published) the com- plete spar for a mid-wing aircraft is housed in a rectangu- lar sealed tube the whole distance through the cabin. The Focke-Wulf Aircraft Co. uses one or more pressure cabins which are interconnected with airlocks. The flying and engine controls are duplicated and fitted both inside and outside of the cabin. An additional feature is that the pressure and air conditioning of the cabin, and also the air locks, can be controlled from a central station as well as individually. Pressure Cabin for Military Reconnaissance A scheme by the Dormer Co. has advantages from a military standpoint and comprises a cabin in the shape of a body of revolution which is mounted with its axis horizontal in a cut-away portion of the nose of the aircraft. It projects above the back and sides of the fuselage so as to give the occupants a clear view along it towards the rear and also, vertically downwards on each side. To maintain its advantages in service the cabin would require numerous transparent panels. With a pressure cabin these are usually arranged in the form of layers of glass and Perspex of suitable thicknesses, with a space AIR LOCK between them. If numerous they would add considerable weight, and in addition would necessitate a discontinuity of section in the cabin shell. As a result the structure would have to be considerably reinforced at these points, adding still further to the structure weight. The possible A sealed tun-nel houses the sparthrough the cabin in thisH e n sc h el design. SEALED TUBE SPAR source of leakage from such panels might become a problem in service. A double-walled pressure cabin design by the J unkers Co. is characterised by the sections forming the internal skin being jointed by overlap riveting to withstand tension, while the outer skin sections are riveted from one side only and provided with special tension bars located close to the skin and anchored to the front and rear frames of the cabin. Junkers Construction for Double-wall Cabin The sections of the outer skin have external flanges which are riveted or screwed together. Tension members are also attached to the bulkheads and serve to reinforce the top and bottom ends of the cabin. The upper, lower and end portions of the cabin are domed, but the fundamental principle of design for a pressure cabin has been ignored inasmuch as the sides are flat. The constructional features appear to be intended as a means of departing from the usual circular elements for Jthe cabin if, for any reason, it becomes necessary to do so. In this respect the method of construction is clever and appears practical. Typical of recent designs by the Messerchmitt Co. is the custom to provide a continuous wing spar, or spars, extending over the span of the centre section. A method Two or more pressure chambers with intermediate airlocks— Focke Wulf system. A design for military reconnaissance by the Dornier Co. used when it is desired to incorporate a pressure cabin other than of circular section is to reinforce the lateral wall of the cabin against the internal pressure by girders in the form of a "T" section. External to the fuselage" the web of these girders is formed by the wing covering. Inside the fuselage the wing covering is removed, and the flange is formed by the closed wall of the cabin. Stiffeners run between web and flange at the transition points. To depart from a circular cross section for~a pressure cabin usually results in excessive structure weight to provide the necessary reinforcement. It would appear that in this Messerschmitt design the structure weight would be some- what heavy in comparison with the better method of a circular section used by the Henschel Co., described earlier. Of considerable interest, mainly due to the basic prin- ciples involved, is a German design by F. Mannebach. The inventor describes four possible methods of operating armament mounted externally. Two of the-arrangements are illustrated. The first provides for a cylindrical pres sure cabin which houses the gunner. The gun is mounted
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