Ministry of Supply Pressure-cabin Design a Discussion of 'some of the Structural Problems Involved, with Suggestions for Their Solution Pressure-cabin Design -a Discussion of Some of the Structural Problems Involved, with Suggestions for Their Solution

A constructional scheme for making pressure cabins inraune from catastrophic failure without undue weight penalty It seems desirable to m&e some reference here to a construc-tional scheme put forward by the writer in a sequel to the present report". This scheme has its origin in paragraph 6 of Appendix D of the present report, where It is shown (see Fig.ZD) that when the former rings are reduced in pitch to IO in. i.e. about half the conventional pitch, they effectively limit the radial swelling of the interring skip&ringer wall to that suffered by the rings them selves. In other words, the rings reduce the hoop stress in the skrsn almost as effectively as if the mteris.1 in the rings mere incorporated in the skin to increase its thdcness. In the actual scheme described in the sequel the conventional former rings are retained and the shell wall fitted with flat hoops directly 3.ttached to the skin and pitched some 10 in. apart. These hoops have a thickness about four times that of the skin and a width of about 2 in. so that they have a total cross-sectional area (for taking hoop tension) newly equal to that of the skin itself'. They pay for their own weight however by reducing, as explained above, the hoop-tenszon taken by the skin. Not being integral with the skin they should act as potent barriers to any crack that may start in between a pair of hoops. The scheme is described at length in the sequel report above mentioned, and experimental work is in hand to prove that the advantages indicated by theory are borne out in practice. * R.&E. Technical Note NC. Structures 156 "A constructional method for minimising the hazard of catastrophic failure in a pressur+cq.bin". l&.rch 1955. SUMMARY The problems that arise in the design of a pressure cabin are almost entirely due to the numerous structural disoontinu~ties that inevitably break up the otherviise smooth distribution of stress. Some of the main discontinuities, such as are caused by iirlndows, doors, canopies, floors, farmers, bulkheads and. domes, are discussed here, and. design suggestions are made for dealing with then. Partwular attention is called to Appendix D and the Addendum based on it, which refers to a scheme for making pressure cabiils safe against catastrophic failure 166th little weight penslty.