Semi-rigid

Semi-rigid in this context refers to an airship type using some structure to support the balloon.

Semi-rigid airships were first produced by the French, but were subsequently developed extensively by the Italians before, during, and after World War I when they attained a capacity of over a million cubic feet.
The semi-rigid resembles the non-rigid in that the form of the envelope is maintained by internal pressure, but differs in the method of distributing the load. In the semi-rigid a longitudinal keel girder fitted to the underside of the envelope provides a rigid and, in certain types, a slightly flexible, backbone. It is therefore possible for a semi-rigid to fly at a much lower gas pressure than a non-rigid. A lighter envelope fabric can be used, and sufficient weight saved to compensate for the extra weight of the keel girder. To fly a semi-rigid at speed requires a fully inflated envelope, but it can be brought in to land with a partially inflated envelope. This is made possible by dividing the gas container into compartments by means of transverse fabric bulkheads; it also reduces the risk of the airship losing lift through an accidental tear in the envelope.

References

This wiki has 7 patents in category "Semi-rigid".

Patents in category Semi-rigid

• Patent FR-1907-382794 (English title: Improvements in fusiform balloons, Inventors: Leonardo Torres Quevedo, Supplementary to patent: Patent ES-1906-38692, Filing date: 1907-07-10)
• Patent FR-1909-407946 (English title: Semi-rigid envelope with with water proof compartments, for dirigibles, Inventors: Melvin Vaniman, Filing date: 1909-10-16)
• Patent DE-1912-268445 (English title: Semi-rigid airship with a keel designed as a gondola, Filing date: 1912-02-18)
• Patent FR-1913-466846 (English title: Semi-rigid dirigible with modern military application, Inventors: Ernest Henry, Filing date: 1913-12-01)
• Patent ES-1914-57750 (English title: A new semi-rigid airship with solid dorsal beam, Inventors: Enrique Sanchis, Supplementary to patent: Patent BE-1913-253298 • Patent BE-1914-253298.264297, Filing date: 1914-03-16)
• Patent FR-1914-466846.19502 (English title: Semi-rigid dirigible with modern military application, Inventors: Ernest Henry, Supplementary to patent: Patent FR-1913-466846, Filing date: 1914-06-09)
• Patent GB-1918-125893 (English title: Improvements to non-rigid and semi-rigid airships, Inventors: Thomas Mill Ritchie, Filing date: 1918-11-13)

Publications referring to semi-rigid

• Hartcup, 1974 (Simple title: The achievement of the airship)

Enclosing categories	LTA
Subcategories
Keywords	LTA, Balloon, Ballonet, Frame
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