હેલિકોપ્ટર: આવૃત્તિઓ વચ્ચેનો તફાવત

* [http://patimg2.uspto.gov/.piw?Docid=01848389&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO1%2526Sect2%3DHITOFF%2526d%3DPALL%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsrchnum.htm%2526r%3D1%2526f%3DG%2526l%3D50%2526s1%3D1848389.PN.%2526OS%3DPN%2F1848389%2526RS%3DPN%2F1848389&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+pageUS US patent #1848389 - Sikorsky's helicopter patent (requires Quicktime plugin)].

* [http://www.archive.org/details/Helicopt1953 1953 archive video about uses and flight physics of helicopters], (features vintage models). Published by Encyclopaedia Brittanica but now Creative Commons license, Prelinger Archives.

 

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[[શ્રેણી:યાંત્રિક પ્રૌદ્યોગિકી]]

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