** An outstandingly rare WW2 Restricted military intelligence report, every distributed copy with its own unique security number, this being 'Copy No. 234'.
Very few examples of this classified and security-numbered report have survived. Because of the report's extreme rarity, few collectors know these documents exist; only a tiny handful actually owns one.
WW2 RESTRICTED report Copy No 234 Doblhoff Jet Propelled Helicopter
CIOS Intelligence Report. XXXI-5. Combined [British/US] Intelligence Objectives Sub-Committee (CIOS). August 1945.
** A special report covering the research work conducted by Friederich Doblhoff and associates at Wiener Neustadter Flugzeugwerke from October 1942 to the end of the war on the WNF-342 jet-propelled helicopter.
CIOS 'Black List of targets for urgent investigation' category: Jet propulsion
Duplicated typewritten report in English, 10 x 7.5 inches, 25 x 19 cms. 50 pages, 14 figures and photographs, numerous graphs.
Very good in original stapled card wrappers. Protected in a modern clear archival jacket.
Doblhoff's work was seminal research in helicopter development. The WNF-342 was the first helicopter in the world to take off and land using blade-tip jets to drive the rotor,