DESCRIPTION: One-of-a-kind cyanotype or blueprint conceptual design document for a system of electrically-controlled hydraulic rams designed to protect airfields from unwanted landings.
"Air field protection columns can be raised or lowered at will thus allowing landing of friendly planes, and within 1 or 2 minutes raised as protection against landing of enemy planes or gliders."
The blueprint includes a detailed design drawing of a single protection column and a topographic layout of the airfield protection system including the airfield protection columns, central control station, compressor pits and electrical control cables.
By Donald Phelps of Highland Park, Illinois. Dated September 7, 1940.
With a letter (and envelope) dated March 30, 1942 from Donald Phelps to the National Inventor's Council at the U.S. Department of Commerce seeking advice as to whether the system would be of value to the U.S. or British governments. Phelps was associated with the Phelps Agency, Steamship and Vessel Agents of Chicago, Illinois.
PUBLICATION DATE: 1940
GEOGRAPHIC AREA: United States
BODY OF WATER: N/A
CONDITION: Good.
 Blueprint very clean and without condition issues. Folds. Tiny margin at left.
COLORING: Blue
ENGRAVER: 
SIZE: 18
" x
13 "
ITEM PHYSICAL LOCATION: 9
PRICE: $250
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