Collection Item Summary:
An early predominant manufacturer in the United States, Spencer Heath's American Propeller and Manufacturing Company was first to use machines for mass production of aircraft propellers. Under the Paragon trademark, these were widely used in World War I. Like most propellers of that era, construction was a wood laminate because of light weight, strength, fabrication ease, and resistance to fatigue in a vibrating and flexing environment.
A manufacturer's brochure notes: "Where the power is large or the propeller speed is low the propeller must of necessity have very high pitch in relation to diameter. In such cases the three-bladed propeller should be preferred in order to use a lower pitch without increasing the diameter."
Paragon three-bladed propellers were first made in 1909, and served on both Navy and Army Signal Corps aircraft. The manufacturer also noted that: "Three-bladed Paragons have nearly always given better results than two-bladed propellers of any type."