Biplane-bladed Helicopter

n 1921, Argentinian inventor Raúl Pateras Pescara created this advanced helicopter with counter-rotating props–each made of SIX small biplane wings! The 1931 version looked considerably more modern (Popular Mechanics, April 1921).

By Bundesarchiv, Bild 102-12592 / CC-BY-SA 3.0, CC BY-SA 3.0 de,
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Bubble Head

This stylish inflatable batter’s helmet (Pop. Mech. May 1921) never caught on, possibly because it provided inadequate coverage. In fact, MLB only began requiring helmets in 1940!

Popular Mechanics, May 1921, p. 662

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