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).

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By Bundesarchiv, Bild 102-12592 / CC-BY-SA 3.0, CC BY-SA 3.0 de, https://commons.wikimedia.org/w/index.php?curid=5480596
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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!

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Popular Mechanics, May 1921, p. 662

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