Ferris, Richard. [from old catalog] · New York, T. Nelson and sons · leaf 224
Blocks for. holding Propelled WHILE ORYtNG. … t f % f ~^ f Scale of inches. A, B, blank from which propelleris shaped; P, P, pencil lines atcentre of bend; C, D, sections ofblade at points opposite; E, G, pro-peller after twisting; H, view ofpropeller endwise, showing out-ward twist of tips; also shaft. 224 MODEL FLYING MACHINES, patience^—and…
Aeronautics
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