Explain the purpose of variable pitch and constant-speed propellers.
During the World War II, the company set up a factory to produce airplane propellers.
The model was forced by its propellers along a wire at a great speed, but so far as an observer could determine, failed to lift itself, notwithstanding its extreme lightness and the comparatively very great power employed.
The fore-legs are elongate and adapted for clasping, while the short and flattened intermediate and hind legs form very perfect oar-like propellers.
Aquatic weed growth can impede navigation, clogging boats' propellers and can also physically impede waterflow.
