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The Art of the Helicopter John Watkinson - Karatunov.net

The Art of the Helicopter John Watkinson - Karatunov.net

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(a)<br />

(b)<br />

O<strong>the</strong>r types <strong>of</strong> rotorcraft 359<br />

Fig. 9.8 (a) Possible configurations <strong>of</strong> multi-rotor helicopters. See text. (b) Florine helicopter did not contrarotate<br />

but used inclined rotors for torque cancellation.<br />

detract from Focke’s technical achievement. <strong>The</strong> Fw-61 used <strong>the</strong> hull <strong>of</strong> a Focke-Wulf<br />

fixed-wing plane, with a forward-mounted radial engine carrying a small airscrew for<br />

cooling. Behind <strong>the</strong> engine was a gearbox that routed power out to each rotor along<br />

slim drive shafts.<br />

Focke’s next machine was <strong>the</strong> Fa 223 which first flew in 1940 and reached production<br />

in 1942. By this time Focke had left Focke-Wulf and formed a company with Gerd<br />

Achgelis, hence <strong>the</strong> designation Fa. This was a large side-by-side machine powered<br />

by a centrally mounted 1000 hp radial engine. With 12 metre diameter rotors it had a<br />

payload <strong>of</strong> 2000 kg, meaning that it could almost have lifted its Sikorsky contemporary.<br />

<strong>The</strong> Fa 223 reached 7500 metres, flew at 200 kph and was a great technical success,<br />

although few orders were fulfilled because <strong>of</strong> bombing raids on <strong>the</strong> factories. After <strong>the</strong>

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