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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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366 <strong>The</strong> <strong>Art</strong> <strong>of</strong> <strong>the</strong> <strong>Helicopter</strong><br />

Fig. 9.17 <strong>The</strong> transmission and rotor heads <strong>of</strong> <strong>the</strong> Flettner Kolibri. (Steve Coates)<br />

operated <strong>the</strong> rudder as well as <strong>the</strong> rotor yaw mechanism. <strong>The</strong> pilot could also change<br />

<strong>the</strong> angle <strong>of</strong> incidence <strong>of</strong> <strong>the</strong> tail plane.<br />

<strong>The</strong> Kolibri was an advanced machine; it had adequate power and was highly<br />

manoeuvrable. In a mock dogfight with a Focke-Wulf 190 <strong>the</strong> fighter was unable to get<br />

<strong>the</strong> Kolibri in it sights. Following <strong>the</strong> end <strong>of</strong> <strong>the</strong> war, a significant amount <strong>of</strong> advanced<br />

German technology found its way to various allied countries. In <strong>the</strong> USA, Charles<br />

Kaman recognized <strong>the</strong> potential <strong>of</strong> <strong>the</strong> synchropter principle and combined it with <strong>the</strong><br />

servo-tab control system to produce a highly successful series <strong>of</strong> machines. <strong>The</strong> Kellet<br />

Co. made some synchropters with three-bladed rotors but <strong>the</strong>se had blade contact<br />

problems and did not reach production.<br />

Kaman’s early synchropters were piston engine powered, culminating in <strong>the</strong> HOK-1<br />

into which was shoehorned a 600 hp radial aircraft engine, which still wasn’t powerful<br />

enough for some purposes. <strong>The</strong> piston engine simply isn’t suitable for helicopters above<br />

a certain size. <strong>The</strong> world’s first turbine engine helicopter was a Kaman synchropter, as<br />

was <strong>the</strong> world’s first twin turbine helicopter. Kaman’s most well-known synchropter is<br />

<strong>the</strong> H-43B, aka Husky. It was also known as <strong>the</strong> Pedro, after a call sign originally used<br />

at a Texas air base. <strong>The</strong> Husky was basically a redesign <strong>of</strong> <strong>the</strong> piston engined H-43A<br />

using a turbine and it became a classic piece <strong>of</strong> industrial design. <strong>The</strong> compact turbine<br />

engine was placed on <strong>the</strong> ro<strong>of</strong> behind <strong>the</strong> transmission, resulting in a large, open cabin<br />

accessed by rear clamshell doors as well as sliding doors at <strong>the</strong> side. <strong>The</strong> servo-tab<br />

control system meant that <strong>the</strong> forces needed from <strong>the</strong> pilot were quite low even though<br />

<strong>the</strong>re was no power assistance.<br />

<strong>The</strong> yaw control was aided by relatively wide rotor head spacing and an automatic<br />

yaw reverser to make <strong>the</strong> pedals work in <strong>the</strong> correct sense in autorotation. <strong>The</strong> Husky<br />

also had an impressive array <strong>of</strong> vertical fin area to maintain directional stability when

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