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helicopter.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Helicopter</title>
<script type="module" src="https://unpkg.com/@google/model-viewer/dist/model-viewer.min.js"></script>
<script nomodule src="https://unpkg.com/@google/model-viewer/dist/model-viewer-legacy.js"></script>
<link rel="stylesheet" href="helicopter.css">
</head>
<body>
<div id="aSide">
<model-viewer src="helicopter_v2/scene.gltf" alt="Helicopter" auto-rotate camera-controls ar"></model-viewer>
</div>
<dl>
<div class="modal__title"><dt><h1>Helicopters</h1></dt></div>
<div class="modal__text">
A helicopter is a type of rotorcraft in which lift and thrust are supplied
by horizontally spinning rotors. This allows the helicopter to take off
and land vertically, to hover, and to fly forward, backward and laterally.
These attributes allow helicopters to be used in congested or isolated
areas where fixed-wing aircraft and many forms of STOL (Short TakeOff and
Landing) or STOVL (Short TakeOff and Vertical Landing) aircraft cannot
perform without a runway.
</div>
<div class="modal__subhead">
<dt>Engine</dt>
</div>
<div class="modal__text">
<p><dd>The number, size and type of engine(s) used on a helicopter determines the
size, function and capability of that helicopter design. The earliest
helicopter engines were simple mechanical devices, such as rubber bands or
spindles, which relegated the size of helicopters to toys and small
models. For a half century before the first airplane flight, steam engines
were used to forward the development of the understanding of helicopter
aerodynamics, but the limited power did not allow for manned flight. The
introduction of the internal combustion engine at the end of the 19th
century became the watershed for helicopter development as engines began
to be developed and produced that were powerful enough to allow for
helicopters able to lift humans.Early helicopter designs utilized
custom-built engines or rotary engines designed for airplanes, but these
were soon replaced by more powerful automobile engines and radial engines.
The single, most-limiting factor of helicopter development during the
first half of the 20th century was that the amount of power produced by an
engine was not able to overcome the engine's weight in vertical flight.
This was overcome in early successful helicopters by using the smallest
engines available. When the compact, flat engine was developed, the
helicopter industry found a lighter-weight powerplant easily adapted to
small helicopters, although radial engines continued to be used for larger
helicopters.
</dd></p>
</div>
<div class="modal__subhead">
<dt>Rotor system</dt>
</div>
<div class="modal__text">
<p>
The rotor system, or more simply rotor, is the rotating part of a
helicopter that generates lift. A rotor system may be mounted
horizontally, as main rotors are, providing lift vertically, or it may be
mounted vertically, such as a tail rotor, to provide horizontal thrust to
counteract torque from the main rotors. The rotor consists of a mast, hub
and rotor blades. The mast is a cylindrical metal shaft that extends
upwards from the transmission. At the top of the mast is the attachment
point for the rotor blades called the hub. Main rotor systems are
classified according to how the rotor blades are attached and move
relative to the hub. There are three basic types: hingeless, fully
articulated, and teetering; although some modern rotor systems use a
combination of these.Turbine engines revolutionized the aviation industry;
and the turboshaft engine for helicopter use, pioneered in December 1951
by the aforementioned Kaman K-225, finally gave helicopters an engine with
a large amount of power and a low weight penalty. Turboshafts are also
more reliable than piston engines, especially when producing the sustained
high levels of power required by a helicopter. The turboshaft engine was
able to be scaled to the size of the helicopter being designed, so that
all but the lightest of helicopter models are powered by turbine engines
today.</p>
</div>
<div class="modal__subhead">
<dt>Flight Controls</dt>
</div>
<div class="modal__text">
<p>
A helicopter has four flight control inputs. These are the cyclic, the
collective, the anti-torque pedals, and the throttle. The cyclic control
is usually located between the pilot's legs and is commonly called the
cyclic stick or just cyclic. On most helicopters, the cyclic is similar to
a joystick. However, the Robinson R22 and Robinson R44 have a unique
teetering bar cyclic control system and a few helicopters have a cyclic
control that descends into the cockpit from overhead. The control is
called the cyclic because it changes cyclic pitch of the main blades. The
result is to tilt the rotor disk in a particular direction, resulting in
the helicopter moving in that direction. If the pilot pushes the cyclic
forward, the rotor disk tilts forward, and the rotor produces a thrust in
the forward direction. If the pilot pushes the cyclic to the side, the
rotor disk tilts to that side and produces thrust in that direction,
causing the helicopter to hover sideways. The collective pitch control or
collective is located on the left side of the pilot's seat with a settable
friction control to prevent inadvertent movement. The collective changes
the pitch angle of all the main rotor blades collectively (i.e. all at the
same time) and independently of their position. Therefore, if a collective
input is made, all the blades change equally, and the result is the
helicopter increasing or decreasing in altitude. A swashplate controls the
collective and cyclic pitch of the main blades. The swashplate moves up
and down, along the main shaft, to change the pitch of both blades. This
causes the helicopter to push air downward or upward, depending on the
angle of attack. The swashplate can also change its angle to move the
blades angle forwards or backwards, or left and right, to make the
helicopter move in those directions.
</p>
</div>
</body>
</html>