Unmanned aerial
vehicle (UAV)
INTRODUCTION
With the advent of new
technologies and ideas in all aspects of life, the concepts of safety and
automation have been of great importance to the engineers. Here we will venture
across the concept of unmanned aerial vehicles (UAVs) – a new and
supposedly safer way of flying an aircraft.
An unmanned aerial vehicle is an aircraft with no
onboard pilot. It can be controlled using a remote control or can fly
automatically using pre-programmed flight plans or more complex dynamic
automation systems. UAVs already exist, and are capable of doing things that
were considered to be virtually impossible! UAVs can carry cameras, sensors,
communications equipment or other payloads. They have been used in a
reconnaissance and intelligence-gathering role since the 1950s, and more
challenging roles are envisioned, including combat missions. The removal of the
human operator from the cockpit makes it the logical choice to replace the
manned aircraft in high risk missions.
UAVs are known by various names,
including drones, remotely piloted vehicles (RPVs), pilotless aircrafts, etc.
It does not matter which name is being used, UAVs have been a feature of
aviation for much of its history, though in limited or secondary roles.
Early UAVs
As already stated, UAVs
were primarily used for military purposes. In fact, the first UAVs were used
for war fighting on August 22, 1849. They were essentially unmanned balloons
loaded with explosives. The first pilotless aircraft, intended for use as
"aerial torpedo" or what we can now call "cruise missile",
was built during and shortly after World War I.
The early successes of pilotless aircraft led to the development of radio
controlled (RC) pilotless target aircraft in
Since then, UAVs have gone through various developments and they have been
used in various other activities, such as for research activities in NASA. A
comprehensive history of UAVs can be read from here.
Types
of UAVs and their characteristics
UAVs typically fall into five categories (although
multi-role airframe platforms are becoming more prevalent):
- Target and decoy -
providing ground and aerial gunnery a target that simulates an enemy
aircraft or missile.
- Reconnaissance -
providing battlefield intelligence.
- Combat - providing attack
capability for high-risk missions.
- Research and development
- used to further develop UAV technologies to be integrated into field
deployed UAV aircraft.
- Civil and Commercial UAVs
- UAVs specifically designed for civil and commercial applications.
Some
UAVs and their characteristics: (Click Back to return to this page)
Which is better for military
operations – UAVs or conventional aircrafts?
Technically it is possible
to fly almost any manned aircraft by “remote control”. Indeed many
aircrafts have been converted into single flight target drones for practice to
missile and gun crews after their service lives were over. When employed in an
efficient manner, the inherent qualities of expendability and low cost make the
UAV capable of significantly complementing manned aircraft platforms in the
role of tactical reconnaissance.
The manned aircrafts and unmanned aerial vehicles
have evolved around different design philosophies. The former has always
remained at the cutting edge of technology and has used performance or agility
as a primary means of survival in a hostile environment. The unmanned aerial
vehicle, on the other hand, has always had modest performance targets and has
relied on its size and unconventional flight profiles to survive in a high
threat environment. This fundamental difference has led to two different
approaches on how to solve the reconnaissance problem and has prompted the
question—which approach is better?
Unmanned aerial vehicles have always relied on already
developed aviation technologies to meet their relatively modest performance
criteria. Most airframe designs have evolved out of the body of knowledge of
aerodynamic design. Reciprocating engines and propeller designs have been
matched with UAV design from proven research. The only major design areas
exclusive to UAV development were guidance and control technology and small jet
engines.
Today UAVs employ the latest sensor and
communication technologies to deliver capabilities that cannot be ignored.
Improvements in miniature solid state gyros and sensors have made the platform
reliable in terms of flight control. The revolution in communication technology
has made up linking of flight and mission commands to the vehicle and down
linking of data from the vehicle possible at much larger rates and over further
distances than what was predicted just a few years ago.
The capabilities of the most recently deployed UAV
—Predator —include carriage of Electro-Optical (EO), Infra-Red
(IR), and SAR sensors, flying at altitudes up to 25000 feet, endurance up to 40
hours (including 24 hour autonomous operation on station), and speeds of 110
knots. Imagery and commands can be transmitted to and from
the UAV either by C-Band line -of-sight or one of two SATCOM data-links (UHF or
Ku-Band). Its radius of action is 500 nm.
Its performance in the early missions in
“I was looking at Predator [imagery display]
yesterday…It was flying over an area…at 25,000 feet. It had been up
there for a long time, many hours, and you could see the city below, and you
could focus on the city, you could see a building, focus on a building, you
could see a window, focus on a window. You could put a cursor around it and
[get] the GPS latitude and longitude very accurately, remotely via satellite.
And if you passed that information to an F-16 or an F-15 at 30,000 feet, and
that pilot can simply put in that latitude and longitude into his bomb fire
control system, then that bomb can dropped quite accurately onto that target,
maybe very close to that window, or, if it’s a precision weapon, perhaps
it could be put through the window…I’d buy a lot of UAVs in the
future.”
A single type of UAV will not meet all requirements
and frequently more than one type of vehicle will be needed to complete the
task. Also, though the UAV overcomes many of the limitations of manned aircraft
in weather, some UAVs suffer from their inability to operate in icing
conditions due to the inherent disadvantages of incorporating extra weight into
such small vehicles.
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The
data presented have been collected from various websites and resources (including
Wikipedia)
Site maintained by Samiu Ahmed Tabib
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biography of the author of this web page