06-06-2013, 12:39 PM
PROJECT REPORT ON 3D THRUST VECTORING
PROJECT REPORT.pdf (Size: 785.78 KB / Downloads: 35)
3D.pdf (Size: 199.71 KB / Downloads: 36)
THRUST.pdf (Size: 254.52 KB / Downloads: 34)
Introduction
Thrust vectoring is the ability of an aircraft or other vehicle to deflect the angle of its
thrust away from the vehicles longitudinal axis. The advantages of thrust vectoring
systems on aircraft include improved post stall performance, the ability to operate on
damaged airfields due to reduced takeoff distances and overall enhanced agility.
These factors can provide substantial benefits for military aircraft, which are
primarily concerned with maneuverability and control.
The concept of thrust vectoring is not a new one. The Germans used graphite control
vanes in the exhaust stream of their V-2 ballistic missile in World War II for some
directional control. Thrust vectoring in aircraft though is a relatively new practice and
the concept came under widespread consideration during the cold war.
There are several methods employed to produce thrust vectoring. Most current
production aircraft with thrust vectoring use turbofan engines with rotating nozzles
or turning vanes to deflect the exhaust stream. This method can deflect thrust to as
much as 90 degrees providing a vertical takeoff and landing capability. However
for vertical thrust the engine has to be more powerful to overcome the weight of
the aircraft, this means the aircraft requires a bigger heavier engine. As a result of
the increased overall weight of the aircraft the maneuverability and agility are reduced
in normal horizontal flight.
Another method to produce thrust vectoring is through fluidic thrust vector
control. This is achieved using a static nozzle and a secondary flow between the
primary jet and the nozzle. This method is desirable for its lower weight, mechanical
simplicity and lower radar cross section.
Advantages and Disadvantages of Thrust Vector Control
Thrust-vectoring research to date has successfully identified and demonstrated many
potential benefits to high-performance aircraft. These include enhanced aircraft
maneuverability, performance, survivability, and stealth. The full extent of these
benefits, however, has yet to be realized even with new generation aircraft because
current mechanical thrust-vectoring configurations are heavy, complex, and expensive.
Agility
A requirement of modern warfare is the improvement of maneuverability and control
capabilities which TVC provides. The agility of aircraft can be determined by such
things as pitch, roll and yaw rates, acceleration and deceleration and turning ability.
Short take off and Landing (STOL)
Aircraft that have small take off and landing zones are largely advantageous as it
reduces the space required for operation of the aircraft. This allows the aircraft to
operate in more compact environments such as aircraft carriers and airports, which as
a result may decrease the size of such things, or allow more aircraft to occupy the
same space as a non STOL capable aircraft.
Fuel Consumption, Flight Range
As evident in figures five and six, an aircraft with TVC requires less thrust to achieve
desired results such flight regimes as cruise, climb and decent. This has the effect it
reduces the fuel consumption of the aircraft due to the lower thrust requirement,
which in turn increases the aircrafts flight range.
History
Rockets
The thrust vector control history first came from rocket. The evolution of the rocket has
made it an indispensable tool in the exploration of space. For centuries, rockets have
provided ceremonial and warfare uses starting with the ancient Chinese, the first to create
rockets. But for centuries rockets were in the main rather small, and their use was confined
principally to weaponry, the projection of lifelines in sea rescue, signaling, and fireworks
displays. Not until the 20th century did a clear understanding of the principles of rockets
emerge, and only then did the technology of large rockets begin to evolve. Thus, as far as
spaceflight and space science are concerned, the story of rockets up to the beginning of the
20th century was largely prologue. Most math and physics used in spaceflight and rocket
was developed 1650-1910.
At the end of the 19th century, soldiers, sailors, practical and not so practical inventors had
developed a stake in rocketry. The first space engineer, Konstantian Tsiolkovsky (Russian,
1857-1935), was examining the fundamental scientific theories behind rocketry. He was
beginning to consider the possibility of space travel. On the other hand, he is the first to
analyze rocket motion using Newton’s Laws of Motion and wrote numerous technical
papers describing artificial satellites, space stations, exploration of space, etc. Tsiolkovsky
stated that the speed and range of a rocket were limited only by the exhaust velocity of
escaping gases. For his ideas, careful research, and great vision, Tsiolkovsky
has been called the father of modern astronautics. His engineering suggestions were
foresighted and technically accurate that he suggested the use of thrust vectoring in
rockets (aiming the rocket to steer the rocket) and the use of liquid fuels in the
propulsions of rockets (prior to that time, only solid, dry chemical rockets had been
built).
Thrust vector control in rockets
All chemical propulsion systems can be provided with one of several types of thrust
vector control (TVC) mechanisms. Some of these apply either to solid, hybrid, or to
liquid propellant rocket propulsion systems, but most are specific to only one of
these propulsion categories. Thrust vector control is effective only while the
propulsion system is operating and creating an exhaust jet. For the flight period,
when a rocket propulsion system is not firing and therefore its TVC is inoperative, a
separate mechanism needs to be provided to the flying vehicle for achieving control
over its attitude or flight path. Hence, there are two types of thrust vector control
concept: (1) for an engine or a motor with a single nozzle; and (2) for those that have
two or more nozzles.
Aircraft
Thrust vectoring is also used as a control mechanism for airships, particularly modern
non-rigid airships. In this application, the majority of the load is typically supported
by buoyancy and vectored thrust is used to control the motion of the aircraft. The first
airship that used a control system based on pressurized air was the Forlanini's Omnia
Dir in 1930s.
When it comes to the history of thrust vector control in aircraft, The Harrier was the
first and only truly successful thrust vectoring with the V/STOL capability’s design
of the many that arose from the 1960s. Hawker Siddeley Harrier and the AV-8A are
the first generation of the Harrier series, the first operational close- support and
reconnaissance fighter aircraft with V/STOL capabilities.
The vectored thrust story
The vectored thrust story started in the mid 1950s when a Frenchman, Michel
Wibault, proposed a single seat fighter that he called the Gyroptere. Wibault
proposed to vector the thrust of four separate centrifugal blowers driven by a
single 8000 HP Bristol Orion engine (fig 1).
The starting point
In October 1960 Hawkers were ready to fly the first P1127. It was decided to look at
the unknowns of hovering before flying the aircraft conventionally. The engine, by
now the Pegasus 2 of 11,000lb thrust, was installed as shown in fig.2. The main
characteristics were a large bifurcated intake and four swivelling exhaust nozzles
interconnected together which enabled the thrust vector to be moved, as required,
from aft to about 18 degrees forward of the vertical.