Click here for the previous lessons, to learn about: Principle of Airframe; Principles of Aerodynamics; Airfoil Characteristics; Primary Flight Control Surfaces; Description and Operation of Helicopter; Miscellaneous Components of an Aircraft…
Turbojets. The basic idea of the turbojet engine is simple. Air taken in from an opening in the front of the engine is compressed to 3 to 12 times its original pressure in compressor. Fuel is added to the air and burned in a combustion chamber to raise the temperature of the fluid mixture to about 1,100°F to 1,300° F.
Why do fighter jets use turbojet engines?
Because of the large jet velocity than can be achieved, turbojets generate large thrust and can be used to propel aircraft to high velocities.
Gas turbine aircraft engines such as turbojets, turboshafts and turbofans often use air/pneumatic starting, with the use of bleed air from built-in auxiliary power units (APUs) or external air compressors now seen as a common starting method. Often only one engine needs be started using the APU (or remote compressor)
The jet engine's major components are the intake, compressor, combustor, turbine, and exhaust.
A jet engine works on the physics concept of conservation of momentum. Momentum is the mass of something multiplied by how fast it is travelling, so things with lots of momentum are hard to stop.
What is the most important part of the jet engine?
Compressor: It is one of the most important parts of the engine, as it determines how much air can be compressed and how efficiently the engine can produce thrust.
There are two main types of compressors used in jet engines: axial compressors and centrifugal compressors.
What is the difference between a turbine engine and a jet engine?
Answer and Explanation: A turbine engine is a type of internal combustion engine that is used to power a rotating shaft. On the other hand, a jet engine is an air-breathing jet propulsion engine that uses the high speed of air to compress incoming air and fuel, which then ignites with an explosive mixture.
Most modern planes are powered by jet engines (more correctly, as we'll see in a moment, gas turbines). What exactly are these magic machines and what makes them different from the engines used in cars or trucks? Let's take a closer look at how they work!
What is a jet engine?
A jet engine is a machine that converts energy-rich, liquid fuel into a powerful pushing force called thrust. The thrust from one or more engines pushes a plane forward, forcing air past its scientifically shaped wings to create an upward force called lift that powers it into the sky.
That, in short, is how planes work—but how do jet engines work?
Jet engines and car engines
One way to understand modern jet engines is to compare them with the piston engines used in early airplanes, which are very similar to the ones still used in cars. A piston engine (also called a reciprocating engine, because the pistons move back and forth or "reciprocate") makes its power in strong steel "cooking pots" called cylinders. Fuel is squirted into the cylinders with air from the atmosphere. The piston in each cylinder compresses the mixture, raising its temperature so it either ignites spontaneously (in a diesel engine) or with help from a sparking plug (in a gas engine). The burning fuel and air explodes and expands, pushing the piston back out and driving the crankshaft that powers the car's wheels (or the plane's propeller), before the whole four-step cycle (intake, compression, combustion, exhaust) repeats itself. The trouble with this is that the piston is driven only during one of the four steps—so it's making power only a fraction of the time. The amount of power a piston engine makes is directly related to how big the cylinder is and how far the piston moves; unless you use hefty cylinders and pistons (or many of them), you're limited to producing relatively modest amounts of power. If your piston engine is powering a plane, that limits how fast it can fly, how much lift it can make, how big it can be, and how much it can carry.
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This is an Aerospace engineering concerned with the development of aircraft and spacecraft, focused on designing aeroplane and space shutlle and it is a study of all the flying wing used within the earth's atmosphere. Also dealing with the Avionic systems that includes communications, navigation, the display and management of multiple systems. Also dealing with Aircraft mishap such as Accident and Serious Incident.
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Click here for the previous lessons, to learn about: Principle of Airframe; Principles of Aerodynamics; Airfoil Characteristics; Primary Flight Control Surfaces; Description and Operation of Helicopter; Miscellaneous Components of an Aircraft…
Sikorsky and a few of his contemporaries brought a technical rigor to the field that finally made vertical flight safe, practical and reliable. As the flight-crazy Russian continued to refine his helicopter designs, he worked out the fundamental requirements that any such machine needed to have to be successful, including:
a suitable engine with a high power-to-weight ratio,
a mechanism to counteract rotor torque action,
proper controls so the aircraft could be steered confidently and without catastrophic failures,
a lightweight structural frame, and
a means to reduce vibrations.
Many of the basic parts seen on a modern helicopter grew out of the need to address one or more of these basic requirements. Let's look at these components in greater detail:
Main rotor blade —
The main rotor blade performs the same function as an airplane's wings, providing lift as the blades rotate — lift being one of the critical aerodynamic forces that keeps aircraft aloft. A pilot can affect lift by changing the rotor's revolutions per minute (rpm) or its angle of attack, which refers to the angle of the rotary wing in relation to the oncoming wind.
Stabilizer —
The stabilizer bar sits above and across the main rotor blade. Its weight and rotation dampen unwanted vibrations in the main rotor, helping to stabilize the craft in all flight conditions. Arthur Young, the gent who designed the Bell 47 helicopter, is credited with inventing the stabilizer bar.
Rotor mast —
Also known as the rotor shaft, the mast connects the transmission to the rotor assembly. The mast rotates the upper swash plate and the blades.
Transmission —
Just as it does in a motor vehicle, a helicopter's transmission transmits power from the engine to the main and tail rotors. The transmission's main gearbox steps down the speed of the main rotor so it doesn't rotate as rapidly as the engine shaft. A second gearbox does the same for the tail rotor, although the tail rotor, being much smaller, can rotate faster than the main rotor.
Engine —
The engine generates power for the aircraft. Early helicopters relied on reciprocating gasoline engines, but modern helicopters use gas turbine engines like those found in commercial airliners.
The main rotor blade rotates around a central hub (yellow) with an engine beneath it. A single engine powers both the main rotor blade and the tail rotor.
Helicopters use the airfoil principle to generate lift. When the blades rotate relative to the air, the special airfoil shape will generate lift force and make them fly (Fig:2A). The blades derive rotation from an engine, more specifically a turboshaft engine. The compressor sucks the air in and pressurizes it.
How does helicopter power work?
Engine — The engine generates power for the aircraft. Early helicopters relied on reciprocating gasoline engines, but modern helicopters use gas turbine engines like those found in commercial airliners.
What starts a helicopter engine?
Most larger helicopters have an auxiliary power unit (APU). The APU is a smaller, gas turbine engine used to start the main engine(s) and possibly pressurize hydraulic systems, among other things. The APU accelerates the main engine's gas generator (the compressor fans) until it reaches a self-sustaining speed
In many piston engine-powered helicopters, the pilot manipulates the throttle to maintain rotor speed. Turbine engine helicopters, and some piston helicopters, use governors or other electro-mechanical control systems to maintain rotor speed and relieve the pilot of routine responsibility for that task
What keeps a helicopter from spinning?
A: Helicopters do use their tail rotor to prevent themselves from spinning, but they use it to stop spinning in the opposite direction as the main rotor. This is called “torque reaction.” A torque is any force that causes something to spin.
How hard is it to control a helicopter?
Generally speaking, it is understood that helicopters are harder to operate as compared to standard light aircraft. While a pilot may be able to undertake long flights in a standard aeroplane and not be all too tired at the end of it, just a few hours of flying a helicopter may be exhausting for some
Many of the basic parts seen on a modern helicopter grew out of the need to address one or more of these basic requirements. Let's look at these components in greater detail:
Main rotor blade — The main rotor blade performs the same function as an airplane's wings, providing lift as the blades rotate — lift being one of the critical aerodynamic forces that keeps aircraft aloft. A pilot can affect lift by changing the rotor's revolutions per minute (rpm) or its angle of attack, which refers to the angle of the rotary wing in relation to the oncoming wind.
Stabilizer — The stabilizer bar sits above and across the main rotor blade. Its weight and rotation dampen unwanted vibrations in the main rotor, helping to stabilize the craft in all flight conditions. Arthur Young, the gent who designed the Bell 47 helicopter, is credited with inventing the stabilizer bar.
Rotor mast — Also known as the rotor shaft, the mast connects the transmission to the rotor assembly. The mast rotates the upper swash plate and the blades.
Transmission — Just as it does in a motor vehicle, a helicopter's transmission transmits power from the engine to the main and tail rotors. The transmission's main gearbox steps down the speed of the main rotor so it doesn't rotate as rapidly as the engine shaft. A second gearbox does the same for the tail rotor, although the tail rotor, being much smaller, can rotate faster than the main rotor.
Engine — The engine generates power for the aircraft. Early helicopters relied on reciprocating gasoline engines, but modern helicopters use gas turbine engines like those found in commercial airliners.
Just as the oceans opened up a new world for clipper ships and Yankee traders, space holds enormous potential for commerce today. The International Space Station (ISS) took 10 years and more than 30 missions to assemble. It is the result of unprecedented scientific and engineering collaboration among five space agencies representing 15 countries. The space station is approximately the size of a football field: a 460-ton, permanently crewed platform orbiting 250 miles above Earth. It is about four times as large as the Russian space station Mir and five times as large as the U.S. Skylab.
The idea of a space station was once science fiction, existing only in the imagination until it became clear in the 1940s that construction of such a structure might be attainable by our nation. As the Space Age began in the 1950s, designs of “space planes” and stations dominated popular media. The first rudimentary station was created in 1969 by the linking of two Russian Soyuz vehicles in space, followed by other stations and developments in space technology until construction began on the ISS in 1998, aided by the first reusable spacecraft ever developed: the American shuttles.
Until recently, U.S. research space onboard the ISS had been reserved for mostly government initiatives, but new opportunities for commercial and academic use of the ISS are now available, facilitated by the ISS National Lab.
Reagan directs NASA to build the ISS January 25, 1984
"Just as the oceans opened up a new world for clipper ships and Yankee traders, space holds enormous potential for commerce today". President Ronald Reagan's State of the Union Address directs NASA to build an international space station within the next 10 years.
First ISS Segment Launches November 20, 1998
The first segment of the ISS launches: The Zarya Control Module launched aboard a Russian Proton rocket from Baikonur Cosmodrome, Kazakhstan. Zarya (translates to "sunrise") supplied fuel storage, battery power and rendezvous and docking capability for Soyuz and Progress space vehicles.
First U.S.-built component launches December 4, 1998
Unity Node 1 module—the first U.S.-built component of the International Space Station— launches into orbit two weeks later during the STS-88 mission. Joining Unity with the Zarya module was the first step in the assembly of the orbiting laboratory.
First Crew to Reside on Station November 2, 2000
NASA Astronaut Bill Shepherd and cosmonauts Yuri Gidzenko and Sergei Krikalev become the first crew to reside onboard the station. Expedition 1 spent four months onboard completing tasks necessary to bring the ISS "to life" and began what is now more than 20 years of continuous human presence in space.
U.S. Lab Module Added February 7, 2001
Destiny, the U.S. Laboratory module, becomes part of the station. The lab—that increased onboard living space by 41%—continues to be the primary research laboratory for U.S. payloads.
U.S. Lab Module Recognized as Newest U.S. National Laboratory December 30, 2005
Congress designates the U.S. portion of the ISS as the nation's newest national laboratory to maximize its use for other U.S. government agencies and for academic and private institutions.
European Lab Joins the ISS February 7, 2008
The European Space Agency’s Columbus Laboratory becomes part of the station.
Japanese Lab Joins the ISS March 11, 2008
The first Japanese Kibo laboratory module becomes part of the station.
ISS 10-Year Anniversary November 2, 2010
The ISS celebrates its 10-year anniversary of continuous human occupation. Since Expedition 1 in the fall of 2000, 202 people had visited the station.
NASA Issues Cooperative Agreement February 2011
NASA issues a cooperative agreement notice for a management partner.
NASA Selects the ISS National Lab July 2011
NASA selects the Center for the Advancement of Science in Space to manage the ISS National Lab.
The First ISS National Lab Research Flight September 30, 2013
Proteins can be grown as crystals in space with nearly perfect three-dimensional structures useful for the development of new drugs. The ISS National Lab's protein crystal growth (PCG) series of flights began in 2013, allowing researchers to utilize the unique environment of the ISS.
This is an Aerospace engineering concerned with the development of aircraft and spacecraft, focused on designing aeroplane and space shutlle and it is a study of all the flying wing used within the earth's atmosphere. Also dealing with the Avionic systems that includes communications, navigation, the display and management of multiple systems. Also dealing with Aircraft mishap such as Accident and Serious Incident
