Albert Einstein Quotes

Albert Einstein
The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science. He to whom this emotion is a stranger, who can no longer pause to wonder and stand rapt in awe, is as good as dead: his eyes are closed.

Albert Einstein
A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeed be in a poor way if he had to be restrained by fear of punishment and hope of reward after death.

Albert Einstein
The further the spiritual evolution of mankind advances, the more certain it seems to me that the path to genuine religiosity does not lie through the fear of life, and the fear of death, and blind faith, but through striving after rational knowledge.

Albert Einstein
Now he has departed from this strange world a little ahead of me.

That means nothing. People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion.

Albert Einstein
You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat.

Albert Einstein
One had to cram all this stuff into one's mind for the examinations, whether one liked it or not. This coercion had such a deterring effect on me that, after I had passed the final examination, I found the consideration of any scientific problems distasteful to me for an entire year.

Albert Einstein
...one of the strongest motives that lead men to art and science is escape from everyday life with its painful crudity and hopeless dreariness, from the fetters of one's own ever-shifting desires. A finely tempered nature longs to escape from the personal life into the world of objective perception and thought.

Albert Einstein
He who joyfully marches to music rank and file, has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would surely suffice. This disgrace to civilization should be done away with at once. Heroism at command, how violently I hate all this, how despicable and ignoble war is; I would rather be torn to shreds than be a part of so base an action. It is my conviction that killing under the cloak of war is nothing but an act of murder.

Albert Einstein
A human being is a part of a whole, called by us 'universe', a part limited in time and space. He experiences himself, his thoughts and feelings as something separated from the rest... a kind of optical delusion of his consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty.

Albert Einstein, Sign hanging in Einstein's office at Princeton
Not everything that counts can be counted, and not everything that can be counted counts.

Albert Einstein
Imagination is more important than knowledge.

Albert Einstein
Gravitation is not responsible for people falling in love.

Albert Einstein
I want to know God's thoughts; the rest are details.

Albert Einstein
The hardest thing in the world to understand is the income tax.

Albert Einstein
Reality is merely an illusion, albeit a very persistent one.

Albert Einstein
A person starts to live when he can live outside himself.

Albert Einstein
I am convinced that He (God) does not play dice.

Albert Einstein
God is subtle but he is not malicious.

Albert Einstein
Weakness of attitude becomes weakness of character.

Albert Einstein
I never think of the future. It comes soon enough.

Albert Einstein
The eternal mystery of the world is its comprehensibility.

Albert Einstein
Sometimes one pays most for the things one gets for nothing.

Albert Einstein
Science without religion is lame. Religion without science is blind.

Albert Einstein
Anyone who has never made a mistake has never tried anything new.

Albert Einstein
Great spirits have often encountered violent opposition from weak minds.

Albert Einstein
There are two ways to live your life - one is as though nothing is a miracle, the other is as though everything is a miracle.

Albert Einstein
Everything should be made as simple as possible, but not simpler.

Albert Einstein
Common sense is the collection of prejudices acquired by age eighteen.

Albert Einstein
Science is a wonderful thing if one does not have to earn one's living at it.

Albert Einstein
The secret to creativity is knowing how to hide your sources.

Albert Einstein
The only thing that interferes with my learning is my education.

Albert Einstein
God does not care about our mathematical difficulties. He integrates empirically.

Albert Einstein
The whole of science is nothing more than a refinement of everyday thinking.

Albert Einstein
Technological progress is like an axe in the hands of a pathological criminal.

Albert Einstein
Peace cannot be kept by force. It can only be achieved by understanding.

Albert Einstein
The most incomprehensible thing about the world is that it is comprehensible.

Albert Einstein
We can't solve problems by using the same kind of thinking we used when we created them.

Albert Einstein
Education is what remains after one has forgotten everything he learned in school.

Albert Einstein
The important thing is not to stop questioning. Curiosity has its own reason for existing.

Albert Einstein
Do not worry about your difficulties in Mathematics. I can assure you mine are still greater.

Albert Einstein
Equations are more important to me, because politics is for the present, but an equation is something for eternity.

Albert Einstein
If A is a success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut.

Albert Einstein
Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe.

Albert Einstein
As far as the laws of mathematics refer to reality, they are not certain, as far as they are certain, they do not refer to reality.

Albert Einstein
Whoever undertakes to set himself up as a judge of Truth and Knowledge is shipwrecked by the laughter of the gods.

Albert Einstein
I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones.

Albert Einstein
In order to form an immaculate member of a flock of sheep one must, above all, be a sheep.

Albert Einstein
The fear of death is the most unjustified of all fears, for there's no risk of accident for someone who's dead.

Albert Einstein
Too many of us look upon Americans as dollar chasers. This is a cruel libel, even if it is reiterated thoughtlessly by the Americans themselves.

Albert Einstein
Heroism on command, senseless violence, and all the loathsome nonsense that goes by the name of patriotism -- how passionately I hate them!

Albert Einstein
No, this trick won't work...How on earth are you ever going to explain in terms of chemistry and physics so important a biological phenomenon as first love?

Albert Einstein
My religion consists of a humble admiration of the illimitable superior spirit who reveals himself in the slight details we are able to perceive with our frail and feeble mind.

Albert Einstein
Yes, we have to divide up our time like that, between our politics and our equations. But to me our equations are far more important, for politics are only a matter of present concern. A mathematical equation stands forever.

Albert Einstein
The release of atom power has changed everything except our way of thinking...the solution to this problem lies in the heart of mankind. If only I had known, I should have become a watchmaker.

Albert Einstein
Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence.

Albert Einstein Education Quotes

Albert Einstein
Most teachers waste their time by asking questions which are intended to discover what a pupil does not know, whereas the true art of questioning has for its purpose to discover what the pupil knows or is capable of knowing.

Albert Einstein
Never regard your study as a duty, but as the enviable opportunity to learn to know the liberating influence of beauty in the realm of the spirit for your own personal joy and to the profit of the community to which your later work belongs.

Albert Einstein
Humiliation and mental oppression by ignorant and selfish teachers wreak havoc in the youthful mind that can never be undone and often exert a baleful influence in later life.

Albert Einstein
The aim (of education) must be the training of independently acting and thinking individuals who, however, can see in the service to the community their highest life achievement.

Albert Einstein
Teaching should be such that what is offered is perceived as a valuable gift and not as a hard duty.

Albert Einstein
In the teaching of geography and history a sympathetic understanding (should) be fostered for the characteristics of the different peoples of the world, especially for those who we are in the habit of describing as "primitive.

Albert Einstein Intuition Quotes

Albert Einstein
It is better for people to be like the beasts...they should be more intuitive; they should not be too conscious of what they are doing while they are doing it.

Albert Einstein Life Quotes

Albert Einstein
Only a life lived for others is a life worthwhile.

Albert Einstein
The life of the individual has meaning only insofar as it aids in making the life of every living thing nobler and more beautiful. Life is sacred, that is to say, it is the supreme value, to which all other values are subordinate.

Albert Einstein
The most precious things in life are note those one gets for money.

Albert Einstein Peace Quotes

Albert Einstein
He who cherishes the values of culture cannot fail to be a pacifist.

Albert Einstein
The conscientious objector is a revolutionary. On deciding to disobey the law he sacrifices his personal interests to the most important cause of working for the betterment of society.

Albert Einstein
My pacificism is an instinctive feeling, a feeling that possesses me because the murder of people is disgusting. My attitude is not derived from any intellectual theory but is based on my deepest antipathy to every kind of cruelty and hatred.

Albert Einstein
There are two ways of resisting war: the legal way and the revolutionary way. The legal way involves the offer of alternative service not as a privilege for a few but as a right for all. The revolutionary view involves an uncompromising resistance, with a view to breaking the power of militarism in time of peace or the resources of the state in time of war.

Albert Einstein
It is characteristic of the military mentality that nonhuman factors (atom bombs, strategic bases, weapons of all sorts, the possession of raw materials, etc) are held essential, while the human being, his desires, and thoughts - in short, the psychological factors - are considered as unimportant and secondary...The individual is degraded...to "human materiel.

Albert Einstein
To my mind, to kill in war is not a whit better than to commit ordinary murder.

Albert Einstein
Nationalism is an infantile disease. It is the measles of mankind.

Albert Einstein
Nationalism, on my opinion, is nothing more than an idealistic rationalization for militarism and aggression.

Albert Einstein
He who joyfully marches to music rank and file, has already earned my contempt. He has been given a large brain by mistake, since for him the spinal cord would surely suffice. This disgrace to civilization should be done away with at once. Heroism at command, how violently I hate all this, how despicable and ignoble war is; I would rather be torn to shreds than be a part of so base an action. It is my conviction that killing under the cloak of war is nothing but an act of murder.

Albert Einstein Philosophy Quotes

Albert Einstein
Everything is determined by forces over which we have no control. It is determined for the insect as well as for the star. Human beings, vegetables, or cosmic dust - we all dance to a mysterious tune, intoned in the distance by an invisible piper.

Albert Einstein Science Quotes

Albert Einstein
After a certain high level of technical skill is achieved, science and art tend to coalesce in esthetics, plasticity, and form. The greatest scientists are always artists as well.

Albert Einstein
You cannot love a car the way you love a horse. The horse brings out human feelings the way machines cannot do. Things like machines may develop or neglect certain things in people ... Machines make our life impersonal and stultify certain elements in us and create an impersonal environment.

Albert Einstein
I believe that the horrifying deterioration in the ethical conduct of people today stems from the mechanization and dehumanization of our lives - the disastrous by-product of the scientific and technical mentality. Nostra culpa. Man grows cold faster than the planet he inhabits.

Albert Einstein
Betterment of conditions the world over is not essentially dependent on scientific knowledge but on the fulfillment of human traditions and ideals.

Albert Einstein Youth Quotes

Albert Einstein
People do not grow old no matter how long we live. We never cease to stand like curious children before the great Mystery into which we were born.

Albert Einstein
I am content in my later years. I have kept my good humor and take neither myself nor the next person seriously.

Other Albert Einstein Quotes

Albert Einstein
Human beings can attain a worthy and harmonious life only if they are able to rid themselves, within the limits of human nature, of the striving for the wish fulfillment of material kinds. The goal is to raise the spiritual values of society.

Albert Einstein
I admit thoughts influence the body.

Albert Einstein
Nothing is more destructive of respect for the government and the law of the land than passing laws which cannot be enforced. It is an open secret that the dangerous increase of crime in this county is closely related with this.

Albert Einstein
I am absolutely convinced that no wealth in the world can help humanity forward, even in the hands of the most devoted worker in this cause. The example of great and pure personages is the only thing that can lead us to find ideas and noble deeds. Money only appeals to selfishness and always irresistibly tempts its owner to abuse it. Can anyone imagine Moses, Jesus or Gandhi with the moneybags of Carnegie?

Albert Einstein
Anger dwells only in the bosom of fools.

Albert Einstein
The tragedy of life is what dies inside a man while he lives.

Albert Einstein
A photograph never grows old. You and I change, people change all through the months and years but a photograph always remains the same. How nice to look at a photograph of mother or father taken many years ago. You see them as you remember them. But as people live on, they change completely. That is why I think a photograph can be kind.

Albert Einstein
The gift of fantasy has meant more to me than my talent or absorbing positive knowledge.

BASICS AEROSPACE KNOWLEDGE

Classification by method of lift
Lighter than air - aerostats

A hot air balloon (aircraft) in flight.

Aerostats use buoyancy to float in the air in much the same way that ships float on the water. They are characterized by one or more large gasbags or canopies, filled with a relatively low density gas such as helium, hydrogen or hot air, which is less dense than the surrounding air. When the weight of this is added to the weight of the aircraft structure, it adds up to the same weight as the air that the craft displaces.

Small hot air balloons called sky lanterns date back to the 3rd century BC, and were only the second type of aircraft to fly, the first being kites.

Originally, a balloon was any aerostat, while the term airship was used for large, powered aircraft designs - usually fixed-wing - though none had yet been built. The advent of powered balloons, called dirigible balloons, and later of rigid hulls allowing a great increase in size, began to change the way these words were used. Huge powered aerostats, characterized by a rigid outer framework and separate aerodynamic skin surrounding the gas bags, were produced, the Zeppelins being the largest and most famous. There were still no aeroplanes or non-rigid balloons large enough to be called airships, so "airship" came to be synonymous with these aircraft. Then several accidents, such as the Hindenburg disaster in 1937, led to the demise of these airships. Nowadays a "balloon" is an unpowered aerostat, whilst an "airship" is a powered one.

A powered, steerable aerostat is called a dirigible. Sometimes this term is applied only to non-rigid balloons, and sometimes dirigible balloon is regarded as the definition of an airship (which may then be rigid or non-rigid). Non-rigid dirigibles are characterized by a moderately aerodynamic gasbag with stabilizing fins at the back. These soon became known as blimps. During the Second World War, this shape was widely adopted for tethered balloons; in windy weather, this both reduces the strain on the tether and stabilizes the balloon. The nickname blimp was adopted along with the shape. In modern times any small dirigible or airship is called a blimp, though a blimp may be unpowered as well as powered.

Heavier than air - aerodynes

Heavier-than-air aircraft must find some way to push air or gas downwards, so that a reaction occurs (by Newton's laws of motion) to push the aircraft upwards. This dynamic movement through the air is the origin of the term aerodyne. There are two ways to produce dynamic upthrust: aerodynamic lift, and powered lift in the form of engine thrust.

Aerodynamic lift is the most common, with aeroplanes being kept in the air by the forward movement of wings, and rotorcraft by spinning wing-shaped rotors sometimes called rotary wings. A wing is a flat, horizontal surface, usually shaped in cross-section as an aerofoil. To fly, the wing must move forward through the air; this movement of air over the aerofoil shape deflects air downward to create an equal and opposite upward force, called lift, according to Newton's third law of motion. A flexible wing is a wing made of fabric or thin sheet material, often stretched over a rigid frame. A kite is tethered to the ground and relies on the speed of the wind over its wings, which may be flexible or rigid, fixed or rotary.

With powered lift, the aircraft directs its engine thrust vertically downwards.

The initialism VTOL (vertical take off and landing) is applied to aircraft that can take off and land vertically. Most are rotorcraft. Others, such as the Hawker Siddeley Harrier, take off and land vertically using powered lift and transfer to aerodynamic lift in steady flight. Similarly, STOL stands for short take off and landing. Some VTOL aircraft often operate in a short take off/vertical landing mode known as STOVL.

A pure rocket is not usually regarded as an aerodyne, because it does not depend on the air for its lift (and can even fly into space); however, many aerodynamic lift vehicles have been powered or assisted by rocket motors. Rocket-powered missiles which obtain aerodynamic lift at very high speed due to airflow over their bodies, are a marginal case.


Fixed-wing aircraft
NASA test aircraft
A size comparison of some of the largest aeroplanes. The Airbus A380-800 (largest airliner), the Boeing 747-8, the Antonov An-225 (aircraft with the greatest payload) and the Hughes H-4 "Spruce Goose" (aircraft with greatest wingspan).

Aeroplanes or airplanes are technically called fixed-wing aircraft.

The forerunner of the aeroplane is the kite. Whereas an aeroplane relies on its forward speed to create airflow over the wings, a kite is tethered to the ground and relies on the wind blowing over its wings to provide lift. Kites were the first kind of aircraft to fly, and were invented in China around 500 BC. Much aerodynamic research was done with kites before test aircraft, wind tunnels and computer modelling programs became available.

The first heavier-than-air craft capable of controlled free flight were unpowered aeroplanes. A glider designed by Cayley carried out the first true manned, controlled flight in 1853.

Besides the method of propulsion, aeroplanes are generally characterized by their wing configuration. The most important wing characteristics are:

* Number of wings - Monoplane, biplane, etc.
* Wing support - Braced or cantilever, rigid or flexible.
* Wing planform - including aspect ratio, angle of sweep and any variations along the span (including the important class of delta wings).
* Location of the horizontal stabiliser, if any.
* Dihedral angle - positive, zero or negative (anhedral).

A variable geometry aircraft can change its wing configuration during flight.

A flying wing has no fuselage, though it may have small blisters or pods. The opposite of this is a lifting body which has no wings, though it may have small stabilising and control surfaces.

Seaplanes are aircraft that land on water, and they fit into two broad classes: Flying boats are supported on the water by their fuselage. A float plane's fuselage remains clear of the water at all times, the aircraft being supported by two or more floats attached to the fuselage and/or wings. Some examples of both flying boats and float planes are amphibious aircraft.

Some people consider wing-in-ground-effect vehicles to be aeroplanes, others do not. These craft "fly" close to the surface of the ground or water. An example is the Russian ekranoplan (nicknamed the "Caspian Sea Monster"). Man-powered aircraft also rely on ground effect to remain airborne, but this is only because they are so underpowered—the airframe is theoretically capable of flying much higher. (Hovercraft are not considered to be aircraft, since they rely wholly on the pressure of air on the ground beneath, and have no other lift mechanism).

Rotorcraft
Main article: Rotorcraft
Mil Mi-26, the world's largest production helicopter.

Rotorcraft, or rotary-wing aircraft, use a spinning rotor with aerofoil section blades (a rotary wing) to provide lift. Types include helicopters, autogyros and various hybrids such as gyrodynes and compound rotorcraft.

Helicopters have powered rotors. The rotor is driven (directly or indirectly) by an engine and pushes air downwards to create lift. By tilting the rotor forwards, the downwards flow is tilted backwards, producing thrust for forward flight.

Autogyros or gyroplanes have unpowered rotors, with a separate power plant to provide thrust. The rotor is tilted backwards. As the autogyro moves forward, air blows upwards through it, making it spin.(cf. Autorotation)
US-Recognition Manual (very likely copy of German drawing)

This spinning dramatically increases the speed of airflow over the rotor, to provide lift. Juan de la Cierva (a Spanish civil engineer) used the product name autogiro, and Bensen used gyrocopter. Rotor kites, such as the Focke Achgelis Fa 330 are unpowered autogyros, which must be towed by a tether to give them forward ground speed or else be tether-anchored to a static anchor in a high-wind situation for kited flight.

Gyrodynes are a form of helicopter, where forward thrust is obtained from a separate propulsion device rather than from tilting the rotor. The definition of a 'gyrodyne' has changed over the years, sometimes including equivalent autogyro designs. The most important characteristic is that in forward flight air does not flow significantly either up or down through the rotor disc but primarily across it. The Heliplane is a similar idea.

Compound rotorcraft have wings which provide some or all of the lift in forward flight. Compound helicopters and compound autogyros have been built, and some forms of gyroplane may be referred to as compound gyroplanes. Tiltrotor aircraft (such as the V-22 Osprey) have their rotors horizontal for vertical flight, and pivot the rotors vertically like a propeller for forward flight. The Coleopter had a cylindrical wing forming a duct around the rotor. On the ground it sat on its tail, and took off and landed vertically like a helicopter. The whole aircraft would then have tilted forward to fly as a propeller-driven aeroplane using the duct as a wing (though this transition was never achieved in practice.)

Some rotorcraft have reaction-powered rotors with gas jets at the tips, but most have one or more lift rotors powered from engine-driven shafts.

Other methods of lift
X24B lifting body, specialized glider

* A lifting body is the opposite of a flying wing. In this configuration the aircraft body is shaped to produce lift. If there are any wings, they are too small to provide significant lift and are used only for stability and control. Lifting bodies are not efficient: they suffer from high drag, and must also travel at high speed to generate enough lift to fly. Many of the research prototypes, such as the Martin-Marietta X-24, which led up to the Space Shuttle were lifting bodies (though the shuttle itself is not), and some supersonic missiles obtain lift from the airflow over a tubular body.
* Powered lifts rely entirely on engine thrust to hold them up in the air. There are few practical applications. Experimental designs have been built for personal fan-lift hover platforms and jetpacks or for VTOL research (for example the flying bedstead). VTOL jet aircraft such as the Harrier jump-jet take off and land vertically in powered-lift configuration, then transition to conventional configuration for forward flight.
* The FanWing is a recent innovation and represents a completely new class of aircraft. This uses a fixed wing with a cylindrical fan mounted spanwise just above. As the fan spins, it creates an airflow backwards over the upper surface of the wing, creating lift. The fan wing is (2005) in development in the United Kingdom.

Classification by propulsion
Unpowered

Gliders

Heavier-than-air unpowered aircraft such as gliders (i.e. sailplanes), hang gliders and paragliders, and other gliders usually do not employ propulsion once airborne. Take-off may be by launching forwards and downwards from a high location, or by pulling into the air on a tow-line, by a ground-based winch or vehicle, or by a powered "tug" aircraft. For a glider to maintain its forward air speed and lift, it must descend in relation to the air (but not necessarily in relation to the ground). Some gliders can 'soar'- gain height from updrafts such as thermal currents. The first practical, controllable example was designed and built by the British scientist and pioneer George Cayley, who many recognise as the first aeronautical engineer.

Balloons
Main article: Balloon

Balloons drift with the wind, though normally the pilot can control the altitude, either by heating the air or by releasing ballast, giving some directional control (since the wind direction changes with altitude). A wing-shaped hybrid balloon can glide directionally when rising or falling; but a spherically-shaped balloon does not have such directional control.

Kites
Main article: kite

Kites are aircraft that are tethered to the ground or other object (fixed or mobile) that maintains tension in the tether or kite line; they rely on virtual or real wind blowing over and under them to generate lift and drag. Kytoons are balloon kites that are shaped and tethered to obtain kiting deflections, and can be lighter-than-air, neutrally buoyant, or heavier-than air.

Powered
Propeller aircraft
A turboprop-engined DeHavilland Twin Otter adapted as a floatplane

A propeller comprises a set of small, wing-like aerofoils set around a central hub which spins on an axis aligned in the direction of travel. Spinning the propeller creates aerodynamic lift, or thrust, in a forward direction. A contra-prop arrangement has a second propeller close behind the first one on the same axis, which rotates in the opposite direction.

A tractor design mounts the propeller in front of the power source, and a pusher design mounts it behind. Although the pusher design allows cleaner airflow over the wing, tractor configuration is more common because it allows cleaner airflow to the propeller and provides a better weight distribution.

A variation on the propeller is to use many broad blades to create a fan. Such fans are traditionally surrounded by a ring-shaped fairing or duct, as ducted fans.

Many kinds of power plant have been used to drive propellers.

The earliest designs used man power to give dirigible balloons some degree of control, and go back to Jean-Pierre Blanchard in 1784. Attempts to achieve heavier-than-air man-powered flight did not succeed until Paul MacCready's Gossamer Condor in 1977.
Gossamer Albatross, a human-powered aircraft

The first powered flight was made in a steam-powered dirigible by Henri Giffard in 1852. Attempts to marry a practical lightweight steam engine to a practical fixed-wing airframe did not succeed until much later, by which time the internal combustion engine was already dominant.

From the first controlled powered aeroplane flight by the Wright brothers until World War II, propellers turned by the internal combustion piston engine were virtually the only type of propulsion system in use. (See also: Aircraft engine.) The piston engine is still used in the majority of smaller aircraft produced, since it is efficient at the lower altitudes and slower speeds suited to propellers.

Turbine engines need not be used as jets (see below), but may be geared to drive a propeller in the form of a turboprop. Modern helicopters also typically use turbine engines to power the rotor. Turbines provide more power for less weight than piston engines, and are better suited to small-to-medium size aircraft or larger, slow-flying types. Some turboprop designs (see below) mount the propeller directly on an engine shaft, and are called propfans.

Since the 1940s, propellers and propfans with swept tips or curved "scimitar-shaped" blades have been studied for use in high-speed applications so as to delay the onset of shockwaves, in similar manner to wing sweepback, where the blade tips approach the speed of sound. The Airbus A400M turboprop transport aircraft is expected to provide the first production example: note that it is not a propfan because the propellers are not mounted direct on the engine shaft but are driven through reduction gearing.

Other less common power sources include:

* Electric motors, often linked to solar panels to create a solar-powered aircraft.
* Rubber bands, wound many times to store energy, are mostly used for flying models.

Jet aircraft
Main article: Jet aircraft

Air-breathing jet engines provide thrust by taking in air, burning it with fuel in a combustion chamber, and accelerating the exhaust rearwards so that it ejects at high speed. The reaction against this acceleration provides the engine thrust.
A jet-engined Boeing 777 taking off

Jet engines can provide much higher thrust than propellers, and are naturally efficient at higher altitudes, being able to operate above 40,000 ft (12,000 m). They are also much more fuel-efficient than rockets. Consequently, nearly all high-speed and high-altitude aircraft use jet engines.

The early turbojet and modern turbofan use a spinning turbine to create airflow for takeoff and to provide thrust. Many, mostly in military aviation, use afterburners which inject extra fuel into the exhaust.

Use of a turbine is not absolutely necessary: other designs include the crude pulse jet, high-speed ramjet and the still-experimental supersonic-combustion ramjet or scramjet. These designs require an existing airflow to work and cannot work when stationary, so they must be launched by a catapult or rocket booster, or dropped from a mother ship.

The bypass turbofan engines of the Lockheed SR-71 were a hybrid design - the aircraft took off and landed in jet turbine configuration, and for high-speed flight the afterburner was lit and the turbine bypassed, to create a ramjet.

The motorjet was a very early design which used a piston engine in place of the combustion chamber, similar to a turbocharged piston engine except that the thrust is derived from the turbine instead of the crankshaft. It was soon superseded by the turbojet and remained a curiosity.

Helicopters
HAL Dhruv, a multi-role utility helicopter.

The rotor of a Helicopter may, like a propeller, be powered by a variety of methods such as an internal-combustion engine or jet turbine. Tip jets, fed by gases passing along hollow rotor blades from a centrally-mounted engine, have been experimented with. Attempts have even been made to mount engines directly on the rotor tips.

Helicopters obtain forward propulsion by angling the rotor disc so that a proportion of its lift is directed forwards to provide thrust.

Other forms of propulsion

* Rocket-powered aircraft have occasionally been experimented with, and the Messerschmitt Komet fighter even saw action in the Second World War. Since then they have been restricted to rather specialised niches, such as the Bell X-1 which broke the sound barrier or the North American X-15 which travelled up into space where no oxygen is available for combustion (rockets carry their own oxidant). Rockets have more often been used as a supplement to the main powerplant, typically to assist takeoff of heavily-loaded aircraft, but also in a few experimental designs such as the Saunders-Roe SR.53 to provide a high-speed dash capability.
* The flapping-wing ornithopter is a category of its own. These designs may have potential, but no practical device has been created beyond research prototypes, simple toys, and a model hawk used to freeze prey into stillness so that it can be captured.

Classification by use

The major distinction in aircraft types is between military aircraft, which includes not just combat types but many types of supporting aircraft, and civil aircraft, which include all non-military types.


Military aircraft
Main article: Military aircraft
Saab Gripen, a Swedish multi-role fighter aircraft.

Combat aircraft divide broadly into fighters and bombers, with several in-between types such as fighter-bombers and ground-attack aircraft (including attack helicopters).

Other supporting roles are carried out by specialist patrol, search and rescue, reconnaissance, observation, transport, training and Tanker aircraft among others.

Many civil aircraft, both fixed wing and rotary, have been produced in separate models for military use, such as the civil Douglas DC-3 airliner, which became the military C-47/C-53/R4D transport in the U.S. military and the "Dakota" in the UK and the Commonwealth. Even the small fabric-covered two-seater Piper J3 Cub had a military version, the L-4 liaison, observation and trainer aircraft. Gliders and balloons have also been used as military aircraft; for example, balloons were used for observation during the American Civil War and World War I, and military gliders were used during World War II to land troops.

Civil aircraft
The Premium Class cabin of Jet Airways Boeing 777.

Civil aircraft divide into commercial and general types, however there are some overlaps.


Commercial aircraft

Commercial aircraft include types designed for scheduled and charter airline flights, carrying both passengers and cargo. The larger passenger-carrying types are often referred to as airliners, the largest of which are wide-body aircraft. Some of the smaller types are also used in general aviation, and some of the larger types are used as VIP aircraft.

General aviation
Eurocopter EC 145 of the Rega air rescue service.

General aviation is a catch-all covering other kinds of private and commercial use, and involving a wide range of aircraft types such as business jets (bizjets), trainers, homebuilt, aerobatic types, racers, gliders, warbirds, firefighters, medical transports, and cargo transports, to name a few. The vast majority of aircraft today are general aviation types.

Within general aviation, there is a further distinction between private aviation (where the pilot is not paid for time or expenses) and commercial aviation (where the pilot is paid by a client or employer). The aircraft used in private aviation are usually light passenger, business, or recreational types, and are usually owned or rented by the pilot. The same types may also be used for a wide range of commercial tasks, such as flight training, pipeline surveying, passenger and freight transport, policing, crop dusting, and medical evacuations. However the larger, more complex aircraft are more likely to be found in the commercial sector.

For example, piston-powered propeller aircraft (single-engine or twin-engine) are common for both private and commercial general aviation, but for aircraft such as turboprops like the Beechcraft King Air and helicopters like the Bell JetRanger, there are fewer private owners than commercial owners. Conventional business jets are most often flown by paid pilots, whereas the new generation of smaller jets are being produced for private pilots.

Experimental aircraft

Experimental aircraft are one-off specials, built to explore some aspect of aircraft design and with no other useful purpose. The Bell X-1 rocket plane, which first broke the sound barrier in level flight, is a famous example.

The formal designation of "experimental aircraft" also includes other types which are "not certified for commercial applications", including one-off modifications of existing aircraft such as the modified Boeing 747 which NASA uses to ferry the space shuttle from landing site to launch site, and aircraft homebuilt by amateurs for their own personal use.

Model aircraft
A model aircraft, weighing 6 grams.

A model aircraft is a small unmanned type made to fly for fun, for static display, for aerodynamic research (cf Reynolds number) or for other purposes. A scale model is a replica of some larger design.

Life is a Game,Just play it

Roll the dice again
for nothing more than less.
Go ahead and take a turn
for a second chance at happiness.

Maybe we'll win this time,
it could be our lucky day.
To make this life worthwhile,
to make things go our way.

End up with a number,
go on and take those steps.
Walk on to a new beginning,
forgive and pay your debts.

Take a chance on love,
you never know what you may get.
Evin if you play the wrong card,
you can pick another from the deck.

Life is like a game,
play along cause it's your call.
The only way you truly lose
is if you don't try to play at all ..

I Dont Cry For the Past

Even though u have your times
Times were u r negative
Times were u doubt
Times when u say stuff u don't mean to say
Don't cry

I will always be there for u
I may get mad
But not for long
I never can be mad at some1 as amazing as u
Don't cry

I'm sorry for getting upset with u
During those times
I will always be by your side
Don't cry

I need you like the wolf needs the moon to guide it threw the night
Without the moon
The wolf would be lost
Blind
No where to go
Don't cry

The moon may eclipse on the wolf
But the wolf will wait it out n stay strong
We may have our eclipse like the wolf
That eclipse only last for so long
Just remember when that moon comes back
I will be there waiting for u to make it full again
Don't cry !

After Me ..

After Me ..

When I will not be here,When i will be gone forever,When i will be dead,Just Come to My Grave,Dont Cry ..

Just put Some Wild Flowers Beside me,Sit along the Yard for Few Moments,Talk to me,Cheer Me up ..

Remember the Times When We Were Together,When We Were Friends,Listen To My Quiet Reply..

Enjoy Those Moments , Try to understand the Unsaid Words & Consider How Much You still Mean To Me :)

One Day You'll Also Love Me

Why do you hurt me?
Do you like seeing me cry?
How can you just walk away?
When you know I'm dying inside!

How can you drag me,
Through this heartache and all this pain?
You know everything about her,
But do you even know my name?

Do you know how much I love you?
Do you even really care?
How can you let me love you?
Why are you so unfair?

Why won't you let me move on?
Let me be happy once again?
You want me in your life I know,
But I want to be more than just your friend!

Baby, just let me go!
I don't even me a thing.
But I don't want you to let me go!
I love you... Can't you see?

Why Me ?

Sitting against the wall,
Pressing hands to ears,
Blasting music,
Rocking back and forth,

Asking,
Why me,
Why me,
Why me?

Why can't I be with the one I love?
Why can I never be happy?
Why do I go through so much stress?
I just want to die at times.

I have good friends,
A few good choices,
They help me,
And I help them.

So why do I choose to ask these questions?
Why am I so unsure?
Am I not believing in my friends?
Or is it the depression?