How does aircraft propellers work?
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The airplane prop works just like the prop in a outboard motor in a boat. The prop has blades which have a pitch on them (angle) which in trun "paddles" through the air - the air is pulled over the blades and in turn pulls the motor through the air. (which of course, is attached to the wing which creates the lift required to get the plane off the ground)\n\nThe boat prop is a great example to use because you can see the water and how it flows over the blades.
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As an aircraft moves through the air, the wing is inclined to the flight direction at some angle. The angle between the chord line of the airfoil and the flight direction is called the angle of attack. Angle of attack has a large effect on the lift generated by a wing. During takes off, the pilot applies as much thrust as possible to make the airplane roll along launch rail. But just before lifting off, the pilot "rotates" the aircraft. The nose of the airplane rises, increasing the angle of attack and producing the increased lift needed for takeoff.\n\nThe amount of lift generated by a wing depends on how much the flow is turned, which depends on the shape of the object. The lift is, in general, a very complex function of the shape.the greater the air flow turning, the greater the lift.\nIt is important to note that the acceleration of the air does not just involve the air molecules "bouncing off" the lower surface of the wing. Rather, air molecules closely follow both the top and bottom surfaces, and so the airflow is deflected downward. The acceleration of the air during the creation of lift has also been described as a "turning" of the airflow.\nWhen the air is bent around the top of the wing, it pulls on the air above it accelerating that air down, otherwise there would be voids in the air left above the wing. Air is pulled from above to prevent voids. This pulling causes the pressure to become lower above the wing. It is the acceleration of the air above the wing in the downward direction that gives lift.\n\n\nThe amount of lift generated by an object depends on the size of the object. Lift is an aerodynamic force and therefore depends on the pressure variation of the air around the body as it moves through the air. The total aerodynamic force is equal to the pressure times the surface area around the body. Lift is the component of this force perpendicular to the flight direction. Like the other aerodynamic force, drag, the lift is directly proportional to the area of the object. Doubling the area doubles the lift.\n\n\nThe greater the angle of attack, the greater the vertical velocity. Likewise, for the same angle of attack, the greater the speed of the wing the greater the vertical velocity. Both the increase in the speed and the increase of the angle of attack increase the length of the vertical arrow. It is this vertical velocity that gives the wing lift.
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airplane wings work because of their curvature - the upper surface of the wing is more curved than the lower surface, so air moving over the top of the wing has to take a longer path.  \n\nthis longer path causes the air to thin out over the top surface of the wing, and this leads to a lower pressure on the top surface.  the higher-pressure air on the underside of the wing pushes the wing upwards into the lower-pressure region, just like the higher pressure inside a balloon pushes the balloon outwards into the lower-pressure atmosphere.\n\nanyway, i think you can think about a leaf on a windshield as acting like a wing of sorts.  air will flow faster over the upper surface of the leaf but stay trapped underneath.  if the leaf is solid, then the pressure differential pushes outward on the leaf, away from the windshield.  \n\non the other hand, if there is a slit in the leaf, then the higher-pressure air underneath can move through the slit and equalize the pressures, so there is less force on the leaf pushing it away from the windshield.\n\nas for holes, perhaps if the holes were big enough, you would no longer have the smooth ("laminar") flow over the surface, and instead get turbulent air that causes a vortex to form.  \n\nvortices are lower pressure areas so that might suck the leaf off.  or, a big hole might cause an edge of the leaf to flip up into the airstream and catch some of the air, forcing it down under the leaf and pushing it off the windshield - whereas a slit might still allow the air to flow smoothly over the leaf yet still equalize the pressure.\n\ni'm totally guessing, but i guess it's a reasonable theory.
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They perform that feat by two methods. The classical method that was been taught since the mid 1700's is called the Bernoulli effect discovered by Daniel Bernoulli, a Swiss mathematician. This effect is that a fluid flowing with a greater velocity has a lower pressure than a fluid flowing with a lesser velocity. This pricipal has been put into effect with the construction of the aircraft wing. The upper surface of the wing is curved and has a longer surface over which air must flow than the lower surface. Therefore the air must flow faster over the upper surface than the lower surface. This lowers the air pressure over the upper surface of the wing and causes a lift by the pressure of the air on the lower surface.\n\nThis however is not the only force acting to keep the aircraft afloat though it has been taught as the force for many years. \n\nThe second force that is used, is cause by the angle of attact of the wing on the air. As the aircraft is in level flight the wing is tilted slightly upward. This causes the air to push against the bottom of the wing at a slight angle. \n\nTake your left hand and hold it at a slight angle to the horizontal in front of your eyes with the fingers pointing toward the right. Then with the fingers of the other hand pointing opposite to the fingers of the hand held at an angle, push horizontally against the palm of the hand.\n\nWhen you do this you will notice that the left hand tends to rise as you push against it. That is the second force that helps keeps the plane afloat.
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On an airplanes wing, the top is curved in shape, and the bottom is straight.  When the plane gains speed, the air will be forced to move faster over the curved portion.  The faster moving air applies less pressure than over the straight portion therefore creating "lift"
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I have to assume that you're familiar with general aerodynamics. If not, there's really not enough space to answer your question here.\n\nThe biggest physics differences between a helicopter and an airplane are torque, translational lift, and retreating blade stall.\n\nA helicopter's fuselage will tend to turn opposite the direction of the rotor, particularly at a hover or a slow speed. (Some streamlining occurs in flight.) The "tail rotor" is actually called an "anti-torque rotor" because its installation is designed to counteract the main rotor's torque. (Notice that twin rotor helicopters don't have anti-torque rotors because the main rotors rotate in opposite directions and counteract each other's torque.)\n\nNext is effective translational lift. At a hover and at slow speeds, generally below 30 KIAS, a helicopter is flying in its own rotor wash. A lot more lift and constant control inputs are required to maintain steady flight. Lift in a helicopter is created by the rotating blades and is increased (or decreased) by raising the collective (a “joystick by the pilot’s left leg) which increases (or decreases) the rotor’s angle of attack. Note: During all of this, the rotor maintains a constant R.P.M….it does not spin faster when climbing and slow down when descending.\n\nAlso, some of this lift is used for thrust to move the helicopter forward, or sideways, or backward. This is why you see a helicopter nose down when it’s taking off. The rotor is the “wing and the propeller” at the same time.\n\nFinally, retreating blade stall limits the speed of a helicopter. Sitting on the ground and in a still wind at operating R.P.M. the wind is blowing over the blades at a steady speed. (Of course the blade root’s speed is much lower than the blade’s tip because it has less far to travel.) But in forward flight at, say 100 KIAS, the advancing blade has an extra 100 knots relative wind added to its speed. The retreating blade, going opposite to the relative wind is LOSING 100 knots relative wind. The faster you go, the more the retreating blade loses lift and eventually stalls; that is loses lift completely and the helicopter will roll over.\n\nThis is about all I can tell you in a short time, but it’s all very interesting and surprisingly inefficient. I’ve attached some links that will go into more detail. Hope this helps!
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The body of the Helicopter will rotate OPPOSITE of the blades.  This is called reactive torque, and it is the whole reason why a helicopter will have a tail rotor in the first place.  The tail rotor keeps the body of the helicopter from spinning out of control.\n\nTo demonstrate the concept of reactive torque, get a cordless drill.  Note that the chuck spins one direction (let's say clockwise).   Grab onto the chuck with one hand and you will notice that the drill will want to spin the OPPOSITE direction (counter-clockwise, in our example).  This is reactive torque, and the same principle is at work in a helicopter.\n\nSome helicopters actually have an enclosed turbine and pipe to just develop thrust off to one side on the tail.  This is considered to be a safer design since it does not have an exposed rotor.\n\nAlso there are helicopters that have two main rotors that spin in opposite directions.  Because they spin in opposite directions, the reactive torque of each is cancelled out.
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I'm assuming you're talking about jet engines compared to stationary energy turbines.  I'm not sure what you're asking, so I'll just try to be general.  \n\n1st- Pressure and Velocity\nPressure and Velocity are related (in incompressible, inviscid flows -  pretty applicable to just get a feel for it) by Bernoulli's principal.  Basically it states that Stagnation Pressure (the pressure if you stopped the gas) is conserved along a streamline (the path air follows around or through an objet).  It is equal to the static pressure (pressure you feel outside) + 1/2 * Density * Speed ^2.  This boils down to if you do no work to the fluid, and allow a pressure drop, the gas will speed up (think water coming out of a hose).  \n\nNozzles\nNozzles work to reduce the area the fluid can flow through.  By shrinking the area, you force the fluid to move faster for the same amount of mass (rather then having 2 people walk through a door at the same time, they'd have to walk twice as fast in a single file line to get through).  The Nozzle increases the pressure in the chamber, forcing the gas to speed up at its exit - this is how the whole putting your thumb over the garden hose works, you force the flow to build up pressure behind your thumb so that it can escape at the same rate that it is being allowed to enter the hose.  \n\nThe converging nozzles on jet engines compress the flow to the speed of sound.  Rockets on the other hand have converging-diverging nozzles (they shrink then get bigger) which allows for a supersonic exhaust.  \n\nBypass Ratio /turbofan/turbojet\nThe bypass ratio refers to a turbofan engine.  A turbojet, turbofan, and turboprop all have a turbojet engine at the core, a turbo prop uses that engine to turn a propeller, a turbojet simply uses the engine to accelerate gases out of it, and a turbofan is kind of a hybrid of the two - it turns a 'fan' which also acts as a compressor.  The bypass ratio is the ratio of the airflow that only goes through the fan (and therefore bypasses the turbojet portiion of the engine) as compared to the amount of air that flows through the turbojet portion.  By bypassing the turbojet, the air moves more slowly - but the fan moves more of it so you get more efficent thrust, but a lower maximum speed.  The prop works ont eh same way, but moves even more air, with an even lower maximum speed, but a much higher efficiency.  \n\nTurbojet engine\nA turbojet engine runs on a Brayton cycle.  Basically you have 4 stages, compressor, combustion, turbine, exhaust.  As the air comes into the engine, it hits the compressor, which raises the pressure of the air, and allows it to stagnate (its hard to burn fuel when the air is moving).  Once the air is finished with the compressor, it enters into the combustion chamber, where it is mixed with fuel and burns.  This hotter high pressure air is then allowed to expand through a turbine (like a windmill or pinwheel) driving the turbine (the turbine is connected to the cmpressor through a shaft sot hat it drives the compressor).  The hot gases are then either put into an afterburner, where the air is heated up again, or not - and then forced through a nozzle to accelerate it (converting its pressure into speed).  The air leaving the engine is moving much faster then it was when it was taken in (its leaving at mach 1 - the speed of sound varies based on temperature, so its much faster then mach 1 of an airplane flying).  This is how it produces thrust.
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The different control surfaces on the wings and tail can control both the angle of the plane and the amount of lift that the wings provide, while varying the engine power can control speed. For example, before landing, a plane is going much slower than crusing speed, but the flaps on the wings are extended, creating a little more drag, but increasing the lift.
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Wind turns the propellers, which is connected to a turbine engine that converts the wind energy to electrical energy. I believe it is stored by batteries sometimes, or more commonly it is tied into the power system that it is associated with. Typically seen on farms because of their proximity to traditional power sources. Wind mills make it convenient because in the plains, there is an abundant source of wind.
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The short answer is, the same way all fixed wing aircraft do.\n\nWings on aircraft product lift, by taking advantage of something called Bernoulli's Principle. It says, in essence, that faster moving air causes air pressure to be lowered. You'll notice that the upper surface of aircraft wings are curved, and have more length to them than the underside of the wings. Since the airflow over the wing's surface has a greater distance to go on top than on bottom, the speed of the airflow is faster on top of the wing, hence lower pressure.\n\nStill, the best designed wing in the world won't help an aircraft get airborne without something known as the thrust/weight ratio. The P-47 was a very heavy aircraft in its day, but had a massively powerful radial engine that produced more than enough thrust to get it airborne and let Bernoulli's Principle take over...\n\nA great aircraft with an impressive war record.
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- A DC brushless electromotor is mainly a step-motor with a rotor made out of permanent magnet, and a stator made out of coils (mostly 4 coils, but it depends on the type of step-motor). As this is a step-motor, it needs some kind of regulator, which is made on a little electronic board. So... a DC brushless motor is made out of 3 things: \n\n1 Electronic Circuit Board \n2 Coils \n3 Permanent Magnet \n\n- Electronic Circuit Board and Coils: \n\n- This part is doing the trick - rotating the permanent magnet. There are in most every case only 4 coils in a normal fan, grouped as 2+2. The first group (let's call them the North-South group) is connected to one electrical circuit on the electronic board. And the second - East-West - is connected to the other electrical circuit. \n\n- On the electronic circuit board is located one small device that is most responsible for this trick. It is called Hall-probe (or Hall-sonde), and its location is just under the permanent magnet. \n\n- It's used to detect the south pole of the permanent magnet. The Hall-probe regulates two different electric circuits driven by two transistors, and depending on the pole it detects, it drives the proper circuit. With this type of regulation, it is possible to create a rotating magnetic field, and rotate the permanent maget located around the coils. \n\n- A permanent magnet has two-poles - North and South. Let's look what happens when the fan is powered. \n\n- Depending on the location of the south pole, Hall-probe drives one of the circuits. So, let's say that Hall-probe is sensing the south pole. It drives one of the circuits (let's say north-south circuit). \n\n- When the north and south coils are powered, they produce the magnetic field. This field is of the same direction in both coils, but... :) the Magnet hasn't got the same direction of the magnetic field in both poles. It looks like one coil is pushing the north pole away, and on the other hand, the second coil is pulling the south pole to itself. \n\n- Now, when the magnet is moved, the south pole goes away from the Hall-probe, and as it isn't sensing it anymore, it drives the second transistor (second circuit). With that, east-west coils are turning on, doing the same job as north-south coils did before. \n\n- So, basically the trick was to produce the rotating magnetic field. And it was done very cleverly! :) As coils aren't made as a moving part, it is obvious that there are no brushes, so that's the part where the name came from - 'DC brushless'. \n\n- Permanent Magnet: \n\n- This is the mostly known part of the electromotor. I think that I don't need to explain much about it. It has two poles - north and south, and using the external magnetic field it is possible to move the magnet around. In a fan, the magnet is circuit-shaped and it rotatrd around its axis. \n-------------
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The suggestions given ahead of me are a popular but untrue.\n\nLightning rods are sometimes hit by lightning, but their main purpose is to bleed charge from the ground up thru the point of the rod.\n\nClouds have charge from various sources in the cloud. Small pieces of sand blowing together and other various things. All this charge gets stored up in the clouds.\n\nWhen enough charge builds and has nowhere else to go, the path of least resistance to the ground is where the charge dissipates.\n\nThe actual mechanism is complicated, and there are what are called leaders which travel from the ground UP, and this sets off a series of events leading to the actual discharge.\n\nAnyway......the clouds and the ground act like a giant capacitor in essence.\n\nThe points on the lightning rods are areas of extremely high electric fields. The points are placed on them on purpose and for this reason. This ensures that charge will bleed off AT the points of the rods. The charges that bleed off then end up mixing with the excess and opposite charges in the clouds in the vicinity. This helps reduce the electric field, which is responsible for causing lightning in the first place.\n\nIf this field can be reduced then the chance for a discharge is also reduced and the structure will (hopefully) be safe from lightning damage.\n\nAll the buildings around the universities here have multiple small spikes on them every few feet, for just this purpose.\n\nTake a look at an airplane wing next time you get a chance. You will see small spikes at the tips, or you will see what looks like a rod with bristles at the end. This is a series of 'points' from which charge from the 'skin' of the plane will be bled of during flight and reduce the chance for interference with communications and other instrumentation on the plane.
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Newtons second law - blance of momentum.\n\nWhen the force acting on the mass to accelerate it is the maximum that the engine, atmosphere, and gravitational attraction to the earth can produce, and those forces are balanced by the the forces acting on the mass to slow it down, then the mass is at its "max speed".\n\nDensity of the air is affected by altitude, temperature, humidity, and weather.  For horizontal, noncompressible flight, that density is a major component of the "dynamic pressure" and therefore the drag.\n\nA very simple model of drag is D=0.5*rho*U^2 *Cd*A where rho is the density of the working fluid (atmosphere), U is the freestream speed of the air, Cd is the coefficient of drag of the airplane, and A is the frontal cross-sectional Area.\n\nIf you set max thrust equals this drag, then you can math out what U is, and call it the max speed of the plane.  If the plane has a headwind or tailwind then its absolute speed will vary.\n\nIf the plane approaches mach then stranger and more energy-demanding phenomena kick in.  If the plan is going beyond the speed of sound there is a third, also complex description for the drag.\n\nIf you are using a prop driven plane then you cant just assume that the thrust equals the planes horsepower, you have to consider the efficiency of the prop and there are equations for that.\n\nDetermining the Cd for a plane is complex because the wing, body, and tail all interact to change the overall Cd.
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How Thrust is Created\n\nA jet engine's one purpose is to create enough thrust to zip you and your luggage across the sky. What's thrust? It's power, the force that pushes you deep into your seat as you speed down the runway for takeoff.\n\nBasic Scientific Principles Behind Jet Propulsion\nNewton's Third Law of Motion\nFor every action, there is an equal and opposite reaction. Thrust is created when air is pushed through a jet engine at a higher speed (velocity) than that of the air entering it. This force propels the plane forward. Imagine an inflated balloon that is released -- the pressurized, escaping air propels it forward.\n\nBernoulli's Principle\nFaster moving air exerts less pressure on surfaces than slower moving air.\nThe shape of the wing (an airfoil) is what allows the airplane to fly. The arched top of the wing forces air to travel faster and over a greater distance than air flowing across the flat bottom. The faster moving air exerts less pressure than the slower air on the bottom, thus creating lift. The blades of a propeller are also airfoils. The "lift" they generate pulls the plane forward.\n\nBoyle's Law\nThere is a relationship between a fixed amount of air's pressure and volume.\nWhen air is squeezed into a smaller volume Ð compressed Ð its pressure increases proportionally. Unless the temperature is held constant by external means, it will rise with pressure. In a jet engine, superheated, pressurized air is mixed with jet fuel and ignited.\n\nThe Basic Components\nIn its simplest form, a jet engine has three major components, called the core: \nCompressor: A series of blades or airfoils, some rotating (rotors) some stationary (stators), that draws air in and compresses it. More complex engines will have many rows of blades. As the air moves through these rows, its pressure will increase by as much as 40 times and the temperature will rise dramatically. \nCombustion Chamber: The compressed air is then pushed rearward into the combustion chamber. In the combustor, fuel injectors mix jet fuel with the air and it is ignited. The flow and burn of the air/fuel mixture is controlled to ensure that the engine sustains a continuous flame. The expanding exhaust gases flow quickly toward the rear of the engine. \nTurbines: The speeding gases that exit the combustor exert force against the turbine blades (airfoils), similar to the way a gust of wind spins a windmill. The turbine is connected to the compressor by a shaft. The force Ð or energy Ð created by the turbine spins the compressor, which pulls in more air, beginning the whole cycle again. The compressor is actually powered by the air it has already fed through! \nAll of these components are housed in a durable metal casing that is then installed into the nacelle, a megaphone-shaped engine enclosure that is mounted to the airplane's wing or fuselage (body).
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Before an airplane can take off, pilots are supposed to file a flight plan. This involves consulting nav charts and checking weather and reporting their intentions. They then plot their course one these charts and take the vectors they need to fly this course from the charts. Then of course, they have to fly the correct heading that will give take them along these vectors. While the larger airplanes and even many small ones do have autopilot, they are not actually "flown by computers." They autopilot makes navigation correction based on the information that is fed into them. Do it wrong, and the autopilot will be happy to fly you right into a mountain, it doesn't know the difference.
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The top of an aircrafts wings are usually rounded to a certain extent, while the bottom of the wing is flat, this causes the air that flows over the top of the wing to speed up as the aircraft itself gains speed. the sped up air flow tries to catch up with the faster air flow at the bottom of the wing, causing lower air pressure at the top of the wing, and the higher air pressure on the bottom of the wing actually pushes the aircraft up.