Why should a helicopter have a flapping hinge?
927536
Sarah, flapping hinges on a helicopter are to address a problem called dissymmetry of lift, which occurs when a rotorcraft is moving laterally.\nhttp://www.cavalrypilot.com/aerodynamics/lift_dissymetry.html\n\nHowever, while flapping hinges solve one problem, they cause another. Flapping hinges have caused rotor blades to break due to high stresses, caused by coriolis force. The installation of another hinge, the lead-lag hinge solved that problem.\nhttp://www.copters.com/aero/lead_lag.html\n\nThis .pdf document contains some excellent illustrations of flapping hinges:\nhttp://www.apnet.com/bookscat/samples/0750650753/0750650753.pdf
326740
So a "Swiss Seat" harness can be made for rappeling.  Also can use it to secure yourself to the floor of a helicopter if the seats have been removed...
607424
I've looked for near an hour and for the life of me I can't the history of it.  I thought it would be pretty simple, but boy was I ever wrong.  I'm sure you already found the sites that make and sell them, not to mention an airplane called a Windsock, but all the help I can give you today is good luck.  Sorry I couldn't help.  But I had to give you some sort of answer because nobody else has posted anything.
1110236
Airflow over the lifting surfaces creates pressure differences between top and bottom sides, which gives you the lifting force.  You have to shove the lifting surfaces through the air in order for them to generate the lift, though, hence why true aeroplanes must have engines to push them along.   If you don't have an engine then you are a glider, and barring thermal upcurrents you will be perpetually falling.   Until...\n\nI think passenger jets can glide at about a 1:20 downward slope with no engine power.
1116744
H-1, Bell - Iroquois commonly known as the "Huey", \n\nCertainly, it was an awesome bird. \n\nIt was developed from 1955 US Army trials from the Bell Model 204, the initial designation of HU-1 (helicopter utility) led to its nickname. It was first used by the military in 1959 and went into triservice production in 1962 as the UH-1. The last were produced in 1976 with more than 10,000 made in total, of which the majority (7,000 or so) were deployed in Vietnam. In Vietnam 2,202 Huey pilots were killed and 5,086 helicopters lost. \n\nLength: 57.1 ft (17.4 m) with rotors\nWidth: 8.6 ft (2.6 m)\nHeight: 14.5 ft (4.4 m)\nWeight: 4.7 tons\nPayload: 1.5 tons internal, 2 tons external\nEngines: Pratt and Whitney T400-CP-400\nSpeed: 127 mph (204 km/h)\nRange: 318 miles (512 km)\nService ceiling 14,200 ft (4,300 m)\nCrew: varies depending on role, usually 2 to 4\nPassengers: 11 to 14\nArmament: M240 7.62 mm machine gun, or GAU-17 7.62 mm machine gun, or GAU-16 .50 calibre (12.7 mm) machine gun (Bell UH-1F). 2 x 7 shot or 19 shot 2.75 in (70 mm) rocket pods
1053885
It is very beneficial to aeronautics as different layers of the atmosphere have different pressures and affect how a plane or shuttle flys.  Similarly a helicopter can only maintain its altitude within very low levels of the atmosphere.
1151935
The noun "porpoise" has entered the language as a verb to describe the slight up-and-down waving motions of out-of-trim airplanes.\n[An out-of-trim craft will, at altitude, climb several feet, losing speed; then drop several feet, gaining speed... in almost endless cycles.]
32
A helicopter gets its power from rotors or blades. When its rotors are spinning, a helicopter doesn't look much like an airplane. But the rotor blades have an airfoil shape like the wings of an airplane. So as the rotors turn, air flows more quickly over the tops of the blades than it does below. This creates enough lift for flight.
872091
Autorotation works just like a parachute.  Its standard part of helicopter pilot training.  My very first time up, the instructor took me up about 1000 feet above the airport and the said "Now lets disengage the engine."  We started a rapid but controlled decent and safely landed in a grassy area at the airport.  No damage to either us or the helicopter.
480159
An airplane's design helps it create and maintain lift and thrust. A needle's does not.
390487
as far as the airplanes are concerned the bernouli (probably spelled wrong) principle was the accepted belief for a long time but has recently been disproven as the primary reason.  Bernouli's principle was the high pressure under the wing and low pressure atop creating lift. \nThe new theory is something to do with the air flowing over the wing sticks to it due to a vaccum created on the surface by moving air. the air then shoots downward off the back of the wing causing the wing to react upward kinda like a jet engine. That was my very loose understanding of it. apparently a barn door creates as much lift as an airofoil teardrop shapped wing.
1182585
Technically, depending upon the type of airplane and speed of the head wind, a plane can "hover".  As long as air moves over the surface of the wing fast enough to create enough lift to make the airplane fly, it will fly--it just may not have very much forward speed.\nWhy does an airplane fly?  The Bernoulli principle.  Air flowing around the wing does so at two different speeds due to the shape of the airfoil.  It flows around and over the top more quickly than along the flat bottom of the wing.  This creates higher pressure on the bottom pushing up.  As long as there is enough push to overcome gravity (or weight), the plane will fly. You might ask, then without moving forward and in no wind, how does a helicopter fly?  Well, its airfoils are always moving through the air as long as it is running--the rotors are its wings.
974136
From what I have been able to find on the subject, the shuttle cock must have all the feathers from the same wing of the bird in order for it to spin correctly to stabilize in flight.  Since all feathers must come from the same wing, someone at some time decided to use feathers from the left wing.  i suppose they could have selected the right wing just as well but they had to select all their feathers from either the left or the right and somehow the left was selected.
827952
in 1799, Sir George Cayley, a baronet in Yorkshire, near Scarborough, England, conceived a craft with stationary wings to provide lift and "flappers" to provide thrust. It also had a movable tail to provide control. So convinced was he that this idea is an earth-shaker, he engraved a drawing of this craft on a silver disk. Cayley wass the first to separate the different forces that keep an aircraft in the air, and his engraving was the first recorded drawing of a fixed-wing aircraft -- an airplane. So It was dear old blighty that came up with it.
144449
you could flap your arms all day long a (BMPH) Billion Miles Per hour.heheh And you never get lift. See to under stand how birds fly you have to understand a birds body. First off a birds bones are hollow. Meaning less weight. Secondly the birds wings are shaped like a windfoil which gives lift. to explan how a wing works we will go into alittle physics of flight. To understand flight you have to understand how the wing is designed. \n\nfirst take a peice of postit note from one of the 5x3 inch pads. you need a pensile. bring the bottom side of the post it note to the top side where it is sticky. stick it together. Now you have a piece of paper simular to a tear drop. what you going to do is run the pencle between the opening to the other side. let the pice of paper float freely. hold the pencile with both hands one on one side of the paper and the other on the other side of the paper. Not put the not about 5 inches in front of your mouth and blow. Notice what happens the paper lifts. This is what is called lift. This is how birds fly. basicly when you blow on the paper the under side high presure goes under and low presure goes over the top. We will call it a win for now. But pending on how the wind is hitting it will depend on what direction the wing will go. If the tail end is faced up then the wing will go down it it's faced down the wing will go up. When it goes up that is called lift. and thats how birds fly.
1060459
stops eddies/drag at the rotor tips, cf the upturned wingtips of modern aircraft..\n\nmore significant in water turbines.\n\nThe shroud may contribute to strength of structure, if fixed to blade, but will add mass where it is not wanted \n\nAlso stops people putting their hands in the way of spinning object.
363865
As the car moves along, air passes over the top of the roof, creating an area of low pressure.  The air pressure inside the car, having a higher pressure than outside, then forces the canvas upward.\n\nThe principle is similar to that of an airplane wing.  Of course though, there isn't anywhere enough lift generated to make the car fly.