First flying machine

There are conflicting views as to what was the first flying machine. There are many confident histories, with a large numbers of supporters, that have different views. This may be influenced by the fact that local heroes make more interesting histories, as well as national pride. Different definitions of first flying machine are emphasized, which leads to different claims.

Technical details of defining flight

Flight can be defined as simply not falling when in the air. To do this, some force is needed to counter gravity. If a craft's countering force is not as strong as gravity, then the craft still falls, although slower. To rise from a starting point, the force must be greater than gravity. Since medieval times, rockets were known to provide sufficient energy, but were usually seen as too hazardous for manned experiments. The more common method involved a craft that was, in total, less dense than air. Before treated or synthetic materials were invented, balloons had to be made of many small pieces of natural materials, which couldn?t be made completely air-tight. This limited all early lighter than air craft to hot air balloons. However, such craft can only ascend and descend; they have little or no ability to steer, only work well in cold weather, and quite susceptible to drifting away in even light breezes. Although balloons fly, they are of such limited use that people continued to search for something with a more practical ability to fly.

Related Topics:
Gravity - Synthetic

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While useful flight is distinct from falling, there are many grey areas between them. Flying squirrels, for instance, can't sustain level flight, and may be doing little more than falling, yet what they achieve is certainly useful, since it is part of their natural adaptation for survival.

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The type of falling that merely avoids injury on landing is usually termed "parachuting". This simply requires increasing air resistance to the point where terminal velocity is low enough to make landing safe. However, the slower one falls, the greater time in the air, and the greater the influence of other forces relative to gravity. This means it doesn't take much effort to achieve distance from initial momentum, or even steering from minor adjustments to the shape of whatever is providing the air resistance. In recent years, use of parasails, hang gliders and similar craft have erased most distinction between parachutes and gliders.

Related Topics:
Air resistance - Terminal velocity - Parasail - Hang glider

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An aerofoil is a surface that adds lift when air moves over it. By the shape of the aerofoil, the air over the top is forced to move faster than the air under. Slower air has more pressure, so there is a net upward pressure on the aerofoil, which is lift. The wings of most gliders and aircraft are aerofoils, but kites use the principles of aerofoils also.

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There are various methods of getting air to move over an aerofoil. Forward motion makes the aerofoil move relative to the air. A headwind does the same. A kite is held stationary by a string, and wind moves the air over the kite. A helicopter uses rotating aerofoils.

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For flying machines that use aerofoils, the method of getting the air to move is used by some to classify the invention.

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Anything that falls can easily trade height for some forward motion, and get lift from aerofoils. A glider is usually defined as an aerofoil craft that relies on starting height rather than its own generated energy. But having an internal source of energy (an engine) doesn't always mean it is an aircraft rather than a glider; the engine may be so weak that it doesn't influence the craft's flight. How strong does the engine have to be before it is considered a true aircraft? A good breakpoint would be if the craft provides enough energy that it doesn't lose speed or altitude for a long period. But taking off at the start of a flight is a different situation; this often requires trading speed for height even on modern craft. Treating the takeoff separate from the rest of the flight has complications, as many craft needed ramps to help convert potential energy to forward momentum, catapults to give an initial push, or a starting height to allow a quick trade-off to forward motion. It is difficult to determine how much influence these extra take-off assistances had on the rest of the flight. Some craft didn't seem to need any obvious assistance, yet still required a headwind to add to the effect of the aerofoils in order to take off.

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