Presentation1 Glider
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Transcript of Presentation1 Glider
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A light engineless aircraft designed to glide
after being towed aloft or launched from a
height.
Glideris the noun form of the verb to glide
Glider aircraft are heavier-than-air craft and
are supported by an upward force of air.
What is Glider???
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Essentially there are 4 aerodynamic forces thatact on an airplane in flight
These are:
a)lift: upward force(generated by wing)
b)gravity: downward force(due to weight of
the plane)
c)thrust: forward force(power of the airplanesengine
d)drag: backward force(resistance of air
How airplanes fly????
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So for airplanes to fly, the thrust must be
greater than the drag and the lift must be
greater than the gravity.
This is certainly the case when an airplane
takes off or climbs.
However, when it is in straight and level flight
the opposing forces of lift and gravity are
balanced.
During a descent, gravity exceeds lift and to
slow an airplane drag has to overcome thrust.
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A glider can be divided into three main parts:
a)fuselage
b)wing
c)Tail
As shown in the fig.
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The wings can be attached to fuselage by either
making a slot in the fuselage,
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or by dividing in two parts and then attaching
WITHOUT SLOT
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If we are breaking the wing in two parts then wehave an advantage that we can give dihedral angle
to the wing.
But typically for first time users, it is advisable to
cut a slot into the fuselage and then attach the
wing.
Since in this way the wing remains firmly attachedand also since the model is of small size, dihedral is
of little importance.(dihedral :explained in later
slides)
Some tips
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Wing
It is the most essential part of a plane.
When air flows past it, due to the difference in
pressure of fuselages upper and lower parts, alift is generated.
This lift is responsible for balancing the weight
of the plane, and the body can thus fly.
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Basic terminology of wings.
1. Airfoil: Cross sectional shape of a wing2. Leading Edge: Front edge of wing
3. Trailing Edge: Back edge of wing
4. Chord Line: Line connecting LE to TE
5. Camber line: A line joining the leading andtrailing edges of an airfoil equidistant from the
upper and lower surfaces . High camber found
on slow flying high lift aircraft.
6. Camber: It is the asymmetry between the top
and the bottom curves of an aerofoil in cross-
section.
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Figure showing Basic terminology of wings.
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Shape of an airfoil
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The point in airfoil where the lift can be
supposed to be concentrated upon is called the
centre of pressure.
Generally it is located at c/4, where c is thechord length.
The point where the weight of the glider acts is
termed as centre of gravity (CG).
For weight balance, the centre of gravity must
coincide with the centre of pressure.
Important thing regarding wings.
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To bring the CG to c/4 we add some weight at
the nose in the form of coins and paper clips.
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How wings generate lift?
A cross section of a airplane wing showing the top surfaceto be more curved than the bottom surface. This shaped
profile is called an 'airfoil' (or 'aerofoil').
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As the fluid elements approach the wing, theysplit at the leading edge and meets again at the
trailing edge
As a result, the air must go faster over the top
of wing since this distance traveled is larger
Bernoullisequation implies that pressure willbe lower on the upper surface.
This net pressure difference causes lift
How wings generate lift?
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Arrows A and B is air getting split at the same moment,
and meeting up again at the same moment.
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