Thames & Kosmos Wind Racer handleiding
Handleiding
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HOW ARE SAILS
LIKE WINGS?
GEEK
OUT!
Sails and keels work just like the
wings of a plane, but sideways.
The sail produces a sideways “lift”
perpendicular to the direction of the
wind. The keel produces a sideways
“lift” in the water to counteract the
force on the sail.
Wings need cambers, or curved top
surfaces, to produce lift. The bottom
surface is either flat or less curved.
This shape is called an airfoil. In the
case of the sail, it must have a concave
inner surface along which the airflow
is shorter than the airflow along the
convex curve of the outer surface.
The air flowing over the curved
top surface of a wing has to travel
farther than the air flowing under
the surface. After all, the shortest
distance between two points is a
straight line. The same number of
air molecules flowing over a greater
distance results in faster moving air
and thus a lower air pressure above
the wing. Bernoulli’s principle states
that air pressure decreases as its speed
increases. Because the air pressure
is higher under the wing, it pushes
the wing upward. The low pressure
above can’t push as hard downward
as the higher pressure below can push
upward.
Wings and sails also create lift
in another way. As the wing moves
through the air, its lower surface hits
air particles, which push back on it,
generating additional upward force.
The greater the angle of attack, or the
angle of the wing relative to the air
flow, the greater the lift. But only to
a point, because if the wing’s angle is
too great, turbulence forms at the back
of the wing. This turbulence disrupts
the smooth flow of air, and the wing
cannot generate any lift without a
smooth airflow.
Lift
Airfoil
Faster air, lower
pressure
Slower air,
higher pressure
Top surface Camber line
Smooth
airflow
Angle of
attack too great
Turbulence
Bottom surface Chord line
Mid airfoilUpper airfoil Lower airfoil
Hint: They
b o t h h a ve
a c u r ve d
surface...
16
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Productinformatie
| Merk | Thames & Kosmos |
| Model | Wind Racer |
| Categorie | Niet gecategoriseerd |
| Taal | Nederlands |
| Grootte | 5764 MB |
