How does a Glider work?
Gliders
are autonomous submarine vehicles designed to
observe for long time periods the interior of vast
ocean areas at lower cost than oceanographic ships
and moorings. Structurally, a buoyancy control
allows Gliders vertical motions in the water column.
Besides, Gliders employ their hydrodynamic shape and
small fins to induce simultaneous horizontal
motions. In summary, changing buoyancy together with the hydrodynamic
structure allow Gliders to carry out saw-tooth
trajectories between the ocean surface and a
prescribed depth along prescribed directions. When
the Glider is at surface, positions obtained by GPS
and the data collected at depth are transmitted to
the land base via a 2-way satellite communication
system. This also allows to
change its mission programming or to command it back
to the base.
In
general, the instrumentation integrated in the
Glider is limited by the electrical consumption and
the hydrodynamic drag. Presently, Gliders transport
conductivity, temperature and depth (CTD) sensors
with similar accuracy to those employed from
oceanographic ships. Integration of optical sensors
is still under development.
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Gliders are driven by positive and negative
buoyancy created
by
a change in volume.
No propeller is required.
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Wings convert vertical velocity into forward
velocity.
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Glide downward when denser than surrounding
water and
upward when buoyant, in a sawtooth pattern.
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Control of mass distribution : effect on
vertical velocity,
roll and pitch
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Control of angle of descent/ascent and
direction |
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