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The StratoSail® balloon flight path control system
takes advantage of the natural difference in wind speed
at different altitudes in the atmosphere. The wing is
suspended 9 miles below the balloon gondola using a
long thin tether. It hangs on end, so its "lift"
acts sideways rather than upward as in an airplane.
The sideways lift force drags the balloon across the
wind and enables the balloon to be maneuvered towards
regions of interest or away from unfavorable conditions
with a small velocity change applied over a long time.
Computer simulations and operational experience show
that without trajectory control long-duration stratospheric
balloons can driftvirtually anywhere: over politically-sensitive
areas, over high-population density areas, away from
desired payload recovery sites, or even into the other
hemisphere (north or south). The StratoSail® flight
path control technology will be used to divert balloon
flights around uncooperative countries and dangerous
weather systems, or even for interplanetary missions
such as steering balloons at Venus, Mars or Titan. By
providing control over the balloon's direction of flight,
the StratoSail® system will enable new science observation
strategies, increase safety, reduce balloon launch and
landing complexities and increase the probability of
successful payload recovery.
The prototype StratoSail® balloon flight path control
system consists of a wing assembly, winch system, and
9.3-mile long ultra-lightweight tether. The wing assembly
includes a 18-ft long by 3.6-ft wide wing and a 8-ft
long by 2-ft wide rudder, constructed of lightweight
composites, which is attached to a 20-ft long tubular
aluminum boom. The entire prototype wing assembly weighs
only about 125 lbs. The 9-mile long flight tether, developed
by Cortland Cable Company, weighs only 26 lbs. A winch
system testbed has been built and tested to simulate
the characteristics of a system designed to lower a
wing assembly from a balloon gondola at 22 miles in
altitude to about 13 miles altitude, still above controlled
airspace.
Future uses of the StratoSail® balloon flight path
control system include controlling the trajectories
of networks of a few to hundreds of stratospheric balloons
that act as a huge sensing platform from which a variety
of concurrent science observations can be made.
For more specifics,
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