Balloons set for safer flight

Global Aerospace Corporation has rolled out a full-scale prototype StratoSail balloon flight path control system that will help control the flightpath of NASA’s stratospheric balloons. Currently balloons simply drift with the wind

A StratoSail balloon flight path control system is a lightweight and low power means of steering balloons and, according to Global Aerospace, nothing like it currently exists.

The StratoSail balloon flight path control system is said to take 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 aeroplane.

The sideways lift force drags the balloon across the wind and enables the balloon to be manoeuvred towards regions of interest or away from unfavourable 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 drift virtually anywhere.

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 reportedly 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 an 18-ft long by 3.6-ft wide wing and an 8-ft long by 2-ft wide rudder, constructed of lightweight composites, which is attached to a 20-ft long tubular aluminium boom.

The entire prototype wing assembly weighs about 125 lbs. The 9-mile long flight tether, developed by Cortland Cable Company, weighs 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.