Hot Air Ballooning Utilizes New Technology
The first hot air balloon flight, back in 1783, was made by a duck, a sheep, and a rooster. On October 15th 1873, a few months after the barnyard team made their historic flight, the French scientist Pilatre De Rozier was carried by his balloon the "aerostat Reveillon" to the end of its 250 foot teather. He stayed aloft for 15 minutes and landed safely. Just a month later, De Rozier and the Marquis d'Arlandes flew, untethered, to 500 feet, and traveled about five and a half miles in a 20-minute flight. That balloon was heated by a straw fire that caused the balloon to catch on fire. Fortunately, the burning balloon landed, its two occupants unhurt. It did however illustrate that ballooning has some inherant dangers.
Since that first flight in 1783, scientists have been applying technology to make balloon flights higher, longer, and safer. Some of the ideas haven't worked out well. Pilatre de Rozier, the world's first balloonist, was killed in his attempt to cross the English channel when his experimental balloon system consisting of a hydrogen balloon and a hot air balloon tied together, exploded half an hour after takeoff. Deciding that hydrogen was not going to work well, scientists tried helium, and the double balloon system (using helium instead of hydrogen) is one of the most successful designs for long distance ballooning, and in fact, is the design that in 1999 Bertran Piccard of Switzerland and Brian Jones of Britain used in their successful attempt to fly non-stop around the world in a balloon.
Some of the other dangers of ballooning have been solved with technology. One of the most obvious dangers is that balloons aren't steerable -- they just float along on the wind, going wherever they are blown. Back in the old days, balloonists would disappear into the blue and no one would know where they's gone, and maybe they wouldn't either. Today we have reliable advanced radios for balloon-ground communication, up-to-date weather information, GPS receivers for location, and locator beacons. In fact balloons now carry much of the same instrumentation one would find upon an airliner.
One of the most dangerous times in a plane flight is during take off. This is true of balloons as well. Getting a good launch can be tricky. Initially the balloon is lying on the ground (hopefully in the correct orientation for the prevailing wind) waiting to be filled with hot air. The capsule is anchored to the launch pad with ropes. As the balloon is filled it picks up the weight of the capsule. When it is filled enough it will have "free lift", the ropes are cut, and the balloon will ascend to its float altitude. Unfortunately, what constitutes enough "free lift" is not necessarily easy to guess. Cut the ropes too soon and the balloon sort of bumps sideways along the ground being blown by the breeze where it could hit a car, a power line, or a tree before developing enough lift to get safely above the obstructions on the ground. Modern balloonists have solved this problem by incorporating load cells into the tie downs. The free lift is measured by the tie-down load cells. A read out tells the crew when enough lift has developed, and they fire little explosive cutters that releases the tie downs, and the balloon lifts off with enough speed to rise safely above the various obstructions.
In addition to solving the question of enough initial lift for a launch, load cells are used to monitor feul use on a balloon. Instead of burning straw, like De Rozier did back in 1873 when he set the balloon on fire, todays balloonists use propane burners mounted above the heads of the passengers to heat the air in the balloon. Like an airplane that runs out of fuel, a balloon that has no propane is going to descend. To avoid unplanned landings, aballoon pilot needs to monitor the fuel being used. One way this is done is by suspending each fuel tank on a load cell. The weight of the tank tells the pilot how much fuel he has burned, and how much he has left.
One of the appeals of ballooning is its simplicity. Even so, modern balloonists avail themselves of every advantage modern technology has to offer including many instruments that are also found on airplanes. Some of the instruments carried by the 1999 Around the World Balloon Race contenders included:
Satcom-C transceivers
Mini-M satellite system
Marine and Aircraft VHF/HF radio
Satellite GPS receiver
INMARSAT C
INMARSAT M
HF radio and VHF radio
EPIRB: Satellite emergency locator
Radar transponder
Marine band radio
406 MC satellite recovery beacon
Janan Frasier writes about the use of Load cells and other technology in our everyday lives.
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