After seeing Steve Fossett embark upon his second attempt at a solo circumnavigation of the world in a hot air balloon, I had to wonder: How does he ensure that the balloon actually goes around the world?
Is it a matter of the winds having a constant westerly or easterly vector at a certain altitude (or various altitudes)?
Is there some sophisticated wind measuring and predicting device that allows him to know in which direction the wind will go and at what altitude?
If the answer to either of these questions is true then I can understand that he could control the balloons directional flight by simply varying its altitude.
Otherwise, is there some other method of steering a hot air balloon? Balloons do not seem to have anything resembling sails.
This also brings up another semi-related question: What is the definition of circumnavigation anyway?
If I start very close to one of the poles, can I just walk around in a little circle and say that is circumnavigating the planet?
I am pretty sure that Fossett isn’t going to follow the equator all the way around so what criteria is necessary in order to have completed a circumnavigation?
I tis my understanding that no, one cannot steer a hot air ballon, it si soley dependent upon the winds. In Fosset’s case, he was doign it at very high altitudes and was being pushed along by the jet stream, I think…
As far as circumnavigation, well, I’m sure someone will come along and answer that one…
There is no steering of a hot air balloon. Your choices are: make the balloon go up (within your balloon’s limits), make it go down (or land), or stay at your altitude.
That said, winds are really a fascinating and complex subject. They can blow in different directions at different altitudes. Depending on the altitude, they may be affected by geography, the local weather, or prevailing winds.
There are prevailing wind streams, depending on the time of year, that blow (more or less) consistently in a given direction. Sailing ships used to depend on these heavily for major routes.
You don’t necessarily use any devices for measuring where the wind goes at different levels, as you’ve asked; instead you look up the weather history for the regions of interest.
So when planning a long trip like this, you need to study in detail the major trade winds, the altitudes they are at, and when they change. What he’s trying to do is certainly possible, but I’m sure it has to take a lot of planning, and studying where the winds go.
As for circumnavigation, since there is no one “judging” his feat, it’s really a question of public opinion. If he looks like he took as long a trip as a straight equator trip would be, or close to it, that would satisfy most people. On the other hand, if you make a trip to within 5 feet of one of the poles as you suggest, and make a little circle around it, people will be far more impressed with your trip to the pole than they are with your trip around the world.
Q: What constitutes “around the world?” The Earth is 25,000 miles around at the Equator, but Fossett is staying well south and probably won’t travel that far. Will his flight still qualify?
A: Yes. As established by the Fédération Aéronautique Internationale, the rules say a pilot must set a course of waypoints within a band of the Earth that stays at least 30° latitude south of the North Pole or 30° north of the South Pole. The lines joining those waypoints (on a “great circle” projection) must stay outside those polar caps, although parts of the actual flight can drift inside them.
Actually, if conditions are right, you can steer a hot air balloon to a limited degree
(for the persnickety - my source was the pilot flying a hot air balloon I happened to be riding in)
As already pointed out, you can go up and down in a balloon. It is not uncommon for the winds to be traveling in slightly different directions at different altitudes. So, at the surface the wind may be blowing due east. At 5000 feet, it may be blowing east-north-east. Stay low, you’ll travel more or less east. Go high, your course will veer to the north. Under such conditions you can’t possibly travel south or west, but the difference in wind direction at various altitudes may be sufficient to steer you towards a certain point, or away from an obstacle.
The real trick is having some idea of where the wind is blowing, how hard, and how to make the best use of it.
These guys circumnavigating the globe tie into every weather reporting system they can in order to track winds, and go up to stratospheric heights to catch the jetstream. The sport is also highly seasonal, since jetstream hieght, direction, and speed changes with the season. It’s pretty complicated once you get into the details, and since I’m not a balloon pilot I’ll take a pass on anything more detailed than the above.
There are also weather models that provide global coverage. That means that, even though the high altitude winds were not directly measured, they are interpolated and forecasted based on upstream winds.
Weather satellites would also be useful. Although they don’t directly measure windspeed aloft, you can watch how fast the clouds are moving in a time lapse loop. And the jet stream shows up pretty well in water vapor images.
Fossett’s ground crew couldn’t tell him exactly what the winds are at every altitude, but they might still be able to give him some general advice.
Actually, balloon envelopes rather closely resemble sails. It’s their lack of anything resembling a keel that makes them non-dirigible. A sailboat is steerable because it partakes of two media – water and air – whose motions are rarely identical. Remove the connection with either, and an object must then merely drift (or use some sort of stored power).
As Broomstick said, balloons can be steered in the right conditions.
At the Albuquerque International Balloon Fiesta they have a ‘key grab’ competition. The game is this, they put a set of car keys on a 30 or 40 foot pole with a flag attached to the keys. The Balloonist who can pilot the balloon close and grab the keys wins the car. I don’t know how far away the Balloons start since I never went to that particular event but I do know it takes alot of skill to win that event. For more details click http://www.aibf.org/events/schedule.htm
During the mass ascention more than 650 balloons take off in a short period of time.
I grew up in ABQ and the balloon fiesta was an event I always looked forward too. There is nothing more magical then walking out the door and seeing hundreds of balloons in the pure blue New Mexican sky.
The Balloon Glow ® is also really cool. They get all 600+ balloons together on the launch field at night and light them all up. A truely amazing thing to see.
I recently got to participate in a high-altitude research balloon flight. There is a general known trend for altitude vs. wind speed and direction, based on decades of measurements with weather balloons and aircraft. Weather balloons are still launched regularly (daily in some places), which provides updates on current wind conditions at various altitudes. But in the end it comes down to trial and error - adjust the altitude until you find a wiln blowing in the right direction at the right speed. In our case the wind at the target 41,500 meter altitude was slower than predicted, and we had to lower the balloon by about 1,000 meters to catch a faster wind.
The following won’t apply to Steve Fossett, but you can steer a balloon if you can make the balloon move either faster or slower than the wind. This was the method used by Solomon Andree in his attempt to reach the north pole by balloon in 1897.
The balloon was to trail three very long ropes which would drag on the ground and cause the balloon to move slower than the wind. A sail was rigged to the front of the balloon to serve as a reverse rudder. (Actually the sail arrangement was more complicated than this, but I’m not competent to describe it accurately)
In test flights Andree was able to deviate 30 degrees from the direction of the wind.
Needless to say, he didn’t make it to the north pole.