| For practical purposes, hot air balloons | | | | eventually the air within the envelope is too |
| really can't compete with airplanes and | | | | thin to support the weight of the balloon. |
| helicopters. They're extremely difficult to | | | | The more air within the balloon, the greater |
| steer, and they can only move as quickly as | | | | the buoyancy-so bigger balloons can go higher |
| the surrounding winds. But as a recreational | | | | than smaller ones. |
| activity, hot air ballooning can't be beat. | | | | |
| You're outside, feeling the wind in your hair | | | | A pilot can cause the balloon to rise by |
| and the sun on your face, drifting serenely | | | | turning on the propane burner and heating the |
| over the earth. If you've ever been in a hot | | | | air within the envelope. To bring the |
| air balloon, you know it's an experience you | | | | balloon down, the pilot releases the |
| won't soon forget. | | | | parachute valve. That's a vent in the top of |
| | | | the envelope that allows some of the hot air |
| Hot air is less dense, and lighter, than cold | | | | to escape, cooling the temperature of the |
| air. Because it's lighter, it tends to rise. | | | | remaining air within. This causes the |
| If you've ever taken a dive into a pool, you | | | | balloon to sink gradually. |
| may have felt this effect in water: the | | | | |
| surface water is warm, but as you move | | | | There are no horizontal controls in a |
| deeper, the water gets cooler. That's | | | | balloon, but pilots can still control the |
| because warm water is lighter than cool water | | | | horizontal movement by raising and lowering |
| and tends to rise to the top, like air. | | | | the altitude of the craft. Winds at |
| | | | different altitudes move in different |
| The air within a hot air balloon is heated, | | | | directions. If a pilot has a good working |
| and as it rises, it takes the balloon-and | | | | knowledge of the wind currents in the area, |
| anything attached to it-with it. A cubic | | | | she can raise and lower the balloon to catch |
| foot of air within a balloon can lift about | | | | a current moving in the right direction. |
| seven grams of weight. This isn't a lot of | | | | |
| weight, which is why the balloon has to be so | | | | Still, piloting a balloon isn't an exact |
| big. | | | | science. It's impossible to target the |
| | | | precise location where you'll land. That's |
| The balloon itself is called an "envelope." | | | | why it's usually necessary for someone on the |
| It's usually made of nylon, which is the | | | | ground to follow the balloon by car to meet |
| perfect fabric for hot air balloons: it's | | | | the balloon where it lands and transport the |
| lightweight but sturdy, and it can withstand | | | | equipment. |
| heat without melting easily. | | | | |
| | | | Launching and landing generally take more |
| Below the balloon, a burner is positioned to | | | | work than actually flying a balloon. The |
| send a jet of flame upward into the envelope. | | | | inflation process takes only about ten or |
| The burner uses propane as a fuel. The fuel | | | | fifteen minutes, and is done with a powerful |
| is stored as a highly compressed liquid in | | | | fan. Once the balloon is full of air, it |
| canisters attached to the burner with a fuel | | | | will still lie on the ground until the burner |
| hose. Because it's so highly compressed, the | | | | is fired, heating the air in the envelope and |
| liquid fuel flows quickly through the hose to | | | | causing it to rise. |
| the burner when the pilot turns it on. | | | | |
| There, it's ignited by a pilot light. The | | | | A balloon descends gradually, but can still |
| flame heats up the surrounding metal of the | | | | land with a bit of a bump if the pilot isn't |
| burner, which turns the fuel to gas before it | | | | experienced enough to know how to bump the |
| gets lit. This makes the flame stronger and | | | | basket along the ground to lessen the impact. |
| the fuel usage more efficient. | | | | The wicker basket helps absorb the force of |
| | | | the landing. Wicker is lightweight and |
| If you look at a hot air balloon, you'll | | | | flexible, and absorbs the energy of landing |
| notice a big hole in the bottom where the | | | | better than a solid, less flexible basket |
| burner is. So why doesn't the hot air escape | | | | would. This way, riders aren't jarred when |
| through the hole at the lower end? Simple: | | | | the ride is over. |
| buoyancy. Hot air is buoyant, which means it | | | | |
| can only rise-it can't sink and drain out the | | | | There's nothing like soaring over the earth |
| bottom of the balloon. As long as the air | | | | in a balloon. Hot air balloons are exciting, |
| stays hot, it will continue to rise. | | | | fascinating, and pure fun. If you've never |
| | | | taken a ride in one, you're definitely |
| It won't rise forever, though. The | | | | missing out on an experience you'll never |
| atmosphere thins as it goes up, and | | | | forget. |