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