All hot air balloons are considered FAA-regulated aircraft with a classification of "Lighter-Than-Air." This classification is given to any aircraft without lateral control. As you will learn, a hot air balloon does not have the ability to turn to a specific heading or go where the pilot would like for it to. They are required to undergo regular maintenance as specified by the FAA and must adhere to certain flight restrictions, again, as identified by the FAA. This is all for the safety of the passengers in the balloon and all others on the ground in the line of flight.
Basic anatomy of a Balloon
This is the light-bulb shape that holds everything in the sky. The envelope is made of a very durable, rip-stop nylon. This of your wind-breaker. Same thing. Some manufacturers have created their own, patented weave of nylon, one of which is called Diamond Weave. If you look at this up close, the horizontal weave is in a diamond pattern which further enhances the rip-stopping capabilities. The individual grooves of an envelope are called gores. Each of these gores are constructed with individual panels of fabric. Each seams consists of 3 stitches and each gore is held together with the same 3-stitch process but also includes a heavy nylon webbing that holds nylon-coated kevlar rope that span from the top of the balloon to the basket - about 100-120 feet each for average-sized envelope.
Balloons are measured by their volume of hot air they are able to contain and can range from very small 25,000 cubit feet to the largest (that I'm aware of) of more than 1 million cubit feet. For comparison, think of a basketball. A basketball is 1 cubic foot in size. These hot air balloons could hold 25,000 basketballs in the envelope. The average size for a commercial ride balloon is between 120k-260k but there are certainly much larger ones!
At the top of the envelope, you will find what is called the parachute top. This is the part of the envelope used by the pilot to slowly release hot air and cause the balloon to descend. He does this by simply pulling on a rope that is tied off inside the basket.
The bottom of the envelope has the skirt. In the diagram pictured, this is an extra piece of fabric that is meant to protect the burners' flame from outside wind forces. On newer balloons, the skirt is used to funnel air into the balloon to assist with inflation.
Typical life for an envelope is approximately 600 flight hours.
These are the balloons' engines. They are the heat source that warms the air inside the envelope to gives the aircraft the power of flight.
Notice we have 2 burners shown here. Smaller balloons will only have 1, much large balloons will have 4. Each burner can emit upwards of 12 million BTU (british thermal units). Yes, I said million! That's not a mistake. Together, they will produce 25 million BTU of heat. In comparison, your backyard barbecue grill produces about 65,000 BTU.
These burners are made of all stainless steel for a lifetime of use and are mounted on a stainless steel frame that allows for full movement. This allows the pilot to direct the 30 foot flame they produce into the mouth of the envelope during inflation.
You will also notice two color of triggers - one of red and one is blue. The red is the full-power throttle. It burns the fuel the fastest and the provides the hottest output for quicker transitions in flight. The blue trigger provides a brighter, more yellow flame. This does not burn as much fuel or product the hotter flame, but, sure makes the balloon look pretty during that evening balloon glow event!
The Basket (a.k.a. The Gondola)
The basket, gondola, "bottom end" - whatever you call it, however you refer to it, it serves the same purposes. This is where you will be standing for the entire flight.
Once again, these also come in all shapes and sizes depending on the number of passengers that are expected. The smaller the basket, the smaller the envelope require to lift.
They are all made of rattan wicker for its durability and long life. Wicker is the go-to choice for balloons manufacturers because due to its ability to flex along with the frame of the basket. Many have tried using plexiglass or sheetmetal used to build cars, but, both of these materials were either too rigid and inflexible or were ruined upon the first landing. Can you imagine taking your balloon basket to the auto-body shop for repairs? Wicker, if properly taken care of, can last 20+ years. It is also lighter than the other options.
Reinforced cut-outs in the wall of the basket are used as step-holes for easier entry and departure for passengers. The entire basket is trimmed out with leather that provides protection of the wicker on the bottom corners/edges and around the top bolsters for the safety of the passengers during flight. These are also padded for additional comfort.
Each corner of the basket you may find a fuel tank. No need to be alarmed, some of these fuel tanks were used in space. They are very strong under many high-pressure scenarios. Fuel lines are run from each tank up to the overhead burners.
Fuel & Fuel Tanks
Tucked away in the corners of the basket, you will find our fuel tanks, just as depicted in the image above. The fuel of choice for your balloon adventure is liquid propane gas (LPG), just like your backyard grill. Propane is a stable and predictable fuel, but highly volatile (burns easily). It is carried in liquid form, under pressure in the tanks, and supplied to the burners through flexible hoses. Your grill runs on the vapor off the top of the tank, whereas, these fuel tanks feed propane off the bottom of the tank in pure liquid form.
Each tank typically holds about 15-gallons of LPG. This provides sufficient fuel for about 1.5 hours of flight, although, the typical ride is only between 45-60 minutes.
There are many other items and tools found on a hot air balloon. Here is a quick run-down of some additional features you will find:
- Turning Vents - The envelope may have large 'slits' around the center of the fabric (known as the 'equator'). These openings in the fabric allow the pilot to expel hot air out of the side of the balloon, causing the entire aircraft to rotate on it's 'Y' axis. This is useful for ensuring a logo on the balloon is seens by spectators on the ground or to prepare for landing with the proper side down.
- Cushioned Floor - If you are going to be standing for the entire ride, you want to be comfortable, right?
- Drop Line - This will be hanging in a bag on the inside of the basket and connected via carabiner to a rope handle between two fuel tanks. This is used to provide grounds-person a tether in order to maneuver the balloon to a better landing location - to pull balloon away from trees, power lines, or back to dry land (if stuck over a lake) and into a more open location.
- Flight Electronics - Most pilots today will use a GPS with a moving map that shows exactly where they are at any given moment. They will also utilize a flight computer that displays rate of ascent/descent as well as temperature at the top of the balloon (either via a cable or wireless remote).
- Communication Devices - In order to direct ground crew to the landing location, pilots will use 2-way radios. These can be either standard family radio systems (FRS) that can be purchased at your local sporting goods store or more expensive UHF/VHF radios which are able to provide a more private conversation. They will also carry an aviation radio in order to communicate with other local air traffic and air traffic control towers, as necessary. A cell phone is also handy to have in case the battery on the 2-way radios weren't charged the night before.