HOT AIR BALLOONING
Hot Air Information
Since the dawn of time, humans have been intrigued by the mystery of flight and the apparent magic that allows birds to take to the air and soar for hours. Attempts to copy birds by building wings that could be flapped by attaching them to the arms failed consistently through the years, and it wasn't until these methods were abandoned that ultimate success was achieved. A hot-air balloon was the first aircraft that successfully allowed man to break the bonds of gravity and to experience flight. The first manned hot-air balloon flight took place in 1783 in Paris, France. The balloon was made of a silk and paper fabric by brothers Jacques-Etienne and Joseph-Michel Montgolfiers, who owned a paper manufacturing business and were looking for a new type of product. Their observation was that paper when burned in an open flame tended to rise. From this they concluded it was the smoke, not the heat that provided the lift. The first manned flight in this balloon was on November 21, 1783, when J.F. Pilatre Rozier and Marquis d' Arlandes ascended to 3,000 feet in the balloon, fueled by damp straw (to make smoke). They traveled five miles during the twenty-five-minute ride. Elizabeth Thible, the first woman to fly in a balloon, went aloft at Lyons, France, on June 4, 1784. The first British-designed balloon was flown by its builder, James Satler, on October 4, 1784, and the first balloon flight in the United States was conducted by Frenchman Jean-Pierre Blanchard at Philadelphia on January 9, 1793. Blanchard and the American Dr. John Jeffries had been the first humans to fly across the English Channel, on January 7, 1785. (In that same year, Blanchard invented, and first used, the parachute.) Modern hot-air balloons are made of ripstop nylon, supported by steel cables. Propane is used to fuel burners, which can produce as much as 8 million BTU's of heat. The wicker baskets, which carry the propane tanks and passengers, are not just traditional, but serve a functional purpose in that in case of hard landings and high wind conditions, they tend to absorb some of the impact. Ballooning is, however, strictly a fair-weather sport and generally does not take place when there is a threat of thunderstorm or in winds exceeding 10 mph. Because low wind conditions are most common right after sunrise and just prior to sunset, most balloon flights take place at these times. Balloon festival spectators, who have risen before sunrise to see the morning launch, are usually rewarded with spectacular ascension.
Quick Facts About Balloons…. How do they steer the Hot-Air Balloon? Generally speaking, you don't. The balloon goes where the wind goes. The trick is to pick the altitude that has the wind direction you want. Surface winds are sometimes blowing 90 degrees opposed to the winds at 3,000 feet above the ground; and sometimes even 180 degrees, and are reasonably predictable. What are the ropes for? The crown line on top of the balloon is used to stabilize the balloon during inflation. "Tether lines" are used to tie the balloon down for display purposes. A "drop line" is sometimes released by the pilot just before landing so the ground crew can pull the balloon to a desired location. How fast do they go? As fast as the wind blows. But if it is higher than 8 mile per hour at ground level, the balloons normally are not going to inflate, as the probability of being dragged, burning the balloon fabric, and landing difficulty increases. How high can they go? Flight in this type of balloon of over 53,000 feet has been recorded, but it is rare. The sport of ballooning is most rewarding at 200-500 feet floating over the countryside. Over populated areas, balloons usually maintain an altitude of at least 1,000 feet. How long do can they stay up? Normally about 2 1/2 hours depending upon ambient (outside) air temperature, and on the weight carried. On a cold day with only one person flying, a 3 1/2 hour flight would not be uncommon. Some are equipped with enough fuel to stay up for over 20 hours to establish distance and duration records. What are they made of? The envelope (bag) is made of about 1,000 sq. yards of reinforced nylon fabric called rip-stop nylon. It is very light (1.3 oz. per sq. yard) but very strong (25 lbs. per sq. inch).
The fabric is chosen particularly because it will not support a flame and retains its strength in such a way that any tears will not usually propagate. Some holes may be seen around the balloon where the flame touched the fabric during inflation and melted it. These are readily patched between flights and don't affect a balloon's performance noticeably. What happens if it gets a hole in it? Little holes up to one square foot are of no consequence. An accumulation will definitely slow the rate at which it will rise, and increase the rate of descent, but not appreciably. How much does a balloon cost? The average balloon costs from $10,000 to $16,000, which includes the envelope, gondola, fuel tanks, and instruments, but does not include any ground support equipment. It is also possible to buy "used balloons" for lower prices. What do you fill it with? These balloons use air only; hot air, of course, makes them rise; as it cools, it will descend. Propane is the fuel carried to burn. Gases such as helium an hydrogen are rarely used in balloon in this country because of expense and volatility. How long does it take to inflate and deflate the balloon? A good ground crew can inflate and launch a balloon in fifteen minutes or less. It takes about the same amount of time to deflate and pack up the balloon after the flight. What kind of fuel is used? Common propane is used which can be purchased most anywhere. Each balloon carries at least 20 gallons and some much more. It is a very stable and predictable fuel, but is highly volatile. It is carried in liquid form, under pressure, in tanks, and routed to the burners in flexible hoses. There it is atomized from the heat and ignited as it is directed upwards into the balloon. The flame may shoot out as far as six to eight feet in the wide-open blast that the pilot controls. Why is the angle of the sun important? The sun is the source of wind, because it heats the earth unevenly. Sunlight falls directly on the equator, for example. The North Pole receives weaker, slanted rays of sunlight. Clouds may keep one area cool while another heats up. Water and land heat up at different rates. Hot air is lighter than cool air, so it rises. As hot air rises, cool air slides in to replace it. The result: wind.
It isn't safe to fly during the daytime when different pockets of air are rising and falling. The Unsung Heroes We are who? We are crew! If you ever have seen a hot-air balloon in flight you know that there is a pilot who is license to take the balloon into the air. "Who are all those people around the balloon?" How does the balloon get in the air in the first place? That's where the ground crew (or chase crew, two names, same job) comes in. Our #1 job is to assist the pilot. This includes setting up the balloon, helping to make sure the basket is arranged and stocked with those things the pilot likes to take along, and to help achieve a safe lift off. Once that is done, we take the chase vehicle and follow the balloon for an hour or so. When the pilot has located a nice field for landing, we will be informed (usually by radio) of the landing site. The goal of the crew is two fold here; we want to have the vehicle at the landing field before the pilot lands, and still have enough time to be waiting in the selected field to assist in any way with the landing operation. Sound pretty simple? Well... it is, most of the time! I have often explained our task as 90% just plain common sense, and 10% training. Every task the crew performs has a reason for why it is done a certain way, and once that reason is discovered, it makes perfect sense. The trick to learning is to ask questions. Lots of questions. I have met many pilots, and have assisted with the set up of every major brand of balloon. I have asked hundreds of questions. I have yet to have any pilot treat a question like it was silly of me to ask. One thing that makes ballooning difficult for the ground crew is one of the same things that make it exciting: the weather. Here in Texas the winds are almost always changing. Depending on what phase of the flight is being accomplished when those winds change means the ground crew must adapt their methods to deal with those changes. This is exactly why hot air ballooning is so exciting.
Every single flight is different! Even if the pilot happens to land in the same field twice (which doesn't happen often) the winds will probably be different. This means the take off and or landing will have something different that needs to happen to help make it a safe flight. That is our job, to help the pilot conduct a safe flight. That's why we are here. (Besides having fun!) How do you become part of a chase crew? You can look up in the sky and follow the next balloon you see until it lands. Please allow the crew to pack the balloon away before you approach the basket. Then all you have to do is tell one of the crew that you are interested in ballooning. You will more than likely be directed to the pilot, who will either snatch you up for their own crew, then and there, or place you in contact with someone who can find you a home. The other way is to look in the phone book (here in Texas we look under "Balloons, Manned"). This will place you in contact with a ride operator (someone who is paid to take you on a balloon flight). You can tell them of your interest in balloons and ask for any information or local club you could contact. Most balloons have a crew of between 3 to 6 people. Most balloon crews are volunteer, and do not get paid. For most of us, it is a hobby. It's how we work off the stresses of the week, and get together to have a good time with an ever-changing hobby. A balloon crew is literally a family affair. Crew people come in all shapes and sizes: singles, married, & entire families can be found. Pick any combination of these types of folks, and they are here too. There are crew people ranging from new born babies, to folks well into their 80's still enjoying the sport. The only special skill needed for the balloon ground crew is a willingness to learn and ask questions. Some tasks require a fair amount of physical strength, but don't worry, there are even more tasks that do not. I have an 8-year-old son who helps with everything he is able to do. But he does help. There are jobs for even young balloonists. I hope you will come back from time to time, as I intend to take a look at each of the major tasks involved during a balloon flight for the chase crew. Anatomy of a Hot-Air Balloon Basically, the hot air balloon consists of three parts: envelope, basket, and burner system. It's a fairly simple piece of equipment, and for what it delivers; it is something of a bargain. If you look at what is available in flying machines, for instance, you may be surprised to find that ballooning is less than half as expensive as the next class of aircraft, the sailplane. Some recent studies have shown that the average price of a new hot air balloon system is about $9,000, but that of a sailplane is $22,000. A piston-driven single-engine airplane with fixed landing gear averages over $31,000, while the same type of plane with retractable gear costs over $64,000. Multi-engine airplanes are three times this price, and helicopters are eight times this price. Turbo-engine aircraft range in the millions. But relatively inexpensive as it is, the hot air balloon is a carefully conceived and crafted flying machine.
Since there are differences in detail among the balloons made by the various manufacturers, we will confine ourselves primarily to discussing the Raven S-55A, one of the most popular types and sizes of balloon in current use. Balloons are categorized by the Federation Aeronautique Internationale (FAI), according to how much air their envelopes can contain. The Envelope The part of the balloon that looks like a balloon is actually called an envelope. Some pilots also affectionately refer to it as "the bag." It is connected to the gondola, or basket, in which pilot and passengers ride, by means of stainless steel suspension cables. The fabric in the envelope is rip stop, fire-resistant nylon, similar to material used in the backpacks or lightweight tents carried by hikers and mountaineers. It is woven in panels, two panels making up what is a gore. There are 24 of these gores, or large vertical sections, in the entire S-55A envelope. The gores are held together by stitching and by heavy duty load tapes, webbing similar to the material used in seat belts in automobiles, which help support the weight of the balloon and minimize strain on the fabric, thus prolonging the useful life of the vessel. The envelope is usually treated with a polyurethane coating to reduce porosity, and in the coating is an ultraviolet inhibitor to help the fabric withstand the rays of the sun. The top cap or crown of the balloon may be designed in one of two ways. The standard top features a circular deflation port that is closed off by a circular panel, which is held sealed during flight by a flexible hook and-loop closure. A deflation port line, usually called the rip line and colored red, extends from the top to the basket and is pulled by the pilot upon landing to effect an instantaneous deflation of the envelope. Pull on the line, and the hook-and-loop closure comes open, and the hot air rushes out. The parachute top also features an opening in the crown, along with a similar circular panel to fill the opening. In this case, the panel is rigged up with lines, as the name suggests, exactly like a parachute. It is used both for effecting a complete deflation of the envelope after landing, and also during flight to vent a limited amount of hot air as a means for controlling vertical ascent or descent. After landing in the parachute top balloon, the pilot pulls on the top line and holds it open for as long as he can until the envelope has been deflated. Balloons built with the standard deflation port also feature an opening in the side known as the maneuvering vent, also initially sealed, like the deflation port by hook-and-loop closure. This vent is operated by a rope called the maneuvering vent line, which extends from the vent to the basket. The pilot pulls the line, causing the side vent to open and allowing the hot air to escape to stop a rate of ascent or initiate a rate of descent. Once the line is released, the vent automatically recloses. A skirt is connected to the bottom section of the envelope with peelable tabs and helps create a stovepipe effect when the burner system is running, channeling the warm air into the balloon and improving fuel efficiency, especially on windy days, by protecting the burner from the wind. Attached to the inside of the balloon envelope, near the top or crown, are temperature indicators known as telltales. These telltales are white when installed but turn black if the air in the envelope exceeds a certain temperature. This permits the pilot to tell at a glance when his balloon may need repair. We mentioned earlier that the cubic capacity of an envelope dictates how many people can be carried aloft safely in a balloon. However, this capacity may be adjusted upward or downward depending on other factors, principally air temperature, altitude and what might be bluntly described as the Fatso Factor. The key is to determine the maximum safe gross weight that can be carried by the balloon on a given day. All balloons are provided with FAA-certified curves for estimating temperature-limited gross weight. These curves show gross weight in pounds versus air temperature in degrees Fahrenheit for operation at various pressure altitudes, usually sea level, 5,000, 10,000, and 15,000 feet MSL.
The Basket Currently, open-air passenger vessels for balloons are made either of wicker or aluminum and fiberglass. A rigid tubular framework extends from the basket upward where it attaches to the 24 stainless steel cables suspended from the envelope. This rigid framework actually serves three purposes: 1 It helps protect passengers; 2 It supports the burner system, which is installed overhead at the top of the basket; and 3 Thanks to the mechanical-fulcrum effect, it provides the basket with stability and less of a tendency to tip over upon landing. Baskets normally come in square or rectangular shapes. Triangular shapes also are available, and on special order one can obtain completely enclosed gondolas, or deluxe baskets with built-in banquette seats and insulated champagne holders. As a minimum, there must, of course, be room on board for securing the necessary fuel tanks and flight instruments. Wicker is the classic or traditional look in a basket, but it is actually not just nostalgia that makes it a popular material, even though it costs more than aluminum-fiberglass varieties. The strong and resilient rattan that is woven around a tubular aluminum frame happens to provide an excellent shock absorber during less-than-perfect landings. The aluminum/fiberglass baskets are quite strong and lighter than wicker, and although they do not have as much "give" on impact, these baskets are often used for commercial ventures where more rugged conditions are the rule. The Burner System If the envelope and the basket are the most visible parts of the balloon, our third major component, the burner system, is the motive force, for it produces the heated air which the pilot uses to lift off and to control his vessel's up-and-down motion once aloft. Normally the burner or burners point directly into the center of the balloon envelope. There is a pilot light very much like the kind found on ordinary gas stoves, and this assures rapid access to heat whenever necessary. There is also a blast valve allowing the pilot to adjust the rate at which fuel flows from the tanks. To draw fuel into the burner, the pilot simply pulls the trigger on his blast valve. The liquid propane gas is carried under pressure from the fuel tank to the burner, where it is set on fire by the pilot light. A pressure gauge on the burner tells what this pressure is. The propane is transferred from tanks in the basket through flexible hose to the burner system. The fuel goes through coils on the burner, which vaporizes the liquid gas. Then the pilot light ignites the vapor, sending a six-to eight-foot flame into the envelope, making a loud whooshing sound and adding heat at the rate of 12 million BTU's (British Thermal Units) per hour. The BTU is defined as the quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit. To give a better idea of the tremendous output of a burner system in a hot air balloon, one burner produces at a rate per hour that would be enough to heat 120 three-bedroom homes comfortably. Propane, the fuel used almost exclusively in hot air ballooning, has the additional advantage of being readily available and quite inexpensive in today's energy-scarce world. Also called liquefied petroleum gas, or LPG, it is a by-product of the petroleum-manufacturing process. Propane is odorless, incidentally, so as a safety measure refineries introduced an ingredient called mercaptan into the gas. Mercaptan has a strong, sweetish scent, which makes gas leaks readily detectable. The propane is stored in fuel tanks, either ten-gallon aluminum or twenty-gallon stainless-steel tanks. The advantage of the more expensive stainless-steel tank is that it is lighter, so you can carry more fuel with less tank weight. On a typical flight, you would carry a minimum of three ten-gallon aluminum tanks or two twenty-gallon stainless-steel tanks. Both types of tanks come equipped with fuel indicator gauges. Experienced pilots consult these gauges but also double check their readings by keeping track of fuel consumption in terms of the amount of time they have been flying. There are two ways of heating air inside the envelope. One is by triggering the blast valve, as mentioned, which when wide open can add heat at the rate of 12 million BTU's per hour. Intermittent blasts during flight enable the pilot to maintain a standard temperature in the balloon, and a standard temperature generally provides a standard altitude for that flight.
The second method of adding heat to the envelope is by using the "cruise" or metering valve. By monitoring the exact flow of propane to the burner, you can then maintain a steady output from the burner, which will provide a standard temperature. This would enable you to maintain a straight and level flight without having to touch the blast valve that often. It's as close as you can come to flying on automatic pilot in a hot air balloon. There are three reasons often cited for including a second burner in a burner system. First and foremost, the second burner provides a safety factor known in the aviation industry as "redundancy." As on a two-engine plane, if one engine fails, the pilot still can get back to earth safely, so in the hot air balloon a pilot can maintain much more control over his destiny if he has a back-up burner to call upon if need be. The second reason is that twice as much firepower is available. This provides more heat instantaneously in case it is needed. Finally, there is a psychological advantage in having the second burner on board. Generally, the more relaxed and confident a balloonist is, the better he flies. Some commercial balloons, incidentally, are equipped with special single burners for super-pressure operations, where certain modifications are used so that the burner can be used for both free and tethered flight.
History of Hot-Air Ballooning
It is now more than two hundred years since the first balloon took to the skies. The Montgolfier brothers, two paper makers from the southern French town of Annonay, were intrigued by the way smoke rises above a fire. They decided to capture its lifting powers with small paper and cotton balloons and, while they were mistaken in their faith in the smoke itself (or 'Phlogiston' as it was referred to at the time), they succeeded in creating the world's first hot-air balloon. On 5 June 1783 they were ready to demonstrate their discovery to the townspeople of Annonay and a small-unmanned balloon was inflated over a fire of straw faggots and then released to fly high above the town square. For their next experiment they sent a sheep, a duck and a cockerel aloft for a flight of eight minutes to ensure that they came to no harm so high in the 'atmosphere'. When these pioneering creatures returned unscathed (except for a broken wing on one of the birds caused by the goat kicking out) they decided it was time for a man to take to the skies. For such an experiment to take place required the permission of the King himself and Louis, concerned by the possible risk to one of his subjects, decreed that two convicts should make the ascent. (If they survived they would be granted a royal pardon, and if they didn't...) The Montgolfier brothers were dismayed by this proposal and after much discussion with the court officials persuaded the king to relent and on 21 November 1783 a brightly decorated balloon rose above an ecstatic Parisian crowd bearing aloft the first aeronauts - the first humans to fly - Pilatre de Rozier and the Marquis d'Arlandes.
Heat for the balloon was generated by a straw fire carried in a brazier slung beneath its mouth and the two men were carried in a narrow gallery encircling it. However as the balloon was only made of paper and cotton they spent much of their time either tending the flames or dabbing out little fires from the smoldering embers with wet sponges fixed on to the end of long sticks. However the Duke d'Arlandes was unable to ignore the splendor of the panorama unfolding down below them, but de Rozier soon reminded him of their plight. 'If you look at the river in that fashion you will be likely to bathe in it soon!' Yet despite the many hazards the balloon landed safely after a flight of thirty minutes. By one of those strange quirks of history, another band of would-be aeronauts had approached the same challenge of manned flight from an entirely different angle. Professor Charles, another Frenchman, had been closely following Faraday's work with the newly discovered gas hydrogen - a gas which has molecules that are more widely spaced and therefore less dense and lighter than air itself. He joined with the Robert Brothers in Paris and together they constructed a rubberized silk balloon to contain enough of the gas to carry a basket or 'gondola' (as it looked like a small boat) and the crew of two. The first of the modern hot-air balloons flew in 1953 and since then there has been a remarkable resurgence of hot-air activity. This has largely been brought about by the marriage of two technologies - lightweight and airtight nylon fabrics, and new powerful burners that burn liquid propane to heat the balloon. All over the world colorful flotillas now dot the sky - including many ingenious special shape balloons in the form of everything from beer bottles to flying cows. The very first of these was the Robertson's Golly, and shown left is a more recent famous flying bear. Nowadays thousands of people throughout the world enjoy the sights and pleasures of going ballooning