Hot Air Balloons Honor

Arts & Crafts

Requirements

  1. Describe the role that each of the following figures played in the development of flying balloons:
    • Joseph Michel Montgolfier and Jacques-Etienne Montgolfier
    • Jean Francois Pilatre de Rozier and Francois Laurent Marquis d?Arlandes
    • Jacques Alexandre Cesar Charles and Nicolas Louis Robert
    • Ben L. Abruzzo, Maxie L. Anderson and Larry Newman
    • Bertrand Piccard and Brian Jones
    • (The Brazilians) Father Bartolomeu de Gusmão and Alberto Santos Dumont

    Answer: 1) Montgolfier brothers (Joseph and Étienne): invented the first hot air balloon, flying on June 5, 1783, in France; they used a fabric structure coated with paper, heated by a fire of straw and wool. 2) Jacques Charles: created the first gas balloon (hydrogen), flying in August/December 1783; he introduced innovations such as the valve at the top, the net over the envelope, the basket, and the use of sand as ballast. 3) Jean-François Pilâtre de Rozier: the first human to fly in a balloon (crewed, 1783) and the first fatal victim of an aviation accident (1785), when he tried to cross the English Channel with a hybrid balloon (hot air + hydrogen). — The Montgolfiers were paper manufacturers in Annonay, France, and their 1783 demonstration balloon reached about 1,000 meters of altitude and traveled 3 km, marking the beginning of aerostation in history.

  2. State Archimedes' principle and briefly describe how this principle applies to the following situations:
    • A piece of cork floating in a container of water
    • A boat floating on the ocean
    • A hot air balloon floating in the atmosphere

    Answer: Archimedes' principle: every body fully or partially immersed in a fluid (liquid or gas) receives an upward vertical force (buoyancy) equal to the weight of the volume of fluid displaced. Applications: 1) Boat/ship on water: it floats because it displaces a volume of water whose weight equals the weight of the boat, generating enough buoyancy to support it. 2) Hot air balloon in the air: the hot air inside the envelope is less dense than the cold air around it; the balloon displaces a large volume of cold air, and when the weight of that displaced air exceeds the weight of the assembly (envelope + hot air + basket + crew), the buoyancy makes it rise. 3) Gas balloon (hydrogen/helium): the internal gas is much less dense than air; the buoyancy of the displaced air exceeds the weight of the assembly and the balloon rises without needing to be heated. — Archimedes (287-212 BC) formulated the principle when he noticed the water displaced in his bathtub, and the same principle explains balloon flight, navigation, and the operation of modern submarines.

  3. Draw a table showing the composition of air with information on weight and volume.

    Answer: Air is composed of approximately 78% nitrogen (N₂), 21% oxygen (O₂), 0.93% argon (Ar), and 0.04% carbon dioxide (CO₂). — The composition of air was determined with precision by Henry Cavendish in 1780 and Lord Rayleigh in 1894, the latter identifying argon as the third largest component.

  4. Draw a table comparing the atomic number, atomic weight, and density of the components:
    • Hydrogen
    • Helium
    • Oxygen

    Answer: Hydrogen has atomic number 1, atomic weight 1.008 u, and a density of 0.0899 g/L (the lightest of the three). — Hydrogen is the most abundant element in the universe (about 75% of visible matter), but rare in Earth's atmosphere because of its low molecular mass, which allows it to escape into space.

  5. Name the 2 gases that are used in gas balloons.

    Answer: The two main gases are hydrogen (H₂) and helium (He), both less dense than atmospheric air, generating natural buoyancy without the need for heating. — The airship Hindenburg exploded in 1937 because it used hydrogen due to an American embargo on helium, leading to the preference for helium in all modern commercial and scientific uses.

  6. Explain how heat/temperature affect the density of air and how this makes hot air balloons fly.

    Answer: Heating the air makes its molecules move faster and spread apart, occupying a greater volume; with the same number of molecules in a larger space, the air's density decreases (it becomes lighter than the surrounding cold air). That is why the balloon flies: the hot air trapped inside the envelope, being less dense than the colder atmospheric air, makes the balloon displace a large volume of heavier cold air. By Archimedes' principle, an upward force (buoyancy) arises equal to the weight of that displaced air. When the buoyancy exceeds the total weight of the assembly (envelope + hot air + basket + crew), the balloon rises; when the air cools and the density increases, the buoyancy decreases and the balloon descends. — At 100 °C, air is about 25% less dense than at 20 °C, according to the ideal gas equation (PV=nRT), providing enough buoyancy to support significant weights in hot air balloons.

  7. Explain the function of each of the following items in the structure and flight of a hot air balloon:
    • Balloon envelope
    • Burner
    • Basket
    • Cylinder
    • Fan

    Answer: Function of each item: 1) Envelope: the large fabric balloon that holds the heated air; its shape and volume determine the buoyancy generated. 2) Burner: burns propane (LPG) to heat the air inside the envelope, reducing its density and generating the flight's buoyancy. 3) Basket/gondola: a compartment of wicker/sturdy material where the pilot, passengers, and gas cylinders are located. 4) Gas cylinders (propane/LPG): store the fuel that feeds the burner. 5) Parachute valve (at the top of the envelope): allows hot air to be released to descend or land; fully opened, it deflates the balloon. 6) Mouth/skirt: the lower opening of the envelope, lined with heat-resistant material, through which the heated air enters. 7) Support cables/ropes: connect the envelope to the basket, distributing the weight. — Modern hot air balloon burners burn up to 10 million BTU per hour and produce flames of up to 4 meters, fueled by propane cylinders carried in the basket.

  8. Name 2 materials that can be used to make the envelope of a hot air balloon and compare the advantages and disadvantages between them, based on their physical properties.

    Answer: You name ripstop nylon (tear-resistant, lightweight, with a silicone coating for heat resistance) and polyester (more resistant to UV and heat, but heavier). — Modern envelopes withstand up to 120 °C, and ripstop nylon is woven with extra threads every 5-8 mm to prevent tears from spreading, in accordance with the FAA standard for certified balloons.

  9. Describe how flying balloons have been useful in:
    • Military campaigns
    • Scientific research

    Answer: 1) Military campaigns: balloons were first used for military purposes at the Battle of Fleurus (1794), serving to observe and reconnoiter the enemy's positions and movements from above. In later conflicts, they continued to be used for surveillance, artillery fire direction, and as barrage balloons to hinder aircraft attacks. 2) Scientific research: balloons became important tools in meteorology, through weather balloons that rise into the atmosphere measuring temperature, pressure, humidity, and winds; they are also used to explore the upper atmosphere and to collect data for scientific studies, carrying instruments to high altitudes that airplanes cannot reach. — British barrage balloons of 1939-45 reached as many as 1,400 simultaneous units over London, forming a network of cables that forced German aircraft to fly higher, making precise bombing more difficult.

  10. At what times of day do recreational balloon flights usually take place? Explain why.

    Answer: Recreational balloon flights generally take place right at dawn (up to about 2 to 3 hours after sunrise) and, less frequently, at dusk (1 to 2 hours before sunset). The reason: at these times the atmosphere is more stable and cool — the winds are weak and steady (no gusts) and there is little thermal turbulence, because the sun has not yet heated the ground enough to generate strong rising air currents (thermals). During the middle of the day, the heated ground produces thermals and more intense, unpredictable winds, which make control difficult and the flight dangerous. In addition, the cooler dawn air increases the density contrast with the hot air in the envelope, generating more buoyancy and requiring less fuel. — Most international ballooning festivals, such as the Albuquerque International Balloon Fiesta in the USA, schedule takeoffs between 6 a.m. and 8 a.m. precisely because of the stable morning thermal inversion.

  11. Describe how the pilot controls the vertical movements of the following balloons:
    • Hot air balloon
    • Gas balloon

    Answer: Vertical control according to the type of balloon: 1) HOT AIR balloon: the pilot ASCENDS by firing the burner, which heats the internal air and reduces its density; DESCENDS by letting the air cool naturally or by opening the valve at the top of the envelope to release hot air. 2) GAS balloon (hydrogen/helium): ASCENDS by releasing ballast (bags of sand or water), making the assembly lighter; DESCENDS by opening the valve at the top to release some of the gas, reducing buoyancy. 3) Hybrid/Rozière balloon (gas + hot air): regulates altitude mainly by heating or letting the hot air surrounding the gas cell cool, saving gas and ballast for long flights. — The parachute valve was invented by Tracy Barnes in the 1970s and revolutionized safety in hot air balloons, allowing the pilot to abort flights with considerable precision in real emergencies.

  12. Describe how the pilot controls the horizontal movements of a balloon.

    Answer: The pilot controls horizontal direction by changing altitude to find wind currents that follow the desired heading. — The atmospheric boundary layer up to 1,000 m presents wind gradients (wind shear) that pilots exploit for navigation; this technique is called 'box flying' in the USA, discovered in the 1960s.

  13. Do research of at least 250 words on the legislation for unmanned balloons in your country.

    Answer: Law 9,605/1998 (the Environmental Crimes Law), in its article 42, makes it a crime to manufacture, sell, transport, or release balloons. — In 2014, ProClima/SP recorded about 700 fires per year caused by balloons in the Atlantic Forest, prompting reinforcement of enforcement campaigns and of the application of Law 9,605/1998 with criminal penalties.