Kites Honor

Recreational Activities

Requirements

1. Answer the following:
   • When were kites invented?
   • When was the first time someone flew a kite?
   • Cite at least three ways in which kites have aided scientific research and tell how each one affected the world in which we live.
   • Tell the story of Benjamin Franklin and his kite.

   Answer: 1) Kites were invented in China more than 2,000 years ago. The invention is traditionally attributed to the Chinese philosophers Mo Ti (Mozi) and Lu Ban, around the 5th century BC, using light materials such as silk and bamboo. 2) The earliest records of people flying kites come from ancient China, around 500-400 BC. It is said that Mo Ti spent three years building a kite in the shape of a wooden bird, considered the first kite on record; shortly afterward Lu Ban began using bamboo, making them lighter and easier to fly. 3) Three ways kites helped scientific research: (a) In 1752, Benjamin Franklin used a kite to prove that lightning is electricity, which led to the invention of the lightning rod and made houses and buildings much safer against fires caused by electrical discharges. (b) Scientists and weather services began raising kites with instruments (thermometers, barometers) to measure temperature, humidity, and pressure at high altitudes, improving the weather forecasts we use to this day. (c) Lawrence Hargrave (box kite) and the Wright brothers carried out aerodynamic experiments with kites and gliders to understand lift and control, knowledge that led directly to the invention of the airplane and all of modern aviation. 4) The story of Benjamin Franklin: in June 1752, in Philadelphia, Franklin wanted to prove that the lightning of storms was the same electricity he studied in the laboratory. He flew a silk kite with a metal rod at the tip during a storm; on the hemp line, near his hand, he tied a metal key and a dry silk ribbon to protect himself. When a charged cloud passed by, the damp line conducted electricity and he saw sparks jump from the key, proving that lightning is electricity. This discovery led Franklin to invent the lightning rod. — Mo Ti (470-391 BC) is credited with building the first wooden kite. Kites led to the lightning rod (Franklin), aerial photography, and the airplane (Wright). Franklin's experiment was described in a letter from 1752 — he was lucky not to die electrocuted, and the Russian researcher Georg Richmann died repeating the experiment in 1753.

2. Mention some ways in which kites can be used nowadays.

   Answer: You should present to the instructor some current uses of kites: sport and leisure (international festivals and competitions), kitesurfing and kiteboarding (water sports with a board), aerial photography with a camera attached to the kite (KAP), traction for sports such as kite buggy or snowkiting, meteorology for collecting data at altitude, and educational activities in schools and clubs. — Although associated with the children's toy, kites have modern sporting and technical applications. Kitesurfing was born in the 1990s and became an Olympic sport at the Paris 2024 Olympics. KAP (Kite Aerial Photography) has been used in archaeology and low-cost mapping since the 1880s.

3. Explain how kites stay in the air.

   Answer: You should explain to the instructor that the kite stays in the air through the action of the wind pushing it: when the wind meets the kite tilted at an angle of attack, it splits into two currents (above and below), generating a pressure difference and therefore lift. The line balances the wind's pull, keeping the correct angle and the kite aloft. — It is the same aerodynamic principle as the airplane: lift through a pressure difference (Bernoulli) and angle of attack. The line does not pull the kite upward — it only prevents the kite from being carried off by the wind, keeping it tilted. Without wind or without an angle, there is no lift and the kite falls.

4. Define the following terms:
   • kite
   • line
   • good wind
   • bridle
   • tail
   • frame
   • spool

   Answer: 1) Kite: an aerodynamic toy made of thin paper or plastic stretched over a light frame, which flies sustained by the force of the wind while held by a line. 2) Line: the thread (of cotton, nylon, or cerol) that connects the flyer to the kite and through which its height and direction are controlled. 3) Good wind: a steady and moderate wind, neither too weak (does not lift the kite) nor too strong (tears or knocks it down), ideal for flying easily. 4) Bridle: the short line tied to the frame (usually at two points of the spar) where the main line is attached; it is what gives the kite the correct angle of attack to rise. 5) Tail: the long, light tail attached to the bottom of the kite, which serves to balance it, stabilize the flight, and prevent it from spinning or falling. 6) Frame: the light structure (bamboo spars, thin wood, or fiber) that supports and gives shape to the kite, over which the paper or plastic is glued. 7) Reel/spool: the cylinder or support on which the line is wound, used to release and reel in the line in an organized way while flying the kite. — Each term fulfills a specific function in the system. The bridle (also called the harness) is what defines the angle of flight — without it, the kite does not sustain itself. The typical good wind is between 10 and 25 km/h, without gusts, so that the kite stabilizes and rises without diving.

5. What is a common cause of defects in kites?

   Answer: You should explain to the instructor that the most common cause of defects is the kite being out of balance: an asymmetrical frame, spars of different weights or lengths, paper poorly glued on one of the sides, or a bridle with knots in the wrong spots, causing the kite to spin, dive, or fail to rise. The solution is to equalize the spars and adjust the bridle to the central axis. — A kite is a delicate aerodynamic system: a small asymmetry already generates imbalance in flight. That is why the finger test (holding the kite by the towing point and seeing whether it stays straight) is essential before flying. Experienced builders weigh each spar on a precision scale to ensure symmetry.

6. What should be done when a kite keeps spinning while it is being flown?

   Answer: You should explain to the instructor that, when the kite keeps spinning, you should first reel it in and add (or lengthen) the tail, which stabilizes the rear; then check whether the sides are symmetrical and adjust the bridle to shift the towing point slightly until the flight is balanced. The tail acts as an aerodynamic counterweight. — Spinning is a classic sign of longitudinal instability: the center of pressure is ahead of the center of gravity, and the kite cannot self-correct. The tail moves the center of pressure rearward. Flat (diamond) kites almost always need a tail; kites with a three-dimensional frame (box kite) usually do without one.

7. Why is it sometimes necessary to have a tail on the kite?

   Answer: You should explain to the instructor that the tail is necessary to stabilize the kite in the air: it creates aerodynamic drag behind the center of gravity, preventing the kite from spinning, oscillating, or diving in irregular winds. — The tail moves the center of pressure behind the center of gravity, a necessary condition for longitudinal stability. Kites with a three-dimensional frame (such as Bell's tetrahedral or the box kite) already have this balance built in and do without a tail; flat kites almost always require one.

8. Know at least three safety rules for flying kites. Know whether your country has a law prohibiting the use of cerol (cutting line) and why.

   Answer: 1) Three safety rules for flying kites: do not fly near wires and the power grid (risk of electrocution); do not fly on streets, avenues, or near traffic (risk of being run over while chasing the kite); and do not fly on rainy or stormy days (risk of lightning). 2) Is there a law prohibiting cerol? In Brazil, the use of cerol and Chilean line (cutting line) is prohibited by state and municipal laws in several states (e.g., São Paulo, Rio de Janeiro). Why? Because the line reinforced with glass or a cutting product becomes stretched and strung across roads and poles, and can cut and even kill motorcyclists, cyclists, pedestrians, and animals, in addition to injuring the flyer himself. — The combination of cerol + motorcycle causes fatal victims every year in Brazil; that is why Federal Law 14,297/2022 toughened the penalties. Flying near power lines can electrocute — in 2018, cases in São Paulo caused entire blackouts. A storm is a direct risk of death by lightning.

9. Name at least 3 types of accidents that can be caused by the use of cerol (cutting line).

   Answer: At least three types of accidents caused by cerol (cutting line): 1) Serious or fatal injuries to the neck, face, and arms of motorcyclists and cyclists struck by the stretched line strung across the road (using an antenna protector on the handlebars is the common defense); 2) Deep cuts on the hands and fingers of the flyer himself and of anyone handling the line without protection; 3) Injuries to pedestrians and animals (dogs, birds) that run into the line; in addition to falls and being run over when a person chases the kite while looking up, and cuts to those who try to retrieve the line caught in wires. — Cerol and Chilean line (similar) are responsible for dozens of deaths and hundreds of serious injuries every year in Brazil. The line stays invisible, stretched at the neck height of someone on a motorcycle. That is why Federal Law 14,297/2022 made it a crime to manufacture, sell, or use it.

10. Know how to wind the line on a piece of wood. Know how to splice the line with the fisherman's knot.

    Answer: You should demonstrate to the instructor how to wind the line on a piece of wood (holding the stick by the middle and passing the line in a zig-zag figure-eight pattern between the two ends, avoiding tangling) and how to make the fisherman's knot (overlap the two ends, tie a simple knot in each one wrapping around the neighboring line, and pull until tight — this way the two lines are firmly joined). — The fisherman's knot is the classic method for splicing two lines of the same thickness without leaving a weak point. The figure-eight zig-zag on the stick distributes the tension and prevents the line from twisting as it unwinds. This pattern is used in fishing, climbing, and kite flying.

11. Make two of the following types of kites and fly them.
    • Sled kite
    • Delta kite
    • Diamond kite
    • Stingray kite
    • Tetrahedral kite
    • Flat kite
    • Box kite

    Answer: You should build and fly for the instructor two different types of these kites: diamond kite (rhombus shape with two crossed spars), flat sled/parafoil kite (flat and wide, without a tail), box kite (three-dimensional rectangular structure), sled kite (without a rigid frame, in a flexible U shape), delta kite (triangular delta shape), tetrahedral kite (modules of four triangular faces), or flat kite, showing each one flying. — Different kites explore distinct aerodynamic concepts: Alexander Graham Bell's tetrahedral kite (1903) uses triangular modules for maximum lift per weight; the box kite (Lawrence Hargrave, 1893) inspired the first airplanes; the sled kite is stable without a tail because of its flexible pocket shape.