Participants launch paper planes at the 2025 Moorim Paper Korean Cup Paper Plane Competition, held Sept. 27, 2025, at the main stadium of Jinju General Sports Complex in Jinju, South Gyeongsang Province. Moorim will hold this year's competition at the same venue on Oct. 17. [Moorim Paper]
Participants launch paper planes at the 2025 Moorim Paper Korean Cup Paper Plane Competition, held Sept. 27, 2025, at the main stadium of Jinju General Sports Complex in Jinju, South Gyeongsang Province. Moorim will hold this year's competition at the same venue on Oct. 17. [Moorim Paper]

Moorim Paper Korean Cup Paper Plane Competition set for Oct. 17 in Jinju

Official paper is 90 g/㎡ 'Neostar Baeksang' — one A4 sheet weighs about 5.6 g

World records in distance (98.43 m) and hang time (31.2 sec) both held by Chinese teams

What is the ideal paper weight for folding a paper plane? Instinct suggests lighter paper would stay airborne longer, but industry insiders say that is not necessarily true. Paper that is too thin causes the wings to buckle under aerodynamic drag at high speed, robbing the plane of lift. Paper that is too thick, on the other hand, adds weight that works against sustained flight. Like a real aircraft, a paper plane is subject to the competing forces of gravity, lift and drag.

The 7th Moorim Paper Korean Cup Paper Plane Competition, set for Oct. 17 at the main stadium of Jinju General Sports Complex in Jinju, South Gyeongsang Province, offers a chance to see that paper science in action. Hosted by Moorim Paper and officially certified by the Korea Paper Plane Association, the event features three disciplines: distance, hang time, and a relay event introduced this year.

A paper plane's performance hinges on several properties of the paper itself: basis weight (the mass per unit area), stiffness, surface smoothness, and formation (how uniformly the pulp fibers are distributed). To ensure a level playing field, organizers supply every participant with identical sheets. "Results can only be evaluated objectively when everyone competes under the same conditions," a Moorim official said. "We plan to distribute the competition paper we produce to all participants."

In the distance and hang-time events, competitors must use only the official paper distributed on site, and the plane must be made by folding alone — no cutting or gluing allowed.

Why Moorim chose 90 g paper for its competition

The official competition paper is Moorim Paper's own Neostar Baeksang, a 90 g/㎡ uncoated woodfree sheet. Uncoated woodfree paper carries no surface coating layer and is widely used for books, notebooks, writing paper and general printed materials — distinct from coated papers such as art paper, which receive a pigment layer to enhance printability and gloss.

The "90 g/㎡" designation is the paper industry's standard measure of basis weight: one sheet measuring 1 meter by 1 meter weighs 90 grams. A standard A4 sheet (210 mm × 297 mm) has an area of 0.0623 square meters, meaning roughly 16 A4 sheets fit within one square meter. Cut to A4 size, a single sheet of 90 g/㎡ paper weighs about 5.6 grams — compared with about 5 grams for the 80 g/㎡ copy paper common in offices. The difference is just 0.6 grams, but that amounts to roughly 12.5 percent more weight per sheet.

Dropping to a lower basis weight — 70 g or 80 g — does not automatically mean longer flight times. Lighter paper loses stiffness, and when the plane is thrown, aerodynamic drag deforms the wings. If the two wings end up at different angles, the plane rolls or yaws, bleeding energy.

Going too heavy creates the opposite problem: stiffness is easy to achieve, but the airframe itself becomes heavier. In the hang-time event particularly, a higher wing loading — the ratio of the plane's weight to its wing area — makes it harder to descend slowly.

That trade-off is why Moorim settled on 90 g/㎡ for official competition use. According to materials Moorim released based on input from national team paper plane athletes, some adult-focused international competitions use 100 g/㎡ paper, while Moorim's event — which welcomes children and teenagers alongside adults — uses the lighter 90 g/㎡ grade.

Surface quality is another variable significant enough to affect results. The Neostar Baeksang 90 g product has a thickness of 106 ± 3 micrometers and a smoothness rating of at least 45 seconds. Smoothness measures how even a paper's surface is under set conditions: fewer microscopic irregularities and more uniform fiber distribution make it easier to fold both wings into identical shapes.

"Research," the Guinness World Record holder for the farthest flight by a paper aircraft. The plane flew 98.43 meters at an indoor sports facility in Shanghai, China, in December last year, setting a new world record. [Guinness World Records]
"Research," the Guinness World Record holder for the farthest flight by a paper aircraft. The plane flew 98.43 meters at an indoor sports facility in Shanghai, China, in December last year, setting a new world record. [Guinness World Records]

Distance record: 98.43 m — hang-time record: 31.2 seconds

Even with the same sheet of paper, the optimal plane design differs sharply depending on whether the goal is distance or hang time. The Guinness World Record for distance stands at 98.43 meters, set in Shanghai, China, on Dec. 28 last year by a Chinese team led by Liu Liwen with a design called "Research." The previous record was 88.31 meters, set by an American team in 2022.

The shape of "Research" illustrates the design logic for distance flying: a sharp nose, a long fuselage and relatively narrow wings. Rather than generating lift with broad wings at low speed, the design prioritizes withstanding the high velocity of a powerful throw while minimizing drag and maintaining a straight trajectory.

Hang-time design works in the opposite direction. The current Guinness record is 31.2 seconds, set on Feb. 11 this year at an indoor sports center in Kunshan, Jiangsu Province, China. The Chinese team broke the 29.2-second record that Japan's Takuo Toda had held since 2010 — ending a roughly 15-year reign. China now holds both world records, in distance and hang time.

The hang-time record plane, called "Unite," features a heavily folded nose section to center the weight, paired with wide wings to maximize lift area. The design focuses on maintaining lift at low speed and slowing the rate of descent. Competition footage shows the thrower launching the plane nearly straight up toward the ceiling, after which it glides slowly back down to the floor.

Will the weather cooperate? An outdoor venue adds another variable

Unlike most major paper plane competitions, the Moorim event is held not in an indoor gymnasium but at the open-air main stadium of Jinju General Sports Complex. Wind, humidity and rain can all affect results. At the 2024 competition, heavy rain broke out after the qualifying rounds, forcing organizers to suspend the event; the hang-time and aerobatics finals, along with the Super Cup, could not be completed as planned because wet paper changes in both mass and stiffness.

That outdoor setting makes direct comparisons with Guinness world records difficult. The 31.2-second hang-time record set this year was achieved inside the Kunshan Sports Center, where wind interference is minimal. At the Moorim competition, on-site weather conditions are simply part of the contest.

Despite those challenges, the top distance mark at the Moorim competition has climbed steadily — from 50.7 meters in 2023 to 64.52 meters in 2024 and 72 meters last year. Whether a plane at the Oct. 17 competition in Jinju will surpass last year's 72-meter mark is one of the event's main storylines.

"Even a small difference can affect competition results, which is why the quality of the paper itself matters above all else in paper plane competitions," said Jung Tae-young, head of Moorim's customer technology support team. "The Neostar Baeksang has an even, smooth surface and the right level of stiffness, making it the optimal paper for stable paper plane flight."


hong@heraldcorp.com