A paper plane (also known as a paper airplane or paper dart in American English, or paper aeroplane in British English) is a toy aircraft, usually a glider, made out of a single folded sheet of paper or paperboard. It typically takes the form of a simple nose-heavy triangle thrown like a dart.
History Paper airplanes are known to have been made as far back as the mid 19th century, based on an American children's book describing their construction from 1864. The construction of a paper airplane, by Ludwig Prandtl at the 1924 banquet of the International Union of Theoretical and Applied Mechanics, was dismissed as an artless exercise by Theodore von Kármán:
Prandtl was also somewhat impulsive. I recall that on one occasion at a rather dignified dinner meeting following a conference in Delft, Holland, my sister [Josephine], who sat next to him at the table, asked him a question on the mechanics of flight. He started to explain; in the course of it he picked up a paper menu and fashioned a small model airplane, without thinking where he was. It landed on the shirtfront of the French Minister of Education, much to the embarrassment of my sister and others at the banquet. Over time, paper model aircraft have gained design improvements in velocity, lift, propulsion, style, and fashion.
Advanced paper gliders
Developments Paper gliders have experienced three forms of development in the period 1930–1988:
High flight performance Scale modeling Use of CAD software Ongoing development of folded/origami gliders over the same period has seen similar sophistication, including the addition of the following construction refinements
Increased fold-count, sometimes of an intricate nature Explicit kirigami (cutting of paper) as a component of design Requirements for additional ballast to ensure flight performance
Technological introductions Technology responsible for the proliferation of advanced paper plane construction:
Inexpensive CAD software for 2D part design Widespread manufacture, and inexpensive nature of acetal air-annealed glues, e.g. Bostik Clear-bond. Inexpensive ink and laser computer printers, for accurate aircraft part reproduction The advent of the Internet, and widespread information sharing
Material considerations Compared to balsa wood — another material commonly used to fabricate model planes — paper's density is higher; consequentially, conventional origami paper gliders (see above) suffer from higher drag, as well as imperfectly aerodynamic wing chords. However, unlike balsa gliders, paper gliders have a far higher strength-to-thickness ratio: a sheet of office-quality 80 g/m2 photocopier/laser printer paper, for example, has approximate in-scale strength of aircraft-grade aluminium sheet metal, while card stock approximates the properties of steel at the scale of paper model aircraft.
Directions in advanced paper aircraft design Unmodified origami paper aircraft have very poor glide ratios, often not better than 7.5:1 depending on construction and materials. Modification of origami paper gliders can lead to marked improvements in flight performance, at the cost of weight and often with the inclusion of aerodynamic and/or structural compromises. Often, increases in wing loading can encourage breakdown of laminar flow over a wing with a hybrid of origami and glued and taped construction. Professors Ninomiya and Mathews developed more directed design strategies in the late 1960s and the 1980s. Previously, paper model aircraft had been designed without an emphasis on performance in flight. By using aerodynamic design, and fluid dynamics, both professors were able to design models that exceeded previous flight performance criteria by a very wide margin. Ranges of flight increased from the typical 10+ meters to 85+ meters, depending on energy input into the gliders on launch. At present, the work of the two professors remains the last serious research work on improving the flight performance of paper model gliders. Collaborative work by enthusiasts through online forums and personal websites are mostly developments of these original glider types. In the field of scale model design, there are at present many possibilities for advanced design. Profile gliders encounter a limitation for improvement of flight performance based on their wing types, which are typically curved-plate aerofoils. In addition, fuselages are either balsa-paper or paper laminates, prone to warping or breakage over a very short time. Improvement in performance is possible through modelling three-dimensional fuselages which encourage laminar flow, and in internally braced wings which can then have high-lift aerofoil profiles, such as the Clark Y or NACA 4 or 6 series, for high lift.
White Wings
In Japan in the late 1960s, Professor Yasuaki Ninomiya designed an advanced type of paper aircraft, which were published in two books, Jet Age Jamboree (1966) and Airborne All-Stars (1967). Designs from these books were later sold as the 'White Wings' Series of paper glider packs from the 1970s to the present day. White Wings are a stark departure from conventional paper aircraft, in that their fuselages and wings are paper templates cut and glued together. They were designed with the aid of low-speed aerodynamic engineering design principles. Construction of the models is of Kent paper, a grade of cartridge paper sold in Japan. The early models were explicitly hand drawn, but by the 1980s these had their parts drafted with the use of CAD software. Ninomiya's designs also included, for the first time in any paper model, working propellers driven by airflow, in particular for his profile scale models of the Cessna Skymaster and Piaggio P.136 of 1967. Noteworthy as well was the careful design of gliders so that they could fly without ballast – his F-4 Phantom II model is able to be flown immediately without recourse to paperclips, etc. The high performance gliders have fuselages that are kept rigid by the use of a balsa fuselage profile bonded to the paper components. The paper used is quite heavy, approximately twice the weight of standard drawing cartridge paper, but lighter than lightweight cardboard. Original White Wings were entirely paper, requiring patience and skill. Later however, balsa-wood fuselages were used, and White Wings were sold "pre-cut", making construction easier. The aerofoil used is a Göttingen 801 (curved plate), and a pattern is supplied as a cutout part of each kit.
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