Paper Airfoil Aerodynamics

Missing figures

Two basic principles of fluid dynamics underlie all objects in flight: The forces of Lift, opposing the downward acceleration of gravity, and the forces of drag due to air-resistance. Both forces, properly harnessed and controlled lead to such ingenious devices as the parachute and the helicopter. Aerodynamics, the field of fluid dynamics involving the flow of gasses, even has applications in fields as separate as the automotive industry, fire-safety, and golfing.

The aerodynamics of paper airfoils, and additionally, the study of airfoils of small size and low mass are allowing the emergence of a new generation of aircraft: low-speed, affordable aircraft for a variety of uses: military reconnaissance, civilian law enforcement, and interplanetary exploration.

This web-project will explore and discuss some of the fundamentals and phenomena regarding such low-speed airfoils. Constructing paper airfoils is one easy and enjoyable way to study such aerodynamics.

Daniel Bernoulli, a member of the Swiss family of mathematicians, studied the dynamics of fluid flow. He is honored today with a principle of fluid flow named after him: Bernoulli?s Principle. Bernouli?s principle shows that the average velocity of an ideal fluid is directly proportional to the pressure (A force over an area) it exerts upon a surface along that flow.

Figure 1.1 shows an example of a device used to measure the velocity of moving fluids utilizing this principle. A pitot-tube utilizes the differences in pressures between the stagnant air at the tip and the moving air across the opening to determine the velocity. A greater difference in pressures means a greater fluid speed.

According to popular myth, Archi...

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...t. Although, typically, increasing the thickness of a wing generally increases its curvature, leading to greater lift. For the case of paper airfoils, which are mostly flat, increasing the curvature of the wing leads to a loss in stability and a very large increase in drag.

5. Airfoils with shorter chord lengths typically suffer from less viscous drag than those of longer chord lengths. These wings are called high-aspect ratio wings, The aspect ratio is the ratio of the wing's wing-span to it's surface area. For paper airfoils, due to lack of rigidity at long lengths and short chord lengths it is possible for a wing to fold in on itself at speeds of sustainable flight. This typically puts an upper limit to a wing's span of only a few tens of centimeters when it is constructed of paper, and therefore most paper airfoil wings are low-aspect ratio.