In this laboratory or demonstration exercise, we mount a small airfoil with its long axis vertical at one end of a nearly frictionless rotating platform.1 Air from a leaf blower2 produces a sidewise lift force L on the airfoil and a drag force D in the direction of the air flow (Fig. 1). The rotating platform is kept in equilibrium by adding weights (the measured values of L) to the lower end of a string passing over a pulley and connected to the other end of the rotating platform (Fig. 2). Our homemade airfoils are similar to those tested by the Wright brothers in 1901. From our lift plots in Fig. 3, we can draw the same conclusions as the Wrights about the influence of an airfoil's curvature and shape on lift.
REFERENCES
1.
PASCO Rotating Platform ME-895, www.pasco.com. Cost $400.
2.
Weed Eater Leaf Blower EBV 200 W. Cost $40.
3.
P. L.
Jakab
, Visions of a Flying Machine
(Smithsonian Institution Press
, 1990
), pp. 120
, 141, 147, 150, 198.4.
R. M.
Heavers
and M. G.
Medeiros
, “Laminar and turbulent flow in a glass tube
,” Phys. Teach.
28
, 297
–299
(May 1990
).5.
Our model foil (8 cm long, 1.6 cm high, camber = 0.20) was cut from the lid of a plastic yogurt container.
6.
7.
The Papers of Wilbur and Orville Wright
, Vol. 1
, 1899–1905, edited by M. W.
McFarland
(McGraw-Hill
, 1953
), p. 176
.8.
E. L.
Houghton
and P. W.
Carpenter
, Aerodynamics for Engineering Students
, 5th ed. (Elsevier
, 2003
), p. 38
.© 2011 American Association of Physics Teachers.
2011
American Association of Physics Teachers
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