For the design of their gliders in 1900 and 1901, the Wright brothers used the Lilienthal Table given in Figure 1.65 for their aerodynamic data. Based on these data, they chose a design angle of attack of 3 degrees, and made all their calculations of size, weight, etc., based on this design angle of attack. Why do you think they chose three degrees? Hint: From the table, calculate the ratio of lift to drag, L/D, at 3 degrees angle of attack, and compare this with the lift-to-drag ratio at other angles of attack. You might want to review the design box at the end of Section 1.8, especially Figure 1.36, for the importance of L/D.

Transcribed Image Text:

L/D (a)(L/D) max (L/D) max Angle of attack, a Figure 1.36 Schematic of the variation of lift-to-drag ratio with angle of attack.