# spl7b - τ τ 3 (1) ref where the constants are set to...

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Airfoil Characterization 23 Mar 06 Lab 7 Lecture Notes B Six airfoils suitable for a multipurpose light electric aircraft are shown overlaid in Figure 1. The thickness/chord ratios vary from τ = 0 . 07 to τ = 0 . 12 . Computed drag polars are shown in Figure 1: Six airfoils suitable for light electric aircraft. separate plots. The drag coeﬃcient is in eﬀect a function of the three variables ( c , Re, τ ). For optimization calculations, it is desirable to approximate this function, preferably with explicit formulas. A suitable approximation is Re ± ² ³ ´ Re µ a c d ( c , Re, τ ) c d 0 + c d 2 ( c c 0 ) 2 1 + k
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Unformatted text preview: τ τ 3 (1) ref where the constants are set to match the computed polars over narrow parameter ranges of interest. The following constants give a reasonable approximation for the “slow” range, 0 . 8 ≤ c ℓ ≤ 1 . 0, 40000 ≤ Re ≤ 60000. Re k c d 0 = 0 . 020 (2) c d 2 = 0 . 05 (3) c ℓ 0 = 0 . 8 (4) τ = 350 (5) ref = 50000 (6) a = − . 8 (7) The following constants give a reasonable approximation for the “fast range, . 2 ≤ c ℓ ≤ . 3, 80000 ≤ Re ≤ 120000. Re k c d 0 = 0 . 0115 (8) c d 2 = 0 . 0 (9) c ℓ 0 = 0 . 2 (10) τ = 350 (11) ref = 100000 (12) a = − . 5 (13) 1...
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## This note was uploaded on 01/28/2012 for the course AERO 16.01 taught by Professor Markdrela during the Fall '05 term at MIT.

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