Comparison With Span Efficiency Factor
It is frequently assumed that Oswald efficiency number is the same as the span efficiency factor which appears in Lifting-line theory, and in fact the same symbol e is typically used for both. But this assumes that the profile drag coefficient is independent of, which is certainly not true in general. Assuming that the profile drag itself has a constant+quadratic dependence on, an alternative drag coefficient breakdown can be given by
where
-
is the constant part of the profile drag coefficient, is the quadratic part of the profile drag coefficient, is the wing span efficiency factor from inviscid theory, such as Lifting-line theory
Equating the two expressions gives the relation between the Oswald efficiency number e0 and the lifting-line span efficiency e.
For the typical situation, we have .
Read more about this topic: Oswald Efficiency Number
Famous quotes containing the words comparison with, comparison, span, efficiency and/or factor:
“What is man in nature? A nothing in comparison with the infinite, an all in comparison with the nothing—a mean between nothing and everything.”
—Blaise Pascal (1623–1662)
“Envy and jealousy are the private parts of the human soul. Perhaps the comparison can be extended.”
—Friedrich Nietzsche (1844–1900)
“... we’ve allowed a youth-centered culture to leave us so estranged from our future selves that, when asked about the years beyond fifty, sixty, or seventy—all part of the average human life span providing we can escape hunger, violence, and other epidemics—many people can see only a blank screen, or one on which they project fear of disease and democracy.”
—Gloria Steinem (b. 1934)
“Nothing comes to pass in nature, which can be set down to a flaw therein; for nature is always the same and everywhere one and the same in her efficiency and power of action; that is, nature’s laws and ordinances whereby all things come to pass and change from one form to another, are everywhere and always; so that there should be one and the same method of understanding the nature of all things whatsoever, namely, through nature’s universal laws and rules.”
—Baruch (Benedict)
“Weapons are an important factor in war, but not the decisive factor; it is people, not things, that are decisive. The contest of strength is not only a contest of military and economic power, but also a contest of human power and morale. Military and economic power is necessarily wielded by people.”
—Mao Zedong (1893–1976)