mawingho From Hong Kong, joined Jul 2012, 40 posts, RR: 0 Posted (9 months 1 week 1 day 20 hours ago) and read 2086 times:
In the Bank Angle section of the material I am reading, it said "Turning decreases climb performnace due to the additional induced drag".
As I know, Induced Drag is caused by Lift. When turning / rowing, upper wing's lift increase and lower wing's lift decrase which means that the induced drag in total is the same, right?
vikkyvik From United States of America, joined Jul 2003, 8220 posts, RR: 28 Reply 1, posted (9 months 1 week 1 day 19 hours ago) and read 2073 times:
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Quoting mawingho (Thread starter): As I know, Induced Drag is caused by Lift. When turning / rowing, upper wing's lift increase and lower wing's lift decrase which means that the induced drag in total is the same, right?
No. It is true that the upper and lower wing have slightly different amounts of lift in a turn, but in a standard turn without loss of altitude, they are both ABOVE regular unbanked lift.
When you bank, you tilt the lift vector by the bank angle. Gravity doesn't tilt with it, though, so now you have less vertical lift than gravity, and the airplane will start to descend. So you apply back pressure to maintain altitude, which increases the lift coefficient of the wings, which equals more induced drag.
So for a 30 degree bank, for example, the wings have to produce:
lift = (1/cos30)*weight = 1.154*weight.
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vikkyvik From United States of America, joined Jul 2003, 8220 posts, RR: 28 Reply 5, posted (9 months 1 week 1 day 17 hours ago) and read 2027 times:
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Quoting mawingho (Reply 2): Thank you for your reply. However, I am not quite sure how to do this calculation, can you explain more a bit?
Ummm, not really...
The lift generated in a banked level turn is approximately equal to the weight of the aircraft divided by the cosine of the bank angle (where theta is the bank angle):
L = W / cos(theta)
(that's the same equation I wrote before, I just removed the "1/" since it was unnecessary)
tdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80 Reply 6, posted (9 months 1 week 1 day 14 hours ago) and read 1971 times:
Quoting mawingho (Thread starter): When turning / rowing, upper wing's lift increase and lower wing's lift decrase which means that the induced drag in total is the same, right?
No. Induced drag is higher on both wings, although it's even higher on the upper wing.
Quoting mawingho (Reply 4): Why is (1/cos30)*weight, any picture can illustrate this?
Quoting mawingho (Reply 4): is it the compoent of weight to make this formula?
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