Ralgha From United States of America, joined Nov 1999, 1614 posts, RR: 6 Reply 1, posted (13 years 10 months 6 days 3 hours ago) and read 541 times:
Induced drag is a by-product of lift, and the higher your airspeed, the less induced drag is produced. Details follow:
At low airspeeds, the wing must be at a higher angle of attack (AOA)to produce the lift required to hold the airplane in the air. This causes more high pressure air from below the wing to sneak around the wingtips into the low pressure air on top. This causes "wingtip vortices" which are the main source of induced drag. At higher airspeeds, less AOA is required to hold the plane in the air, resulting in less air sneaking around the wingtip, resulting in less powerful vortices and less induced drag.