It's light weight frame and powerful flight muscles might lead you to believe that the eagle uses brute force to lift itself into the air, but this is only partially true. Eagles get a little help from nature. To understand how an eagle flies (or for that matter how a jet plane flies), you have to understand some physics.

Look at the cross section at the right. The air flowing over the top of the wing is what actually lifts the bird into the air. Air flowing over the top of the wing moves faster, causing lower air pressure. Because the air pressure on the top of the wing is lower than on the bottom, the wing lifts. The faster the air moves over the top of the wing, the lower the air pressure. If the air moves fast enough, the wing will lift not only itself but also anything attached to it, in this case an eagle's body.

Original: January 1998
Updated: 11 February 1998
Comments: bradwood@indiana.edu