Could someone help me out with a simple question about the angle of attack of an airfoil. What I don't understand, and cannot get an answer to is this:- If an aircraft is climbing the angle of attack is said to be greater than if the same aircraft were flying horizontally. When the aircraft is fying horizontally I can understand that the air rushing over and below the wing is coming from a head on horizontal direction. However, when the aircraft climbs, surely the 'oncoming' airflow is meeting the wing at exactly the same angle as the wing is cutting through the air. I don't know if I'm making sense so bear with me: When I look at 'angle of attack' illustrations and drawings of airfoils and how they behave in relation to air passing over and beneath them, the wing is shown pitched at an angle, and the aiflow is shown to be coming at the wing horizontally. I can't understand how this can be and hope someone can put me out of my misery.
Thanks, john
replied to: johncooper123
Replied to: Could someone help me out with a simple question about the...
John, I haven't gotten into many discussions on this type subject in a while. However, having received my degree from the Navy Post Grad School, and spent 31 years flying jets with the Navy, maybe we can put it in layman's terms. When you are flying straight and level, we assume we are in equilibrium. This we have lift and weight as opposing forces and thrust and drag as opposing forces and all are such that we are neither climbing descending or accelerating or decelerating. If we change the angle of attack on the airfoil, then we must assume some new condition exists. Are we still in level flight? If so, then something must change to keep us there. Do you see where I am heading? If we are no longer in level flight, then something must be changing. Let's assume we enter a steady state climb. We still have a horizontal vector, although if we don't increase our indicated airspeed, then the chord of the airfoil is going to assume the line of instantaneous aircraft velocity, and the actual horizontal velocity will be less than before. Likewise, since we increased the aoa of the airfoil, we will have a vertical vector so we will be climbing. the change in our angle for the airofil chord will essentially be the aoa until such time as we are actually in the steady state climb, and then the aoa will revert back to the instantaneous line between the chord and the new steady state wind. And, we continue to climb from the verticle vector we established. I'm not a professor, and i don't have any of my books with me here, i just teach math in high school now that I am retired. But if required, i can probably refer you to someone who can give you the detailed gritty parts of this idea. For a lot of this stuff, one must assume an isolated body and surrounding air. that also comes into play. Hope this helps a bit. CaptainE
