PPRuNe Forums - View Single Post - Thirty Years of donning it wrong.
View Single Post
Old 3rd May 2001, 16:02
  #4 (permalink)  
Basil
 
Join Date: Jun 2001
Location: UK.
Posts: 4,390
Likes: 0
Received 1 Like on 1 Post
Post

Encarta 98 says that lift is caused by deflection of air downwards due (for the top surface) to Coanda effect, and:
"One of the fundamental forces studied in aerodynamics is lift, or the force that keeps an airplane in the air. Airplanes fly because they push air down. The leading edge of an airplane wing is higher than the trailing edge. As the wing moves through the air, it pushes down the air that flows underneath it. The third law of motion formulated by English physicist Sir Isaac Newton states that every action causes an equal and opposite reaction (see Mechanics: The Third Law). As the wing pushes the air down, the air pushes the wing up. Lift is often explained using Bernoulli’s principle, which relates an increase in the velocity of a flow of fluid (such as air) to a decrease in pressure and vice versa. The pressure on the upper side of an airplane wing is lower than that on the lower side, but this is an effect of lift, not its cause."

I queried this with the Faculty of Aerodynamics at Imperial College a few years ago and they adhered (pun intended) to the view that Bernoulli Effect is a cause, and not an effect, of lift.

I'd have thought that both the Newtonian and Bernoulli theories are valid and inter-related; neither likes alpha>stalling AoA well, unless you're up for a spot of fun

It's at:
http://www.telegraph.co.uk/et?ac=002.../3/wfly03.html
Basil is offline