Bernoulli or Coanda

[Basil]

Who gets the blame in subsonic lift lectures these days; Bernoulli or Coanda?:confused:
(also asked mil forum)

[flying jocks]

The coanda effect is the explanation offered in Microsoft encarta encyclopedia. Allegedly, they get their information from the boeing company.

Every other reference, school or flying club will tell you that bernoulli's theory is the principle for lift.

Unless you are an aircraft engineer designing a new type of wing, does it really matter? Years of classroom teaching supporting the latter method has produced perfectly good pilots. Any other theories might just confuse bloggs at this early stage.

[Blue Heeler]

Newton

Action & reaction. Action: deflection of airflow. Reaction = Lift.

Bernoulli merely gives a hand to this process by causing low pressure on top of wing assisting in the more efficient deflection of airflow.

A lifing body can produce lift - without the asssitance of Bernoulli.

[Oktas8]

Interesting one.

My two cents worth:

Bernoulli - Based on conservation of energy. Quantitatively simple & therefore easy to understand at a basic level. Leads to Lift = 1/2 rho x v squared, which is extremely important later on. Is not particularly accurate - eg cannot handle lift from a flat plate.

Coanda - Based on conservation of momentum. More universally applicable and easier to demonstrate (spoon under running water) than Bernoulli. Unlike Bernoulli, Coanda does explain skin friction & form drag. However, leads to mathematical complexities if the student asks "how much lift is generated?"

What about Newton's laws and Kutta - Joukowski theorem, also known as circulation theory? It's all too mathematical for my poor tired brain... :)

I use Bernoulli because
a) I can answer the question "how much lift at airspeed X?" and
b) it doesn't need much maths.

But then I also add to my briefs "this is just a simplification - the real world is much more complicated."

regards to all,
O8