# Why is it that we ignore height difference when applying Bernoulli in an airfoil

I learn physics myself and sorry if this is a very simple question

1. Why is it that we can apply Bernoulli on above and below the plane even if the are not in the same streamline?

2. Why do we ignore height difference when doing so?

Any help whatsoever is highly appreciated.

Bernoulli shouldn't be used to try and explain the workings of an airfoil, as the NASA page I linked to clearly explains.

It's basically an 'urban myth' that the Bernoulli principle can explain airfoil lift; it isn't true.

• Please consult the title of the question. – Gert Nov 30 '20 at 20:30

• By "total pressure", the wiki article presumably means the Bernoulli constant $(1/2) v^2 +P$. – mike stone Nov 30 '20 at 12:53