In article 4f56d67d-f259-46e7-8e3f-
, ,
Dudley Henriques says...

On May 22, 7:04*pm, Mxsmanic wrote:
Dave Doe writes:
Does anyone have any figures and references for about what ratio lift is
produced by Newton's Laws and Bernoulli's Laws?

All lift is produced by Newton's third law of motion. Air is forced downwards
by the wings, and this produces an equal and opposite force that attempts to
raise the wings, and that is lift. How the air is forced downwards is
irrelevant, as long as it happens. In practice, principles discovered by
Bernoulli and others play a role in diverting the air flow when this is
accomplished by an airfoil.

Actually, if I'm reading you right, I would rephrase this just a bit,
as it feeds into the problems we as instructors have in "re-
explaining" lift to students.
STRESSING either Newton or Bernoulli in the lift explanation causes
more than a modicum of confusion UNLESS it's done by including BOTH
theories in the explanation. You've done that actually. I would just
enhance things a bit more :-)
Read what Orval says above. He is absolutely correct. BOTH Newton and
Bernoulli are COMPLETE explanations for lift, which is interesting in
another respect, as neither man had lift in mind with their work.
The simple truth of it is that each explanation is totally correct and
is interchangeable with the other. Each explains the same thing
without relying on the other and BOTH are occurring simultaneously.
It's a common misconception that Bernoulli and Newton EACH contribute
INDIVIDUALLY to form a TOTAL of the lift produced. This explanation is
incorrect and should be discouraged.

While it's true that the Bernoulli effect is part of Newtonian mechanics
- I want to know what the ratio of (gonna have to rephrase this aren't
I) is:
* an airfoil where the camber on both sides is equal and opposite
(mirroed)
vs
* an airfoil that is shaped to produce lift via Bernoulli effect.

When I dealt with the lift issue with instructors in seminar, my
personal approach was to favor the Newtonian explanation as in my
opinion student pilots can grasp Newton a lot easier than Bernoulli,
but I've ALWAYS made it habit NEVER to leave Bernoulli out in the
cold.
The correct way to deal with the lift issue is to explain to those
asking that BOTH explanations are complete by themselves, and Newton
might be the easier of the two to explain.
Dudley Henriques

I'll rephrase it a second time. What percentage of extra lift is gained
from:
a) a plank of wood (can only produce lift via angle of attack)
vs
b) a plank of wood that is an airfoil - and is getting lift from both
angle of attack and the Bernoulli effect.

I hope that is clearer.

Here are some articles - but they produce no data to show the
addidtional lift obtained by the Bernoulli effect.

http://en.wikipedia.org/wiki/Airfoil

http://en.wikipedia.org/wiki/NACA_airfoil

http://en.wikipedia.org/wiki/Lift_(force)

http://www.grc.nasa.gov/WWW/K-12/airplane/bernnew.html

And here is a third re-phrase...
* A yacht that has a sail made of unbendable stiff material
(will not point as high and go as fast as)...
* A yacht that has a sail of normal material and has an effective
airfoil shape and produces lift perpendicular to the sail (via the
Bernoulli effect).

Is it not a simple enough question? - I mean, really. While results
will undoubtably vary among plane types and airspeed - I'm just looking
for an approximate percentage.

Do read that: http://en.wikipedia.org/wiki/NACA_airfoil page!

And I don't want to get stuck on the pedantics of Newtonian physics
encompassing the Bernoulli effect - just really looking at, as said
(rephrase #4)...
- lift produced by an airfoil that has a mirrored camber top and bottom
(the zero lift line is the same as the chord line)
vs
- lift produced by a traditional airfoil

--
Duncan.