Menu Sign In Contact FAQ
Banner
Welcome to our forums

Ailerons - theory of operation, and a general discussion of lift

… Bernoulli …

Bernoulli’s prínciple alone can not explain the generation of lift by a wing. The subject is a little bit more complex than that… A good introduction is given in the following page and the three or four pages after it:

https://www.grc.nasa.gov/www/k-12/airplane/wrong1.html

EDDS - Stuttgart

Fenland_Flyer – yes I think I get it, some of these questions have been done to death in the past, but they do provoke interest, they often do bring up something different as the debate evolves and they almost always result in a certain amount of controversy, all so it happens a little like my question about over controlling a landing in a crosswind. I think they do help Peter and the forum along in the way he requested, as long as we all chip in as well, becasue that is how something different is teased out of the discussion. The trouble is there is only so much that can be discussed and there are always a certain number of discussions that tend to get us pilots “going”.

The Napier-Stokes partial differential equations remain incomplete (a substantial prize is outstanding on this), and fluid dynamics does not recognise circulation theory (Kutta-Zhukovsky), which is the mathematics developed in Russia.

In short the fluid dynamics of flight is more complex than current mathematical models can describe.

Oxford (EGTK), United Kingdom

It’s not complicated at all. Any stewardess can explain it.
Here – tells us @1:40

Airplanes are MAGIC !!



Last Edited by EuroFlyer at 11 Jul 17:59
Safe landings !
EDLN, Germany

I used to believe in Lift Fairies, now I’m in Newton’s camp.

Fly safely
Various UK. Operate throughout Europe and Middle East, United Kingdom

A useful little video for those interested in airflow around a wing, not quite as many have been taught!

Last Edited by Tumbleweed at 12 Jul 19:02

It’s a very nice video. The missing piece of the puzzle is that the video would look much the same if, instead of something that looked like a classic cambered aerofoil section, you did the experiment with Euroflyer’s hand, a piece of flat wood, or indeed the symmetric aerofoil section you see in some aircraft.

Hmm…. So the air does travel faster on the upper side, but it doesn’t meet with the lower side at the end. So we have higher speed and lower pressure on the upper side. Still, there is an element of downforce created by the deflection. That’s still there. Right ?

Safe landings !
EDLN, Germany

Bookworm is spot on of course. The aerofoil section is a redherring (irrelevant).

All these things are unavoidably part of the same picture

  • faster airflow on top
  • less pressure on top
  • airflow redirected downwards

Result = upward lift

There is no way to get lift with less than all three of these things happening. All three will always happen at the same time. All are parts of the same picture.

One could argue the first two are “more Bernoulli” and the 3rd is “more Newton” But really all three are “Newton” if applied to individual molecules, which is impractical, hence Bernoulli came with a better practical explanation.

Administrator
Shoreham EGKA, United Kingdom

This is why discussions about aerodynamic invariably dry out while remaining inconclusive

Biggin Hill
Sign in to add your message

Back to Top