Can a Plane Really Fly Upside Down?

[glueball8]

Just out of curiosity, can a plane fly upside down? (it can, right?) then how?

 

[Danger]

All can for a limited period (as long as the structural integrity allows a roll-over and the carb will still feed the engine). That is because flight does not rely upon Bornoulli's (sp?) formula to the extent that most people think. A large part of lift is simply airflow being directed downward. Even an upside-down wing will do that. Those designed for extended inverted flight have differently shaped wings.

 

[turbo]

Those designed for extended inverted flight have differently shaped wings.

Or REALLY powerful engines, like the Pitt Special. Those rascals can do vertical prop-hangs..

 

[Danger]

Oh, my... yes! My buddy was an aerobatics instructor, and had one of those. Sweet ride!

 

[turbo]

Oh, my... yes! My buddy was an aerobatics instructor, and had one of those. Sweet ride!

A long time ago (probably 31 years or so, when my wife and I were first married) I took my wife to an air show. An aerobatics specialist (who moonlighted as a dentist, IIR) named Chuck Caruthers had navigated from the mid-west to Maine in his Pitt Special by following interstates, etc, and he put on a fantastic show. In the right hands, those little biplane monsters are freaking amazing.

 

[Danger]

Yeah. Anyone who has trouble envisioning aerobatics should watch 'The Great Waldo Pepper'. There's a lot of crap involved, but the aerial sequences are stunning. Those old stagger-wings beat the hell out of Top Gun Tomcats any day for thrills.

 

[russ_watters]

More to the point, airplanes designed to fly upside down have symmetrical cross section wings: they perform identically upside-down as right side up.

 

[ruko]

More to the point, airplanes designed to fly upside down have symmetrical cross section wings: they perform identically upside-down as right side up.

So, it really isn't Bernoulli that keeps an airplane up.

 

[turbo]

So, it really isn't Bernoulli that keeps an airplane up.

Angle of attack, power, etc...

 

[rcgldr]

So, it really isn't Bernoulli that keeps an airplane up.

Bernoulli approximates how the air behaves in response to pressure differentials away from the interaction between wing and air that creates those pressure differentials. It doesn't explain how those pressure differentials are created, but it does correlate by how much the air will be accelerated by those pressure differentials once they are created, so in that sense, Bernoulli is a factor in how much acceleration of air occurs, which corresponds to how much lift (and drag) a wing produces.

As far as flying upside down goes, it just creates more drag to generate the same amount of lift if the wings use a cambered airfoil. The lift itself is the result of a wing with a certain size and shape, it's forward speed, and it's angle of attack, which diverts the relative flow to produce a component perpendicular to the direction of travel, which creates the pressure differentials and corresponding acceleration of air.

 

[russ_watters]

So, it really isn't Bernoulli that keeps an airplane up.

No, it still is Bernoulli. It just has to be applied right. The "equal transit time" myth does not follow from Bernoulli's principle.