Can a Plane Really Fly Upside Down?

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Discussion Overview

The discussion centers around the question of whether a plane can fly upside down, exploring the mechanics of flight, particularly in relation to wing design and lift generation. Participants examine the implications of different wing shapes and the role of Bernoulli's principle in flight dynamics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that all planes can fly upside down for a limited time, depending on structural integrity and engine performance.
  • It is suggested that lift is not solely dependent on Bernoulli's principle, with airflow directed downward being a significant factor.
  • Participants mention that planes designed for inverted flight have symmetrical wings, allowing them to perform similarly in both orientations.
  • There is a discussion about the role of angle of attack and power in maintaining lift, particularly when flying upside down.
  • One participant elaborates on the complexities of Bernoulli's principle, noting that while it correlates with lift and drag, it does not fully explain how lift is generated.
  • Another participant argues that Bernoulli's principle still applies but must be understood correctly, challenging the "equal transit time" myth associated with it.

Areas of Agreement / Disagreement

Participants express differing views on the role of Bernoulli's principle in flight, with some arguing it is not the primary factor in lift generation, while others maintain that it still plays a role when applied correctly. The discussion remains unresolved regarding the extent to which Bernoulli's principle influences flight mechanics.

Contextual Notes

There are unresolved aspects regarding the definitions and applications of Bernoulli's principle, as well as the specific conditions under which planes can fly upside down.

glueball8
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Just out of curiosity, can a plane fly upside down? (it can, right?) then how?
 
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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.
 
Danger said:
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..
 
Oh, my... yes! My buddy was an aerobatics instructor, and had one of those. Sweet ride!
 
Danger said:
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.
 
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.
 
More to the point, airplanes designed to fly upside down have symmetrical cross section wings: they perform identically upside-down as right side up.
 
russ_watters said:
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.
 
ruko said:
So, it really isn't Bernoulli that keeps an airplane up.
Angle of attack, power, etc...
 
  • #10
ruko said:
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.
 
  • #11
ruko said:
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.
 

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