Inverted flight : Principle

[Checkboard]

The main aerodynamic difference in inverted flight, from a pilot's perspective, is that the rudder operates in what the pilot might assume is the "wrong sense".

For a coordinated upright turn, you use right aileron and right rudder (matching inputs).
For a coordinated inverted turn, you use right aileron and left rudder (opposite inputs).

There is a good explanation of this effect in Neil Williams's book, Aerobatics.

[MrBernoulli]

If I were conducting an interview I'd be interested to know whether the applicant could tell me under what conditions you could be flying at 5 knots IAS and NOT have a stalled wing.

I'd be very impressed to see any airspeed indicator that could reasonably and accurately register 5 knots IAS! But I think I know what you mean. A gentle-ish, but sustained, bunt from a vertical climb could probably still have a wing flying i.e. unstalled, and going around 5 kts ....... but it would be tricky to perform accurately, lol!

[Lightning Mate]

My display sequence included stall turns - no speed and no buffet either - seemples.

I also included inverted turning - controls work as advertised in erect flight. Mind you, I didn't use rudder.

However, I did find that bottom rudder in a Derry turn helped the roll rate.

[AerocatS2A]

Originally Posted by Daniel 11000

I simply highlighted the fact that lift is generated by ‘deflection’ , therefore ‘Deflecting’ is the correct word, independently of how/ who /what deflects whatever fluid. In order to ‘lift’ , a wing must deflect – no deflection, no lift – everybody must agree on that !

Daniel 11000, "deflect" is a poor word choice. Deflect typically means to change something's direction by putting a barrier in its way. You could use the word to describe what the wing does to the air hitting the underside, but it does not describe what happens to the air going over the top of the wing. That's what John means when he says that deflection of air can't account for all of the lift, because it ignores the upper airflow, and that is very important. A better way to describe lift is to say that the air mass is turned or accelerated by the wing. When I say accelerated I mean in its strict physics sense, that is, its vector is changed. By accelerating the airmass downward, lift is generated, F=MA. You can also use Bernoulli to calculated the pressure differential around the wing and come up with the same answer, but that is neither here nor there.

[Lightning Mate]

You could consider downwash.

[AerocatS2A]

Downwash is the result of the downward acceleration of he air mass, it is considered.

[bubbers44]

You can fly a barn door if you choose to use it as a wing and it will fly. However not very well so they designed the wing to give more lift and efficiency by an assymetrical airfoil making it efficient and not just using barn door effect. Aerobatic airplanes usually have a symetrical airfoil so it will fly quite well either way if you wish to fly inverted.