Copilot would fail an aerodynamics exam :-)

So, based on a theme under discussion at a flight simulation thread I decided to load Copilot in my browser and make the two following questions and the received answers, which make no sense as you can easily understand ...

Of course the questions themselves aren't formulated in the best way, lack detail, etc.. 

That's AI ...  when not used by "HI"... 🙂

A) On a twin prop aircraft with both engines rotating clockwise, weight distribution even in turn of the logitudinal axis, is it expected to see a right rolling moment develop?

Answer:

Yes, on a twin prop aircraft with both engines rotating clockwise, you can expect to see a right rolling moment develop. This phenomenon is due to the P-factor (asymmetric propeller loading) and gyroscopic precession.

Here’s a breakdown:

P-factor: When the aircraft is at a high angle of attack, the descending blade of each propeller (on the right side) generates more thrust than the ascending blade (on the left side). This creates a yawing moment to the left, which can also induce a rolling moment to the right.

Gyroscopic Precession: The rotating propellers act as gyroscopes. When the aircraft pitches up or down, the gyroscopic effect causes a force 90 degrees ahead in the direction of rotation. For clockwise-rotating propellers, this results in a right rolling moment when the aircraft pitches up.

These effects combined can cause a right rolling moment, even if the weight distribution is even along the longitudinal axis.

B)  In an aircraft can a left yawing moment cause a right rolling moment?

Answer:

Yes, a left yawing moment can indeed cause a right rolling moment in an aircraft. This interaction is primarily due to the aerodynamic coupling between yaw and roll axes, often referred to as adverse yaw.

Here’s how it works:

Adverse Yaw: When an aircraft yaws to the left, the right wing moves faster through the air than the left wing. This increased speed on the right wing generates more lift compared to the left wing, causing the aircraft to roll to the right.

Dihedral Effect: The dihedral angle of the wings (the upward angle of the wings from the horizontal plane) also plays a role. When the aircraft yaws left, the right wing’s increased lift due to its higher speed, combined with the dihedral angle, creates a rolling moment to the right.

Propeller Effects: In twin prop aircraft, the asymmetric thrust from the propellers can also contribute. For example, if the left engine fails, the right engine’s thrust can cause a left yawing moment, which might induce a right rolling moment due to the factors mentioned above.

 

DUH !!!!

Edited July 30, 20241 yr by jcomm