Wow, guys this is amazing!

Now we’re bringing in issues that are far outside the scope of my original post.

Just to be clear; the intent of my OP was to point out that adding right thrust to a model, does not and can not, by any law of physics, do anything to counter or reduce the torque on an airplane. Notice I did not say the effects of torque, just the torque itself.

Right thrust can only directly counter the effects of “P-factor”.

That is the only purpose to my post to stop you guys from saying “Right thrust is added to counter torque.”

Jet Plane, your comments in post 34, only go to prove that many folks, even with the highest credential repeat what they have been taught as “truth” without question. I found this most evident in one of the dozens of aerodynamic text books I mentioned earlier. One gentleman starts his document with “question everything you read here to make sure it is correct and to advance the science.” Then he proceeded just rattled off the spiral causes yaw on the fin, without question.

To answer your statement in post #34: My opinion is based on the fact that there are NO equations in all of aerodynamics to account for the slipstream swirl. There is ONE mention of a value for it and it was from empirical wind tunnel data. No one has mathematically modeled the effect. Furthermore, as pimmnz pointed out in several of his posts, show us ONE PHOTOGRAPH of an aerobatic airplane (in straight and level slow flight, yeah I can find one in the middle of a snap roll too) where the smoke from the smoke system is wrapping around the fuselage, shoot just show us one where the smoke is doing ANYTHING but flowing straight back parallel to the centerline of the fuselage.

And the way it is taught TOTALLY IGNORES what the teacher is saying!

If you will please examine my three attachments.

The first image is how Spiraling slipstream is taught.

The swirl of air, induced by the propeller, wraps around the fuselage, striking the vertical fin from the left, causing a higher angle of attack on the right side of the fin, causing the aircraft to yaw to the right. Note that this is taught as a CONSTANT not just at take off on a tail dragger where this yaw, OR as dabigboy pointed out in post 46 under high power and low airspeed.

The second image is how Spiraling slipstream would be in reality, and what is conveniently overlooked.
IF the spiral is real, and constant, this shows what should be really happening to the aircraft. The same force that is causing the massive yaw to the left should uniformly affect the wings and stabilizer causing a MASSIVE ROLL to the RIGHT. Yet this is NEVER taught or even mentioned in ANY aerodynamics or pilotage text books.

My theory.

No one seems to have a problem with the “P-factor” explanation; i.e. the propeller at higher aircraft AOA produces more thrust off the right side than the left side due to a combination of relative airspeed and angle of attack on the propeller disc. Actually the illustration in Lnewqban’s post #45 is a great place to start; it shows there is more force or thrust coming off the propeller blade at the 3 o’clock position.

Dabigboy (Matt) pointed out another item to add to the confusion in post #46, he threw in the yet to have been used term “Gyroscopic precession”. IF no one has a problem with P-factor, then no one should have a problem with the statement: At high angles of attack, where P-factor is greatest, the resultant force from the P-factor, acting through the propeller, transmitting the force to the airframe will cause the aircraft to PITCH UP. In Matt’s example, the aircraft pitching down applied a force on the prop at the 12 o’clock; this resulted in the aircraft yawing to the left because of the reaction of that force at the 3 o’clock position AND the P-factor of his full thrust-low airspeed condition.

We have two forces to consider here; the actual thrust from the prop, the increased airspeed is acting at the 3 o’clock position of the propellers rotation. This high speed air is flowing faster down the right side of the fuselage than it is flowing down the left side of the fuselage. BUT…the resultant force on the propeller, applied at the 3 o’clock position, MUST by gyroscopic precession react at the 6 o’clock position of the propeller’s rotation. The FORCE from the P-Factor thrust again cannot cause the plane to yaw right; it causes it to pitch up!

Finally have a look at figure three, the alternate explanation.

So what could be another possible explanation? We still have one item we haven’t looked at, what happens to the P-factor air when it flows aft? Contrary to the spiral theory shown in the second figure the P-Factor high speed air increases the AOA of the right wing and right horizontal stab, adding a LEFT ROLL. This matches the behavior we see from the aircraft. It also does exactly what the spiral theory is trying to say; it causes high speed air on the right side of the fin, increasing the AOA of the fin and causes a LEFT YAW!

And that’s about all I have to say on that.

My point, please learn the correct terminology to use with the hobby and use it.

Thank you,