Two Unrelated Technical Questions

[nosehair]

Originally Posted by tgrayson

The rest of us seem to manage it.

?? I actually don't understand that response, except as a snippet of superiority - which I don't think you mean.

Certainly you have had students who "lead" the rudder/aileron application with aileron. It's especially easy to do in Cessnas, they are designed to have minimum adverse aileron yaw, minimizing the need for rudder in normal turns. This leads to lazy rudder application. So does landing with a trycycle vs landing with a tailwheel. In theory, there's no difference, but in practice, there's a world of difference.

And the rudder isn't a steering mechanism even in this scenario. Where the nose is pointed has little to do with which way the airplane is going.

?? Again? What are you doing? Even in theory, the rudder is at least one third, along with aileron and elevator, responsible for which way the airplane is going.

And I submit to you, that in real-life practice, where the nose is pointed has most to do with which way the airplane is going. Of course the ailerons and elevator give a much finer tune to the way it is going, but the rudder is primary.

I don't accept that a butchered explanation of how airplanes fly is of a net benefit to a student, and it surely cripples his ability to achieve a more sophisticated understanding later in his career.

Sorry I came off as a "butchered" explanation - I was simply explaining a specific technique that I add to the way of accomplishing the motor skill of overcoming the negative trasfer that will occur during the initial attempts at controlling this 3-D vehicle through space and time.

Yes, I explain the aerodynamics as explained exactly in the AFH and other places, but I also talk about 'How', as in Application; and 'How' becomes very personal.

[seagull]

Originally Posted by nosehair

? Again? What are you doing? Even in theory, the rudder is at least one third, along with aileron and elevator, responsible for which way the airplane is going.

And I submit to you, that in real-life practice, where the nose is pointed has most to do with which way the airplane is going. Of course the ailerons and elevator give a much finer tune to the way it is going, but the rudder is primary.

Sorry I came off as a "butchered" explanation - I was simply explaining a specific technique that I add to the way of accomplishing the motor skill of overcoming the negative trasfer that will occur during the initial attempts at controlling this 3-D vehicle through space and time.

Yes, I explain the aerodynamics as explained exactly in the AFH and other places, but I also talk about 'How', as in Application; and 'How' becomes very personal.

I will be kind and just say you might want to consider opening your mind up enough to understand what Taylor is trying to tell you. He is right.

[tgrayson]

Originally Posted by nosehair

?? I actually don't understand that response, except as a snippet of superiority - which I don't think you mean.

You claimed your explanation helps students understand the manipulation of the ailerons and rudder during landing. My point is that you're the only one that I've *ever* heard provide the explanation you do, yet everyone else manages to teach students to land the airplane properly (more or less). Your reversal of the two controls is thus unnecessary, and I can't help believing that it will inhibit long-term growth.

Certainly you have had students who "lead" the rudder/aileron application with aileron...This leads to lazy rudder application.

Of course, but I'm astonished at your proposed cure for that, teaching them that heading control is via rudder. I would also suspect you're just exchanging "lazy rudder" for "lazy aileron."

Again? What are you doing? Even in theory, the rudder is at least one third, along with aileron and elevator, responsible for which way the airplane is going.

We were mainly discussing landing. Stomping on the rudder makes the aircraft yaw around the vertical axis, but the airplane doesn't follow its nose. Quite a basic mistake for a student to attempt to return to centerline during the hold off by applying rudder. Doesn't work, just makes the airplane land with a side load, still off centerline.

Changing your heading requires moving your CG in a different direction and this requires a very large force acting perpendicular to the flight path of the aircraft. The rudder *can* do this in a very small way, due to two mechanisms:

1) Fuselage side force generated by the yawed aircraft, and
2) A component of thrust that acts perpendicular to the flight path of the aircraft.

These effects are very small and a turn using rudder-only is a very large radius turn.

The way to get a more significant turn is to use the main wing to generate this force and it's much, much more powerful than anything the rudder can produce. Yawing into or out of the turn (skidding or slipping), using the rudder, can help or hinder the turn, via the effects I listed above, but only by a small percentage, depending on the airplane. (Some airplanes generate more fuselage side forces than others.)

And I submit to you, that in real-life practice, where the nose is pointed has most to do with which way the airplane is going. Of course the ailerons and elevator give a much finer tune to the way it is going, but the rudder is primary.

The nose ends up pointing in the direction of travel through a mechanism called "directional stability", provided by the vertical stabilizer. So the aircraft must be moving in the desired direction before the nose points there. This is true even for a Ercoupe, many of which lack rudder pedals. Your students could only travel in one direction in such an airplane, since it obviously can't change heading.

[nosehair]

Originally Posted by tgrayson

Stomping on the rudder makes the aircraft yaw around the vertical axis, but the airplane doesn't follow its nose. Quite a basic mistake for a student to attempt to return to centerline during the hold off by applying rudder. Doesn't work, just makes the airplane land with a side load, still off centerline.

Ahh, you misunderstand my objective. I never said stomp on a rudder, or try to get back to centerline with rudder. I said maintain directional control, which is heading, with rudder, and control the bank, which is how you return to centerline, with aileron. You slide the airplane left/right with aileron, while using ruder to maintain runway alignment. That's how you do it. You focus on heading control - ruway alignment - with rudder and aircraft body over centerline with aileron.

You are right about the "lazy aileron" if you just teach rudder. This is like the debate over power vs pitch for airspeed control. It isn't either/or; it's coorelation of both. I am not singleing out rudder as the exclusive control for heading; it usually takes manipulation of both controls to effect a coordinated turn, or intentional cross-controlled for climbing turns or landings, or whatever.

But the rudder controls heading and the aileron controls bank, and that is my point of primary training. There are times when you want them coordinated, and times when you don't. The primary student needs to know when.

You make the point that everyone else teaches a certain way, and I am ther only one who 'mucks it up', and everyone else does a fine job.

I'm not satisfied with the general outcome of most of the training that I see. I think it is incumbent on all of us, as professionals, to find a better way. As a matter of fact, that is one of the definitions of professionalism in the Instructor's Handbook: "Professionals cannot limit their actions and decisions to standard patterns and practices."

Most pilots who learn on trycycle gear airplanes do not land on the centerline with no side drift. Almost all pilots land with a little crab - even in a no wind condition. Most don't account for gyroscopic precession and changing P-factor during the flare in a no wind condition, and they touch down with a slight yaw, because they have 'lazy feet', and probably don't even notice a slighly yawed condition.

If they were in a tailwheel, the slight yaw would immediately start exaggerating, and a quick rudder dance would teach the pilot to keep the nose from yawing with the rudder, whilst (usually) applying opposite aileron - but, in all cases, using the feet on the rudder to keep it straight and using the hands on the wheel to control left/right movement of the body.

If we all taught (enforced) absolute runway alignment before touch-down, as if it were a tailwheel, then I would agree that most everyone is doing a good job, and I wouldn't try to change things, but TG, that ain't happening; today's pilots are not making yawless touchdowns.

[tgrayson]

Originally Posted by nosehair

That's how you do it. You focus on heading control - ruway alignment - with rudder and aircraft body over centerline with aileron.

I don't agree that where the nose is pointed is your "heading". I believe that heading is more properly identified with "velocity vector". In other words, heading is which way the airplane is going with respect to the body of air.

You make the point that everyone else teaches a certain way, and I am ther only one who 'mucks it up', and everyone else does a fine job.

Well, what I'm saying is that your explanation is incorrect and I believe that it's inevitable that a student's incorrect mental model will produce consequences. I don't believe that *everyone else* is necessarily doing a fine job, but if they don't burden their students with conceptual roadblocks, at least they haven't done any lasting harm.

Whether you take heading to mean the nose or the velocity vector, the rudder only has very limited effect on either. The rudder can move the nose plus or minus 15 degrees or so, nothing more. A banked aircraft will cause the nose to yaw 360 degrees, so in the end, the directional stability of the aircraft is the most powerful yaw producer on the aircraft. The rudder can only fine tune it a bit.

Professionals cannot limit their actions and decisions to standard patterns and practices.

Perhaps, but I don't equate that with "making stuff up." Each of us must prepare our students for future instruction. We can't miseducate them in the short term for our own purposes.

I don't expect to convince you, since I haven't ever convinced you of anything.

[nosehair]

Originally Posted by tgrayson

I don't agree that where the nose is pointed is your "heading". I believe that heading is more properly identified with "velocity vector". In other words, heading is which way the airplane is going with respect to the body of air.

They call that a "track". The aircraft is "tracking" a certain course over the ground (or through the air, if you include the HCL).
You are technically correct. Your 'technical correctness' is admirable. I have followed your technical explanations with much awe, respect, and admiration. I copied the multi-engine/ engine-out airflow pictures on this thread because they give a very good picture of what happens when banking against the rudder force and why the airplane slides sideways.

But you gotta give me that we all think of "heading" as the way the nose is pointed. Heading vs track. And, yes, wing bank, or lack thereof, will affect 'track' during landing. That's why we are controlling it with the aileron.

I don't expect to convince you, since I haven't ever convinced you of anything.

I wasn't aware that you were trying to convince me of anything. I thought it was me trying to convince you of control technique that I have found to be useful.

But to back up and start from the beginning:
What I have said so far is a specific technique to emphasize rudder control; not an aerodynamic explanation of things, but a control technique. I explain from the AFH and the PHAK - those are my books of knowledge. I then go on th say something like, " Your objective is to become coordinated with rudder and aileron application, but no one is able to accomplish this fine touch of control application at first try, so I want you to lead with the rudder, and try to apply aileron at the same moment to keep it coordinated."

It is like the power vs pitch debate. I won't get into that here, but we all know the bottom line is to learn to coordinate the two forces to accomplish airspeed/altitude control. Once the pilot has it, it doesn't matter which way he learned it, but from my experience, for training, it matters which way it is taught.

That's how I feel about the rudder/aileron control movement. It makes it easier for the beginner to seperate rudder / aileron control movements.

Here is another, related, contol technique that I use that you may not have heard of:

I don't teach "step on the ball", like most people do.

It's usually more than that. Usually, when you are in a turn, and you notice the ball is out of center, and if you only apply rudder in that direction, or 'step on the ball', the ball will center, but the bank will also increase; if that's what you want - ok, but if you want to keep the same bank, you will slightly step on the ball while applying opposite aileron to 'pull' the ball back into center. As a matter of fact, if you can accept a decrease in bank, you can just 'pull the ball', (apply opposite aileron - away from the ball) back to center - which is how I teach instrument flying.

Pushing on the ball in instrument flying can be deadly. Try this:

Unusual attitude recovery:

Put the airplane in a steep (60 degrees) slightly nose low attitude with a significant slip into the turn. An immediate knee-jerk response of 'stepping on the ball' here will roll the airplane over on it's back. An initial knee-jerk response of 'pull the ball back-to-center' with aileron will roll the airplane back to level.

What's happening aerodynamically is not important at that moment - only the knee-jerk response that happens in the moment of heat is important.