Light-Sport Aircraft Yahoo group Re: What makes an airplane turn?

No question that the horizontal component of lift when plane is banked left is what starts moving the plane to the left.

{And of course as we all know the plane WILL turn with no rudder applied (even if it's a lousy uncoordinated turn you CFI would frown on).}

But if that (horizontal component of lift) were ALL that was going on when you bank left all that would happen would be the plane horizontally moving sideways to the left and or sliding slipping downward to the right if insufficient vertical upward component were left.
In other words, the classic answer we give on FAA written tests and when asked by CFIs ("the horizonatal component of lift in a bank is what makes the plane turn") is accepted but incomplete.

The remaining question is "What turns the _nose_ of the plane to the left and keeps it turning?"

What is missing IMO in the often sophisticated explainations I see here an other places claiming to answer that remaining question is a clear credible answer to that question... .At least those answers have never been clear and credible to me.

I finally got a clear and very simple answer to that one from one engineer that I paraphrase in my own words as follows:

"OK, you bank left, and as you say the plane begins to move SIDEWARDS to the left from that horizontal component of lift. So now the plane almost immeadiatly has a relative-wind component coming against it from the left. In fact I should say 'almost immeadiatly' as you notice there's a slight delay between the time you bank and the nose starts turning left. As you know all planes 'weather vane' turning their nose into the wind even on the ground if nothing (such as brakes tie-downs, or chocks) stop them. That's because among other things there's that big vertical horizontal tail catching all that relative wind on its left side and being pushed to the right."

So in a manner of speaking very nitpickingly banking left and left horizonatal component of lift doesn't make the plane _turn_ but initiates conditions (left horizontal slide and relative wind compenent coming from the left) that in turn makes the plane turn.

As a practical matter of course we all know you can turn a plane left by banking, rudder, or of course coordinated use of both.

My two cents.

Alex

--- In Sport_Aircraft@yahoogroups.com, "Jim Bair" <jimbair@...> wrote:
>
> Is this the list where we had the discussion about what makes an airplane turn? I think the original question was, What is the primary control used in turning an aircraft?
> I made a little video that attempts to answer that question. http://www.youtube.com/watch?v=VbaexiBw7jg
>
> Jim
>









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