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

My $.005
The horizontal component of lift will cause the plane to go sideways. The location of
the center of that lift will make it turn. Imagine knife edge flight for a bit. Pull
back on the stick and the nose rises. Push and the nose goes down. Since from the
nose's perspective, rising is turning when compared with the Earth, we call that a
turn. Same for nose down. That's why turning takes two inputs - one to reposition the
nose about our longitudinal axis (aileron), followed by one to give upness to the nose
from this new perspectice (elevator). All of one without the other doesn't turn.

Now for those who input ailerons and find it turns anyway, you are actually adding
elevator without knowing it. The heavy end of the airplane is up front. The elevator
actively pushes the tail down to achieve straight and level flight. This being called
neutral is misleading. When you roll the plane, you lose the vertical component of
lift and must replace it with more elevtor down or your nose will drop. This gives the
elevator input needed to turn, so the apparent failing premise doesn't actually fail
the criteria.

Bill Watson
bill@part103.org


---------- Original Message -----------
From: "circicirci" <acensor@fastmail.fm>
To: Sport_Aircraft@yahoogroups.com
Sent: Thu, 04 Oct 2012 16:44:49 -0000
Subject: 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
> >
------- End of Original Message -------



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