Re: Light-Sport Aircraft Yahoo group Answer to Rich's Question

Hi Bill,

I have no idea where my elevator is.  The actual position will vary with CG, solo or dual for example.  I put my elevator wherever it needs to be to make the airplane do what I want.  In what you describe, if my nose started to move to the left while rolling left, I would push forward on the stick to keep my nose where I want it. I'm not actually looking back at my elevator.  I don't really care if it's neutral, slightly up, or slightly down.  I don't even recall "neutral elevator" being mentioned, but if I did, it was meant metaphorically not as a precise position.  So yes, I would point my nose away from that lift vector, or in other words, I would push forward stick until the lift vector magnitude dropped to zero.  I dislike the crabbing analogy.  I don't think it describes what is going on at all.

 

90% of this audience is flying a symmetrical wing?  I don't think that's what you meant to say. 

 

Jim Bair

 

From: Bill

Sent: Saturday, March 10, 2012 9:09 AM

To: Sport_Aircraft@yahoogroups.com

Subject: Re: Light-Sport Aircraft Yahoo group Answer to Rich's Question

 

 

Maybe this will clear it up? If in knife edge, your elevator was neutral, there would
still be a lifting vector from the main wing and your path would not stay over the
runway/intended path without doing something about it. For best results, you would
point your nose away from this lift vector as if there were a cross wind. If you were
upright, you would call this crabbing.

Why is there a lift vector with a neutral elevator? That would assume you are not
flying a symmetrical wing airplane like 90+% of this audience. IIRC, you said you fly
a Decathlon and it only has a semi-symmetrical wing.

Bill

---------- Original Message -----------
From: "Jim Bair" <mailto:jimbair%40live.com>
To: <mailto:Sport_Aircraft%40yahoogroups.com>
Sent: Sat, 10 Mar 2012 06:25:59 -0600
Subject: Re: Light-Sport Aircraft Yahoo group Answer to Rich's Question

> I guess [UTF-8?]I’m just not getting the point and what it has to do with the
> discussion about what turns the airplane. You mentioned crab in the previous
> post and since I had always heard the word crab used in relation to a
> crosswind I had no idea what you were talking about and I still [UTF-8?]don’t. I
> think we have a definition problem that is not allowing us to communicate. I
> [UTF-8?]don’t know what crab means in the context you are using it. I also [UTF-
8?]don’t
> understand what you mean by looping vector.
>
> But definitely, rolling the lift vector to the left or right does turn the
> plane IF we have lift associated with the vector. We go where our lift vector
> takes us. In the movies, fighter pilots are always looking through their
> gunsight because that looks cool on the big screen. In reality, they spend
> their life looking straight out the top of the canopy, because [UTF-8?]that’s
where
> the lift vector is and [UTF-8?]that’s where they are going. (For the nitpickers,
> yes, of course a portion of the flight is spent looking straight back and
> some looking straight forward.)
>
> When I am rolling towards knife edge, my nose [UTF-8?]doesn’t loop toward the
center
> (i.e., begin a turn) because I do what you said, I [UTF-8?]‘properly’ remove the
> elevator input and place it to neutral. But then you say banking would crab
> us in the direction of bank and [UTF-8?]I’m not following that at all. The bottom
> line for me is that I move the controls in the direction it takes to keep the
> nose exactly where I want it to roll around a point without turning. Control
> inputs during a roll include aileron in one direction and rudder and elevator
> in both directions at different points in the roll. Whatever it takes to keep
> the nose sitting in [UTF-8?]it’s proper spot. [UTF-8?]I’m just not getting the
point
> [UTF-8?]you’re trying to make and [UTF-8?]don’t get the crab part.
>
> Jim Bair
>
> From: Bill
> Sent: Friday, March 09, 2012 9:32 PM
> To: mailto:Sport_Aircraft%40yahoogroups.com
> Subject: Re: Light-Sport Aircraft Yahoo group Answer to Rich's Question
>
> I guess the distinction that aileron rolling the lift vector to the left or
> right does not turn a plane, it only would crab the plane. The rotation about
> a point to the left or right comes from the elevator up that loops the plane
> when the looping vector isn't offset by the weight of the nose in a turn. Bill
>
> ---------- Original Message -----------
> From: "Jim Bair" <mailto:jimbair%40live.com>
> To: <mailto:Sport_Aircraft%40yahoogroups.com>
> Sent: Fri, 9 Mar 2012 20:46:50 -0600
> Subject: Re: Light-Sport Aircraft Yahoo group Answer to Rich's Question
>
> > Hi Jim,
> >
> > Are you missing some of what is going on?
> >
> > Hi Bill,
> >
> > Probably. That would be normal. haha.
> >
> > In level flight, so that we have positive stability, we have our CG ahead of
> > our CP(center of pressure) - ie: we are nose heavy. To counter that, we apply
> > up elevator for our straight and level flight. When we go towards knife edge,
> > that non-neutral elevator will cause the nose to rise (loop), since the
> > elevator isn't *fully* being used up keeping our nose up from gravity's pull.
> > This, in effect, will cause us to 'climb/loop' towards the center of the
> > circle when we bank. If we 'properly' remove the elevator and place it in true
> > neutral (down from straight and level flight), then banking would only crab us
> > in the direction of bank. It is only the elevator's uppness that causes us to
> > turn when we are on our side, or any fraction thereof.
> >
> > Actually, I thought [UTF-8?]that’s what I said. [UTF-8?]It’s our elevators
> uppness that
> > makes us turn. OK, I give. What am I missing?
> >
> > Jim
> >
> > Bill
> >
> > .
> ------- End of Original Message -------
------- End of Original Message -------

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