on this list do not fly a symmetrical wing, most likely.
If your wing is not symmetrical, then it presumably has a Bernoulli uppness vector
(air pressure lift) all by itself. Many small planes have the main wing also angled
high in the front to cause a Neutonian uppness vector (air deflection lift) that will
also have to be countered in knife edge.
My guess is you point your nose down in knife edge to counter all that uppness. Also
likely that for that plane, you'd consider that pointed down-ness to be neutral.
I call pointing your nose somewhere else than the intended direction of flight
crabbing. Maybe there's a better word for it?
Bill
---------- Original Message -----------
From: "Jim Bair" <jimbair@live.com>
To: <Sport_Aircraft@yahoogroups.com>
Sent: Sat, 10 Mar 2012 11:10:18 -0600
Subject: 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. [UTF-8?]I’m not actually looking back at my elevator. I
> [UTF-8?]don’t really care if [UTF-8?]it’s neutral, slightly up, or slightly
down. I
> [UTF-8?]don’t even recall [UTF-8?]“neutral [UTF-8?]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 [UTF-8?]don’t think it describes what is going on at all.
>
> 90% of this audience is flying a symmetrical wing? I [UTF-8?]don’t think [UTF-8?]
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 -------
------- End of Original Message -------
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