Flat-bottom airfoils are always lifting. The only time they don't lift is sitting on the ground or in a stall, and/or the AOA is at a negative angle with the relative wind. They also have a pitching moment which means the wing will pitch over if there nothing to counteract it like a stabilizer.
From my understanding, wings produce a lift vector to counteract the weight of the aircraft to make it fly. In level flight, both wings are lifting equally and the aircraft flies straight on a heading.
What control surface unbalances that lift vector (flat-bottom wings only)? Is it the elevator? Help me out here. Maybe I need to learn to fly all over again :)
Ralph
--- In Sport_Aircraft@yahoogroups.com, "Richard Williams" <rkwill@...> wrote:
>
>
> Ralph,
>
> Your first paragraph is quite good.
> Then you really missed the boat with the second paragraph.
>
> The wings are producing lift when ever the AOA is positive, even on symmetrical
> airfoils. Gravity has nothing to do with the production of lift.
> banking the airplane results in the lift vector being tilted toward the bank,
> the amount of lift vector tilt is exactly in line with the amount of bank.
>
> The tilted lift vector pulls the airplane toward the low wing (in a bank).
> The elevator can ONLY modify the AOA. When in a bank, the increase in AOA
> results in increased lift, which strengthens the pull into the turn (resulting
> in a small turn radius).
>
> When banking, the amount of the vertical lift component to overcome gravity is
> reduced (due to part of the lift vector now having a horizontal component.)
> Since the vertical lift to overcome gravity is no longer enough to keep the
> airplane flying straight and level. This results in the nose dropping and
> altitude loss. However, the falling nose results in a turn.
> The use of the elevator is to increase the AOA, thereby increasing the total
> lift. This increases both the horizontal and vertical components of the
> 'tilted' lift. When the lift is increased, the rate of descent is reduced and
> the increased horizontal component of the lift vector pulls harder at the
> airplane, thereby tightening the radius of the turn.
>
> I.E. it is the wings banked that creates the turn.
>
> The elevator can only modify the AOA.
> The AOA modification can change the radius of the turn and the sink rate.
> The rudder can only assure the airplane is pointed in the same direction it is
> moving.
> (note: knife edge banks exaborate(sp) certain side effects that are not being
> discussed here)
>
> Since more lift is needed in a turn to maintain altitude (the vertical component
> of the lift needs to be increased which is one of the side effects of increasing
> the AOA).
> One side effect of being in a bank/turn is more lift is needed to maintain level
> flight. The creation of more lift slows the airplane which reduces the lift.
> To maintain level flight in the turn, the engine must produce more power.
> (soaring conditions being ignored for this discussion)
>
> R. Williams
>
>
>
> ---------- Original Message -----------
> From: "Ralph" <rstar447@...>
> To: Sport_Aircraft@yahoogroups.com
> Sent: Thu, 15 Mar 2012 13:25:23 -0000
> Subject: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
>
> > The ailerons initially change the lift component on each wing and
> > upsets the balance of lift and the airplane begins a change in
> > directional heading. The elevator combined with rudder then keeps
> > turning the aircraft. Once in a turn (if the aircraft is properly
> > trimmed), all control surfaces can be neutralized and the aircraft
> > will continue in a turn if it has neutral stability. Negative
> > stability will continue causing the aircraft to steepen its turn.
> > Positive stability will allow the aircraft to return to level flight.
> > The dihedral effect enhances positive stability trying to keep the
> > wings level.
> >
> > If an aircraft has a symmetrical airfoil and is flying sideways in
> > knife edge flight, there is no lift on the wings. This is because
> > gravity it pulling perpendicular to lift on the wings. What holds the
> > airplane in the air is the side of fuselage and the rudder acting like
> > the elevator. Notice aircraft like the Kolb have no side fuselage and
> > cannot fly in knife-edge flight. This is what may have contributed to
> > John Williamson's death when he was in a very steep turn low to the ground.
> >
> > Ralph
> >
> > --- In Sport_Aircraft@yahoogroups.com, "Jim Bair" <jimbair@> wrote:
> > >
> > > It changes the ‘direction’, but I know what you are referring to. The
> heading. Yes, I agree. So do the ailerons (the control surface you are
> referring to) change the heading? Or does lift do it?
> > >
> > > So what exactly do the ailerons do?
> > >
> > > Jim Bair
> > >
> > > From: Ralph
> > > Sent: Wednesday, March 14, 2012 10:20 PM
> > > To: Sport_Aircraft@yahoogroups.com
> > > Subject: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > >
> > >
> > > The elevator does change the lift component, but it's the same for both
> wings in level flight because there is an elevator on both the left and right
> side of the aircraft. It doesn't change the direction of the aircraft until
> something else unbalances the lift component of both wings. I can't imagine what
> that control surface might be?
> > >
> > > Ralph
> > >
> > > --- In mailto:Sport_Aircraft%40yahoogroups.com, "James Bair" <jimbair@> wrote:
> > > >
> > > > It looks like Gary got busy doing something else or got tired. I think my
> last question about the sum total lift of the ailerons may have been poorly
> worded. If my questions are truly building block questions, the person answering
> should get each one right. The down aileron provides lift up, the up aileron
> provides lift down, and the net result is a roll around the longitudinal axis of
> the airplane. So, the answer to the question was that there is not a net lifting
> force, but simply a rolling force.
> > > >
> > > > So far we have:
> > > > 1. Turns are caused by a horizontal component of lift.
> > > > 2. This lift is controlled by the elevator.
> > > > 3. This lift amount, or quantity, can be positive, negative, or zero.
> > > > 4. The direction of lift, or the lift vector, is controlled by the ailerons.
> > > > 5. The ailerons provide no lifting force, simply a rolling force.
> > > >
> > > > It has been stated that turns are a result of lift being directed in the
> horizontal. We have also figured out that the elevator, not the ailerons,
> controls lift. If lift is zero, is it possible for a turn to take place? The
> answer is, “No.â€ÂÂ
> > > >
> > > > In the end, following a logical path, it becomes obvious that by asking
> ourselves questions, we find that since lift is required to make a turn, and
> ailerons do not control lift, only its direction, that ailerons do not make an
> airplane turn. Therefore:
> > > >
> > > > 6. Since lift is required to make a turn (see #1), if we lower the lift to
> zero by use of elevator (see 2&3), no turn will take place, no matter where we
> place our lift vector. (see 4&5)
> > > > 7. Although ailerons ‘appear’ to make us turn, what they really
> do is to roll our lateral axis, basically the wings, in a new direction, and if
> lift exists (and in 1 G flight as we usually find ourselves, it does) then, and
> only then, we turn. If the lift is negative, and by pushing forward it certainly
> could be, we would turn in the opposite direction.
> > > >
> > > > The point of this exercise is to learn more about how airplanes fly and
> what our controls actually do and the real cause of turns and effect of control
> inputs.
> > > >
> > > > Jim Bair
> > > >
> > > >
> > > > From: Gary
> > > > Sent: Tuesday, March 13, 2012 12:46 PM
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > >
> > > > Net lifting force changes.
> > > >
> > > > Sent from my Verizon Wireless 4GLTE Phone
> > > >
> > > >
> > > > -----Original message-----
> > > >
> > > > From: James Bair <jimbair@>
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Sent: Tue, Mar 13, 2012 17:37:00 GMT+00:00
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > > LOL. Yes, or a checkride. You are doing quite well, BTW. What a surprise.
> haha.
> > > >
> > > > So far we have:
> > > > 1. Turns are caused by a horizontal component of lift.
> > > > 2. This lift is controlled by the elevator.
> > > > 3. This lift amount, or quantity, can be positive, negative, or zero.
> > > > 4. The direction of lift, or the lift vector, is controlled by the ailerons.
> > > >
> > > > One aileron goes up, the other down. Does the sum total of aileron
> movement provide a net lifting force? Or simply a rolling force? (2 questions at
> once. Hope you aren’t overloaded.)
> > > >
> > > > From: Gary
> > > > Sent: Tuesday, March 13, 2012 12:03 PM
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > >
> > > > This is like a bfr. I say the ailerons.
> > > >
> > > > Sent from my Verizon Wireless 4GLTE Phone
> > > >
> > > >
> > > > -----Original message-----
> > > >
> > > > From: James Bair <jimbair@>
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Sent: Tue, Mar 13, 2012 16:50:50 GMT+00:00
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > > So far we have determined that turns (in the horizontal is the matter
> under discussion. Turns in the vertical can also occur.):
> > > > 1. are caused by a horizontal component of lift.
> > > > 2. This lift is controlled by the elevator.
> > > > 3. This lift amount, or quantity, can be positive, negative, or zero.
> > > >
> > > > What control surface controls the direction the wings are pointed (i.e.,
> the lift vector) in their possible range of right and left all the way from
> straight up to straight down and all angles between?
> > > >
> > > >
> > > >
> > > >
> > > > From: Gary
> > > > Sent: Tuesday, March 13, 2012 10:40 AM
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > >
> > > > Yes
> > > >
> > > > Sent from my Verizon Wireless 4GLTE Phone
> > > >
> > > >
> > > > -----Original message-----
> > > >
> > > > From: James Bair <jimbair@>
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Sent: Tue, Mar 13, 2012 13:46:55 GMT+00:00
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > > Is it possible to control the lift the wing produces through a range from
> positive lift (lift in an upward direction relative to the top of the wing) to
> zero lift to negative lift (lift in a downward direction relative to the bottom
> of the wing.) by moving the elevator?
> > > >
> > > > From: Gary N Orpe
> > > > Sent: Tuesday, March 13, 2012 3:49 AM
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Subject: RE: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > >
> > > > Elevator
> > > >
> > > >
> > > > Gary
> > > >
> > > >
> > > > From: mailto:Sport_Aircraft%40yahoogroups.com
> [mailto:mailto:Sport_Aircraft%40yahoogroups.com] On Behalf Of James Bair
> > > > Sent: Monday, March 12, 2012 10:45 AM
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > I’ll buy that. I am trying to develop a method for teaching this
> concept to students and I need a willing participant. What I would like to try
> is asking a series of questions and see where it takes us. But I need a
> participant with an open mind and a desire to learn or if he already knows the
> answer, help others learn. So, if you’re game I’ll ask some
> questions. If you’re not, just don’t answer.
> > > >
> > > >
> > > > What control surface controls the amount of lift the wings produce?
> > > >
> > > >
> > > >
> > > > From: Gary
> > > >
> > > > Sent: Monday, March 12, 2012 11:41 AM
> > > >
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > >
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > >
> > > >
> > > > Horizontal components of lift
> > > >
> > > > Sent from my Verizon Wireless 4GLTE Phone
> > > >
> > > >
> > > >
> > > > -----Original message-----
> > > >
> > > > From: James Bair <jimbair@>
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > > Sent: Mon, Mar 12, 2012 16:27:09 GMT+00:00
> > > > Subject: Re: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > > Gary,
> > > >
> > > > I am curious. What do you believe makes airplanes turn? You do not need to
> mention any particular flight control in your answer if you don’t wish to.
> If you wish to, that is fine, too.
> > > >
> > > > Jim Bair
> > > >
> > > >
> > > > From: Gary N Orpe
> > > >
> > > > Sent: Monday, March 12, 2012 11:15 AM
> > > >
> > > > To: mailto:Sport_Aircraft%40yahoogroups.com
> > > >
> > > > Subject: RE: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > >
> > > >
> > > >
> > > >
> > > > I never mentioned the elevator
> > > >
> > > > Gary
> > > >
> > > > -> -----Original Message-----
> > > > -> From: mailto:Sport_Aircraft%40yahoogroups.com
> > > > -> [mailto:mailto:Sport_Aircraft%40yahoogroups.com] On Behalf Of Michael
> Huckle
> > > > -> Sent: Monday, March 12, 2012 8:17 AM
> > > > -> To: Sport Aircraft
> > > > -> Subject: Light-Sport Aircraft Yahoo group Re: Answer to Rich's Question
> > > > ->
> > > > ->
> > > > ->
> > > > -> > Posted by: "Gary N Orpe" mailto:garyo%40bak.rr.com
> > > > -> > Can anyone actually do this turn thing? Amazing.
> > > > -> > Hahaha ;-)
> > > > -> > Gary
> > > > ->
> > > > ->
> > > > -> ;-)
> > > > -> Yes, try it for yourself Gary.....
> > > > -> Fly North, and then turn either Northwest or West.
> > > > ->
> > > > -> (see if the elevator is your primary turn control) (I'm betting it's
> > > > not.)
> > > > ->
> > > > ->
> > > > -> Mike
> > > > ->
> > > > ->
> > > > ->
> > > > -> .
> > > > ->
> > > > ->
> > > > ->
> > > > ->
> > > > ->
> > > > ->
> > > > -> ------------------------------------
> > > > ->
> > > > -> Yahoo! Groups Links
> > > > ->
> > > > ->
> > > > ->
> > > >
> > >
> ------- End of Original Message -------
>
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