Wind correction / wings level take 2

[David Lockhart]

The "crab" angle needed is the same whether straight and level, straight up,
or straight down - assuming airspeed is constant.  Once the "crab" angle is
set to get the desired track, no inputs are needed other than those needed
to maintain the attitude and airspeed (not synonomous with groundspeed) of
the plane as compensation for wind gusts or altitude variations.  I say
"crab" in quotes because the airplane is not really crabbing (unless you are
holding rudder, or "slipping" with opposite rudder and aileron) - it only
appears to be crabbing because we (pilots and peanut gallery) are standing
on the ground (a fixed reference, not moving like the air the plane is
flying in).

The crab angle needed is simple vectors - direction the plane is pointed
(attitude) plus the crosswind component equals track of the plane - if the
track isn't what you want, change the attitude of the plane.  Given constant
airspeed, the vector sum (track) does not change whether the plane is
horizontal or vertical up/down - because the vector sum does not change - so
there is no need to use aileron or rudder in the corners or anywhere else.

BUT - always an exception(s) right?  It is very difficult to truly maintain
constant speed, and wind gusts are real - so those are some reasons
adjustments to the attitude of the plane need to be made (whether done with
rudder or aileron, the direction of the plane is changed).  And when the
plane is not on the desired line, the crab angle must be increased or
decreased to get back to the desired line.  And in strong winds, extreme
crab angles rarely get scored well - it gets very hard to score a "10" to a
square loop that has a 30 degree difference between track and attitude (in
pitch, assume wind is down the runway), or a stall turn that leans 30
degrees in yaw (direct crosswind) and only rotates 120 degrees at the top.

Changing the crab angle of the plane (actually changing the vector heading
of the plane is what we really want) can be done several ways - banking the
wing, holding the rudder, or in corners by slightly dropping a wing - which
is a "stealth" way to make the change.

I have left out some details - but they get pretty specific to airplane
design and setup - suffice to say the "best" piloting technique is not
exactly the same for all planes - but we are getting down to the last couple
% at that point.

Regards,

Dave Lockhart
DaveL322 at comcast.net

----- Original Message -----
From: "Wayne Galligan" <wgalligan at goodsonacura.com>
To: <discussion at nsrca.org>
Sent: Monday, August 09, 2004 6:43 PM
Subject: Re: Wind correction / wings level take 2


> Ken,
>
> The best way to visualize this is get a stick plane.  Hold at a crab angle
> say 15 degrees.  The elevator is working at an angle to the intended path
> thus the wings will not follow that same path unless corrected with the
> ailerons.  All your doing is correcting to make the wings level in the
path
> and not cheating the angle for wind drift.  I had a mess of a time with
this
> and understanding it till I used my stick plane to help draw the path the
> plane would take for the given maneuver.  Its obvious if wings aren't
level
> when pulling to an up line but gets more complicated when crab angle and
> push/pull is involved.
>
> Wayne Galligan
>
>
> ----- Original Message -----
> From: "Ken Velez" <kvelez at comcast.net>
> To: <discussion at nsrca.org>
> Sent: Monday, August 09, 2004 5:32 PM
> Subject: Re: Wind correction / wings level take 2
>
>
> >    I still don't understand why are the wings moving or why they need to
> be
> > moved.  If you fly a horizontal line left to right with the same wind
> > condition as described by Jim, once you achieved the crab angle to
> maintain
> > a straight line no more rudder is needed unless the wind changes. The
> > airplane should maintain that heading and wings level. In case of  the
> > reverse humpty if you push from the top with the crab angle in and the
> wings
> > are level before the push the track is maintained without the help of
wing
> > movement. That's what we are looking for anyway, track straight with
wings
> > level. If thru that push or pull the wings move I think the problem lies
> > somewhere else. As far as Dave Lockhart we fly together some times and I
> can
> > tell you if you see any roll movement thru a loop or loop segment the
> source
> > of  the roll correction is other than wind correction. If wing position
is
> > used to wind correct in my opinion it should be downgraded.
> >
> > Regards
> > Ken V.
> > ----- Original Message -----
> > From: <js.smith at verizon.net>
> > To: <discussion at nsrca.org>
> > Sent: Monday, August 09, 2004 2:41 PM
> > Subject: Re: Wind correction / wings level take 2
> >
> >
> > While attending the Sayre contest this past weekend, my friend and I
> decided
> > to do a little practice judging while Dave Lockhart flew.  We were
amazed
> to
> > see him doing exactly that.blending the roll while executing loops.  In
> fact
> > we had a discussion after his flight trying to figure out how he did it.
> > Our conclusion was "you roll into the wind" while pulling or pushing.at
> > least for quarter loops.
> >
> > When Dave flew, you couldn't see the roll correction.just the fact that
> the
> > track was perfect going in and perfect coming out and the wings were
> always
> > level or square to the flight line.  A real treat to watch!
> >
> > Scott
> >
> > >
> > > From: Jim_Woodward at beaerospace.com
> > > Date: 2004/08/09 Mon PM 01:39:25 EDT
> > > To: discussion at nsrca.org
> > > Subject: Wind correction / wings level take 2
> > >
> > > Hi All,
> > >
> > > I think discussion about 1 single maneuver will address everything I
> sent
> > > initially below.  P05, Reverse humpty-bump, 2/4 down, 1/2 roll up:
> > > Scenario.  The wind is blowing 20 mph 90 degrees out.
> > >
> > > 1.  Entry;  the plane is flying a horizontal inverted track at the top
> of
> > > the box right to left, the fuselage is yawed 10 degrees  inward to
> > > compensate for the wind.
> > > 2.  Entry Radius:  Pilot pulls up elevator while simultaneously adding
> > > aileron and rudder to transition the plane to a vertically tracked
> > > downline, fuselage is angled into the wind to maintain vertical track.
> > > 3.  2/4 is performed maintaining track (still angled in to compensate
> for
> > > the wind)
> > > 4.  Bottom radius:  The pilot pushes around the bottom adding rudder
to
> > > maintain track, ailerons to level the wings around the bottom, then
> > > opposite rudder to lean "into" the wind on the upline. (obviously,
pilot
> > > nor judge wants to see banked wings at the bottom this maneuver which
> > > would result if no aileron was added due to downline cant/angle of
> > > fuselage to maintain track).
> > > 5.  1/2 roll is performed still angled in somewhat.
> > > 6.  Pilot switches rudder input to still compensate for the wind on
the
> > > upline.
> > > 7.  Exit radius:  Pilot pushes out, using rudder to maintain heading,
> and
> > > aileron to create wings level across the top of the box.  Blended in
> with
> > > the exit, the plane is now wings level angled "in" to compensate for
the
> > > wind, heading into the reverse double I.
> > >
> > > There is a lot of "flying" going on in the 3 different radii of this
> > > maneuver.  The wings/plane MUST actually roll to achieve the various
> > > "wings-level" positions of the: downlines, bottom radius, upline, and
> upon
> > > exit.  Is this amount of "flying" done in the radii simply addressed
in
> > > the wind correction statements like:  "each maneuver must be
> > > wind-corrected to preserve the overall geometry"?
> > >
> > > My contention again is that the plane MUST perform a blended rolling
> > > element during the radii to create a cross-wind corrected maneuver.  I
> > > think the best looking thing to do is move the wings at a rate
> > > proportional to the arc of the radii - thus, you don't "see" a
discreet
> > > aileron fix.  A discrete aileron fix at the end of the radii would be
a
> > > certain queue to downgrade.  I believe I've learned the correct way to
> fly
> > > a cross wind condition, but I have not heard anyone really discuss the
> > > amount or "flying" going on in the various radii to handle a cross
wind
> > > condition.
> > > Thanks,
> > > Jim W.
> > >
> > >
> > >
> > >
> > >
> > > ----- Forwarded by Jim Woodward/BEA on 08/09/2004 01:05 PM -----
> > >
> > >
> > > Jim_Woodward at beaerospace.com
> > > Sent by: discussion-request at nsrca.org
> > > 08/09/2004 09:12 AM
> > > Please respond to discussion
> > >
> > >
> > >         To:     discussion at nsrca.org
> > >         cc:
> > >         Subject:        Wind correction / wings level
> > >
> > >
> > >
> > > Hi All,
> > >
> > > I want to bring up a discussion point about wind correction.  This may
> > > seem obvious to some but I want to ensure I have the right picture in
my
> > > mind (started thinking about this since Don S. posted his comments
about
> > > Q.S. flying wind correction in finals, and confirmed during some
> practice
> > > yesterday).
> > > 1.  Wind correction is supposed to be done while maintaining wings
> level.
> > > 2.  You are supposed to use the yaw angle to correct for the wind.
> > > Situation:  Pilot is flying a square loop ( at center).  Wind is
blowing
> > > 90 degree out 20 mph.  Pilot fly's past center at a some yaw angle in
to
> > > compensate for the wind blowing out.  The pilot pulls a 90 degree
radius
> > > to a vertical upline.  The fuselage is canted in to the wind to
> compensate
> > > for the wind blowing out.  *Point of discussion:  If the pilot were to
> > > pull another 90 degree radius, the wings would become "unlevel" as the
> > > plane reaches the top leg of the square loop.  *Point of discussion:
> So,
> > > if the pilot is using the correct technique for wind correction (wind
> > > correcting force being yaw angle), then every time the pilot creates a
> > > radius, you should definitely "see" the ailerons moving the wings
> through
> > > the radius to ensure that as the radius is finished, the wings are
level
> > > for the next line and the fuselage is yawed for wind correction.  Same
> > > thing next radiu s;  The pilot adds pitch, moves the wings,  and adds
> the
> > > correct rudder to transform the top of the box line to the next
downline
> > > (wings level, yawed into the wind), etc.
> > >
> > > *Point of discussion:  We spend a lot of time concentrating on wings
> level
> > > for normal pattern flying and usually "any" type of aileron or wing
> > > movement is a visual key for a downgrade using the 1 pt / 15 degree
> rule.
> > > However, this is false to accurately judge flying on a windy day.  In
> > > order to fly in a crosswind, nearly EVERY radius will have some amount
> of
> > > roll induced (and necessary) to ensure that the "lines" can be flown
> with
> > > wings level and in order to utilize yaw as the wind-correcting force.
> > >
> > > That said/ when and how much roll should be used?  I would guess that
> you
> > > would want to seamlessly input the pitch, aileron, and rudder so that
> the
> > > plane just appears to go from one wind corrected line to the other
> > > magically.  What is the judging criteria for inputting a roll function
> in
> > > the radius to ensure the wings stay level & fuselage stays canted
> (yawed)
> > > into the wind from one wind corrected line to another?  Should the
> amount
> > > of aileron needed to go from one wind corrected line to another line
> start
> > > and finish corresponding to the actual duration of the radius?  What
if
> > > the pilot only correct s the wing as the plane is nearing the end of
the
> > > radius, is this some downgrade because the correction was placed near
> the
> > > end of the radius instead of "evenly-througout" the radius?
> > >
> > > I'm sure I'm exaggerating this situation and I am purposefully, to
> > > stimulate some talk on the subject.  Again, my contention is that for
> some
> > > wind conditions, in order to maintain the overall geometry of the
> maneuver
> > > that there MUST be roll correction during radii to seamlessly move
from
> > > one wind corrected line to another, and this roll correction should
not
> be
> > > downgraded.
> > >
> > > Any takers?
> > > Jim W.
> > >
> > >
> >
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