[NSRCA-discussion] Rudder

Wed Oct 10 17:50:48 AKDT 2007

Doesn't this almost happen as the plane slows to do a spin if you do not
correct with rudder, especially in a strong cross wind?  When the plane is
flying (forward motion) the stab helps "stabilize" the plane.  The faster
you go the less evident it is.

Stu

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From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dave Lockhart
Sent: Wednesday, October 10, 2007 7:15 PM
To: 'NSRCA Mailing List'
Subject: Re: [NSRCA-discussion] Rudder

So if I follow that theory to its conclusion, the airplane would rotate in
yaw until it was pointed directly into the wind?  This of course assumes the
moment of side area is greater aft of the CG (which it is for pattern
planes, otherwise we'd find ourselves regularly using "bottom" rudder as
with many a 3D foamy).

Just a question.  I'm not pledging support to either side of the discussion
<G>.

Dave

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From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Stuart Chale
Sent: Wednesday, October 10, 2007 6:11 PM
To: 'NSRCA Mailing List'
Subject: Re: [NSRCA-discussion] Rudder

It does.  That is what causes the plane to weather-vane, weather-cock or
whatever you want to name it into the wind.  The nose does turn into the
wind (again from my experience).  The faster you are flying the less this
occurs due to the aerodynamics of the vertical fin etc coming into play..  

Theory on my part

There is a point on the plane close to the CG where the plane will yaw
around when a force is applied be it with rudder or wind blowing from the
side.  If the forces were equal in front and behind this point the plane
will just blow with the wind.  If the force is greater behind this point
(think of the vertical fin and rudder on a long moment arm, the fuse) then
the plane should turn into the wind.  The wind blowing on the rear of the
plane will produce a greater force than the wind blowing on the plane in
front of this point. I do not think it matters if the plane is on the ground
or flying.  It will still turn the same way, obviously much greater with the
plane on the ground and a friction point available.

Stuart

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From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Jerry Voth
Sent: Wednesday, October 10, 2007 4:34 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Rudder

I've been folloing this thread and there is one thing that puzzles me. The
vertical fin and rudder are (and I'm guessing) about 20% of the total side
area of a pattern plane. If it were weathervaning,why wouldn't the nose be
more prone to blow in the direction of the wind?

----- Original Message ----- 

From: Del <mailto:drykert2 at rochester.rr.com>  K. Rykert 

To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>  

Sent: Wednesday, October 10, 2007 2:23 PM

Subject: Re: [NSRCA-discussion] Rudder

Thank goodness judges don't have a T & B ball in a panel in front of them to
watch how many are skidding through the air.. grins..  I have always felt if
all things are pure the pattern airplane in true corrected crab maintains it
same speed when pulling to vertical and the crosswind component stays
constant then no further input is needed till your speed starts to decay
when pulling vertical.  What many are doing is flying one wing low when in
level fight then when they pull vertical have to sneak in some extra
correction for pulling a highly visible vertical to the judges. 

    Del 

----- Original Message ----- 

From: Woodward, <mailto:jim.woodward at baesystems.com>  Jim 

To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>  

Sent: Wednesday, October 10, 2007 1:31 PM

Subject: Re: [NSRCA-discussion] Rudder

Bob - the correct answer on using aileron during a radius, for the purpose
of wind correction, is that if you are NOT using it is a downgrade(able).
It's impossible in every way to use only rudder through a radius actually
keep the "wings-level" to the intended flight path.

Maneuvers are to be wind-corrected and flown in a single vertical plane -
anything less is uncivilized :-) 

The wings should be "level" at every part of the curve/radius, and the only
way to do that is by rolling the plane, slightly.

Thanks,

Jim W.

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bob Richards
Sent: Wednesday, October 10, 2007 1:19 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Rudder

That is the best description I have read so far. Agree 100%.

Not long ago, I was talking with someone about wind correction and mentioned
that a very small amount of aileron should be used when pulling a radius to
a vertical line. He said if he ever saw me do it while he was judging, he
would downgrade. I told him if I do it right, he will never see it. :-)

Bob R.

J N Hiller <jnhiller at earthlink.net> wrote:

This has been an interesting discussion. The airplane dose not establish a
crab angle on it's own when in the air. The airplane has a crab angle in
horizontal flight and when it is pulled vertical the wings will not be
perpendicular to the flight path without a roll correction. The need for the
correction will be apparent and automatically applied prior to finishing the
radius. When a roll input is applied with elevator it changes the heading in
the direction of roll, (think barrel roll) in this case into the wind as it
finishes the radius. Most of the time it will be excessive requiring a
little opposite (down wind) rudder correction unless the upwind wing was
high entering the pull-up. Once the airplane is leaning to one side in a
vertical the lean will increase and is especially noticeable as it slows.
Some increase is needed to maintain wind correction and the need for
opposite rudder to maintain a vertical track depends on how rapidly the
airplane is decelerated. Most of the time I will try to apply some down wind
rudder with the roll correction at about 45 degrees, before the need becomes
visible as it is nearly always required. In short just point the airplane in
the direction you want it to go and stir the sticks as necessary.

Jim Hiller

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