[NSRCA-discussion] Rudder

Wed Oct 10 07:48:45 AKDT 2007

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

-----Original Message-----
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 6:49 AM
To: 'NSRCA Mailing List'
Subject: Re: [NSRCA-discussion] Rudder

You guys have me a bit confused as well.  I do not think it is as simple as
the plane blows with the wind.  Most pattern designs will "weather-vane" .
They will, on there own, establish a crab angle into the wind.  I am sure it
varies by design.  The more area behind the CG compared to in front of the
CG would make it weather-vane into the wind more (as I see it).  If the
plane did not "feel" the wind then why is it easier to stall turn into the
wind then with it?  Stalling with the wind (stalling out with a cross wind
blowing out) is difficult at best.  When the plane crabs into the wind (on
its own) the prop direction (thrust) is now counteracting some of the just
getting blown with the wind.  In a perfect design the increased side thrust
from the prop would compensate for the opposite movement of being blown by
the wind.  I think once you go to knife edge or do rolling maneuvers the
added area of the wing getting blown by the cross wind and the fact that
the plane will not "weather-vane" in its pitch axis when on its side causes
the plane to "just get blown with the wind" and go along for the ride.

Stuart

  _____

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bob Wilson
Sent: Wednesday, October 10, 2007 9:20 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Rudder

Wow, and this was just an innocent question about a stall turn!
Now, as I pull vertical for the stall turn maneuver, in a cross wind, my
mind is going to internally hemorrhage trying to sort out who said what:)

On 10/10/07, Bob Richards < bob at toprudder.com <mailto:bob at toprudder.com> >
wrote:
No, it depends on how fast it is coming down. :-)

Ken Thompson < mrandmrst at comcast.net <mailto:mrandmrst at comcast.net> > wrote:
Wild guess...there is none ;-)
----- Original Message -----
From: Kurt Bozarth <mailto:kurt at bozarthhomes.com>
To: 'NSRCA Mailing List' <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, October 09, 2007 7:49 PM
Subject: Re: [NSRCA-discussion] Rudder

Guess what the wind chill factor is when riding in a hot air balloon?

Kurt

  _____

From: nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org>  [mailto:
nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org> ] On Behalf Of Del K.
Rykert
Sent: Tuesday, October 09, 2007 2:39 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Rudder

I still find it amazing after all these years it is people with full scale
experience that rarely have a problem with the concept Bill just mentioned.

    Del
----- Original Message -----
From: billglaze <mailto:billglaze at bellsouth.net>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, October 09, 2007 3:28 PM
Subject: Re: [NSRCA-discussion] Rudder

Correct.  The airplane does NOT know the wind is blowing.  If we were moving
in the same direction/velocity the wind is moving, (thus matching the
airplane direction/velocity), the airplane would have no vector.
----- Original Message -----
From: Terry Beachler <mailto:terryb at beachlers.com>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, October 09, 2007 2:59 PM
Subject: Re: [NSRCA-discussion] Rudder

J & B
Weather vane implies the wind blowing the tail away from and the nose into
the wind which would be desirable for (self)correcting for crosswind. This
would imply that an airplane on a cross country flight would self correct
into a crosswind, no crab necessary. Or the reverse, pilot would have to
hold rudder for a couple of hours on a cross country flight. Talk about a
way to induce asymmetrical leg muscles...wow!

Rudder is used to point the noise into the wind i.e. to induce crab. Full
scale pilots make a small coordinated turn into the wind to create crab
angle and the desired ground track. I think I read in some pattern stuff
that pattern pilots can induce crab and it either presents better to a judge
or they can sneak the crab in a way not so easily detected by the judge.
Weathervaning would only happen on the ground with a taildragger, usually
the beginning of a ground loop. Or with the airplane on a pylon on the
vertical axis, just like a weathervane.

Crab angle and track apply here. Crosswind acts upon the whole airplane in
flight, not just the tail surface. If we turn this whole situation 90
degrees and fly into a headwind and pull up, the airplane would flop over on
its back because of the greater exposed surface of the wing area. The wing
would have a greater weathervane effect. But it does not work thataway.

Bob and I have been having fun with this one for a while.

Terry Beachler

At 13:01 10/9/2007, you wrote:
weathervane by cause of wind. If you straighten the plane out to look
vertical, the track (actual line drawn) will move with the wind and not be
vertical and be cause for a downgrade. Someone has a clip from the rule book
covering all parts of this.

Regards,
Jason
www.jasonshulman.com <http://www.jasonshulman.com/>
www.shulmanaviation.com <http://www.shulmanaviation.com/>
www.composite-arf.com <http://www.composite-arf.com/>
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org>  [
mailto:nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org> ]On Behalf Of Terry
Beachler
Sent: Tuesday, October 09, 2007 12:53 PM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Rudder
Do you mean crab (induce by rudder) or weathervane as if the wind is
applying a force upon the tail and causing a turn toward the wind about the
vertical axis.
Terryb
At 12:10 10/9/2007, you wrote:
Hi Bob,

The airplane should weathervane into the wind, as long as the track of the
plane is straight (track- actual line/path of the plane).

Regards,
Jason
www.jasonshulman.com <http://www.jasonshulman.com/>
www.shulmanaviation.com <http://www.shulmanaviation.com/>
www.composite-arf.com <http://www.composite-arf.com/>
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org>  [
mailto:nsrca-discussion-bounces at lists.nsrca.org]On
<mailto:nsrca-discussion-bounces at lists.nsrca.org%5DOn> Behalf Of Bob Wilson
Sent: Tuesday, October 09, 2007 8:53 AM
To: nsrca-discussion at lists.nsrca.org
<mailto:nsrca-discussion at lists.nsrca.org>
Subject: [NSRCA-discussion] Rudder
Some great ideas.
I'm going to give the 60-70% rudder expo a shot and see how it works.
I'd like to do the stall turns on low rate, as Jason reccommends, but when
stall turning into the wind my practice airplane will not go vertical (on
the downline) unless I have high rates (it weathervanes slightly towards the
wind).
I also liked John Pavlick's recommendation on the two consecutive rolls.
I'm probably being too anal in coordinating rudder, aileron and elevator
because I always seem to run out of room.
So much to learn and the damn winter is coming!
Thanks guys,
Bob Wilson
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