[NSRCA-discussion] basic judging question

Wed Oct 7 14:53:08 AKDT 2009

I'm not sure why we are talking about IMAC.  Joe sites the pattern
description.  

So, let me say this.  For several years, I flew the stall turns trying to
maintain a vertical track (not attitude of the model).  As the plane slows
more wind correction is required and I applied it.   At the last NATS I was
practicing with 2 FAI pilots and they thought this was incorrect and were
scoring it accordingly.  After that discussion, I quit trying to wind
correct the lines by letting the plane skid into the wind and have been
scoring better since.  

The FAI rules do not allow the "skid" before the turn, but, they also say
that the lines must have exactly vertical and horizontal flight paths.  I'm
not sure how you get a vertical line in a crosswind without applying more
crab angle as the model slows.

Don

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Joe Lachowski
Sent: Wednesday, October 07, 2009 12:53 PM
To: NSRCA Discussion List
Subject: Re: [NSRCA-discussion] basic judging question

The description of stall turns does refer to Figure-M's and the like. 

Stall Turns: Stall turns consist of lines and partial loops as well as stall
turns. The following criteria apply to all maneuvers containing stall turns
(e.g., Figure M, Stall Turn with Half Rolls, etc.). 
1. Lines must have exactly vertical and horizontal flight paths. 
2. Entry and exit must consist of partial loops with equal radii. 
3. Length of the vertical line is not a criterion. 
4. All rolls must be placed in the center of the lines. 
5. Maximum pivot radius is one-half (1/2) wingspan. A pivot radius of more
than one and one- half (1-1/2) wingspan should be considered a major defect
and be downgraded by at least two (2) points. 
6. If the model shows a pendulum movement after the pivot, the maneuver is
downgraded by one (1) point. 

  _____  

Date: Wed, 7 Oct 2009 10:12:41 -0700
From: bob at toprudder.com
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] basic judging question

Jim,

What you said is exactly how I remember the judging discussion presented at
the Youth Masters re: IMAC stall turns. And I remember thinking to myself
that this is not the way we did it in pattern in the '90s. Oh, well, I did
not want this to turn into a pattern vs IMAC discussion again. :-\

Getting back to my original question, I think the stall turn should be wind
corrected as much as possible through the stall turn itself. However, that
is not how the maneuver description is written for the Figure M or the
Double Stall Turn. The language used for the regular Stall Turn w/ or w/o
Rolls should be duplicated, IMHO.

Bob R.

--- On Wed, 10/7/09, Woodward, Jim (US SSA) <jim.woodward at baesystems.com>
wrote:

From: Woodward, Jim (US SSA) <jim.woodward at baesystems.com>
Subject: Re: [NSRCA-discussion] basic judging question
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Date: Wednesday, October 7, 2009, 11:02 AM
Bill - I can see where the confusion is -  as I perfectly relayed the
information as taught in the SE judging seminar and confirmed in the
practical judging practice held on Sundays.  The IMAC judging committee
interprets the definition to mean that the attitude (fuselage) must be in
the vertical plane during the rotation.  They further back this up by
stating that if the plane were to be in the "wind-corrected" attitude (not
perfectly vertical) during the rotation, that it would be subject to the 0.5
pt per 5 degree rule.  I've been in the room 3 times when Wayne M. has
explained this and answered many questions from it.

Lots of discussion took place over this in the judging seminar.  Basically
they are teaching that for "yaw" you can remain wind corrected, but for the
pitch axis, you must be in the vertical plane.  Sorry if this seems to
contradict the rule, but this is what is being taught and practiced in the
South East.  

I think it looks funny, and I would prefer for the interpretation to allow
"wind-correction" for any time, but I must fly what they teach as the
scoring criteria SE.  On the other hand, I would love to know if this has
changed as well. 
Thanks, 
Jim 

From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bill's Email
Sent: Wednesday, October 07, 2009 9:48 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] basic judging question

Woodward, Jim (US SSA) wrote: 

However, this dovetails into the recent IMAC & Pattern comparison threads.
In IMAC, the plane is supposed to be brought into the "vertical plane" prior
to the stall-turn(pivot) taking place.  This is mostly evident if you are
flying in a strong headwind where you are wind correcting the vertical line.
Just prior to the stall turn, the pilot hast to pitch the plane into the
vertical plane, then yaw around the pivot, then return to the wind corrected
down line. 

 Not sure where you got this about IMAC, but it is incorrect. This may be
the cause of your confusion (from Rule 8.5):

The wings must remain in the vertical geometric plane throughout the
turnaround, and the aircraft's attitude before and after the turnaround must
be absolutely vertical (unless wind correction is required), with no
extraneous tail movement. There must be no rotation around the pitch or roll
axis. If there is movement around any axis other than the yaw axis, often
referred as "torquing" (Fig. 25), there is a deduction of 0.5 points per 5
degrees of axis.

At no time in IMAC is the actual attitude of the plane judged, it is ALWAYS
the track of the theoretical center of mass. You are not required to alter
the pitch of the plane at the point if the rotation starts if the pitch
attitude in not vertical due to wind correction.

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