Long - Snaps, setup, technique, and "tells" (Was Re: Snap Rolls.....are they legitimate/ RE: displacement during snap rolls discussion)

[David Lockhart]

Chris,

I think Bjorn made an extremely good point and analogy comparing the 3 pt
shot to a snap.  I think snaps are precision manuevers.  I don't think luck
with snaps is any different that luck with spin entry/exits or stall turn
entry/exits.  All are difficult to consistently perform without downgrade
(especially the snaps), and that is generally reflected in the KFactor
(oops, another can of worms).

The reason stall turns are often performed conservatively is simple - a zero
for a flopped stall turn is death - the scoring is usually so close at the
top, that a single zero will take a pilot out of the running for the 1,000.
I would say at the top levels, most pilots are 90+ % to complete a tight
radius stall turn (the one that appears to rotate on the CG, and is not
subject to a downgrade).  The same pilots are 99.9% to complete the slightly
open radius stall turn that will get the minor downgrade.  If we as a
pattern community want to see less conservative stall turns, all we need to
do is increase the point deduction for the slightly open radius stall turn -
the risk has to equal the reward, so to speak.

To specifically answer the 2 questions you posed (my opinions of course) -
1)  If it is indeed a true snap (and not a twinkle roll or barrel roll),
then it does add to the capabilities of the pilot.
2)  Until we can achieve a level of consistency in judging snaps, they
detract from the event.

Now, the long part, including some of the "secrets".

Airplane design -
In general, in the early/mid 1990s, most designs migrated towards increased
pitch stability and damping (which is often but not always synonomous with
long tail moment).  This was great for groove/lock in corners and lines, but
not good snaps - and perhaps not a bad bias considering the relatively low
number of snaps in the pattern.  The increased pitch stability made it more
difficult to setup a plane to do good snaps (and spins).  The same designs
also generally migrated towards increased yaw stability (actually good for
snaps, bad for spins, others will not agree).  My personal setups used as
much as 35 degrees of elevator to achieve consistent stall entries to snaps
and spins (and all of the elevator remained during the spin, but not during
the snap) and 40 degrees of rudder in spins (ele/rud only spins).  In recent
years, the number of snaps in patterns have increased, and the newer designs
have shifted towards less pitch stability (and less yaw stability, but that
change is a response to the combined rolling/looping and rolling circle
maneuvers).

Airplane setup -
This is critical with any design, and when a snap is attempted, a couple
things can happen -
- a good snap.
- a twinkle roll (not a snap).
- a barrel roll (not a snap).

The majority of the setups I see are not sufficient to consistently perform
nice snaps.  Consistently meaning the setup is not very tolerant of
differing weather conditions (hot vs cold, snapping in/out of relative
wind), pilot techniques, or entry airspeeds.  I have on more than one
occasion been asked to check a setup for snaps when the owner of the plane
was having problems with snaps.  In some instances, I've been able to
consistently snap a plane with no changes to the setup, but improvements to
the setup made it easier for the owner to consistently snap the plane.  The
below descriptions are generalizations based on my experience flying a
variety of planes and observing a variety of planes and pilots from a
variety of perspectives (amazing how much differently snaps look from
different perspectives).  And, the below does not take into acount the
effects of wind on track and offer relative descriptions of control throws
(exact control throws are influenced by design, weight, pilot technique,
etc).  The most critical setup element is pitch - if enough pitch authority
is not available, the break can not be achieved - the adjustment to make is
more elevator throw, or a more rearward CG (and if neither work, the design
has too much stability in pitch to snap properly).

- The "twinkle" roll - The plane that has too little elevator, a little bit
of rudder, and a boatload of aileron.  Very common.  The plane has little or
no displacement from track (or the path is an extremely tight barrel) during
the "twinkle" and returns to the original track with zero displacement or
deviation in track.  The rotation rate is probably equivalent to a full
stick deflection aileron roll (might be marginally higher due to a slight
assymetry in lift between wing panels caused by the minor amount of rudder
used).  The tail follows the nose exactly and no "cone" is inscribed.  The
advantage of flying a "twinkle" roll is that there is very little if any
loss in track, the entry is non-critical, airspeed loss in the "twinkle" is
minimal, and the only variable the pilot needs to concentrate on is getting
the wings level at exit.  As with the stall turn, it is a risk/reward
thing - why risk doing a real snap if the "twinkle" is getting scored?  The
other benefit of the setup for a "twinkle" is that less elevator throw is
used, and that makes the plane smoother in all other manuevers.

- The "barrel" roll - this one can be easy to see, or hard to distinguish
from a snap, and the setup that yields this result is often variable.  A
very tight diameter barrel roll is hard to distinguish from a good snap
because it will exhibit a pitching element on entry and the plane will
displace from track in pitch and yaw during the snap, but will generally
return to track for full snaps (1, 2, 3....rotations) and generally remain
displaced of the track (in pitch and yaw) by the diameter of the barrel for
1/2 snaps (.5, 1.5, 2.5 ....rotations).  Very little if any cone inscription
is visible after the entry to the barrel.  The large diameter barrel has the
same characteristics of tight diameter barrel, but easy to see, simply
because of the large diameter alone.  Any change in the control inputs
during the "barrel" are generally very easy to see - because the plane is
not stalled and responds readily to any change in surface deflection.
Insufficient elevator to initiate the break is generally the cause of
barrels.  Adding aileron usually increases the rotation rate, and often
reduces the diameter.  Adding rudder may reduce the diameter of barrel,
increase the rotation rate, give the appearance of the inscription of a cone
(but it is only in yaw, and not in pitch, and the airplane is not in a
stalled condition), and may also add the look of a "cartwheel".  The benefit
of the "barrel" setup is that less control throw is used (smoother in other
maneuvers), the rotation rate is slow (easier to hit exit) and the track is
unchanged (but might be dispaced).

- The "good" snap - I hope we know what it is in writing by now (actually
seeing it takes practice), so just some notes.  Theoretically, the break can
occur without displacement in pitch - but this never happens in practice
(angular acceleration, mass, and other physics properties are
real.........blame Newton).  A good clean break (very fast elev servo and
fingers) will reduce the amount of track deviation and displacement in both
pitch and yaw.  The rotation rate of the snap will be marginally effected
(if at all) by low / high rate aileron - ailerons don't work very well when
the plane is stalled.

Piloting Technique and more setup -
To me, a good setup for snaps has a bigger "sweet" spot - the exact entry
airspeed and exact timing of the control inputs can vary and still yield a
good snap.  And the good setups "feel" the same whether snapping left or
right, positive or negative.  I fly with triple rates - normal flying is rud
on high, elev and ail on medium.  For spins, everything is on high.  For
snaps, I use a variety of rates setup to make the variety of snaps feel
balanced and I attempt to get the snaps from different perspectives in
different manuevers to "present" the same.  It takes a lot of time to setup.
The technique for all types (different rotations in different attitudes) of
snaps is similar (lead with elevator, then rudder, then aileron) but the
timing of each input usually varies a bit on both the addition and removal
of the inputs.  And each specific snap is usually a little different - I
"feel" the plane approaching the entry to the snap and try to gauge exact
airspeed, wind condtions, evaluate what the track is and if I want to change
the track, etc.....and then I make very small changes to the addition of the
inputs to get the desired effect (ie, I might use more elevator lead to
change the track in pitch if the plane was diving slightly in pitch track
prior to the snap, or lower than usual on airspeed).  During the snap
itself, I watch the progression of the snap and decide if I got the entry I
wanted (expected), and if I need to make any changes on the timing of the
removal of control inputs on the exit of the snap (ie, maybe hold the same
rudder or imediately go to opposite rudder on the exit to immediately
correct a deviation in yaw track).  The more I fly, the better I can make
these adjustments because I seem to see things better, the snaps seem to
take longer, my fingers seem to move faster, and I better know what the
mental image of the plane should be at any instant during the snap.

"Tells" and "cheats"
One of the easiest snaps to judge is the 45 downline snap (airplane is
upright and executing a single positive snap).  The airplane is front and
center, and the break in pitch is easy to observe - and it is actually easy
to confirm.  Odds are, if you don't see a break, you will see the track of
the line steepen as the airplane passes through 90 degrees of rotation -
because the rudder is now "bottom" rudder (and the plane is still flying, or
if snapping, the break was in yaw, not pitch), and the track of the plane
will be steeper than 45 degrees at the finish of the snap.  Kinda of odd to
see a 45 downline get steeper after a positive snap??  Big tell, and pretty
common to see.  I see the same thing on 1.5 snaps on a 45 downline.  The
same thing also happens on 45 uplines when the line substantially flattens
out after the snap, but with an added variable - the flattening may be
partly due to reduced airspeed and gravity (but the plane will show the
initial loss in track at the 90 degree point in rotation).

Exits - exits are generally judged more critically than entrances - for
snaps, rolls, and radii. A "cheat" to help with the exit of a snap is to
take out elev and rud before the snap is complete - such that all the pilot
is doing is completing a roll to level flight, and completing a roll is
easier than completing a snap - the tell is a substantial change in roll
rate (rotational inertia exists and for our models, the heavy wing monster
that appreciably demonstrates this is rare).  This type of cheat is also
employed on spin exists and on the exit of part and full rolls.  The roll
rate is slightly reduced as the rolling element nears completion to make it
easy to nail wings level.  Most judges will downgrade for the wings not
being level, fewer will catch the change in roll rate.  The same thing
applies to corner radii - they are often softer close to the exit to make it
easier to hit the line.  The reason the cheats are employed is because
downgrades are not being applied - "no whistle, no foul".

How do some guys maintain distance during the entire flight (including stall
manuevers) when flying in a crosswind?  They don't.  They are just sneaky at
hiding the wind drift, and make corrections / allowances where they are the
hardest to detect.  Humans having pretty poor depth perception at 150 meters
also helps.  This past fall, I had a trusted observer stand in the field
underneath my flight track and was told that the flight track was about 145
meters, +/- 3 meters (a bit more variation after spins).  And the observer
was surprised to see how visible the rudder corrections were - as the same
observer saw far fewer rudder corrections when viewing similar flights as my
caller.

Prior to spins and stall turns, you will usually see a very small "cheat"
into the wind, and then a little drift with the wind allowed immediately
after the stall manuever, followed by a small "cheat" into the wind to
return to the original track.  A single 15 degree change in track is easy to
see and downgrade.  Very aggressive compensation for wind (difference
between attitude and track) while technically correct rarely scores well.
Three 5 degree changes in track are harder to see and harder to downgrade,
and present nicer (even if not as correct technically).

With snaps - to hide the lateral displacement and yaw track change in a
snap, the "cheat" is normally opposite the direction of the snap prior to
the snap entry - 5 degrees nose in before a snap and 5 degrees nose out
after the snap is harder to detect than simply being 10 degrees off after
the snap.  And of late, there is no doubt in my mind that being 10 degrees
off before the snap will earn little or no deduction if the exit of the snap
is nailed.  All deviations in roll, pitch, and yaw track should be equally
downgraded whether before or after the snap - it is a goal that needs to be
achieved.  The change in track during a snap can often be hidden (or
mitigated) to a large extent by wind - this is simply smart piloting by
choosing to snap into (usually) the wind.  And in the instance of a snap at
the end of the box, where the displacement or loss of heading in yaw is
particuarly easy to see, a more pronounced and aggresive break in pitch can
be used to minimize the deviation in yaw, as the deviation in pitch is
harder to see (and thus harder to downgrade).

Regards,

Dave
DaveL322 at comcast.net



----- Original Message -----
From: White, Chris
To: discussion at nsrca.org
Sent: Thursday, December 30, 2004 4:11 PM
Subject: RE: Snap Rolls.....are they legitimate/ RE: displacement during
snap rolls discussion


Consistent snap rolls.....how much skill....how much luck?

Do I read from the responses that the consensus is that snap rolls are
precision maneuvers?   I believe that may be true in full-scale aerobatics
particularly in slower snapping aircraft because you can actually see
outside and judge entrance timing based on real time entry speed (ASI) and
judge exit because of roll rate perceived via outside reference directly
relative to the horizon without any parallax as you would get from our
ground perspective.   I'm trying to say that the pattern airplanes that I've
flown snap differently and usually quickly.   I've seen very good pilots who
feel a real sense of accomplishment (or luck) when they hit the snap right
on....however, I still believe to a degree that it might be a little more
luck than precision to hit them consistently.  It seems a shame to have a
pilot miss an exit by 5 degrees to get a 1/2 point hit....particularly when
the perspective of a 5 degree bank at 150 meters away could vary with judges
and parallax considerations. (Or that a given judge may not see enough
conical rotation of the tail)
Please consider that I have nothing but admiration for the FAI pilots in the
finals when reading the following: Consider how conservative  stall turns
were performed during the FAI finals ( yes it was intelligent to fly them
that way)  you will notice that very few pilots flew great stall turns, they
were more like tight wingovers with the reason being obvious....who wants to
risk a flopped zero at the level where you have very few points separating
the standings.   Snap rolls seem to have more risk.

I would love to see the consensus on the following questions:

1) Do snap rolls add or detract from the legitimacy of judging precision
aerobatic pilots capabilities?
2) Do snap rolls add to the credibility of precision aerobatics?

Respectfully submitted by a new guy,
Chris

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Bjorn Lehnardt
Sent: Thursday, December 30, 2004 2:04 PM
To: discussion at nsrca.org
Subject: Re: Snap Rolls.....are they legitimate/ RE: displacement during
snap rolls discussion


Bob,

A good three point shooter in the NBA has mastered a maneuver that is
uncontrollable except for the first part, yet few question the validity of
his skill or it's part in the game.  Figuring out and mastering the
requirements for proper setup-entry under many different circumstances is
what makes a three point shot or a snap roll such an interesting part of the
game.

I would seem a real shame to say that pattern and pattern flyers are not
capable is mastering the art and science of the stalled maneuvers.

Snaps are still fairly new to pattern and so growing pains are to be
expected.  Resistance is natural and will go away with practice.  That both
flying practice and judging practice.


Bob Pastorello <rcaerobob at cox.net> wrote:
That is an excellent point, Chris.  And your modesty to not add
"Intermediate National Champion" to your credentials is noted.
    The issue of a virtually-uncontrollable maneuver EXCEPT for entry and
exit, does bring a valid question about it's place in our game.  I think Ed
Miller mentioned (sorry if wrong) that longer-duration maneuvers with more
easily-visible segments have their OWN level of difficulty.
    In '99, when I was working on the Rules Committee, and we were designing
new sequences one of the suggestions in Masters was a Center maneuver, a
square loop with 2/4 on U/D, 1/2 on horizontal legs.  We were TRASHED for
even suggesting such a thing!!!
    The reason I mention that is to consider difficulty and pilot challenge,
wouldn't most of us agree that the square loop I describe would be more
easily judged, and more challenging for the majority of pilots than the
downline SINGLE snap we have in '05 ???

Since we're in a rules cycle year, maybe this is a good time to rethink the
"required elements" of every class, and look more for "what do guys WANT to
have in the sequence?"

Great thread starter, Chris.

Bob Pastorello
NSRCA 199  AMA 46373
rcaerobob at cox.net
www.rcaerobats.net


----- Original Message -----
From: White, Chris
To: discussion at nsrca.org
Sent: Thursday, December 30, 2004 8:49 AM
Subject: Snap Rolls.....are they legitimate/ RE: displacement during snap
rolls discussion



Please excuse me if I'm repeating, or committing a "faux pas" ( I think I
spelled that right:) ) ....but I am really interested in hearing opinions to
the following:

1) Do snap rolls add or detract from the legitimacy of judging precision
aerobatic pilots capabilities?
2) Do snap rolls add to the credibility of precision aerobatics?

I'm new to the game, but a "stalled" maneuver is a maneuver that is not
"flown on the wing" .  An overwhelming percentage of the other maneuver
segments in our patterns are flown on the wing and are able to be judged
accurately and with a minimum of "impression" influence.  Since the Snap
Roll it is not "flown" through it is not fully controlled....lack of control
indicates somewhat of a wildcard that penalizes capable pilots experiencing
a "bad" maneuver.

I have seen many good snap rolls in competition, some done by great pilots,
some by new guys.....my question is: Should there be a "wild card"
allowance?  Is anyone capable of flying consistent snap rolls that are
consistently judgeable to clear and concise requirements?   I believe I'm
hearing an overwhelming "NO".  If the answer is no, then maybe they should
be removed.

I fly RC pattern because in my opinion it is more graceful and precise in
appearance as compared to IMAC.... not that I don't respect IMAC pilots
capabilities and enjoy the show.  But, I sometimes I wonder how "Snap Rolls"
fit into RC Pattern....and it sounds as if I'm not the only one.   (I like
to see snaps....I just feel there are variables beyond the pilots control
which penalize inconsistently)  I think a pilot should be judged on
control....not inertial physics. (is that a real term????:) )

Just my thoughts and question to the group....respectfully submitted,
Chris

(as a CFII, airshow nut and pattern guy and whatever other credibility I can
throw in:) )
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Ed Miller
Sent: Wednesday, December 29, 2004 7:11 PM
To: discussion at nsrca.org
Subject: Re: Displacement during snap rolls (was Why is it so quiet?)


Seems the never ending snap discussion was beat to death here last year too.
This will be long but hear me out. No doubt what I'm about to say will at
the very least be controversial. That's fine with me as I think we need to
think outside the box more often. My wife enjoys watching figure skating.
Being the "supportive spouse", on occasion I will watch for a bit with her.
It seems in figure skating, the multiple rotation jumps, triples and even
quadruple rotation variations is where all the judging ( and viewing )
emphasis is placed in a skaters routine. It also seems the judging is
focused on 2 things, the entry to the jump and "sticking" the landing.
Frankly, those that say they can see every element of the skaters rotation
are, IMHO, full of blank. It plain happens too fast. I have better eyesight
than most, in my younger days I could pick up the stitching and rotation of
a baseball thrown at 90mph. I'll admit, some of that sharpness is gone but,
I honestly cannot pick up all the rotation elements in a figure skaters jump
in real time ( we all can when they replay it in slow-mo ). Ever since the
snap roll was introduced into precision aerobatics, an oxymoron IMHO, we
have had the same problems judging snaps as professional figure skating
judges have judging triple toe loops. I have watched ( and learned some )
from the real snap masters, aka Lockhart and Pappas, yet, when in the judges
chair I look for departure in pitch ( entry ) and "the landing " of the
maneuver ( exit ) . So, to me, we've introduced snaps into precision
aerobatics to separate the wanna be pattern jockey hackers like me from the
gifted, talented folks like Lockhart, Pappas, Hyde, etc. but in fact what
we've done is actually dumbed down our judging criteria. These talented
flyers will find the setup and stick movements to present a maneuver such
that it defies the laws of gravity. However, most of us are only humans and
as judges, only judge what can we realistically see and honestly assess in a
snap roll. Most all snap rolls I've seen done and performed rotate at such a
speed that again, the exit is the focus. Once in awhile you can pick up the
obvious aileron roll exit. There are many more elements of a snap roll
besides entry and exit yet as I read/delete/read/delete, etc. the discussion
we are having here, it boils down to entry and exit positions. The
ex-masters maneuver of 2 rolls in opposite directions. It is a thing of
beauty when done properly  takes a lot of time to perform, especially
compared to our beloved snap rolls, has many more places for the pilot to
screw up that are EASILY VISIBLE to the judges besides the entry and exit
points. That's precision aerobatics IMHO. AMA pattern was always smooth and
graceful until someone decided as the FAI does, so must the AMA. Some will
say it's progress, new maneuvers, it's just raising the bar to let the cream
rise to the top. I'm on the side that the bar has sunk into the cream. Maybe
the some of the lost NSRCA members felt similarly.
Ed M.
----- Original Message -----
From: Doug Cronkhite
To: discussion at nsrca.org
Sent: Wednesday, December 29, 2004 4:33 PM
Subject: RE: Displacement during snap rolls (was Why is it so quiet?)


The rules for family 9.9 are as follows:

"Snap rolls represent one of the greatest challenges to judge. This is
primarily due to two factors: (1) the "snapping" characteristics of
different types of aircraft are unique; and (2), snap rolls are a high
energy maneuver that occur very quickly. Snaps happen so fast, in fact, that
is is virtually impossible for a judge to determine the exact order in which
events occur, especially at the beginning of the snap. There are no
criteria, therefore, for seeing nose and wing movement initiated at the same
time as with the other autorotation family, Spins."

The rest of the paragraphs deal with snaps not autorotating through the
complete revolutions and so forth but there is no criteria whatsoever for
line displacement. This would be impossible to deal with actually since
aircraft snap so differently from one type to another. A top level unlimited
airplane like an Edge, Cap, or Sukhoi displaces very little, but people
flying lower classes in Decathlons, Clipped Wing Cubs and so forth displace
a great deal in a snap. There's just no way to fairly judge with a single
standard across all aircraft types.

-Doug






From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On
Behalf Of Dean Pappas
Sent: Wednesday, December 29, 2004 1:15 PM
To: discussion at nsrca.org
Subject: RE: Displacement during snap rolls (was Why is it so quiet?)


Thanks Doug,
You don't happen to have the piece of text in a form that could be pasted
into this forum, do ya'?

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On
Behalf Of Doug Cronkhite
Sent: Wednesday, December 29, 2004 4:14 PM
To: discussion at nsrca.org
Subject: RE: Displacement during snap rolls (was Why is it so quiet?)


No track downgrade Dean. Since a snap roll is a yaw induced maneuver (or
should be at least) it's nigh-impossible to actually snap the airplane and
not displace the line a little. Especially when you consider the low weight
and inertia of our airplanes as compared to full scale.

-Doug





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