[NSRCA-discussion] How I became an expert Snap Judge (TIC)
mike mueller
mups1953 at yahoo.com
Thu Oct 15 04:27:38 AKDT 2009
I like that description Vince.
Stuart I'd say it's a 0. Mike
--- On Thu, 10/15/09, Stuart Chale <schale at optonline.net> wrote:
> From: Stuart Chale <schale at optonline.net>
> Subject: Re: [NSRCA-discussion] How I became an expert Snap Judge (TIC)
> To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
> Date: Thursday, October 15, 2009, 6:44 AM
>
>
>
>
>
>
> Is an avalanche with a perfect loop a 0 if the roll is a
> barrel or
> axial roll? Or should it be a 5 or 6?
>
> Stuart
>
>
>
> Vicente "Vince" Bortone wrote:
>
> #yiv971651320 p
> {margin:0;}
>
> Hi Mike and all,
>
> Shall we change the description
> from:
>
> OLD DESCRIPTION:
>
> Snaps: A Snap roll is a
> simultaneous,
> rapid autorotation in the pitch, yaw and roll axes of
> flight in a
> stalled wing attitude. The following criteria apply:
>
> 1.
> Since the maneuver is defined as a stalled maneuver,
> initiated by a
> stall of the wing induced by a rapid change in pitch
> attitude, the nose
> of the fuselage must show a definite break in pitch
> attitude from the
> flight path in the direction of the snap (positive or
> negative) while
> the track closely maintains the flight path. The lack of a
> discernable
> pitch break is downgraded by 5 points. Large deviations
> from the flight
> path, indicative of a delayed stall, are to be downgraded
> using the 1
> point per 15-degree rule for each axis of the excursion
> before stall.
> For example, it the model pitches 15 degrees nose up and
> the wings
> rotate 15 degrees before the stall, the maneuver should be
> downgraded 1
> point for pitch and 1 point for roll.
> 2. The track
> visualized as the
> path of the Center of Gravity (CG) should closely follow
> the geometric
> flight path of the maneuver while the nose and tail auto
> rotate through
> opposite helical arcs around the flight path. Lack of these
> helical
> arcs (or coning) is indicative of an axial roll and is
> scored zero
>
> to: Please
> fell free to add
> or change to improve it.
>
> SUGGESTED NEW DESCRIPTION:
>
> Snaps:
> A
> Snap roll is a
> simultaneous, rapid autorotation in the pitch, yaw and roll
> axes . The
> following criteria apply:
>
> 1. Barrel rool
> and or axial roll shall be downgraded 10 points.
>
>
> 2. The track
> visualized
> as the path of the Center of Gravity (CG) should closely
> follow the
> geometric flight path of the maneuver while the nose and
> tail auto
> rotate through opposite helical arcs around the flight
> path. Lack of
> these helical arcs (or coning) is indicative of an axial
> roll and is
> scored zero
>
> Vicente "Vince" Bortone
>
>
>
> ----- Original Message -----
>
> From: "mike mueller" <mups1953 at yahoo.com>
>
> To: "General pattern discussion"
> <nsrca-discussion at lists.nsrca.org>
>
> Sent: Wednesday, October 14, 2009 8:04:23 PM GMT -06:00
> US/Canada
> Central
>
> Subject: Re: [NSRCA-discussion] How I became an expert Snap
> Judge (TIC)
>
>
>
> You calling me Mark??? Opps thought you said Mueller.
>
> Man you guys are pretty darn smart. I'm just sitting
> back and taking
> it all in. Jerry Budd is amazing. His snaps look like real
> snaps to me.
>
>
> I can't help to think that Don Ramsey has it right.
> If it ain't a roll
> and it ain't a barrel roll then assume it's a snap.
> Thing is I really
> believe that most of us know what a snap looks like and
> pretty much
> judge it correctly. You just got to feel it. Mike
>
>
>
> --- On Wed, 10/14/09, Atwood, Mark <atwoodm at paragon-inc.com>
> wrote:
>
>
>
> > From: Atwood, Mark <atwoodm at paragon-inc.com>
>
> > Subject: Re: [NSRCA-discussion] How I became an expert
> Snap Judge
> (TIC)
>
> > To: "General pattern discussion"
> <nsrca-discussion at lists.nsrca.org>
>
> > Date: Wednesday, October 14, 2009, 8:19 AM
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Not to fear… We can
>
> > use Nov and Dec to discuss the
>
> > physical impossibility of maintaining constant roll
> rates
>
> > for rolling circles
>
> > in the wind, and then save Jan – March for finding
>
> > center for the Snap,
>
> > Opposite 4/8 and Snap, Opposite 4pt in F-11.
>
> >
>
> >
>
> >
>
> >
>
> > And if that doesn’t work,
>
> > we can always rehash why were explicitly
>
> > not allowed to touch the aircraft in
>
> > flight… Anyone?
>
> > Anyone? Bueller? Bueller???
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Mark
>
> > Atwood
>
> >
>
> > President
>
> >
>
> > Paragon
>
> > Consulting
>
> >
>
> > office ~ 440-684-3101 ext. 102
>
> >
>
> > mark.atwood at paragon-inc.com
>
>
> >
>
> >
>
> >
>
> > IT Solution Providers:
>
> > Custom Software Development. Staff
>
> > Augmentation.
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > From:
>
> > nsrca-discussion-bounces at lists.nsrca.org
>
> > [mailto:nsrca-discussion-bounces at lists.nsrca.org]
> On
>
> > Behalf Of Chris
>
> > Moon
>
> >
>
> > Sent: Wednesday, October 14, 2009 9:19 AM
>
> >
>
> > To: General pattern discussion
>
> >
>
> > Subject: Re: [NSRCA-discussion] How I became an
>
> > expert Snap Judge (TIC)
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Hey Mark,
>
> >
>
> >
>
> >
>
> > I was going to add that it doesn't take a
> rocket
>
> > scientist to have to
>
> > explain all of this to us....then Jerry posted. :)
>
> >
>
> >
>
> >
>
> > You are right, we are making this much more
>
> > difficult. The real problem
>
> > is - we are not going to have this discussion all
> winter
>
> > long as usual since it
>
> > was brought up in October!
>
> >
>
> >
>
> >
>
> > Chris
>
> >
>
> >
>
> >
>
> > Atwood, Mark wrote:
>
> >
>
> > So at the end of the day, we
>
> > don’t really do a
>
> > snap…ever. I think many have always known
>
> > that but this
>
> > (assuming Sir Budd’s math is correct) basically
> ends
>
> > the debate.
>
> >
>
> >
>
> >
>
> > So what we’re doing then
>
> > in Pattern is trying to emulate
>
> > the look of a snap…not actually snap. As such,
>
> > I have a VERY hard
>
> > time with the zeroing of a poor attempt. Downgrade
>
> > yes, but not the
>
> > spurious snap nazi zero. (I’m pretty sure I
>
> > just set myself up for
>
> > a few of them)…
>
> >
>
> >
>
> >
>
> > This suddenly because a lot
>
> > easier. It’s like
>
> > judging a loop. Instead of trying to draw a circle
>
> > were trying to make
>
> > the plane look like it snapped… and some will do a
>
> > better job than
>
> > others. As with the loop there will be
>
> > variances… Loops big
>
> > and small, snaps tight or open, etc, but at the end
>
> > of the day, if you
>
> > recognize the maneuver, it should probably be scored.
>
> >
>
> >
>
> >
>
> >
>
> > My $0.02
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Mark
>
> > Atwood
>
> >
>
> > President
>
> >
>
> > Paragon
>
> > Consulting
>
> >
>
> > office ~ 440-684-3101 ext. 102
>
> >
>
> > mark.atwood at paragon-inc.com
>
> >
>
> >
>
> >
>
> >
>
> > IT Solution Providers:
>
> > Custom Software Development. Staff
>
> > Augmentation.
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > From: nsrca-discussion-bounces at lists.nsrca.org
>
> > [mailto:nsrca-discussion-bounces at lists.nsrca.org]
>
> > On Behalf Of Budd Engineering
>
> >
>
> > Sent: Wednesday, October 14, 2009 6:13 AM
>
> >
>
> > To: General pattern discussion
>
> >
>
> > Subject: Re: [NSRCA-discussion] How I became an
>
> > expert Snap Judge (TIC)
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Chris, Vicente, et al.,
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Angle of attack, alpha or AOA, for the
>
> > aircraft is the difference
>
> > between the flight path angle, gamma, and the
> aircraft
>
> > attitude, theta
>
> > (assuming the airfoil zero lift angle is essentially
>
> > aligned with the aircraft
>
> > reference datum, which for all practical purposes on
> our
>
> > designs, it is).
>
> > Reference:
> http://www.aerospaceweb.org/question/aerodynamics/q0165.shtml.
>
> > Flight path angle is the aircraft trajectory, or in
>
> > pattern speak,
>
> > "track" but along the pitch axis, i.e.
> climbing
>
> > or descending.
>
> > In level, steady state flight (~1-g), the flight
> path
>
> > angle is zero.
>
> > Which means that the angle of attack is equal to
> the
>
> > aircraft pitch
>
> > attitude. If you run the numbers using a reasonable
>
> > airfoil lift curve
>
> > slope at a representative level flight speed for our
> planes
>
> > you'll find that
>
> > our planes trim out around ~ 0.5 degrees alpha (Lift
> =
>
> > Weight = CL * Qbar * S
>
> > where CL is the lift coefficient, Qbar is the dynamic
>
> > pressure, and S is the
>
> > reference wing area). This is because of our
>
> > extremely low wing loading,
>
> > it simply doesn't take a lot of angle of attack
> to
>
> > generate 1-g of lift when
>
> > your airplane only weighs 10 or 11 lbs. Here's
>
> > the other part: with the
>
> > exception of velocity (or airspeed), the equation is
>
> > linear, which means that
>
> > if you double the aircraft weight, for the same
> flight
>
> > speed, you get twice the
>
> > alpha (again, for 1-g trim). Or if you kept the
>
> > weight at say 10 lbs, but
>
> > cut the wing area in half, the angle of attack would
> then
>
> > double to ~ 1 degree
>
> > (again, for level, steady, 1-g flight). Velocity is
> a
>
> > little trickier to
>
> > account for because it's a non-linear second
> order
>
> > function in the lift
>
> > equation (remember Qbar? Reference:
> http://en.wikipedia.org/wiki/Dynamic_pressure,
>
> > Qbar = 1/2 * rho * V**2) where rho is air density and
> V is
>
> > the velocity).
>
> > Essentially, the lift doubles every time we
> increase
>
> > Qbar by 2, or
>
> > velocity by the square root of 2 (or 1.414). So if
>
> > you're flying along in
>
> > level flight at 60 mph (88 feet per second), and you
> speed
>
> > up to 85 mph mph
>
> > (124.45 feet per second), you've doubled your
> dynamic
>
> > pressure (Qbar) and to
>
> > stay at level 1-g flight, you'd have to retrim
> your
>
> > plane in pitch to 1/2 of
>
> > what your AOA was before (or you'll start
> climbing).
>
> > In this case the AOA
>
> > would be ~ 0.25 degrees (as would the pitch
> attitude).
>
> > One last bit of
>
> > info for the point I'm about to make is that the
> lift
>
> > curve slope for our
>
> > airfoils at the Reynolds Numbers we are operating at
> is
>
> > linear out to around
>
> > ~15-16 degrees alpha, with separation of lift
> occurring
>
> > above that, closer to
>
> > 18-20 degrees alpha (Reference:
> http://www.aerospaceweb.org/question/aerodynamics/q0136.shtml).
>
> > Note that the onset of separation is independent of
>
> > airspeed, it's purely
>
> > a flow angle phenomenon, i.e. you can stall an airfoil
> at
>
> > any airspeed, or
>
> > attitude (if you can get to a high enough angle of
>
> > attack). That's
>
> > essentially what Chris is saying below.
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > So what does this all mean?
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > If you look at the numbers, for our
>
> > planes, you can't get to
>
> > stall from steady level flight (at any reasonable
> cruise
>
> > speed) without
>
> > inducing a significant G-loading on the aircraft
> (which
>
> > will cause a
>
> > noticeable, and very observable, change in the flight
> path
>
> > angle), BEFORE the
>
> > airfoil stalls.
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Here's some more numbers to help
>
> > you connect the dots:
>
> > from level 1-g trim flight at 1/2 degree AOA,
>
> > you'd have to induce nearly
>
> > 30 g's to get to ~ 15 alpha, not likely you'd
> be
>
> > able to do that without seeing
>
> > it. Even starting at 2 degrees AOA (which is a lot
>
> > for our models), you
>
> > have to generate nearly 5-6 g's to reach stall
> (think
>
> > you'd notice that?).
>
> > Don't believe me? OK answer this: Have you
>
> > ever quickly but
>
> > smoothly from level upright 1-g flight at a normal
> cruise
>
> > speed input full aft
>
> > stick for a second or two and then release it but no
>
> > lateral input? What
>
> > happens? Unless something is grossly wrong with
> your
>
> > airplane you're
>
> > likely to see a rapid pitch up and a corresponding
> change
>
> > in flight path angle,
>
> > probably to something approaching a near vertical
> attitude,
>
> > but not much else.
>
> > Why? Our planes are so lightly loaded that only
>
> > at spin entry and
>
> > landing speeds can we induce enough angle of attack
> to
>
> > approach stall on the
>
> > airfoil on the plane without inducing significant
> g's
>
> > and grossly altering the
>
> > flight path angle (and flight path angle is what we
> really
>
> > see when we're
>
> > flying at cruise speeds BTW, not so much the pitch
> attitude
>
> > until we're at much
>
> > lower speeds. That's because we mentally
>
> > integrate the velocity vector in
>
> > our minds but that's a topic for another
> time/day).
>
> > Full scale aerobatic
>
> > planes (and to a lessor degree IMAC planes) don't
>
> > suffer this problem nearly so
>
> > badly since their wing loadings and inertia's are
> much
>
> > higher (dynamic stability
>
> > is somewhat more complex than static stability so
> I'm
>
> > not going to go much
>
> > further than this on this topic). The bottom line
> is
>
> > this: we're
>
> > not stalling the wing when we do our snaps, not even
> a
>
> > portion of it (unless
>
> > you're VERY low on airspeed at entry such as a
> spin).
>
> > We're too lightly
>
> > loaded to get to stall at any reasonable airspeed,
> the
>
> > airplane will respond
>
> > too quickly in the pitch axis resulting in a rapid
> change
>
> > in flight path
>
> > angle, effectively unloading the AOA during the
>
> > response.
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > So what are we doing to make the plane
>
> > present what appears
>
> > to be a snap roll when we can't actually be
> stalling
>
> > the wing asymmetrically to
>
> > induce autorotation like many claim? Lots of
> control
>
> > power in pitch and
>
> > roll coupled with additional rolling moment induced
> by
>
> > dihedral effect
>
> > (sideslip driven by rudder input). Pretty much
>
> > everyone knows that at
>
> > higher AOA you can command/control roll with rudder,
> well
>
> > that's due to
>
> > dihedral effect (roll with rudder), it gets more
> powerful
>
> > with a little AOA.
>
> > That's where you get the part of the dynamic
> that
>
> > visually emulates a
>
> > full scale snap roll but physically is quite different
> (you
>
> > can make it look
>
> > like a full-scale snap, but it really isn't).
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > So the bigger question is should
>
> > emulating a full-scale snap
>
> > roll be a pattern judging criterion or do we even
> care? (we
>
> > know what the
>
> > answer is for full scale aerobatics and probably IMAC
> too
>
> > but we are neither of
>
> > these). Until we decide the answer to THAT
> question,
>
> > we're really just
>
> > debating "how many angels can dance on the head
> of a
>
> > pin"...
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > OK, it's really, really late out
>
> > here on the left coast,
>
> > I've gotta get to bed. Shoot away.
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Thx, Jerry
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Budd Engineering
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > jerry at buddengineering.com
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > http://www.buddengineering.com
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > On Oct 13, 2009, at 8:54 PM, Chris
>
> > Moon wrote:
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Ahhh.
>
> > angle of attack is not the same as the aircraft
>
> > attitude.Websters defines angle
>
> > of attack as "the acute angle between the chord
> of an
>
> > airfoil and the line
>
> > of relative air flow". The relative wind flows
>
> > parallel and opposite
>
> > the direction of the wing's movement through the
>
> > air.The wing's attitude as we
>
> > see it from the ground is NOT the same as angle of
> attack.
>
> > If you are in a
>
> > vertical climb is the wing stalled? After all it is
>
> > 90 degrees ATTUIUDE
>
> > from your perspective on the ground, right? But the
> wing is
>
> > not stalled because
>
> > the relative wind is coming parallel and opposite the
>
> > direction of flight. You
>
> > can be in a nose low descent and stall a wing. Now
>
> > take a straight and
>
> > level pass and give it an instantaneous large amount
> of up
>
> > elevator. What
>
> > happens? First, the plane continues in the direction
> it was
>
> > going (straight
>
> > ahead) for a short time, but what is important is that
> the
>
> > angle between the
>
> > relative wind (straight ahead) and the wing which is
> now
>
> > pivoting up increases
>
> > until it reaches the critical angle of attack and it
>
> > stalls. Without
>
> > knowing the specifics of that wing design, we
> can't
>
> > know when exactly this will
>
> > occur, but it can be extremely fast and at a
> relatively low
>
> > ATTITUDE in
>
> > relation to the ground. Hence, you do not need a
> high
>
> > nose ATTITUDE in
>
> > order to have a high angle of attack. There are too
> many
>
> > variables for one to
>
> > say that they need to see a nose high attitude in
> order to
>
> > define a high angle
>
> > of attack and thus a stall. Remember also, that
>
> > different wings have a
>
> > different critical angle of attack where a wing will
>
> > stall. How does
>
> > anyone know where that angle is without a wind tunnel
> and
>
> > testing? and who am I
>
> > to say it did not pitch up enough to stall therefore
> I
>
> > giveth the pilot a 5 or
>
> > zero even though I cannot possibly know the
> particulars of
>
> > the wing that I am
>
> > watching.
>
> >
>
> > My comment of the 1-2 degrees was to say that we do
> not
>
> > know how closely any
>
> > particular wing is flying from it's critical angle
> of
>
> > attack. If it is in
>
> > fact close, a change of only 1-2 degrees can cause a
>
> > stall. We are trying
>
> > to be aerodynamic engineers from the ground and
> deciding
>
> > for ourselves what the
>
> > angle "should" look like and downgrading
>
> > accordingly. Now throw
>
> > in the conceptual difference between angle of attack
> and
>
> > aircraft attitude, and
>
> > it is easy to come to the wrong conclusion about stall
> or
>
> > no stall. Are we
>
> > fling only 1-2 degrees from the critical angle most of
> the
>
> > time, no but the
>
> > point it that there is absolutely no aerodynamic
>
> > requirement for a very nose
>
> > high ATTITUDE to be a requirement in order to get a
> high
>
> > angle of attack on the
>
> > wing.
>
> >
>
> >
>
> >
>
> > Chris
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Vicente "Vince" Bortone wrote:
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Chris,
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > I am copying
>
> > from the first sentence FAI rule book:
>
> > " A snap-roll (or
>
> > flick roll/rudder
>
> > roll) is a rapid autorotative roll where the model
> aircraft
>
> > is in a stalled
>
> > attitude, with a
>
> > continuous high angle of attack"
>
> > The question: Is 1-2 degrees consider a good amount
> to
>
> > define a high angle of
>
> > attack?
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Vicente
>
> > "Vince" Bortone
>
> >
>
> >
>
> >
>
> > ----- Original Message -----
>
> >
>
> > From: "Chris Moon" <cjm767driver at hotmail.com>
>
> >
>
> > To: "General pattern
> discussion" <nsrca-discussion at lists.nsrca.org>
>
> >
>
> > Sent: Tuesday, October 13, 2009 3:07:01 PM GMT -06:00
>
> > US/Canada Central
>
> >
>
> > Subject: Re: [NSRCA-discussion] How I became an expert
> Snap
>
> > Judge (TIC)
>
> >
>
> >
>
> >
>
> > I think what this goes back to is the erroneous belief
> that
>
> > you need to see an
>
> > exaggerated pitch departure or it should be severely
>
> > downgraded. Keep
>
> > reading the maneuver description. It needs
>
> > "A" pitch break, and
>
> > depending on the current aoa (angle of attack) that
> can be
>
> > a difference of just
>
> > a degree or 2 if you are near the critical aoa.
>
> > Please don't tell me
>
> > guys, you are looking for MORE than a simple exceeding
> of
>
> > the critical aoa and
>
> > resulting stall. An exaggerated pitch break just to
>
> > prove to naysayers
>
> > that you make a break is wrong, wrong, wrong. It
> says
>
> > it needs
>
> > "A" break. Please keep re-reading it.
>
> > Same for spin
>
> > entry. It needs to stall, not go 30 degrees nose up
>
> > to "prove"
>
> > a stall. We are getting wound up over a
>
> > misunderstanding of the mechanics
>
> > of a stalled condition. As Don and Verne are
> alluding
>
> > to, it really is not
>
> > that complicated.
>
> >
>
> >
>
> >
>
> > Chris
>
> >
>
> >
>
> >
>
> > verne at twmi.rr.com wrote:
>
> >
>
> >
>
> >
>
> >
>
> > Or you
>
> > could just write in "DNO".... I always seem
> to see
>
> > the break as in, nose up, tail down, and my 56 year
> old eyes
>
> > are lousy. Verne ---- "Vicente "Vince"
>
> > Bortone" <vicenterc at comcast.net>
>
> > wrote:
>
> >
>
> > Verne,
>
> > Following AMA description: if we don't see the
>
> > break is 5 points downgrade. That is 1/2 of the
> snap
>
> > roll maneuver. Therefore, if we see the snap roll
>
> > but don't see the break the judge has the right to
> write
>
> > down 5 points score assuming that all other components
> are
>
> > perfect. Therefore, base on the rule book the snap
>
> > roll without a break has a value of 5 points.
> Vicente
>
> > "Vince" Bortone ----- Original Message -----
> From:
>
> > verne @ twmi . rr .com To: "General pattern
>
> > discussion" < nsrca -discussion at lists. nsrca
>
> > .org> Cc: "Don Ramsey" <don. ramsey @
>
> > suddenlink .net> Sent: Tuesday, October 13, 2009
> 2:14:02
>
> > PM GMT -06:00 US/Canada Central Subject: Re:
>
> > [NSRCA-discussion] How I became an expert Snap Judge
> (TIC)
>
> > Is there anybody involved in this discussion that
> honestly
>
> > can't recognize a snap when they see one? I'm
> just
>
> > asking..... Verne ---- Don Ramsey <don. ramsey @
>
> > suddenlink .net> wrote:
>
> >
>
> >
>
> > Vince,
>
> > What about the next sentence in the FAI
> definition,
>
> > “If the stall/break does not occur and the model
>
> > aircraft barrel rolls around, the manoeuvre must be
> severely
>
> > downgraded (more than 5 points).” How about if
>
> > the break does not show and the model does NOT barrel
> roll
>
> > around. Do you still downgrade by 5 or more points?
>
> > I don’t know what the intent of the rule was but
>
> > I can tell you for a fact that the judges that only
> score
>
> > FAI in Europe do not downgrade it by 5 or more
> points.
>
> > I believe they use the “If it’s not a
>
> > barrel and not an axial roll then it’s probably a
>
> > snap, so judge it that way” because they have been
>
> > instructed in the past to do it that way. Don
>
> > rom: nsrca -discussion-bounces at lists. nsrca
>
> > .org [mailto: nsrca -discussion-bounces at lists. nsrca
> .org]
>
> > On Behalf Of Vicente "Vince" Bortone Sent:
>
> > Tuesday, October 13, 2009 12:10 PM To: General
>
> > pattern discussion Subject: Re: [NSRCA-discussion] How
> I
>
> > became an expert Snap Judge (TIC) Matt,
>
> > I am copying the snap description from the current
>
> > FAI and AMA manuals. I don't see the AND you
>
> > mention in the FAI rule book. See the important
>
> > portion in bold. I see that the AMA description is
>
> > better in this respect. You are correct in regard
> the
>
> > downgrade in FAI . 5 or more points if you
> don't
>
> > see the break and the model barrel rolls. Therefore,
> what is
>
> > the downgrade in FAI if the judge does not see the
> break and
>
> > there is autorotation? I will say 5 points since it
>
> > says 5 or more points if the model barrel rolls.
>
> > Again, it appears that AMA down grad descriptions
> are
>
> > better. FAI : SNAP-ROLLS A snap-roll (or flick
>
> > roll/rudder roll) is a rapid autorotative roll where
> the
>
> > model aircraft is in a stalled attitude, with a
> continuous
>
> > high angle of attack Snap-rolls have the same judging
>
> > criteria as axial rolls as far as start and stop of
> the
>
> > rotation, and constant flight path through the
>
> > manoeuvre is concerned. At the start of a
>
> > snap-roll, the fuselage attitude must show a
>
> > definite break and separation from the flight path,
> before
>
> > the rotation is started, since the model aircraft is
>
> > supposed to be in a stalled condition throughout the
>
> > manoeuvre, If the stall/break does not occur and the
> model
>
> > aircraft barrelrolls around, the manoeuvre must be
> severely
>
> > downgraded (more than 5 points). Similarly, axial
> rolls
>
> > disguised as snap-rolls must be severely downgraded
> (more
>
> > than 5 points). Snap-rolls can be flown both positive
> and
>
> > negative, and the same criteria apply. The attitude
>
> > (positive or negative) is at the competitor’s
>
> > discretion. If the model aircraft returns to an
> unstalled
>
> > condition during the snap-roll, the manoeuvre is
> severely
>
> > downgraded using the 1 point/15 degree rule. AMA:
>
> > Snaps: A Snap roll is a simultaneous, rapid
> autorotation in
>
> > the pitch, yaw and roll axes of flight in a stalled
> wing
>
> > attitude. The following criteria apply: 1. Since the
>
> > maneuver is defined as a stalled maneuver,
>
> > initiated by a stall of the wing induced by a
>
> > rapid change in pitch attitude, the nose of the
> fuselage
>
> > must show a definite break in pitch attitude from the
> flight
>
> > path in the direction of the snap (positive or
> negative)
>
> > while the track closely maintains the flight path. The
> lack
>
> > of a discernable pitch break is downgraded by 5
> points.
>
> > Large deviations from the flight path, indicative of
> a
>
> > delayed stall, are to be downgraded using the 1 point
> per
>
> > 15-degree rule for each axis of the excursion before
> stall.
>
> > For example, it the model pitches 15 degrees nose up
> and the
>
> > wings rotate 15 degrees before the stall, the
> maneuver
>
> > should be downgraded 1 point for pitch and 1 point for
> roll.
>
> > 2. The track visualized as the path of the Center of
> Gravity
>
> > (CG) should closely follow the geometric flight path
> of the
>
> > maneuver while the nose and tail auto rotate through
>
> > opposite helical arcs around the flight path. Lack of
> these
>
> > helical arcs (or coning) is indicative of an
>
> > axial roll and is scored zero. 3. If a stall does
>
> > not occur and the model barrel rolls, the score is
> zero. A
>
> > barrel roll can be identified when the CG, the nose,
> and
>
> > tails scribe the same helical path through the
> required
>
> > rotation of the maneuver 4. Snap rolls have the same
> judging
>
> > criteria as axial rolls as far as start and stop of
>
> > rotation, constant flight path through the maneuver
> and
>
> > centering on lines. 5. If the model returns to an
> unstalled
>
> > condition during the maneuver, such that the
> autorotation is
>
> > not visible and the model rolls or barrel rolls to
> complete
>
> > the maneuver, it would be downgraded using the 1 point
> per
>
> > 15 degree rule. 6. Airspeed is not a criteria which
> should
>
> > be used to judge this maneuver. The wing of the model
> is
>
> > stalled during this maneuver; therefore a significant
>
> > decrease in speed may occur and is not a cause for
>
> > downgrade. Vicente "Vince" Bortone -----
> Original
>
> > Message ----- From: "Matthew Frederick" <mjfrederick at cox.net>
>
> > To: "General pattern discussion" <
>
> > nsrca -discussion at lists. nsrca .org> Sent:
> Tuesday,
>
> > October 13, 2009 9:47:30 AM GMT -06:00 US/Canada
> Central
>
> > Subject: Re: [NSRCA-discussion] How I became an expert
> Snap
>
> > Judge (TIC) ? While speaking with Don Ramsey about
> the
>
> > nuances of judging snaps at a recent contest I found
> that he
>
> > agreed with my interpretation of the FAI snap rule.
> The
>
> > severe downgrade should only be applied if there is no
> break
>
> > AND there is no autorotation (this is exactly what the
> rule
>
> > says). Basically, lack of a break is not substantial
> grounds
>
> > for the severe downgrade in FAI . If the break is not
> seen
>
> > and autorotation still occurs at some point during the
> roll
>
> > the one point per 15 degree rule applies. Since the
> snaps
>
> > happen so fast, for me it's usually not more than
> 1 or 2
>
> > points unless it was blatantly obvious that the plane
>
> > rotated a while before the snap truly began. It's
> the
>
> > same as if you stop the snap before completing
>
> > the rotation and do an axial roll to finish. This
>
> > nonsense of people being so quick to apply a severe
>
> > downgrade has gone too far. One element of a maneuver
>
> > (because I can't think of any sequence that has
> just a
>
> > snap roll) should not ruin a whole flight, or eve n
> that one
>
> > maneuver unless it just wasn't a snap. I like the
> idea
>
> > of "if it's not a barrell roll and not an
> axial
>
> > roll, it's probably a snap." Matt -----
>
> > Original Message ----- From: Vicente
> <mailto:vicenterc at comcast.net>
>
> > "Vince" Bortone To: General pattern
> discussion
>
> > <mailto: nsrca -discussion at lists. nsrca .org>
>
>
> > Sent: Monday, October 12, 2009 5:12 PM Subject: Re:
>
> > [NSRCA-discussion] How I became an expert Snap Judge
> (TIC)
>
> > I believe that the current downgrade is severe.
>
> > AMA 5 points. FAI 5 or more points if my memory
>
> > is correct. In local contest I have been using
>
> > 3 points downgrade. I know that is wrong but it has
>
> > been my best way for me to take into account the
> break
>
> > issue. It used to be zero and it was changed to 5
>
> > points (IMAC still a 10 points downgrade or nada).
>
> > Therefore, Ron is correct. Probably makes sense
>
> > to go 2-3 points downgrade if the judge can not see
> the
>
> > break before rotation. Vicente
>
> > "Vince" Bortone ----- Original Message -----
> From:
>
> > "John Fuqua" <johnfuqua at embarqmail.com>
>
> > To: "General pattern discussion" <
>
> > nsrca -discussion at lists. nsrca .org> Sent: Monday,
>
> > October 12, 2009 1:51:00 PM GMT -06:00 US/Canada
> Central
>
> > Subject: Re: [NSRCA-discussion] How I became an expert
> Snap
>
> > Judge (TIC) Ron makes valid observation which I came
> to many
>
> > years ago at the TOC when Mr. Bill graciously funded
> for
>
> > full scale pilots like Patty Wagstaff do demo flights
> to
>
> > entertain us. The one thing that I came away with
> in
>
> > comparing full scale to our airplanes is the speed of
> the
>
> > snap/rotation. In the full size aerobatics types
> that
>
> > I observed there was plenty of time to see the nose
> pitch
>
> > and then after somewhat of a hesitation yaw and
> rotate.
>
> > In our pattern planes, especially when using a snap
>
> > switch, it all gets to be a blur due to sheer speed.
> I
>
> > have no solution to this issue but to MAKE the pilots
> show a
>
> > break by having severe downgrades. Otherwise the
>
> > concept of a snap will be ignored. Yes
>
> > it's hard to see which makes it incumbent on the
> pilot
>
> > to present it to the judges. -----Original
>
> > Message----- From: nsrca -discussion-bounces at lists.
> nsrca
>
> > .org [mailto: nsrca -discussion-bounces at lists. nsrca
> .org]
>
> > On Behalf Of ronlock at comcast.net
>
> > Sent: Monday, October 12, 2009 1:26 PM To:
>
> > General pattern discussion Subject: Re:
> [NSRCA-discussion]
>
> > How I became an expert Snap Judge (TIC) Here is a
>
> > description that shows technically correct snap
> execution,
>
> > and valid, consistent judging is possible. (Half
> of
>
> > the District One guy need not read this, they have
> already
>
> > heard it) <G> At a small airport
>
> > airshow, one of demos was an in-trail formation of
> four full
>
> > scale AT-6 Texans. As each plane got to stage
> center,
>
> > it did a single positive snap roll. Spectators saw
> four snap
>
> > rolls in a row, about 5 seconds apart. The flight
> of
>
> > four went around, and repeated the maneuver. Some
>
> > spectators are getting bored - even a pattern guy
> could get
>
> > bored with a string of 8 nearly identical maneuvers.
>
>
> > And then, they did it yet again!! What's in
> this
>
> > for us? The snap maneuver by each AT-6 appeared to
>
> > take a second or so, from initiation to
>
> > completion. By the time the fourth plane did a snap,
> you
>
> > could start seeing.... - there is a nose
>
> > pitch up, - then a yaw, - then plane
>
> > rolled in direction of yaw, - plane returned to
>
> > straight and level flight. By the time the flight
>
> > came around for another four snaps, you could see
> more
>
> > details.. - there is a nose pitch up, (somewhat
>
> > sudden, at least sudden for an AT-6) - then a large
>
> > amount of yaw, - then rapid roll in direction of
> yaw,
>
> > (rolling faster than it could with ailerons) -
> plane
>
> > returned to fairly close straight and level, nose
> slightly
>
> > high. By the time the flight positioned for yet
>
> > another four snaps, (Yawn, spectators headed for
> cotton
>
> > candy) the four distinct elements of the snap roll
> maneuver
>
> > were easy to see, and there was time to evaluate
> (judge)
>
> > each element. 1. there is a nose pitch up,
>
> > (somewhat sudden, at least sudden for an AT-6, with
>
> > little rise in altitude) 2. then large amount
>
> > of yaw, (the yaw proceeds the upcoming roll) 3.
>
> > then autorotation at rate faster than it could do
> an
>
> > aileron roll) 4. plane returns to level
>
> > flight track, with nose lowering to level flight
> attitude.
>
> > We can all be expert Snap Roll Judges! Ahhh,
>
> > at least for AT-6 snaps. What I take from all of
>
> > this- The problem is not snap descriptions.
>
> > It's the application of them; observation,
>
> > discrimination and judging of elements in the split
> second
>
> > observation time we have. Is the task beyond
>
> > reasonable expectations of most of us as a judging
>
> > community? I suppose we will continue work started
>
> > over 10 years ago to improve in these areas. In
> the
>
> > meantime, shall we reduce the impact of inconsistent
> judging
>
> > of snaps by limiting the downgrade of the snap portion
> of a
>
> > maneuver to say..two points2? Ron Lockhart
>
> > _______________________________________________
>
> > NSRCA-discussion mailing list NSRCA-discussion at lists.
> nsrca
>
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>
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>
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>
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