As a contestant, I often end up judging lower classes. Last week I gave some zeroes to an advanced guy that snapped with the rudder in the wrong direction and agreed with the other judge that it was not a snap --> no autorotation... everything else was there but no autorotation. In fact the plane rolled at a slower pace than if no rudder was applied at all.

I was discussing of this with a full scale flyer that used to fly IAC competition and he told me I should not have zeroed those snaps. He said that we should look for some sort of cone shaped movement of the tail and that it should have been the case even if the rudder was not properly used.

Is he right ?

I am an Advanced class pilot and have attended an IMAC judging school. I am asked to sit in the judges chair at every contest I have attended in the last 5 years including twice at the SW IMAC Championships. Usually I am asked to judge the Unlimited guys but have judged all the classes. That being said, you were 100% correct in giving that pilot a zero. I have given zeros for the same thing on several occasions.



Shawn

What is the criteria for discerning autorotation in IMAC? What tells you that there was no autorotation?

The reason I ask is becuase in pattern the "speed" of the rotation is not a judging critera although the AMA calls it "rapid autorotation". I just want to be able to differentiate. The criteria in pattern are a visible pitch break and simultaneous rapid autorotation. This is apparent after the break when you see both the nose and tail coning around the cg. If there is no visible coning, its a zero. If there is no nose break it is a severe downgrade in pattern.

For IMAC, I know there is a rulebook I can read (and have some), I am just curious what you guys out there judging are looking for and basing your scoring decisions on.

A zero was correct. It would be almost impossible for it to actually break while using the wrong rudder as long as elevator was also applied in the right direction. That is the reason it rotated so much slower. It probably just did a slow corkscrew w/o actually stalling the wing.

What do you mean by "snapped with the rudder in the wrong direction" and how does that relate to whther or not the plane autorotates? Please explain. I am new to IMAC (but not new to sequence flying) and really want to understand what you are talking about so that I can apply it to how I execute a snap. I know that there are positive and negative snaps, and can execute both, but what difference does it make it the plane snaps positive or negative with left rudder or right rudder?

Mike, when opposite rudder is applied the manuver is no longer a snap roll. The criteria for a snap is that the wing has to stall or in the case of our models must "appear" to stall (but that is another whole topic there). When opposite rudder is used the airplane flys through the roll and thus cannot be called a snap roll. The wrong manuver was flown so the figure gets a zero.


Shawn

If it was a positive snap (Pull) what he did was a Shoulder Snap. Pull, left aileron and right rudder. Or, Pull, Right aileron and left rudder.
A zero in any case.
It will still Auto Rotate that way though.

If he was doing a negative snap opposite rudder from aileron is correct. No zero.

Ok, that answers my question[8D]

I'm new to IMAC and I might get it wrong but I do not understand what means rudder in wrong direction and where you zero a flick. The regular snap roll is just elevator and rudder, no matter which direction. For a CW spinning prop and positive maneuver left rudder wil make the cone wider and faster, right rudder will tighten the cone but the autorotation it's slower. No matter the side, both are autorotational maneuvers. If ailerons are applayed with rudder, as far as I know, it's called accelerated snap roll.
Going back to judging, are you zero a snap if no ailerons are applyed or ailerons are reversed to rudder ?

10X

Ok just to clarify my first statement.

It was a negative snap and the elevator was down and the rudder was applied at the same direction as the ailerons --> hence wrong direction. I do fly unlimited and had attended judging seminars in the past so I was pretty confident my zeroing of this snap was a good thing to do but being a guy that always listens to others that have more experience than me, especially this guy that used fly full scale competition which we are supposed to try to duplicate, I had to ask here... In fact we don't really try to duplicate full scale as we make snaps that don't look like snaps, but that's another story...

I was feeling bad as I zeroed this guy the Humpty bump in advanced for all sequences I judged and this happens to be the critical maneuver with the biggest K factor. That put him back by at least 3 positions in the rankings of that competition.

BTW, last weekend I tried to snap without ailerons at all. Looked much more like a full scale snap and while I was thinking it made a much too deep snap that almost stopped the plane, my friend told me it was almost deep enough for a full scale snap... That rendred my plane useless for the hammer head in unlimited where I have to make 1 1/2 neg snap on the upline; not enough power.

Thanks for your help guys!

I love these conversations...I think I understand the initial question. The poor guy did an outside snap inplace of an inside snap..
Wayne never heard the term shoulder snap before. I know some full scale pilots would kick the opposite rudder to enter the lamchavak (easier said then spelled).
Now the response of "too deep of a snap with rudder only" lost me...If infact you stalled the wing it wouldn't be any deeper, one from the other. Now it may have slowed the rotation due to lack of aileron use at the onset and caused a slower airspeed at the recovery stage but I can't picture a deeper snap. Or maybe we are just now questioning what the high roll rate monoplanes introduced to the IAC world in the 90's "was it a snap or a roll????".
These discussions are much easier to picture at the flying field with a plane handy...

OK to explain a little more. Maybe I use too much elevator for my snaps (I could improve that) but I also use ailerons in competition so the snap is fast enough and the plane does not have time to pitch up very much and I can manage to have speed left for the straight line that has to follow the snap. Now if I do exactly the same without ailerons, the plane has much more time to "pitch up" hence the fact that the snap looks deeper and as you mentioned, the snap takes more time to execute so the exit speed is much lower.

At a field with a plane handy as you said... Much simpler then!

In IMAC there are two things absolutely required for a snap roll:

1) the nose MUST depart the line of flight in the proper direction (towards the canopy in a positive snap, towards the wheels in a negative snap).

2) the plane MUST autorotate.

If EITHER one is absent, the maneuver gets a zero.

Autorotation is a result of the wing being partially stalled (usually one wing) and it causes a rotation that is generally faster than could be accomplished by the use of the controls alone. Be watchful for the crafty pilot that will try to fool you with a little flick of the nose and then a REALLY fast axial roll instead of autorotation. Autorotation is very hard to define, but once you have seen it there is no mistaking it for a fast axial roll.

As a judge it matters not one little bit what controls are used, how much or in what direction. ALL you are doing is judging what the plane does. The figure in the original post would have been zeroed by me as well. It did not autorotate. I don't care if it was "wrong" rudder or whatever. The pilot failed to present the required components for a snap to get scored. Period.

There is a very nice section of a thing I call "The Rulebook" that covers this. It is worth a look!!.

Bill Malvey
Chairman IMAC Rules and Standards Committee

bill, why do you complicate things with references to the rules? all that does is add to the confusion. it makes more sense to solicity input from the iac and pattern guys and anyone on RCU with an opinion.

guys...the rules are clear, published, and easily accessed. What pattern or IAC has to say on the matter is meaningless, although that is easier said than accepted. A judge owes it to the competitors to be well versed on the rules, and so far, bill is the only one to cite the rules to support his answer.


a former chairman of the imac seq committee

Im no IMAC guru but i must say most snaps I see are so far from the full scale equivalent in that they happen so fast I wonder how you guys that do the judging have any idea at all what inputs where put in and what actually happened during the manouvere. I personally snap with minimal possible inputs, and i release the elevator almost immediately for 2 reasons 1) otherwise my plane overrotates too much, 2) i just think it looks alot nicer and you can actually see the motions of the plane through the snap alot easier as it occurs a little more slowly. On the guy swho used same side rudder for a 'shoulder snap', actually although this manouvere isnt really a snap at all i think it can look very graceful and is a nice manouvere to execute. Though obviously out of the schedule!

It does not matter "what inputs" were used. All that matters is that the judging criteria are met as stated above. There is no requirement to be close to "a full scale equivalent" or to be done at a certain rate. Remember, a judge is supposed to be applying the criteria as written in the rules and nothing else. It matters not how the figure is done, all that matters is how closely to perfect it is as defined in the rules.

Sorry, you misunderstand me. I agree with you in IMAC you simply have to follow the shcedule and comply with the rules to be scored accordingly. I was just remarking on the fatc that the manouvere he performed actually is one i quite like, and secondly that most snaps including those that seem within the rules i find too fast for my taste. Just a personal view...

The bottom line in all this discussion about snaps is this: the nose has to break the flight path, the wing has to stall and the whole plane autorotates. If they don't it's a zero - period!!

Usually, it's the upper class guys that try to do a snap roll so quickly that all you can see is the wings rolling around and the nose never breaks. They convince themselves that the nose breaks and they really excited wihen they get a zero because the nose didn't break the flight path - ACCORDING TO THE JUDGES!!

One other comment. This is IMAC - not AMA F3A pattern, not IAC, not full scale - but IMAC! None of the other SIGs makes any difference as they each have their own set of rules and we (IMAC) have ours. Some are different and some are the same, the snap roll is but one instance where there is a difference.

Bobby

I have a question related to snap. It would be interesting to hear all opinions because I couldn't find a clear description on IMAC site.
On a knife edge snap roll, what do you stall first, fuse or wings ? You are flying on the fuse but as counter argument stalling has nothing to do with gravity.
I can find good reasons, at least in my mind, for both ways but I don't believe it's got a duality nature as the light.
My brain switched languages 1 hour ago so, for clarity let me itemize in my mock-up english:

1. You start with the rudder, the nose will departure on vertical. Arguments : easy to see and it feels consistent for judges.
2. You start with elevator and stall the wings. Arguments: the wings are stalled first and even if you're not flying on them I think I've seen it somewhere written as a rule.

Boby

quote:






OK, thats two uncalled for snide remarks to my comments above. You guys are awful quick to make snap judgements. Sure looks like a beef with people outide of "your circle"[:@]
Both of you need to go back and re read the above. In general , my comment was that I understood the rules according to pattern and that I want to understand the rules according to IMAC and the differences in how IMAC judges look at a snap so that I can give IMAC judges what they want to see. I know all about reading the rule book and have done so, dont give me the "read the rulebook" speech. I asked an honest question that is in context to the original question and all I wanted was an honest answer. As we all know when it comes to snaps in competition there is a big difference between what the "rulebook" states, and how people interpret a snap when that are sitting in the judges chair.

I coached girls fastpitch softball for years and one of the 1st things I did before the game was ask the umpire where he wanted to see the ball thrown to call strikes. It often angered them to be asked, but they had to answer. They knew the rules, I knew the rules, I just wanted them to tell me in their own words so that we all knew what to expect come game time and we could give them what they wanted to see.
Its no different here. There are rules. But they are subjective to human perception, all I want to know is what the typical judge is actually looking for so that I can put it where they want it.

Funny thing is, amidst the sickening condescening arrogance, I find that the comments indicate that there is really no difference in what the judges expect to see from one discipline to the other. [8D]

Gee I thought IMAC was suppose to imitate IAC? How can a snap be different between pattern, IAC, IMAC? In a knife edge is the plane truely flying on the fuse as queried above? Why can't questions be asked without people being attacked by others supposedly involved with the SIG?? Why can't a judge explain the maneuver, all he can do is tap the rule book?
This is fun right? And why can't I spell at 9:00 in the morning???

There is such a huge difference in the reynolds number between our planes and the full scale planes along with wing loading that it is impossible for our planes to pitch like the full scale planes do before a snap and still come out on anywhere close to a straight line. With that being said, ours can still most definately break the nose and autorotate, just not to the same extreme.

If you get a chance watch some full scale videos and see how far the plane pitches before a snap and then try the same thing with one of our 35 - 40% planes. The plane won't stall with a pitch of the nose, it will just start climbing.

I'll try and find some links and post them on here later.

How far the nose breaks has nothing to do with it being a snap or not. In other words the nose just has to break the plane for it to be considered, not by any minimum amount of degrees.
That full scale pitch varies according to aircraft also. You may not see a huge break in a full scale snap either, it depends on the entry method. I have seen some experimental's with very little nose break when they attempt the use of ailerons in the snap (like models). Hense the argument of was it really a snap or a bump of elevator with a extreme roll rate.. These same questions came up in the full scale area as well (at least when I was a little involved in the 90's).
I am not trolling here either, I like these discussions. And beleive it or not (even though I will never admit it) sometimes I am wrong and need to be corrected.. It has been a few years since I have gotten to discuss the actual maneuvers, and I can't wait to get my first of many zeros so I can moan and groan.

Supposed to be... In truth it is just big boys playing with expensive toys (dont freak out, you know what I mean) in an amateur game. Other than cost it's no different than little league baseball, fantasy football or playing Halo against your buddies on playstation. We just take it WAY too seriously. I include myself in that bunch. I just dont appreciate being talked "at" or "down to" just because a person happens to know a little more to make themself feel superior. [8D]

Its a game, I just want to learn how to play!

The problem with snaps is it can zero a whole figure because of the perception of judges about autorotation and the nose up thing. About the same discussion as most of you may have had about tail slides...

Big difference betwen tail slides and figures that have snaps incorporated in them is the HUGE K-factor difference. A properly executed snap has much more value than a tail slide. That can account for the excitement level about snaps.

Look at the figure N in unlimited this year. Big K-factor for a not so difficult maneuver but don't miss the snap!