down line & up line snaps
 

Hi all, I'm relatively new to IMAC and I fly 2.3 Comp. ARF. Now, this is a subject that was talked about before but I'm still puzzled with the correct execution of this maneuver. With horizontal snaps I bump the elevator before going with rudder and ailerons same direction and then release rudder just before the exit to finish of the spin with ailerons only. I'm not realy sure if this is correct. It's a bit of cheat I think but at least I feel I have more control on this maneuver.
Now down line snaps do you just do the same thing? If I bump the elevator I seem to loose vertical downline. So how do you perform this one correctly? Also I want to know what do you do on the upline?

RE: down line & up line snaps
 

Do it the same way as horizontal snaps. The line will displace slightly but that is not a downgrade.

RE: down line & up line snaps
 

You won't see snaps until the upper classes on vertical lines or 45's

Note to wgeffon: Frustration graphic included here. I saw the "Shut up and fly" on a plane flown in the XFC.

EXCAP232

RE: down line & up line snaps
 

thanks Wayne, I'm new to IMAC but not new to aerobatics. I've been flying sequencies for a few years but never entered any comp. Until this year I had a crack at sportsman but I think I could handle intermediate or even advanced with a bit of practice. That's why I'm interested in technical details of upline and downline snaps. I can do it but don't know if I do it correctly. Cheers

RE: down line & up line snaps
 

Yes. That was Manuel Santos' plane and he got the SUAF from me.
Killer Graphic you have there!

RE: down line & up line snaps
 

Successful snaps have alot to do with elevator timing. In the Advanced sequence this year there are lots of snaps in all attitudes. What I do is try to get out of the elevator as quickly as I can after I have established a pitch deviation. On an upline snap, practice at first with no elevator input until you get the timing down then start putting in just a tad but get out of it about 1/2 the way through. In most cases where you have a 1 1/2 snap you will have to hold rudder a split second longer to keep headding.



Shawn

RE: down line & up line snaps
 

the way i learned to do positive and negative snaps (in all attitudes) i bought a bunch of gas and burned it all. all i did was snaps on various lines. its the best way to learn. also if some one else arround you knows what to look for, have them watch while you try diffrent ways. have them tell you if it looks correct.

brian s.

RE: down line & up line snaps
 

wayne, could you please cite the rule(s) that describes the exemption of line displacement downgrade for snaps? i didn't see anything in the discussion of judgng positive or negative snaps and i want to make sure i am reading ithe rules correctly.

pk

RE: down line & up line snaps
 

Paul, A snap is downgraded 1 for 10 on rotation and deviation from from flight path. If the plane has displaced but is on the same heading it is not a downgrade. That is how it was taught in judging school by the IAC rules chairman Brian Howard. He is also going to be on the IMAC rules committee.

Where in the judging manual does it say it is a down grade? I haven't looked so I am asking the question.

RE: down line & up line snaps
 

thanks guys for clarifying that for me. Now I can fill up the drum of petrol and go out practising[8D].

RE: down line & up line snaps
 

Actually, Sportsman has snaps on 45 lines. No more snaps on the horizontal, we're jumping right from not doing to snaps to doing them on a 45.

Also, there is nothing in the judging guide about the displacement of a snap. That is how you know not to downgrade for it. The guide will list the downgradable criteria. If you don't see it listed, don't downgrade for it. However, consider for a moment how you would judge a snap that didn't displace. There is no judging criteria regarding displacement so that alone isn't downgradable, but the absence of the displacement would tend to indicate that there wasn't an asymetrical stall. You can consider this corroborating evidence if you didn't see the nose rise prior to the break or if you thought the maneuver was axial. This would zero the manuever.

-Ben

RE: down line & up line snaps
 

Yea, I noticed that in sportsman as well.
I for one think a snap on a 45 downline is easier than one on a horizontal line but what do I know, I have never one a contest :D

RE: down line & up line snaps
 

Greetings All,
I should have checked the sequence schedules a little more carefully for snaps. Next year I should have them memorized. Taken some time off with club affairs for the past few years which led to the graphic design. A few actual pilots will be displaying them soon.

What does "SUAF" stand for?

EXCAP232

RE: down line & up line snaps
 

Shtu up and fly

RE: down line & up line snaps
 

Ahhhhhhhhhhhhhh!

Tried to make it much more complicated.
Like SNAFU (ha ha)!

EXCAP232

RE: down line & up line snaps
 

I don't know where you guys noticed this but this year sportsman has one horizontal positive snap. Not 45 degree one.

RE: down line & up line snaps
 

Correct. The 2005 Sportsman sequence has one horizontal snap. The 2006 Sportsman sequence will have snaps on a 45.

-Ben

RE: down line & up line snaps
 

wow, can you actualy get hold of the next year's sequencies? Or is still a secret?

RE: down line & up line snaps
 

fredo,

There are 3 proposed sequences for each class available at the IMAC website for IMAC members. The IMAC Board made these sequences available for all members to fly and provide feedback. The goal is to use this feedback to make next years' sequences the absolute best they can be.

Ken

RE: down line & up line snaps
 

Not sure I agree with Wayne 100% I use full elevator, rudder and aileron on every snap all the time, alwayse. Works just fine. Won't win against people like Leeseburg, or McConville but I never get zeros on snaps.
Takes a lot of set up and training to get a "cheated" snap to look good.

I know a lot of pilots do it and make them look great, but if your off a little you get a zero pretty fast.
Zeros stink.

The comments made by Brian about snaps not displacing in the future concerns me though. Sounds like he will be encouraging a rule that states we must cheat a snap in order to score it.
Will Berninger

RE: down line & up line snaps
 

Totally Agree !! With our wingloadings (models) it's pretty difficult not to displace, especially on half-snaps !! (which I beleive was the example he used)

RE: down line & up line snaps
 

Will and Bill,

I think you missed read the quote from Brian Howard;

"A snap is downgraded 1 for 10 on rotation and deviation from from flight path. If the plane has displaced but is on the same heading it is not a downgrade. That is how it was taught in judging school by the IAC rules chairman Brian Howard. He is also going to be on the IMAC rules committee."

The downgrade is for a change of heading, not for any displacement as long as its the same heading.

Tom

RE: down line & up line snaps
 

I wish it was true, but no I think we heard him quite clear. He explained that he disagrees with the current rule and that "he will change that". That is all I will say about it here.

In either case, think teaching to cheat snaps is the wrong approach.
Will

RE: down line & up line snaps
 

Before all of you guys get into to much of a uproar over what Brian did or did not say. It think we may have misunderstood Brian and he us, when he was having that particular conversation. I am pretty sure I have a good idea of what Brian was trying to say (and did not explain fully) and it is very difficult to explain in e-mails without pictures or stick planes.

There are two different perspectives on displacement of the airframe during a snap. One is when you a looking directly at a side view of the airframe. The other when you are looking at a plan view (top or bottom) of the airframe.

I am pretty sure Brian will tell you that there should not be displacement of the line when looking at the side view. The line the plane is on should not jump up or down in the side view, from what the line was at the start to where the line is when the snap finishes. However, you will see displacement when looking at a plan view of the airframe. A half snap is a good example this.

I beleive there is a line of thought, in IMAC, that says it is OK for an airframe to displace up or down, in the side view, when snapping. This is what Brian has issues with and is contrary to what the criteria is in full scale.

The devil is in the details..... Snaps have a lot of detail and we have to be careful on what specific aspect of the snap judging criteria we are talking about, lest we get tied up in knots.

By the way, I could be all wet on this and have totally misunderstood what Brian has said in the past.... :-) Hopefully Bill Malvey will jump in here and confirm whether I heard Brian right or not.

Regards,

Anna Wood

RE: down line & up line snaps
 

Anna - You did indeed understand what Brian was saying with the one minor clarification that he does not think that lateral displacement is necessary, or even desirable, in anything except half snaps. And he definitely feels that a vertical displacement (altitude if a horizontal line snap) is not OK.

As the current rules read there is no defined downgrade for displacement of the center of gravity either laterally or vertically during a snap roll of any number of degrees of rotation. There IS a down grade of 1 point per 10 degrees IF the track of the CG prior to and after the snap roll are not the same. This means that the line of track before and after the snap will be parallel and may, or may not, be in perfect alignment (zero displacement).

One other point. All the current rules proposals that can be put into effect for the next rules cycle are in (2007-2008). The next chance to make a non-emergency rules change will be for the 2009-2010 cycle.

Bill Malvey
Chairman IMAC Rules and Standards Committee