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Old 04-23-2019, 12:50 PM
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Snap roll on entry to loop

I'm new to Intermediate this year, and I have a question regarding the snap in maneuver 4 (outside half loop with outside snap on entry and 2-pt roll on exit).

My issue is that I'm expecting some form of path deviation when I exit the snap. Normally, you get a chance to quickly correct and get back to a parallel path without penalty, but how does that work when the snap is on entry to a loop? I thought the criteria is any pause of more than a plane length is a penalty, but that conflicts with giving me a chance to correct the deviation after a snap. I know the correction after the snap has to be quick, but a correction happening inside a plane length will be tough. At 60mph, that's close to 90ft/s, so my correction would have to be within 0.1s.

Don't correct path deviation after snap and loose points because I don't enter loop level and in a parallel flight path or loose points because I went more than a plane length after the snap before pushing into the loop.

What's the expectation?
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Old 04-23-2019, 01:44 PM
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I suggest doing the snap and immediately start the half loop. You will be better off that way than risking a 2 point deduction for drawing the line. Eventually you will find yourself correcting during the very first part of the arc.
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Old 04-23-2019, 01:56 PM
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Quote:
Originally Posted by kwilson View Post
I suggest doing the snap and immediately start the half loop. You will be better off that way than risking a 2 point deduction for drawing the line. Eventually you will find yourself correcting during the very first part of the arc.
Agree.
Although you have the benefit of a doubt.
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Old 04-23-2019, 02:22 PM
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When I don't over-shoot the roll, I'm still off in pitch (likely climbing) and yaw (direction of snap). So, it's no deduction even though I don't start the loop in horizontal flight and I correct the yaw while pushing the outside loop?
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Old 04-23-2019, 05:30 PM
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I would imagine you can tweak and tune the amount of ailerons and rudder used in a snap... also... once the snap initiates... center the elevator...
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Old 04-24-2019, 06:37 AM
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Quote:
Originally Posted by gobigdave View Post
When I don't over-shoot the roll, I'm still off in pitch (likely climbing) and yaw (direction of snap). So, it's no deduction even though I don't start the loop in horizontal flight and I correct the yaw while pushing the outside loop?

Technically yes, but until you are able to correct the snap as it is finishing and immediately push into the half outside loop without drawing a line, you are better off taking the deduction for being off slightly in pitch as entering, while fixing yaw in the first bit of the loop. That way you are not risking a 2 point deduction in addition to anything that may go wrong while you are trying to correct. You will most likely score better this way.
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Old 04-24-2019, 09:38 AM
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By definition, a snap has a pitch deviation. Without it, the whole figure would be zero'd. Are you saying correct the pitch deviation while the snap is in progress? As I said earlier, I don't think it is possible to correct the required deviation in less than a plane length. Between our brain's delay and the radio's, it just isn't happening in a plane length.
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Old 04-24-2019, 10:01 AM
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Ahh we have stumbled into an age old argument/discussion. I wont get sucked in too deeply but here goes. By definition a snap has pitch departure and auto rotation and it must remain in auto rotation throughout the entire snap. You are allowed to immediately correct any attitude issues once complete. As you have noticed this is difficult to do if you are to also immediately enter a radius.



Now if you look at a full scale plane and study how a snap is performed, you will realize that elevator does not need to remain in the entry position throughout to maintain auto rotation. In fact they will even unload the snap about half way through with opposite elevator; and after all, we are mimicking full scale aerobatics. With that said it is perfectly legal to start (pitch correcting) unloading at a point that will allow you to exit level. Now this is not easy, but can be perfected with lots of practice.
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Old 04-24-2019, 10:17 AM
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Watch the elevator closely at the 17 second mark.


Snap Roll and Tumbles (1 min 23 sec)
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Old 04-24-2019, 11:35 AM
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Exactly! If you leave in full elevator you will have what's referred to as a "buried " snap...with lots of pitch all the way around. Which of course makes even harder to fix at the proper time.

The plane also creates a lot of induced drag, which loses energy. The release of the elevator is called "unloading" the snap. Works in full scale and models.
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Old 04-24-2019, 12:49 PM
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I understand unloading the snap, but I still have a pitch deviation that needs opposite correction. It has to be more than just unload the elevator. I've been toying with some logical switches on my Jeti where elevator and rudder are reduced when the right stick is buried in a corner. Definitely made my snaps better and reduced the "bury" factor.

I know some of you will respond with "learn to fly the snap" over me trying something. This was a tip given to me by a former IMAC president, so I figure it might be worth trying.
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Old 04-24-2019, 01:00 PM
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IMAC KNOW INTERMEDIATE 2019 by Sacha Cecconi (4 min 30 sec)


FlightReviewz How To: IMAC Intermediate Sequence (2019) (8 min 54 sec)


I watched these again. On the 4th maneuver, you can see Sacha and Jason exit the snap with a slight pitch deviation (climbing), and they just continue on with the outside half loop. I'm no where up to their skill yet after only 6-8 times through the sequence outside a sim, but my snap exit is very similar in that I have pitch and yaw deviation. The yaw is slight can can easily be corrected while I push the loop. The pitch, however, has not come to me yet.

Would both of these loose points?
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Old 04-24-2019, 03:29 PM
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Quote:
Originally Posted by gobigdave View Post
I'm new to Intermediate this year, and I have a question regarding the snap in maneuver 4 (outside half loop with outside snap on entry and 2-pt roll on exit).

My issue is that I'm expecting some form of path deviation when I exit the snap. Normally, you get a chance to quickly correct and get back to a parallel path without penalty, but how does that work when the snap is on entry to a loop? I thought the criteria is any pause of more than a plane length is a penalty, but that conflicts with giving me a chance to correct the deviation after a snap. I know the correction after the snap has to be quick, but a correction happening inside a plane length will be tough. At 60mph, that's close to 90ft/s, so my correction would have to be within 0.1s.

Don't correct path deviation after snap and loose points because I don't enter loop level and in a parallel flight path or loose points because I went more than a plane length after the snap before pushing into the loop.

What's the expectation?

I'm in the same boat (plane?) with you, and had the same question when I started practicing the new sequence in the fall. After performing this maneuver many times now, the snap gets better the less I think about the sticks and the more I focus on coming out wings and nose level. Having a snap condition to unload the wings mid-way really helps.
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Old 04-24-2019, 08:47 PM
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I've been going through IMAC judging school, and I had a session tonight where I asked this question. I spaced about the school when I posted the other day.

According to the folks teaching the judging school, the pilot is always expected to correct for the pitch and yaw deviation after the snap -- quickly, with no line drawn once the snap stops. Roll corrections are deducted with the usual 1/2 pt per 5 degrees. If a line is drawn after the correction, however, then a -2 pt deduction for a line before the radius is applied.

So it looks like I do get a quick chance to correct the snap deviation and then immediately push into the outside loop. No correction for the deviation after the snap results in entering the half loop not level and/or not parallel to the runway, and that is subject to the standard deductions for entry.

Now, the only problem is how long is too long for a correction, but I'm not going to worry about that now. I will concentrate on practicing the snap and correcting as quickly as possible.
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