[NSRCA-discussion] Snap entry in FAI

[Jon Lowe]

I suggest people re-read the definition ofsnap-rolls from the FAI sporting code.  I did a few minutes ago.  Here it is:


"5B.7.5. SNAP-ROLLS
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."


Note that "the fuselage attitude must show a definite break and separation from the flight path, before the rotation is started..."   That means that simultaneous pitch and rotation is specifically NOT permitted.  I would interpret it as meaning that pitch and yaw could theoretically happen simultaneously, as long as no roll is involved.  Sorry Matt, the rules as written do NOT allow actuation in all three axes simultaneously.  The rule also states that a constant flight path has to be maintained.

Let's face it, the only way to prevent severe downgrading from EVERY judge, not just some judges, is to have a pitch break first.  Takes any question away.


Jon Lowe


-----Original Message-----
From: rcmaster199 at aol.com
To: nsrca-discussion at lists.nsrca.org
Sent: Mon, 16 Jun 2008 10:46 am
Subject: Re: [NSRCA-discussion] Snap entry in FAI


A "Flick" and a "Snap" roll are the same roll in full scale aerobatics parlance and reference material. 
 
Do these mean the same thing in model aerobatics? In my view, they do 
 
The latest FAI regs allow actuation of the three main axes simultaneously...that is, the regs don't specifically differentiate "Pitch Break" from other deviations. I don't think they specifically require that the model must rotate about it's flight path either, I don't believe (.....plane must rotate in a conical fashion about the fight axis....). The model would probably present the best if that's done, so pilots may want to consider that when executing the maneuver. 
 
In my take, a rapid Pitch is desired to preload the wing. Contrary to popular belief, both panels dot not have to stall for a snap to occur. Quite the opposite. Upon rudder deflection, the port panel will practically stall (lift much much less than the other panel) but the starboard panel must be lifting to create the autorotation. If both panels stall, the model will fall out of the sky for a distance and a snap would not occur at the correct moment in time 
 
MattK 
 
-----Original Message----- 
From: Woodward, Jim (US SSA) <jim.woodward at baesystems.com> 
To: General pattern discussion <nsrca-discussion at lists.nsrca.org> 
Sent: Mon, 16 Jun 2008 8:47 am 
Subject: Re: [NSRCA-discussion] Snap entry in FAI 
 
Guys, 
 
I thought the FAI changes explicitly allowed flick rolls? The rule 
reads, "... fuselage attitude must show a definite break and separation 
from the flight path." 
 
It does not say, "MUST SHOW PITCH BREAK." Please DO NOT ERROUNIOUSLY 
APPLY A PASS/FAIL MAJOR DEDUCTION initial assessment to the snap roll. 
Watch the whole maneuver then render your score. 
 
A break and separation from the flight path simply means that the nose 
and tail of the plane must rotate in a conical fashion about the fight 
axis. Yaw, roll, and pitch can all break at the same moment if that is 
how the pilot does it. 
 
Hey :) some really handsome smart guy wrote some stuff at this link 
below about snap rolls to help clarify how they are done in IMAC. 
 
http://www.mini-iac.com/DesktopDefault.aspx?tabid=77 
 
thanks, 
Jim 
 
 
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