F3A - snap roll query

[Wayne Galligan]

"Snaps - A Snap is a simultaneous, rapid autorotation in the pitch, yaw and
roll axis of flight in a stalled wing attitude.  The following criteria
apply:"

If this statement is true in description then:
The nose does not have to show a break first, it should be simultaneous,
only that it break from the intended flight line.
Nose high and tail low with a rotation around the intended flight line.

Seems some people I talk to say the nose HAS to break first then rotation in
order for it to be a snap. I disagree.

WHO'S right?

Wayne G.

----- Original Message ----- 
From: "Don Ramsey" <donramsey at cox-internet.com>
To: <discussion at nsrca.org>
Sent: Wednesday, November 05, 2003 2:10 PM
Subject: Re: F3A - snap roll query


> Here's what I wrote for the KFactor about this subject.
>
>
>
> Snaps!  Now there's a maneuver that causes some heated discussion.  Van
> Putte was asked at the NATS Pilot's Meeting if a snap should be downgraded
> if it displaces from the line.  He took that question in stride and
promptly
> handed it off to me.  I tried to pass it back to him and to Earl Haury but
> no one would answer.  Well my answer was, "It should not displace
> significantly from the flight path for maximum points."  I caught a lot of
> flack for that answer but I believe it is correct.  How did I come to
> believe this?  Here's what the Competition Regulations say about snaps.
>
>
>
> Snaps - A Snap is a simultaneous, rapid autorotation in the pitch, yaw and
> roll axis of flight in a stalled wing attitude.  The following criteria
> apply:
>
>   1.. Since the maneuver is defined as a stall maneuver (initiated by a
> rapid stall of the wing induced by a change in pitch attitude), the nose
of
> the fuselage should show a definite break from the flight path in the
> direction of the snap (positive or negative) while the track closely
> maintains the flight path. The track visualized as the path of the Center
of
> Gravity (CG) should ideally follow the geometric flight path of the
maneuver
> while the nose and tail autorotate through opposite helical arcs around
the
> flight path. A snap that does not show a break and stall to initiate the
> snap, but does enter a stalled attitude during the maneuver is severely
> downgraded.
>   2.. If the stall does not occur and the model barrel- rolls around, the
> maneuver is  zeroed. A barrel roll can be identified when the CG, the nose
> and tail scribe the same helical path through the required rotation of the
> maneuver.
>   3.. 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
> rate are concerned.
>   4.. Snap rolls may be either positive or negative.
>   5.. If the model returns to an unstalled condition during the maneuver,
> such that the autorotation is not visible and the model rolls to complete
> the maneuver, it would be severely downgraded.
>   6.. Airspeed is not criteria which should be used to judge this
maneuver.
> As the wing of the model is stalled during this maneuver a significant
> decrease in speed may occur and is not a cause for downgrade.
> There are several things to notice about snaps.  From #1 above, "the nose
of
> the fuselage should show a definite break from the flight path in the
> direction of the snap." You make the call here.  If you don't see the
break,
> maybe it didn't happen.  The last sentence in #1 says, "A snap that does
not
> show a break and stall to initiate the snap, but does enter a stalled
> attitude during the maneuver is severely downgraded."
>
>
>
> How about displacing from the line?  Again in #1, ". while the track
closely
> maintains the flight path. The track visualized as the path of the Center
of
> Gravity (CG) should ideally follow the geometric flight path of the
maneuver
> while the nose and tail autorotate through opposite helical arcs around
the
> flight path."  And, from #3, ".constant flight path through the maneuver
>  ..."   That's where I got the answer, "It should not displace
significantly
> from the flight path for maximum points."
>
>
>
> So, my answer would be, there would be a downgrade depending on the
severity
> of the displacement but NOT a zero.
>
>
>
> Don Ramsey
>
> NSRCA Judging Committee Chairman
>
>
>
>
>
> ----- Original Message ----- 
> From: "PENNISI Peter" <Peter.Pennisi at publicworks.qld.gov.au>
> To: <discussion at nsrca.org>
> Sent: Tuesday, November 04, 2003 7:58 PM
> Subject: F3A - snap roll query
>
>
>
> Hi Guys,
>
> I recently read that any snap roll which finishes higher than where it
> started should be zeroed automatically even if the jump is slight. I am
> referring in particular to the 1-1/2
>
> How is this ruling being interpreted in your country. If this is the case
I
> will need to perform these snaps at very low speeds.
>
> Given the stability of our modern aircraft and the relatively long tail
> moments this is not an easy accomplishment.
>
> Peter
>
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>
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