Displacement during snap rolls (was Why is it so quiet?)

[Dean Pappas]

Yes, and some small forgiveness needs to be established. Say, half a wingspan?
 
Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of Bob Pastorello
Sent: Wednesday, December 29, 2004 6:48 AM
To: discussion at nsrca.org
Subject: Re: Displacement during snap rolls (was Why is it so quiet?)


Good points, David, but my question is based on a LATERAL, and "Parallel" shift in the track.  Assume that I get 'lucky', and nail the line before the snap, definitively BREAK during the snap, nail the exit on the original heading/track, but shifted sideward maybe 3 feet.
    My experience is that a properly-executed snap manuever - anyplace - MUST translate some forward momentum into angular sideward momentum, thus shifting the track of the manuever.
    If this is a "downgrade", where is the criteria, how much are the downgrades, and since we're not talking about an "angular" offset, the point per 10 or 15 degree deviation rule doesn't seem to fit.
    In fact, I would argue (and I'm confident there are aerodynamicists out here who could calculate and prove it so) that NO appropriately-executed snap manuever CAN occur without offset of the original track.
 
    If someone does the imitation/fake "snap roll" ( the rapid, low-rudder, high-aileron, semi-stall ROLL) there ISN'T an offset, usually.  At least in the fake ones I judged LAST season.

Bob Pastorello
NSRCA 199  AMA 46373
rcaerobob at cox.net
www.rcaerobats.net
 
 
----- Original Message ----- 
From: David  <mailto:DaveL322 at comcast.net> Lockhart 
To: discussion at nsrca.org 
Sent: Tuesday, December 28, 2004 10:40 PM
Subject: Re: Displacement during snap rolls (was Why is it so quiet?)

More than 1 pilot was awarded 1 or more zeros in the 2004 US NATs F3A final on snap maneuvers.  The "average" snap in subsequent flights in the finals showed more break / displacement (of course, any break / displacement is infinitely more compared to none, ahem.....).
 
A stalled entry is a required element of spins - no stalled entry, score equals zero.  No different for snaps.  Judges are required to judge what they actually see (not what they think may have happened), and pilots are required to show / demonstrate / complete all required elements to avoid downgrades (which may be a downgrade to zero).
 
To specifically answer Bob's question - my opinion - if the geometry of the manuever is not compromised, then no downgrade.
 
Another question(s) - In a given maneuver involving a snap, the exit track of the plane is 15 degrees different than the track prior to the snap.  What is the downgrade if the change in track is abrupt?  What is the downgrade if the change in track is smooth?
 
Regards and Happy Holidays,
 
Dave Lockhart
DaveL322 at comcast.net
 
 
 
----- Original Message ----- 
From: Ed Alt <mailto:Ed_Alt at hotmail.com>  
To: discussion at nsrca.org 
Sent: Tuesday, December 28, 2004 11:04 PM
Subject: Re: Displacement during snap rolls (was Why is it so quiet?)

Good topic Bob.  If the model really did a snap roll, it had to displace somewhat.  If not, and if you could actually tell that it did not, that could be an indicator that a snap roll did not actually happen. Generally, the model has to displace to a new track, however slight, from the yawing and pitching moments introduced.  The criteria should perhaps be that you are able to able to maintain the new track exactly in parallel to the pre-snap track.  How much offset is OK is hard to say, but things generally start looking suspicious whan it's much more than a couple of wingspans.  You would generally start to see other obvious problems, such as barrel rolling, if the displacement were really large.  For another perspective, I think the Scale Aerobatics Flying and Judging Guide does a decent job of describing how to grade a snap.
 
Ed
----- Original Message ----- 
From: Bob  <mailto:rcaerobob at cox.net> Pastorello 
To: discussion at nsrca.org 
Sent: Tuesday, December 28, 2004 10:31 PM
Subject: Re: Why is it so quiet?

It can be very, very bad.
Or not.
 
Let's talk about displacement of the flight track during snap rolls.  Whatcha y'all think?  Is it downgradeable, and if so how much, and what is the criteria?

Bob Pastorello
NSRCA 199  AMA 46373
rcaerobob at cox.net
www.rcaerobats.net
 
 
----- Original Message ----- 
From: Mike  <mailto:kerlock at comcast.net> Hester 
To: discussion at nsrca.org 
Sent: Tuesday, December 28, 2004 9:21 PM
Subject: Re: Why is it so quiet?

Ya well, it's definitely not going on the primary bird. For that I have a trusty OS 160FX with vp30 pump. I know it will run when I want it to run.
 
Just like me "testing" a new design, testing my feather cut, testing my composite skillz (or lack of), so far so good. Of course I didn't make the YS, so that one is more of a massochistic tendancy methinks. I'm not skeert to spend a buck. Plus it wouldn't take too much to drop in an OS if it comes to it. I've gotta see for myself if the fire is as hot as it looks. I usually suffer 3rd degree burns right after one of these moments.
 
Classic last words: "How bad could it be?"  =) 
 
-Mike
 
PS Ok ok NEXT year.
----- Original Message ----- 
From: Bob  <mailto:rcaerobob at cox.net> Pastorello 
To: discussion at nsrca.org 
Sent: Tuesday, December 28, 2004 9:47 PM
Subject: Re: Why is it so quiet?

You have less than 3 days, then.  Could be tricky for you.
Besides, how does one "try" something that costs $700+  ?  Sounds a bit like "testing" the $3500 plasma tv.....

Bob Pastorello
NSRCA 199  AMA 46373
rcaerobob at cox.net
www.rcaerobats.net
 
 
----- Original Message ----- 
From: Mike Hester <mailto:kerlock at comcast.net>  
To: discussion at nsrca.org 
Sent: Tuesday, December 28, 2004 8:38 PM
Subject: Re: Why is it so quiet?

YS SUCKS!!!!!!!!!!
 
Better?
 
=)
 
-Mike
 
P.S. I am actually going to try a DZ 160 some time this year. This could mean the apocalypse is near.
----- Original Message ----- 
From: William C. Harden <mailto:flyinbill1 at bellsouth.net>  
To: discussion at nsrca.org 
Sent: Tuesday, December 28, 2004 9:33 PM
Subject: Why is it so quiet?

I know someone out there has something interesting to say.  So stir something up!
 
Bill
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