Snap Roll Setup
07-20-2005 | 07:25 PM
#1
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From: Warren,
AR
Snap Roll Setup
I have just started flying sportsman and would like some advice on the proper setup for snaps. I realize sportsman sequence has just one, but the day will come when I want to move to intermediate and would like to start practicing these. How much surface throw do you have for elevator, aileron, and rudder. Any tricks to getting them right. I am amazed when watching the unlimited guys. There snaps stay right on line and seem to always stop perfectly. Come on guys give up the secrets to the perfect snap.
Thanks
Mark
PS Love the Spin Entry thread. I have seen more zeros on this particular maneuver than any other. Keep the info coming.
Thanks
Mark
PS Love the Spin Entry thread. I have seen more zeros on this particular maneuver than any other. Keep the info coming.
07-20-2005 | 09:39 PM
#2
RE: Snap Roll Setup
No tricks at all---
This is a maneuver which is very dependent on the aircraft design.
Basically , you want the model to pitch (up/down) whilst starting to roll.
The shape of the wing planform can really affect this .
The shape of the leading edge - maybe - but don't bet on it .
The plane needs enough speed to be stable - snaps at an idle work on some really light stuf but for most - a stable speed is necessary.
So -- basic upright spin from level flight:
apply hard elevator input -then aileron and rudder .
Release elevator -then rudder and lastly, aileron.
On some designs a good snap can be from full input of all three and releasing all three at once --you should be so lucky.
But basically , the model must pitch ( stall the wing ) then autorotate till it restabilizes.
A light model is always better .
Why ? The return to stable flight is more predictable .
Any snap , which is NOT started from level flight takes less (typically) rudder and elevator
to continue - a snap started vertically (up or down ) will stall the wing much faster -simply because it is loaded far less in verical attitude than in level flight -
So to recap; level flight snaps require more inputs than vertical -with all in between starting angles some degree less.
Here is more good news--
The more deeply you stall the model -- the more speed you loose and the more chance there is to over rotate from the inertia in the rotation plus the lessened response of the flying surfaces to the direction of flight.
A snap can be done at any speed - so experiment - but start with and try for a snap form a moderate speed
don't "lead the snap BUT if you can think of it -- CHEAT IN a bitte of opposite rudder before the snap is commenced .
Why?
to make the apparant snap stay exactly on heading
A true snap will displace -a little or a lot - the heading.
There are my secrets -
FWIW
This is a maneuver which is very dependent on the aircraft design.
Basically , you want the model to pitch (up/down) whilst starting to roll.
The shape of the wing planform can really affect this .
The shape of the leading edge - maybe - but don't bet on it .
The plane needs enough speed to be stable - snaps at an idle work on some really light stuf but for most - a stable speed is necessary.
So -- basic upright spin from level flight:
apply hard elevator input -then aileron and rudder .
Release elevator -then rudder and lastly, aileron.
On some designs a good snap can be from full input of all three and releasing all three at once --you should be so lucky.
But basically , the model must pitch ( stall the wing ) then autorotate till it restabilizes.
A light model is always better .
Why ? The return to stable flight is more predictable .
Any snap , which is NOT started from level flight takes less (typically) rudder and elevator
to continue - a snap started vertically (up or down ) will stall the wing much faster -simply because it is loaded far less in verical attitude than in level flight -
So to recap; level flight snaps require more inputs than vertical -with all in between starting angles some degree less.
Here is more good news--
The more deeply you stall the model -- the more speed you loose and the more chance there is to over rotate from the inertia in the rotation plus the lessened response of the flying surfaces to the direction of flight.
A snap can be done at any speed - so experiment - but start with and try for a snap form a moderate speed
don't "lead the snap BUT if you can think of it -- CHEAT IN a bitte of opposite rudder before the snap is commenced .
Why?
to make the apparant snap stay exactly on heading
A true snap will displace -a little or a lot - the heading.
There are my secrets -
FWIW
07-21-2005 | 06:32 AM
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From: ,
QC, CANADA
RE: Snap Roll Setup
The biggest "cheat" IMO about snaps is finishing the snap with ailerons only. They are much easier to stop precisely this way. Its a gamble though as if the judge actually sees that the last 45 degrees were not a snap but a roll, he has to deduct 4 points only for that.
The trick is to finish with ailerons but making sure it is not visible by keeping some rudder and/or elevator.
Apparently, Dick does not only know how an engine works, he also knows how to fly.
The one thing I would add is use the least amout of elevator and rudder possible for a good snap. Anything more will eat airspeed and exit heading. Lots of ailerons, a bit of elevator (low rate) and a bit of rudder (low rate).
The trick is to finish with ailerons but making sure it is not visible by keeping some rudder and/or elevator.
Apparently, Dick does not only know how an engine works, he also knows how to fly
.The one thing I would add is use the least amout of elevator and rudder possible for a good snap. Anything more will eat airspeed and exit heading. Lots of ailerons, a bit of elevator (low rate) and a bit of rudder (low rate).
