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Old Nov 19, 2012, 08:24 PM
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HouseOf4Doors's Avatar
United States, CA, Richmond
Joined Dec 2007
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Idea
Bill's Rudder Rules

Confused sometimes about which way to move the rudder stick to get the desired resulting aircraft response? Would you appreciate a systematic approach to learning what to do with rudder stick so you get it right every time? I present "Bill's Rudder Rules"

* * *
Preface

There are consistent, unchanging rules for rudder inputs for all RC aircraft (fixed & heli) that correlate the direction of the movement of the rudder stick on your transmitter as you're facing the aircraft and the direction in which the tail/nose of the aircraft moves as a result of the stick movements.

I'm sure other people have come up with this kind of thing before, but I've never seen it anywhere. Since I am a teacher by profession I try to distill such things into something that could be presented to a student for practice purposes. Therefore, I present you with:

Bill's Rudder Rules:

First realize that the only factors that affects what happens to an RC aircraft as a result of rudder inputs from a pilot standing on the ground are, 1) whether the aircraft is upright or inverted, and, 2) whether the aircraft is moving towards or away from the pilot. See the following:


Rule Category 1) UPRIGHT
1a. aircraft moving towards pilot
rudder stick moves tail in same direction as rudder stick movement
1b. aircraft moving away from pilot
rudder stick moves nose in same direction as rudder stick movement

Rule Category 2) INVERTED
2a. aircraft moving towards pilot
rudder stick moves nose in same direction as rudder stick movement
2b. aircraft moving away from pilot
rudder stick moves tail in same direction as rudder stick movement

There are a related series of rules for the elevator and aileron which are easier to master because the the elevator only changes with upright/inverted and the ailerons only change with towards/away from. But the rudder changes with both upright/inverted & to/from, and therefore takes twice the skill to master.

As for exercises, simply fly the plane around upright and inverted, steering only with the rudder and try to make the plane go where you want it to. Then go to (http://nsrca.us/index.php/sequences) and download the sportsman sequence and fly it in varying levels of quartering crosswind.

There are related rules as well for correlating rudder stick inputs for rolls and knife edge flight:1) when rolling from upright to knife edge, rudder stick moves opposite the aileron stick, and, 2) when going from inverted to knife edge, rudder stick moves in the same direction as the aileron stick.

* * *

What do you think?
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Old Nov 23, 2012, 06:40 PM
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Santa Clara, CA
Joined Nov 2008
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Hmm. I think this works for people who react to deviations in the flight track of their plane, (although, if you are flying a line parallel to the runway as you would in f3a then nose/tail relative to stick movement doesn't work because the stick is moving in-line with the plane) so I would phrase things a little differently:

Upright: outside wingtip moves in the direction of stick movement (regardless of toward/away from pilot, if I move the rudder stick to the right the outside wingtip will move to the right)

Inverted: INSIDE wingtip moves in the direction of stick movement, or, stick in the direction of airplane movement turns the plane to travel AWAY from the pilot's position.

However, in precision I think it's a lot more important to be putting in tiny rudder correction before you need it (and this is something I've just started working on) and there, what's much more important is airframe speed relative to wind, p-factor, and gyro effects on the plane. Therefore you need to be thinking about whether you are pulling negative or pushing positive G's to make the appropriate corrections. For example, in the sportsman sequence maneuver 12 is a vertical upline on center with a push to level upright flight, so on a calm day you better be putting in right rudder as you push over to level or the plane is going to be drastically off track as you achieve level flight. If there's a crosswind, you obviously need to be factoring the rudder input to correct for the crosswind as you slow at the top of that upline with the right rudder needed to maintain track on a calm day.

Peter+
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Old Nov 25, 2012, 10:16 AM
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United States, IL, Chicago
Joined Nov 2007
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Noob here. On the simulator, it goes like this:

"Inverted? Check. Toward? Check. Rules says plane with rudder. <Moves stick.>" And all that only takes about 2 seconds and 100 ft of travel between deciding you want to move the rudder and actually moving the rudder.

On the field, it goes like this:

Upright or Inverted? Check .... OMG I'm inverted I'm too close to the ground I'm going to crash ... No, no. It's ok. You've done this before. Toward or away? Well, it's right in front of me so I'm not sure if it's toward or away ... <Waits until it's moves beyond center> Away. Ok. What's the rule? Plane moves opposite stick. Very good. <Moves stick.>

Seriously, though. It's getting faster.
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Old Nov 26, 2012, 12:40 AM
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Curare's Avatar
in the gutter, again....
Joined Jun 2005
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Beats my way of teaching myself...

'ok, it's coming in on me I need to add some rudder, *adds* bugger, wrong rudder, again!'

Remember kids, the most powerful thing in the world is wrong rudder.
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Old Nov 26, 2012, 12:59 AM
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United States, CA, Richmond
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Quote:
Originally Posted by pvogel View Post
Upright: outside wingtip moves in the direction of stick movement (regardless of toward/away from pilot, if I move the rudder stick to the right the outside wingtip will move to the right)

Inverted: INSIDE wingtip moves in the direction of stick movement, or, stick in the direction of airplane movement turns the plane to travel AWAY from the pilot's position.Peter+
I like what you said about relating the stick to the wingtips.

bp
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Old Dec 23, 2012, 08:35 AM
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Inverted rudder corrections drove me nuts til I learned the "look at the inboard wingtip, push the rudder stick the way you want itto go" rule.
This evolved into "look at whatever's closest to you and push the stick the way you want it to go". You're looking at the nose as the airplane is coming at you, the inboard wingtip as it passes, the tail as it's going away.
I also 'push the tail' when looking at the bottom of the airplane in a vertical line, like after the roll in our 'pull, half roll, push' humpty.
And always remember, when rolling out from inverted the rudder moves the same way as the ailerons.

Scott
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Old Dec 23, 2012, 10:46 PM
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United States, CA, Carson
Joined Dec 2012
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I am new in here and also in aircraft rc.
Had hard time with the rudder during the landing especially crosswind. Mostly mixed up pn the direction. And i cane out that using rudder is an art skill ^_^.

Need to practice with rudder more often till its memory in my finger.
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Old Dec 25, 2012, 07:43 PM
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United States, CA, San Jose
Joined Jan 2004
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"Need to practice with rudder more often till its memory in my finger. "

saab2,

This is the key. When flying it is hard to follow "rules." You need to have your brain in the cockpit and fly from that perspective. Only practice does that (I proved that last year a few times).

Don
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Old Dec 26, 2012, 02:16 PM
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The purpose of the 'rules' is to help you make the right corrections while your fingers are learning to respond to your visual cues. Learning comes slow if you just fly and guess.
Also, 'rules' come in handy when you 'lock up' in the heat of competition. Sometimes you're just not sure what to do and you can fall back on them. Not as quick or smooth as automatic, but better than a guess.
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Old Dec 26, 2012, 07:11 PM
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I wish I could get all the rules, but that hasn`t worked for me..It may work for some..I generally find if I have to think about it I`m almost always wrong...I never realized how much I needed work on rudder input inverted until I tried pattern..At this point I`m trying to fly figure 8s around the field inverted using only rudder for the most part and doing loops and keeping the the the plane parallel to the runway...Not perfect yet, but coming together...Saab, if you need to land crosswind and use the rudder which is always the case, here is a tip...Rotate your hips and point your transmitter the direction you are landing and look over your shoulder slightly. Our field is bad about the crosswind and I teach new guys this..It works...
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Old Dec 26, 2012, 09:34 PM
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To clarify, I don't really use the rules when flying at the field. When flying a real airplane, for the most part, there's too much at stake to be "thinking." When I'm at the field, sometimes I do notice that what I was doing followed one of the rules, but that's about it.

When I use the rules is when practicing on the sim and when imaginary flying with my eyes closed while falling asleep.
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Old Dec 28, 2012, 09:35 PM
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How do you guys do KE rudder rules?

When I do a half-roll from upright I do opposite rudder to the ailerons that performed the roll. When I roll from inverted, I do rudder in the same direction as it took to do the roll.

But this "rule" depends not on the current state of the plane but on the previous state (upright/inverted). Is there a better way?
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Old Dec 29, 2012, 08:23 AM
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Rolling from inverted is always "same". Rolling from upright is always "opposite".
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Old Dec 29, 2012, 07:52 PM
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I woke up this morning and it hit me that there's a simpler rudder rule (excluding rolls) that I formulated originally which is maybe easier to bring to mind in the heat of battle:

Rule Category 1) UPRIGHT
Farthest [longitudinal] airframe extremity (nose or tail) moves in the same direction as the rudder stick

Rule Category 2) INVERTED
Nearest [longitudinal] airframe extremity (nose or tail) moves in the same direction as the rudder stick

I am sorry for not expressing it this way the first time as I think this is better.

bp
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Last edited by HouseOf4Doors; Jan 07, 2013 at 05:57 PM. Reason: clarity
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Old Jan 05, 2013, 09:24 PM
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Bridgewater, NJ
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I simply tell guys to push the rudder stick the direction the plane is going when inverted.

Turning left or drifting left from the wind pushing it, use left rudder.
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