I know its a dumb question but

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swamp crawler

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swamp crawler
what the heck is the purpose of the rudder? i know it controlls the planes nose left and right but sence you turn with the yoke (aerlions?) in what sittuation is the rudder used? of course i only have about .9 of an hour in a plane and am completely new to this, and im sure my instructor covered this but i was trying to absorb so much info and get over the whole fear of death in the 20mph wind thing i suppose i missed it. :mad2:
 
The rudder and ailerons work together to balance and turn the airplane.

When you turn the yoke to start a bank, the force required to raise one wing causes extra drag. This drag out on the wing going up tends to make the aircraft actually turn the wrong way - called adverse yaw.

Many aircraft don't have much adverse yaw and you can get away with lazy feet. My airplane, if you just use the stick, you end up in a side slip and doesn't really turn at all unless you also use the rudders.

Also, if you want to slip (fly sideways) you need both aileron and rudder - typically this is done to lose altitude quickly or to stay lined up with the runway when you are landing with a crosswind.
 
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swamp crawler said:
what the heck is the purpose of the rudder? i know it controlls the planes nose left and right but sence you turn with the yoke (aerlions?) in what sittuation is the rudder used? of course i only have about .9 of an hour in a plane and am completely new to this, and im sure my instructor covered this but i was trying to absorb so much info and get over the whole fear of death in the 20mph wind thing i suppose i missed it. :mad2:
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One way to understand the rudder (and correct me if I'm wrong everyone, although I know you will!), is to look at it this way: you can feel the need for the rudder by the seat of your pants. Kind of like if you take a turn too fast in your car, you will feel yourself kind of sliding to the outside of the turn, the rudder will "fix" that feeling in a plane.

I think this might be a good way to begin to understand when the need to step on the rudder pedals arises. At least, this way to think about it is helpful to me.
 
P.S. No such thing as a dumb question.

(Well, unless you're me and you're asking about landing on freeways... but that's another story for another time..).
 
Answering the question, "What's the purpose of the rudder?" is kind of like asking the 3 blind men to feel an elephant and explain what the elephant is like.

You'll get different answers and a lot of arguments concerning each person's impression and opinion. Here's a good explanation of the rudder and it's usage that should cover most of the purposes...

http://www.airbum.com/articles/ArticleRudder.html

MMM
 
At .9hrs, not a dumb questions at all. If you had a couple hundred, I would say dumb question.
 
Boat: Rudder steers right and left. No banking.

Airplane: Rudder keeps airplane tracking straight. Bank (ailerons) and elevator steer right and left.
 
Rudder is to overcome the inadequacies of the airplanes designer. Birds don't have em.
 
rudders are for doing hammerheads
 
The rudder gives the pilot a way to directly control beta angle, which is the angle between the relative wind and the aircraft's body centerline, measured in the horizontal body frame.

Beta is normally close to zero. This gives the best passenger comfort and best aerodynamic efficiency. It keeps the lift vector pointed vertically up in the aircraft body frame, which means your butt stays in your seat, the ball stays in the middle and you can pour a cup of coffee no matter what your bank angle.

The rudder lets you keep beta close to zero when various effects perturb it (chiefly p-factor and aileron adverse yaw). You can also use the rudder to deliberately achieve a nonzero beta in a forward slip or skid, when you want to have a poor aerodynamic efficiency in order to lose altitude quickly. And you can utilize roll-yaw coupling by using the rudder to increase roll rate when the ailerons are ineffective (e.g. at low airspeeds)
 
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ClimbnSink said:
Rudder is to overcome the inadequacies of the airplanes designer. Birds don't have em.
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They don't look or operate the same, but they still have yaw control surfaces on their tails. We pretty much gave up warping the surfaces for control about 100 years ago (some ultralights and the like notwithstanding), so ours look different, but we all have yaw controls.
 
EppyGA said:
Say what?
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EAA sent me (and most other instructors, I would assume) an audio CD produced by aerobatics champ Rich Stowall, and in one of the segments he addresses this very question. He says that it is the elevator that turns the airplane and goes on to explain very convincingly. Once you have established a bank, the vertical lift vector has been reduced and the only way you can bring it back to its level-flight value is to use back pressure; bank without back pressure and you will lose altitude every time. "Stick and Rudder,' page 198; Airplane Flying Handbook, page 3-7. Works for me.

Bob Gardner
 
bobmrg said:
bank without back pressure and you will lose altitude every time.
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But you'll still turn. Turning requires lift, but to say that it requires elevator is a bit of semantic smartassery on Rich's part, IMHO. Because sin(x)~=x while cos(x)~=1, entering and maintaining a shallow (10 degree) bank from cruise without touching the elevator or pitch trim will effect a turn without losing much altitude - probably rather less than 500ft over a 180 degree turn.
 
Here's a question:

Climbing left turn while maintaining a constant bank angle. What control forces are needed, if any, and why?
 
Depends on the bank angle, power setting, airframe, engine and trim! Could be any combination of right aileron to resist overbanking, left aileron to resist the dihedral stability, right rudder to counteract P-factor, left rudder as needed to damp dutch roll modes, up elevator to keep the climb going, down elevator if the pitch trim is really messed up, etc...

Because there are so many different aircraft dynamic stability modes, each dependent on subtleties of design, trim, airspeed, attitude, power setting etc, it's not possible to say absolutely which ones are dominant and therefore which control inputs are needed. So you just have to get good at learning the tendencies of your particular aircraft under normal operating conditions so you can anticipate them, and also being able to react smoothly and appropriately to changes under more unusual conditions.
 
Turn while taxiing.

What, there's another reason?
 
onwards said:
Turn while taxiing.

What, there's another reason?
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Not a whole lot to do with the actual control surface-the rudder isn't very effective at slow speeds. It just so happens that nosewheel steering in GA aircraft are attached to the rudder pedals.
 
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ClimbnSink said:
Rudder is to overcome the inadequacies of the airplanes designer. Birds don't have em.
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Well, it's more a bone we toss to cost effectiveness anymore. I saw they now have a mechanical flying bird, but it's complex and expensive to build the tail. Then there's also the using down wing split drag to control adverse yaw like on the B2. So, rudders are more to overcome the inadequacies of pilots wallets more so than designers ability lol.
 
GCA319 said:
Not a whole lot to do with the actual control surface-the rudder isn't very effective at slow speeds. It just so happens that nosewheel steering in GA aircraft are attached to the rudder pedals.
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I used to fly a little old Roberts with a tail skid, rudder was ground steering, Beech 18 it's rudders and split throttles with some brake tapping going on as it's a free caster tail wheel (with a lock).
 
I've always wondered how the "rudder" works in a V-tailed airplane like the Bonanza.
 
Erice said:
I've always wondered how the "rudder" works in a V-tailed airplane like the Bonanza.
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I can't say for absolute certain, having not taken a Bonanza apart. But... mechanical mixing of elevator and rudder control inputs.

Dad and I used to fly R/C airplanes, nearly all of them designed by him. We built a few "flying wing" powered gliders -- large constant-chord wing, with a stub fuselage in front for balance and a vertical stab/rudder. They used "elevons" which mixed elevator and aileron controls. It works quite well, and the mechanical mixer was a pretty simple arrangement. I would imagine the Bo and other V-tails would use a similar setup, minus the servos of course. :) I'd like to see a diagram of how it works.
 
Kiloalphadriver said:
Here's a question:

Climbing left turn while maintaining a constant bank angle. What control forces are needed, if any, and why?
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I like to use this example with students (and any pilot demonstrating a lack of understanding at how the engine/propeller effects the airplane and how to compensate for it)

You can go over the forces in the classroom and then demonstrate them in the air. Set up a climb power (I neglected to mention climb power in the question. I assumed people would figure this out on their own. Silly me) , left climbing-constant bank turn (how about 25 degrees? Again, I didn't mention it. Silly me.)

A properly rigged glider in trimmed flight flies straight and true. Hang an engine on the front, and now you have a new set of forces to contend with. Being able to understand and compensate for these for is what makes you a pilot, instead of just someone turning and pushing on the controls.

(I'm going to keep this simple and understandable. My intent is to focus explanations that have practical value to individuals from all backgrounds wanting to learn fly)

Engines with propellers produce the following forces on a front-mounted , tri-gear, single-engine, airplane. (see how I'm covering all of the bases now?)

Torque, P-factor, slipstream, and gyroscopic precession.

Since an airplane spends most of it's time in cruise, the manufacturers design and built their airplanes to compensate for these forces in cruise flight.

Some will cant the engine from centerline. Some will offset the vertical stabilizer. Some will increase angle of incedence on the right wing. Some will increase dihedral.

So, when slower than cruise, the pilot needs to compensate for these factors. The slower and the higher the power setting, the more the pilot has to be involved.

A left climbing, constant bank turn is a great place to demonstrate this. Once you have the plane set up in this climbing turn, let go of the wheel and take you feet off of the rudder petals.

P-factor and slipstream will want to yaw the nose left, and torque will want to increase roll to the left. So, your inputs to maintain this constant bank, coordinated will require right rudder and right aileron. Try this the next time you're out and see for yourself.

Here's something else to observe with yourself and with someone else flying. (This drives me nuts)

You start your takeoff roll and invariably, the plane goes left. The rest of the take off roll is spent trying to get the plane back to the right and on centerline.

Why??

Because torque is trying to roll the airplane left and is creating more drag on the left wheel (why do left tires wear out quicker?? This plus turning around mostly on the left tire)

Although this is a roll issue, the rudder and nose gear steering is responsible for keeping the airplane straight. next time you take off think about this and be ready with the right rudder.

(I used to use torque to my advantage taking off in a high, direct crosswind which split a single runway. And when departing a short strip, like KSBS, in the King Air, I would lag the right engine's torque a couple hundred ft/pounds from a full power brake release to help compensate for the incredible torque. I would bring the right up to full power shortly afterwards)

When you rotate, what happens to the nose?? It goes left because now you've introduced a high angle of attack to a high power setting and P-factor comes in play. You have backed off on the right rudder after the initial roll and now you'll need to add (and hold it again for the climb-out).

Adverse yaw is caused by the displacement of the ailerons necessary to create the desired bank.

In a left turn, the left ailerons deflects up, reducing the wing camber, thus reducing lift AND drag. The right aileron drops, increasing camber, increasing lift AND increasing drag. So, the left wing accelerates while the right wing decelerates creating a yaw in the opposite direction of the intended turn. Applying rudder with the ailerons will prevent the yaw.

Hope this helps!



When departing a short str
 
Erice said:
I've always wondered how the "rudder" works in a V-tailed airplane like the Bonanza.
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By working in opposition (like ailerons) as rudder and in synch as an elevator. There's a nifty bit of linkage involved and many have a aileron tie in that allows you to keep wings level nicely with mostly just your feet preventing the "Bonanza Wag".
 
GCA319 said:
Not a whole lot to do with the actual control surface-the rudder isn't very effective at slow speeds. It just so happens that nosewheel steering in GA aircraft are attached to the rudder pedals.
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Wait a darn minute!! At low speed, the rudder is the ONLY control surface that remains effective. Next time you go flying, get yourself some altitude and clear airspace and with the power off, pull the yoke back as far as it will go and hold it there. Obviously, at that point the elevator is out of the equation. Now rock the ailerons from stop to stop...they will have no effect. Now use the rudder pedals to move the nose left and right. AHA!

This is an excellent way to wean students away from the "a stall will kill me" attitude. With the yoke full back, the student can keep the wings level with the rudder, just like keeping a bicycle vertical at low speed by pushing on the opposite pedal when the bike begins to lean. Of course, you will be going down like a freight elevator, so be sure to clear the area and keep your head on a swivel.

Basic aerodynamics: As you begin the takeoff roll, the rudder becomes effective first (low speed, of course); next come the ailerons and when you achieve liftoff speed the elevator becomes effective. On landing, with diminished airspeed and the prop not blowing air over the horizontal stabilizer as much as in cruise, the elevator loses effectiveness first; less airflow = less aileron control comes next, and the rudder is effective until the very end.

Also, some airplanes have full-swiveling nosewheels, not connected to the rudder pedals in any way.

Bob Gardner
 
bobmrg said:
Wait a darn minute!! At low speed, the rudder is the ONLY control surface that remains effective. Next time you go flying, get yourself some altitude and clear airspace and with the power off, pull the yoke back as far as it will go and hold it there. Obviously, at that point the elevator is out of the equation. Now rock the ailerons from stop to stop...they will have no effect. Now use the rudder pedals to move the nose left and right. AHA!

This is an excellent way to wean students away from the "a stall will kill me" attitude. With the yoke full back, the student can keep the wings level with the rudder, just like keeping a bicycle vertical at low speed by pushing on the opposite pedal when the bike begins to lean. Of course, you will be going down like a freight elevator, so be sure to clear the area and keep your head on a swivel.

Basic aerodynamics: As you begin the takeoff roll, the rudder becomes effective first (low speed, of course); next come the ailerons and when you achieve liftoff speed the elevator becomes effective. On landing, with diminished airspeed and the prop not blowing air over the horizontal stabilizer as much as in cruise, the elevator loses effectiveness first; less airflow = less aileron control comes next, and the rudder is effective until the very end.

Also, some airplanes have full-swiveling nosewheels, not connected to the rudder pedals in any way.

Bob Gardner
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All understood. I meant slow speeds as in taxi speed (unless you taxi at southwest airlines speeds)...I'm well aware that the rudder is the last flight control to remain effective when slowing down.
 
GCA319 said:
All understood. I meant slow speeds as in taxi speed (unless you taxi at southwest airlines speeds)...I'm well aware that the rudder is the last flight control to remain effective when slowing down.
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Still, it depends on the airplane. Some airplanes have plenty of airflow over the rudder at around 1000-1200 rpm. On the other extreme are jets, where you have to steer with a tiller until you get sufficient airflow over the rudder.


Sent from my iPad using Tapatalk HD
 
Fearless Tower said:
Still, it depends on the airplane. Some airplanes have plenty of airflow over the rudder at around 1000-1200 rpm. On the other extreme are jets, where you have to steer with a tiller until you get sufficient airflow over the rudder.


Sent from my iPad using Tapatalk HD
Click to expand...

Plenty of planes out there with a castering nose wheel that do okay until the crosswind gets too stiff.
 
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