bristolflyer
Topic Author
Posts: 2103
Joined: Fri May 14, 2004 1:35 am

Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 1:02 am

So I fly a bit on Flight Sim and have never used rudder, I always us the ailerons to turn. How much is the rudder used in flight by an airliner? I know that lining up with the runway it would be used a lot, but what about at cruising altitude? Are turns made with the rudder or ailerons? Seems that the plane banks a lot which would imply aileron use to me.
Fortune favours the brave
 
Fabo
Posts: 1150
Joined: Tue Aug 16, 2005 1:30 am

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 1:55 am

The rudder is not used to taxi big planes, there is a separate steering wheel. Pedals have some limited nosewheel authority for runway controll on take-off and landing.

Rudder itself is not generally used in flight. It is not required because of several things, amongst them the Yaw Damper system, or aerodynamic correction measures (for ex. spoilers usage for roll controll negates need to use rudder)

However, you need to use rudder control in some situations, such as:
-crosswind control on take-off and landing
-thrust difference, most notably Engine Out Situations

In general hand flight, I have not heard of an airliner that requires rudder usage for turn coordination, usually just banking is enough.
The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
 
imiakhtar
Posts: 611
Joined: Sun Apr 02, 2006 3:35 am

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 2:15 am

Quoting bristolflyer (Thread starter):
How much is the rudder used in flight by an airliner?

Apart from the takeoff and approach/landing phase and an engine failure scenario, the rudder is not used.

Some general aviation and military aircraft may require the use of rudder in a stall or spin but I'm not sure if that's applicable to any commercial airliners.
Whatever happened to Leon Trotsky?
 
HaveBlue
Posts: 2108
Joined: Fri Jan 30, 2004 3:01 pm

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 4:25 am

Quoting imiakhtar (Reply 2):
Some general aviation and military aircraft may require the use of rudder in a stall or spin

Small general aviation aircraft use them in turns, to keep flight coordinated.  
Here Here for Severe Clear!
 
bristolflyer
Topic Author
Posts: 2103
Joined: Fri May 14, 2004 1:35 am

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 4:33 am

Thanks for your replies, makes me feel better that I'm doing something somewhat realistic in Flight Sim. Now if only my radio controlled a/c had ailerons!

Quoting Fabo (Reply 1):

The rudder is not used to taxi big planes, there is a separate steering wheel.

If that was a response to my 'lining up with the runway' comment I should have elaborated further - I was meaning during landing in cross winds. Thanks.
Fortune favours the brave
 
roseflyer
Posts: 9606
Joined: Fri Feb 13, 2004 9:34 am

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 4:56 am

The rudder is sized to react the load of an engine out. Single engine failure in a twin or outboard single engine failure on a quad.

In reality, the rudder is used most heavily when compensating for a tailwind. Quite a bit of rudder deflection can be required to keep the airplane straight during takeoff roll. Above 80 knots, it is all rudder on the ground as the nosewheel has no steering authority.

We all know what can happen when the rudder is used excessively in flight from the AA 587 crash. Alternating use of full deflection is not intended for use in flight. Rudder use should be extremely limited in high speed flight.
If you have never designed an airplane part before, let the real designers do the work!
 
ferpe
Posts: 2651
Joined: Tue Nov 30, 2010 7:44 am

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 8:19 am

The big dividing line is jet or not. For a jet the subject has been covered, here props and sail planes:


PROPS
A prop sends an asymmetrical propwash onto the tail of the A/C, thus single engine prop aircraft has a Vertical tail which has preset twist to counter that. This twist only works for one speed (cruise) therefore you need to kick rudder at high power settings (start, climb) and low (descent, landing) where low is less pronounced. The real art of kicking rudder is when you start with a taildragger, starting a Piper Cub for the first time is a challenge also for an experienced pilot, you also use the rudder when landing the non Super cub as it does not have any flaps and you therefore crab the craft to adjust your finals path and speed. You also push a bit of rudder when turning with a prop.

Prop twins are asymmetrical if both props turn the same way, that is why powerful props crafts has counter rotation props. You kick LOTS of rudder (and lean towards going engine to help with the assymetry) when you train an engine out.


SAILPLANES
These have very wide wings. An aileron that increases camber (outside in turn) creates more drag then the inboard one which reduces camber, therefore the soarer tends to not want to turn into the turn. You kick substantial rudder in a sailplane.
Non French in France
 
bueb0g
Posts: 656
Joined: Fri Jul 02, 2010 5:57 pm

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 11:18 am

Quoting bristolflyer (Thread starter):
Are turns made with the rudder or ailerons? Seems that the plane banks a lot which would imply aileron use to me.
Quoting HaveBlue (Reply 3):
Small general aviation aircraft use them in turns, to keep flight coordinated.

So do big aircraft... Rudders may not be controlled directly by the pilot during turns / at altitude but the yaw damper will use slight rudder deflections to keep ballance during turns and to cull the effects of a phugoid cycle / dutch roll.
Roger roger, what's our vector, victor?
 
KPWMSpotter
Posts: 451
Joined: Tue Dec 26, 2006 1:01 am

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 4:32 pm

Some of the replies above may be quite misleading: large airliners (just like GA, Gliders, etc) must use their rudders in order to make coordinated turns and perform other maneuvers. In large jet airliners the computer is often making these rudder inputs (as in "yaw damper" or similar systems), but the physical rudder is getting the same workout that it would in a small aircraft.

Put simply, an aircraft must be controlled on all three axis. Ailerons control roll, elevators control pitch, and rudders control yaw. Leaving the rudder entirely out of the equation, an aircraft is basically free to pivot on the yaw axis given any side-forces on the aircraft such as asymmetric thrust, gusts, crosswinds, etc. (Note that a stable aircraft's vertical stabilizer will attempt to return the aircraft to be aligined with V0, but this isn't always sufficient or desired).

On any aircraft the rudder is essential on takeoff. Any crosswind component will attempt to weather-cock the aircraft into the wind. This must be counteracted in order to keep the aircraft aligned down the runway. Ailerons, spoilers, and nosewheel steering are all insufficient for this task. Additionally, propeller aircraft will be effected by the gyroscopic and aerodynamic turning tenancies induced by the spinning prop - again, proper use of the rudder counteracts these forces.

In flight, any turning aircraft will be subject to adverse yaw. As the aircraft rolls, the outside wing will accelerate and generate both additional lift and additional drag. This asymmetrical drag force will yaw the aircraft to the outside of the turn, requiring rudder (or spoiler in some FBW cases, but we'll neglect that) to coordinate the aircraft. Lack of rudder will lead to a very messy, and sometimes dangerous uncoordinated turn.

The rudder is an often forgotten flight control, as stable aircraft appear to almost never need it. Flight Sim has further reduced the perception of the rudder with the default "auto rudder" option. Proper use of the rudder is essential in all aircraft, and awareness of its role is fundamental to safety when placed in a nonstandard attitude in any aircraft.
I reject your reality and substitute my own...
 
Fly2HMO
Posts: 7207
Joined: Sat Jan 24, 2004 12:14 pm

RE: Noob Question: Rudder Use In Flight

Mon Jan 30, 2012 7:20 pm

Quoting KPWMSpotter (Reply 8):
Put simply, an aircraft must be controlled on all three axis....

Well said.

Quoting bristolflyer (Thread starter):
So I fly a bit on Flight Sim and have never used rudder,

Might I add, as a former billion hour FS captain turned real-life flight instructor myself, just about everything you learned about flying from FS, toss it. FS will never teach you proper stick and rudder skills. However, it is great for practicing procedural stuff, especially when it comes to flying IFR.
 
bristolflyer
Topic Author
Posts: 2103
Joined: Fri May 14, 2004 1:35 am

RE: Noob Question: Rudder Use In Flight

Tue Jan 31, 2012 12:08 am

Quoting Fly2HMO (Reply 9):
Might I add, as a former billion hour FS captain turned real-life flight instructor myself, just about everything you learned about flying from FS, toss it. FS will never teach you proper stick and rudder skills. However, it is great for practicing procedural stuff, especially when it comes to flying IFR.

So if ever I'm on a 747 half way across the Atlantic and the flight attendant runs into the cabin screaming 'does anybody know how to fly an airplane?' I shouldn't put my hand up? Sheesh, there goes my 15 mins of fame.
Fortune favours the brave
 
Fly2HMO
Posts: 7207
Joined: Sat Jan 24, 2004 12:14 pm

RE: Noob Question: Rudder Use In Flight

Tue Jan 31, 2012 2:17 am

Quoting bristolflyer (Reply 10):

So if ever I'm on a 747 half way across the Atlantic and the flight attendant runs into the cabin screaming 'does anybody know how to fly an airplane?' I shouldn't put my hand up? Sheesh, there goes my 15 mins of fame.

The situation you're talking about is a whole other can of worms that has been discussed ad-nauseam here. However, assuming everybody else has never driven anything more than a car and can't tell a C172 from a C130, then yes you are the best hope.  
 
User avatar
Starlionblue
Posts: 17117
Joined: Fri Feb 27, 2004 9:54 pm

RE: Noob Question: Rudder Use In Flight

Tue Jan 31, 2012 3:31 am

Quoting Fly2HMO (Reply 11):
Quoting bristolflyer (Reply 10):

So if ever I'm on a 747 half way across the Atlantic and the flight attendant runs into the cabin screaming 'does anybody know how to fly an airplane?' I shouldn't put my hand up? Sheesh, there goes my 15 mins of fame.

The situation you're talking about is a whole other can of worms that has been discussed ad-nauseam here. However, assuming everybody else has never driven anything more than a car and can't tell a C172 from a C130, then yes you are the best hope.

Quite. The conclusion to these discussions is normally that yes, you might do better than any random person, but there's a lot more to flying than knowing how to manipulate the controls. If nothing else the "pucker factor" should not be underestimated.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Fly2HMO
Posts: 7207
Joined: Sat Jan 24, 2004 12:14 pm

RE: Noob Question: Rudder Use In Flight

Tue Jan 31, 2012 4:31 am

Quoting Starlionblue (Reply 12):
The conclusion to these discussions is normally that yes, you might do better than any random person, but there's a lot more to flying than knowing how to manipulate the controls. If nothing else the "pucker factor" should not be underestimated.

Indeed. As I said, FS is great for procedural stuff and instrument practice. So much so, I used the PMDG 737 while doing my actual 737 type rating course. Me and my sim partner blew away everyone else on the class by a long shot in performance and praise from our instructors thanks to that. However, nothing prepared us for how it actually handled. Specifically: on the outside it (the 737) looks like it flares significantly, but from the inside it looks like a pretty flat pitch attitude, it was hard to resist the temptation to not flare significantly like you would in a GA plane. Very deceiving.

So I guess my point is bristolflyer, should you face that situation, be sure you know how to work the autopilot/autoland very well and you're set  
 
User avatar
Starlionblue
Posts: 17117
Joined: Fri Feb 27, 2004 9:54 pm

RE: Noob Question: Rudder Use In Flight

Tue Jan 31, 2012 8:24 am

Quoting Fly2HMO (Reply 13):
Indeed. As I said, FS is great for procedural stuff and instrument practice. So much so, I used the PMDG 737 while doing my actual 737 type rating course. Me and my sim partner blew away everyone else on the class by a long shot in performance and praise from our instructors thanks to that.

It should be noted that add-ons such as PMDG go way beyond plain vanilla MSFS. As in the instruments and controls actually work as in the real plane and are "simplified".
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
redflyer
Posts: 3882
Joined: Thu Feb 24, 2005 3:30 am

RE: Noob Question: Rudder Use In Flight

Tue Jan 31, 2012 4:24 pm

Quoting Fly2HMO (Reply 11):
Quoting bristolflyer (Reply 10):

So if ever I'm on a 747 half way across the Atlantic and the flight attendant runs into the cabin screaming 'does anybody know how to fly an airplane?' I shouldn't put my hand up? Sheesh, there goes my 15 mins of fame.

The situation you're talking about is a whole other can of worms that has been discussed ad-nauseam here. However, assuming everybody else has never driven anything more than a car and can't tell a C172 from a C130, then yes you are the best hope.

The best hope only if he didn't eat the fish that was served for dinner.  
My other home is in the sky inside my Piper Cherokee 180.
 
sprout5199
Posts: 1681
Joined: Sat Feb 26, 2005 8:26 am

RE: Noob Question: Rudder Use In Flight

Wed Feb 01, 2012 8:10 pm

Quoting Fly2HMO (Reply 11):
can't tell a C172 from a C130

Oh come on, everyone knows a C172 is bigger than a C130. Thats why i fly a C152, just the right size, not too big, not too small.

Dan in Jupiter
 
hmmmm...
Posts: 1959
Joined: Tue May 18, 1999 8:32 am

RE: Noob Question: Rudder Use In Flight

Wed Feb 08, 2012 3:01 am

An aircraft does not really need a rudder to fly. Not only do ailerons roll the plane, they also effect yaw, which is why you can yaw quite well without a rudder - it's just sloppy - uncoordinated. However, rudder is essential for crosswinds, especially on take-off and landings, when you do not wish to roll the aircraft.

We all remember Air Transat 961 that lost its rudder. Literally. The pilots had no idea what their earlier problems were due to, until they did a post-flight inspection. They thought they were flying with a rudder. The rudder was completely gone.
An optimist robs himself of the joy of being pleasantly surprised
 
User avatar
Starlionblue
Posts: 17117
Joined: Fri Feb 27, 2004 9:54 pm

RE: Noob Question: Rudder Use In Flight

Wed Feb 08, 2012 3:39 am

Quoting hmmmm... (Reply 17):

An aircraft does not really need a rudder to fly. Not only do ailerons roll the plane, they also effect yaw, which is why you can yaw quite well without a rudder - it's just sloppy - uncoordinated. However, rudder is essential for crosswinds, especially on take-off and landings, when you do not wish to roll the aircraft.

Conversely, my model airplane had no ailerons. Turns weren't very elegant to start with but once it had rolled a bit they got better.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
aviopic
Posts: 2423
Joined: Sat Mar 13, 2004 7:52 pm

RE: Noob Question: Rudder Use In Flight

Thu Feb 09, 2012 8:22 pm

Quoting hmmmm... (Reply 17):
An aircraft does not really need a rudder to fly.

An aircraft doesn't need ailerons either as it was done in the old days.


View Large View Medium
Click here for bigger photo!

Photo © Klaas Reinder Sluijs
View Large View Medium
Click here for bigger photo!

Photo © Willem Honders

The truth lives in one’s mind, it doesn’t really exist

Who is online

Users browsing this forum: No registered users and 12 guests