Pilots: What happens if you bank using ailerons one way and apply rudder to turn the other way? (I'm sure it's bad, but I can't quite envision the result)

Slipping is one term for this, but let me give you a commercial pilots perspective.  Aircraft are capable of nearly any aerobatic manuever, whether it be banks, rolls, or turns.  (note that some airliner parts are not rated for them, thus the reason you don't see 757's looping around upside down)The rudder's main purpose in flight is stabilization, not as much steering.  It is sometimes referred to as the vertical stabilizer.  It serves this function in manuevering the plane.  If the nose is yawing side to side because of weather conditions, pilots will use the rudder pedals to stabilize it by applying brief inputs.  The rudder coordinates turns, you just can't apply too much.  The rudder turns the plane's nose left or right, this can assist and stabilize turns.

With this in mind, say I roll the plane to the right with the ailerons.  The aircraft is now leaned to the right, we'll say at about 15 degrees.  If I was not in a climb, the nose will remain mostly level.  A rudder input to either side will push the nose respectively left or right.  This doesn't hurt the plane, it changes the direction. The rudders are used for stabilization during turns to keep the nose at whatever angle is desired and to manuever smoothly.  However, depending on the severity of the bank, the angle of attack, and the pitch of the nose, rudder inputs can also hurt a turn.  When flying, using rudder, elevators, and ailerons is almost done in coordination without thinking about it.  I know what direction/heading I need to rotate to, and I do it in the most logical way.

All of the control surfaces are used together for whatever move is needed.  Using elevators, ailerons, and rudder all at the same time is completely normal and absolutely harmless.  The only problem one runs into with this move is a stall risk.  If you push the plane to extremes in pitch, roll, or airspeed, you could risk a stall.  (stalls are complete losses of lift, a recoverable problem if you have enough altitude)  So I conclude to say that it's not a bad move to bank one way and apply rudder the opposite.  You always have to steer the aircraft sensibly with its limitations in mind.

Hi - What you are describing is called "slipping". It is an effective way to bleed off altitude to correct for a landing approach that is too high, because it steepens the approach angle, or glide slope.

If you were to simply push the nose down in such a situation you would increase your airspeed, which is undesireable when landing.

It is also used to increase your field of view to check blind spots on the ground covered by the wing, particularly in low-wing aircraft. In "tail dragger" aircraft the raised nose during approach can make it impossible to see straight forward, kicking in rudder will allow a forward view of the runway.

Or, you can sideslip to aim fixed weapons if you are shooting at something. Or to avoid being shot by an enemy by creating an illusion that you are actually flying in the direction that the nose of the plane is heading. This deception has actually been used successfully during WWII by less agile airplanes to avoid being shot by more agile enemy attackers.

Of course, you must be sure you are maintaining sufficient airspeed because a slip can send you into a stall.

- Brian.

It's common to kick rudder to lose altitude on final especially with aircraft that don't have flaps, this is called a slip.

Negating the lean from the slip with aieleron isn't a great idea because the natural instinct will be to maintain pitch... Not good.

Applying rudder and oposite aieleron as your question suggest can lead to what's called a crossed control stall, which can e very deadly on short final where there is no altitude to recover from a wing-over.

CORRECTION - Hi - I'm posting this because the site would not permit me to edit my response above.

The 5th paragraph has a sentence that reads "If you bank left and apply some left aileron as well you will achieve a better rate of turn for that given level of aileron input."

It should read "If you bank left and apply some left RUDDER as well you will achieve a better rate of turn for that given level of aileron input."

Hope this makes more sense. - Brian.

Hi!-

To clarify something written above- the rudder on the aircraft is called the VERTICAL stabilizer, (NOT horizontal). Although it does cause the aircraft to move along the HORIZONTAL plane, the term describes the orientation of the control surface itself which is VERTICAL, not horizontal.

To answer your question - the plane would pitch up into a nose-high attitude only if you also pulled back on the controls at the same time. Applying strictly left aileron and right rudder at the same time would not on their own result in any drastic change in attitude. The design of the aircraft restricts the amount of rudder deflection so as to be within safe limits.

Deliberate slipping, even at full rudder deflection, is considered quite "SAFE" and would only result in a stall if your airspeed was insufficient. You would, however, need to maintain an airspeed at some safe level above your stall speed in the particular configuration (flaps, gear, power) that you are flying in at the time.

Of course, I'm talking about wing stall here, not engine stall. The wing stall results in a loss of lift and the plane will fall from the sky, unless you have sufficent altitude and the skills to recover. And of course, ideally you would use your superior intellect to prevent you from getting into a situation which would require your superior flying skills to get you out of. ; )

Also, to clarify- The rudder DOES help turn the aircraft in a co-ordinated way when used in concert with the ailerons. If you bank (roll) left with the ailerons only, you will achieve a given (less than ideal) rate of turn. This is not proper airmanship because it will result in the plane slipping towards the lower wing. (To a lesser degree than if you also added opposite rudder). If you bank left and apply some left aileron as well you will achieve a better rate of turn for that given level of aileron input. This is the proper way to turn an aircraft, and besides maximizing aerodynamic efficiency by reducing adverse yaw and drag, it's more comfortable for the passengers.

Experience will tell you how much rudder to kick in for a given amount of bank, but your instruments (turn-and-bank, or turn co-ordinator) will tell you as well.

I could go into much more detail here, but if you're still not clear about something, just ask.

Regards - Brian.