Strange Instruction

[FlyingMonkey]

An instructor a couple of weeks ago said something that has been bothering me. He said:

 

"Never add any rudder in a turn of 45 degrees or more, especially down low, as you risk a spin."

 

That goes against everything I've ever learned, that says that you ALWAYS fly coordinated. In fact, you can't spin if you stay coordinated, even in a deep stall.

 

Am I mistaken, or is there some "except for when..." caveat I have not heard? As a low time pilot I accept I don't know everything about flying, but like I said this goes against a lot of my teaching and I feel the need to resolve it!

[Ed Cesnalis]

Ask him to demonstrate a 60 degree turn with his feet off the pedals.

[coppercity]

There are a couple cases where you will not maintain coordinated flight which are forward and side slips, otherwise you are correct that you try to maintain coordinated flight. Remember the rudder is used to counteract the adverse yaw created by using ailerons to bank the aircraft for a turn. Once a bank angle has been established the ailerons return to a near neutral position so less rudder is needed to maintain coordination. In a steeper turn the aircraft may have tendency to try and overbank because the outer wing is moving a little faster then the inner. You may find you need opposite aileron pressure and corresponding rudder to get what you need. Also you should not be at steep bank angles below 1500ft AGL. In the pattern especially limit your bank angle to no more than 30 degrees.

[sandpiper]

You may have him out of context. When turning, you do so with aileron and rudder in the direction of the turn. Then neutralize to maintain the bank. So, maybe what he was telling you is not to add rudder in the direction of turn, which would be bottom rudder, which without aileron would put you in a skidding turn, which could stall the bottom wing if you got slow enough, which, close to the ground would not be pretty.

 

This "moose hunters stall" or turn from base to final, low and slow, and you overshoot final, and you want to correct but don't want to get a steep bank close to the ground, so you add rudder to turn but opposite aileron to keep from getting too steep, and you get too slow, and stall from that skidding turn, and suddenly..............

 

Ask him what he meant. Probably just what I described.

 

Certainly you want to remain coordinated so that means you will use aileron and rudder to do that. Regardless of altitude.

[sandpiper]

Unless, as Eric says, you are in a deliberate slip.

[Jim Meade]

The Airplane Flying Handbook, which I hope we all have and read frequently, has a good discussion of rudder use during shallow and medium banked turns in pages 3-7 to 3-12. It's not quite as thorough as we might wish on steep turns. While I am not sure I concur with what your instructor is saying as you presented it, one can see in AFH why excessive rudder use is to be avoided.

 

Interestingly, the book says the student is encouraged to use the rudder freely when learning as it can be corrected, while insufficient rudder use is not a good habit to get into. 3-12.

 

The AFH is free online at the FAA website.

[Jim Meade]

Terminology, per AFH

Shallow turns - less than 20° - airplane wants to level itself

Medium turns - 20° - 45° - plane remains at a constant bank with minimal aileron and the rudder is permitted to streamline (not necessarily put the ball in the middle)

Steep turns - 45° or more - airplane tends to overbank unless you hold "up" aileron

 

The CFI is talking about steep turns, so we should be careful to base our discussions on that.

[Ed Cesnalis]

Steep turns in my CTSW do require me to high side the stick. I use rudder as needed to be coordinated which means a lot of rudder when initiating and top rudder when high siding.

[FlyingMonkey]

I think Sandpiper has it, you sounded just like him there. Sooo...he's saying not to add rudder before starting the turn, or maybe once the coordinated turn is established? I'm still a bit fuzzy on what is being said. Other than the standard cross-control conditions of forward and side slips, I'd still think staying coordinated is good, flying uncoordinated is bad. Am I wrong?

[FlyingMonkey]

CT...what do you mean by "high siding the stick"?

[FastEddieB]

 

Interestingly, the book says the student is encouraged to use the rudder freely when learning as it can be corrected, while insufficient rudder use is not a good habit to get into. 3-12.

.

 

Jim,

 

That sorta kinda almost is what I was getting at when I said I prefer overcontrolling to undercontrolling, at least initially.

 

I think.

[sandpiper]

This is getting way too complicated. Don't over think it. Do what is required to stay coordinated unless intentionally slipping. Don't di skidding turns close to the ground.

[Ed Cesnalis]

CT...what do you mean by "high siding the stick"?

 

Correlate it to what the AFH says about steep turns "Steep turns - 45° or more - airplane tends to overbank unless you hold "up" aileron"

 

up aileron = high siding the stick. I guess its hang glider pilot terminology or close to it, they have a control bar and say something like "high siding". The point is when you are flat enough or steep enough you have to use counter input to maintain the bank. In the middle the plane is stable and maintains the bank angle with no input.

[FastEddieB]

The point is when you are flat enough or steep enough you have to use counter input to maintain the bank. In the middle the plane is stable and maintains the bank angle with no input.

 

I think the "flat enough" part is wrong, if I understand you correctly.

 

In a shallow turn, the plane's inherent stability will make it want to return to wings level flight, so the control input used is not "counter" at all - control input will be with the turn instead.

 

Right?

 

Unless autofill typed "counter input" instead of "control input" or you just mistyped.

 

[Ed Cesnalis]

yes your right

[WmInce]

. . . "An instructor . . . said: Never add any rudder in a turn of 45 degrees or more, especially down low, as you risk a spin." . . .

 

Was the instructor talking about degrees of heading change or bank angle?

 

In a turn maneuver, the primary flight control that "turns" (changes the aircraft's heading) is the elevator. Depending upon the aircraft, the rudder would be used to trim or maintain coordinated flight. In a scenario of 45 degrees of bank or more, there are some high performance aircraft which would not require any rudder input at all.

 

Ever heard of the aviation expression, "banking and yanking?" The implication is to establish a bank and then "pull" the airplane through the turn arc (using elevator control). With LSA's, some rudder input surely is required, as explained in other posts above.

 

Perhaps that is what the instructor was implying.

[Jim Meade]

AFH 3-7

"

LEVEL TURNS

Aturn is made by banking the wings in the direction of

the desired turn. Aspecific angle of bank is selected by

the pilot, control pressures applied to achieve the

desired bank angle, and appropriate control pressures

exerted to maintain the desired bank angle once it is

established. [Figure 3-5]

All four primary controls are used in close coordination

when making turns. Their functions are as follows.

• The ailerons bank the wings and so determine the

rate of turn at any given airspeed.

• The elevator moves the nose of the airplane up or

down in relation to the pilot, and perpendicular to

the wings. Doing that, it both sets the pitch attitude

in the turn and “pulls” the nose of the airplane

around the turn.

• The throttle provides thrust which may be used for

airspeed to tighten the turn.

• The rudder offsets any yaw effects developed by

the other controls. The rudder does not turn the airplane."

 

It is well worth while to read the five pages.

http://www.faa.gov/regulations_policies/handbooks_manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-2of7.pdf

[FlyingMonkey]

Okay, I think my original understanding was correct (don't unintentionally fly out of coordination unless intentionally slipping), and the instructor was just trying to add some 'finesse' to my understanding, which as usual was apparently totally lost on me. So I will continue flying coordinated, and will not step on the ball in a steep turn more than needed to maintain coordinated flight (skid). If anybody thinks this plan will get me in trouble, please let me know.

[FastEddieB]

Thanks for the AFH excerpt.

 

Two observations...

 

• The throttle provides thrust which may be used for

airspeed to tighten the turn.

 

That makes it sound like adding power will tighten the turn. But in a turn, adding power will increase airspeed which will actually increase turn radius, so that seems misleading, or at least poorly put.

 

• The rudder does not turn the airplane.

 

While the rudder is not the primary way to turn an airplane, it certainly will turn the airplane, albeit indirectly. Trim a plane for hands off level flight and do nothing but kick the rudder and see what happens.

[FlyingMonkey]

Agree Eddie, the turn radius will increase...but the turn rate might increase (degrees per second around the circle). This probably comes down to what fighter pilots call "corner speed"...turn rate will continue to increase up to corner speed, then stay constant or fall off beyond that speed. Combat pilots don't generally care about radius of turn, just rate ("how fast can I get the nose to point at the bad guy"). We don't usually care about the distinction, but in this case related to your comment it is probably relevant.

[Jim Meade]

I agree the throttle quote sounds poorly worded. If you want to turn tighter, you have to increase the rate of turn and one way to do that is to slow down. Discussion on that in the same pages.

 

I think you're quibbling on the rudder. Clearly, the intent is to show that the rudder is used to coordinate controls. We all know you can kick the rudder, and when you learn to fly instruments some CFIIs have you use the rudder alone for small changes to stay on the ILS (although some don't). When I'm in tow in a glider, I often use the rudder for slight turns. But in the context of turns as is being described in this section of the AFH, the rudder is not a device to "turn" the airplane. I know you know that.

[FastEddieB]

 

I think you're quibbling on the rudder.

 

"Quibble" is my middle name!

 

Actually, it's "Robert", but there I go quibbling again!