Slow Flight Rudder Control

[gkaiser]

Hey All! I'm about 7 hours into my flight training out of Westosha/Wilmont,WI and my instructor & I were working on slow flight yesterday. For some reason I was having a very hard time seeing any drift and using the rudder to correct it during slow flight training. i've got the concept of right rudder/right turn and left rudder/left turn to keep the ball centered..but I just couldn't see the drift during slow flight and ended up 10 degrees off course. Any rudder tips for slow flight?

Thanks all!

 

[poadeleted20]

When trying to hold heading in slow flight, look outside and use the rudder to keep the nose from moving left or right. Use outside visual cues such as the ground (which, due to the high pitch attitude in slow flight, may be visible only to the sides) or clouds or anything else visible out there to detect any yaw (left/right movement of the nose), and then move the rudder opposite the movement to stop the movement. If you keep the nose from swinging like that, your heading will stay where it was.

 

[saracelica]

I was always told to line the nose up with a road below me and so I'd always see it drift one way or the other.

 

[gkaiser]

I was always told to line the nose up with a road below me and so I'd always see it drift one way or the other.

I like the idea of keeping the nose lined up with a road..we were at a nose up attitude so all I could see were clouds..and I was getting bounced around a bit by that..so even if the turbulence bounces me around still use the rudder pedals to correct..right? Just use the controls to keep the wings level...

 

[poadeleted20]

If you're doing slow flight, you can't see the road well enough over the nose. Also, that only works if there's no wind or the wind is parallel to the road. Sky references are a better choice in that situation (as you said -- all you could see were the clouds), especially since the clouds are moving with the wind so there's no drift issue.

 

[RyanShort1]

Might try a few falling leaf maneuvers. In the process, cover up the ball and see if that doesn't help you connect your seat with your feet.

Ryan

 

[Threefingeredjack]

If you're doing slow flight, you can't see the road well enough over the nose. Also, that only works if there's no wind or the wind is parallel to the road. Sky references are a better choice in that situation (as you said -- all you could see were the clouds), especially since the clouds are moving with the wind so there's no drift issue.

When I was, (I am NOT a CFI ), getting my wife familiar with the controls in case of an emergency we used the "line up with the road technique" so she could get used to handling the Comanche in approach configuration and staying lined up on a runway. We did this at altitude and set a 3000ft floor as our landing altitude. We offset to the left so she could use the right side of the cowling as a guide when the attitude prevented seeing over the nose.

 

[BiffJ]

One thing to remember is that the rudder does not "steer" your plane. All it does is control yaw. If you're holding the wings level with the wheel, stick or whatever than you can fly quite sideways by holding the rudder in either direction and never turn. You will keep the plane flying straight by a coordinated use of both the rudder pedals and the wheel/stick. In slow flight there is more right rudder required in most US planes due to slipstream and P-factor so even to make left turns you may still have right rudder in. Frequently you will find yourself easing off the right rudder in a left turn in slow flight.
Use ground references for controlling drift and yaw and scan instruments rather than watching them. Its hard to detect yaw by instrument but it becomes obvious through reference to outside objects in time.

Frank

 

[TedR3]

When I was practicing for the check ride, I would bug my heading on the DG and scan with altimeter.

You'll get the hang of slow flight, just takes some time. It's all right rudder and maybe a nudge of aileron to get the turn started. I was way too heavy on the controls when I started with it.

 

[j1b3h0]

I would echo Capt Ron's advice: Look outside! You'll note the nose is well above the horizon, so, unless you have a convenient cloud straight ahead, above the nose, there is no way to tell if the airplane is yawing. The trick is to train your self (whenever the nose is above the horizon) to look at where the horizon meets the side(s) of the cowling - and, while you're keeping the wings level, apply just enough right rudder to prevent the airplane from yawing. You'll find it will only take an ounce or two of rudder pressure. Another indication you're not applying the correct amount of rudder pressure is a tendency for the airplane to bank. So, if you have to hold aileron...you probably aren't holding enough (or possibly too much) rudder pressure. One last trick: Put your left foot on the floor. Then you'll find just how little rudder is actually required. Sorry if that's confusing.

 

[j1b3h0]

When I was practicing for the check ride, I would bug my heading on the DG and scan with altimeter.

You'll get the hang of slow flight, just takes some time. It's all right rudder and maybe a nudge of aileron to get the turn started. I was way too heavy on the controls when I started with it.

While an occasional glance at the altimeter is good, the DG not so much...in fact it is a source of much difficulty when pre-solo students are attempting slowflight. A good instructor will draw the student's attention outside the airplane. It's one reason I prefer to teach primary in a non-gyro airplane.

 

[poadeleted20]

When I was, (I am NOT a CFI ), getting my wife familiar with the controls in case of an emergency we used the "line up with the road technique" so she could get used to handling the Comanche in approach configuration and staying lined up on a runway. We did this at altitude and set a 3000ft floor as our landing altitude. We offset to the left so she could use the right side of the cowling as a guide when the attitude prevented seeing over the nose.

That's a great technique for learning how to align with and track a line on the ground (it's essentially one side of the Rectangular Pattern maneuver, and worth doing before adding the turns and turning it into a Rectangular Pattern), but it doesn't address the basic issue of controlling yaw, which appears to be the OP's problem.

 

[TMetzinger]

To further discussion (and improve my own understanding), in straight-and-level slow flight (not turning or climbing/descending), in still air, how much rudder is needed and why?

Asking the same question a different way, if you put the airplane into the landing configuration (gear down, full flaps), and reduce power and add elevator trim until the stall warning is going off and the airplane is maintaining altitude, and you release all the controls.... what happens?

Assuming we come to an agreement on this configuration, we can then discuss what yaw inputs are required when a change in pitch or bank is made.

 

[denverpilot]

Asking the same question a different way, if you put the airplane into the landing configuration (gear down, full flaps), and reduce power and add elevator trim until the stall warning is going off and the airplane is maintaining altitude, and you release all the controls.... what happens?

Depends on where the rudder trim was set.

(Ducking... And running away...hahaha)

 

[j1b3h0]

To further discussion (and improve my own understanding), in straight-and-level slow flight (not turning or climbing/descending), in still air, how much rudder is needed and why?

Asking the same question a different way, if you put the airplane into the landing configuration (gear down, full flaps), and reduce power and add elevator trim until the stall warning is going off and the airplane is maintaining altitude, and you release all the controls.... what happens?

Assuming we come to an agreement on this configuration, we can then discuss what yaw inputs are required when a change in pitch or bank is made.

Tim -

At issue is the question of P-factor, that theory that whenever the angle of attack of the wing increases, so, too does P-factor. Because the descending blade of the propeller is at a higher angle of attack as well. If you're flying a 300hp single, with the gear and flaps down, and attempting a full power stall - a LOT of right rudder is necessary. Same airplane with the throttle at idle, not so much. But here's the real answer: Whatever it takes to make the airplane do what you want it to do. With the wings level, whatever rudder is necessary to make the airplane go absolutely straight...aim it like a rifle.

The question you've asked about what happens when the controls are released is a little more complicated because airframe manufacturers build-in aerodynamic fixes to the effects of P-factor...some cant the engine down and to the right, some attach the left and right wing with different incidence, some mount the vertical stabilizer pointing a few degrees right. Any and all of the methods are but a comprimise, so the pilot might have to overcome them. For instance: Citabrias are built with a offset vertical stabilizer. Works okay in cruise, but in slowflight or climb a little right rudder is needed. Conversely, while diving to do a loop, (to a speed well above cruise) some left rudder is needed to acount for the offset stab.

In any case, a good pilot can get the airplane to do exactly what he pleases with very little effort. In slowflight, I can fly most single engine airplanes with my left foot on the floor, and my thumb and two fingers on the stick or yoke and a hand on the throttle. If one doesn't hold enough rudder, (in addition to not holding heading) the airplane wants to bank to the left. Too much rudder, the opposite. That's why I suggest flying with a very light touch. Does that answer your question?

 

[brcase]

IF you are looking outside either at clouds or the ground at a distance in front of you, roads are great, you will easily stay within the 10 degree requirement. If you are looking at the Directional Gyro or compass you will have trouble holding the heading. You might have to look to the side around the cowling to see the ground.

Brian
CFIIG/ASEL

 

[TMetzinger]

Tim -

At issue is the question of P-factor, that theory that whenever the angle of attack of the wing increases, so, too does P-factor. Because the descending blade of the propeller is at a higher angle of attack as well. If you're flying a 300hp single, with the gear and flaps down, and attempting a full power stall - a LOT of right rudder is necessary. Same airplane with the throttle at idle, not so much. But here's the real answer: Whatever it takes to make the airplane do what you want it to do. With the wings level, whatever rudder is necessary to make the airplane go absolutely straight...aim it like a rifle.

The question you've asked about what happens when the controls are released is a little more complicated because airframe manufacturers build-in aerodynamic fixes to the effects of P-factor...some cant the engine down and to the right, some attach the left and right wing with different incidence, some mount the vertical stabilizer pointing a few degrees right. Any and all of the methods are but a comprimise, so the pilot might have to overcome them. For instance: Citabrias are built with a offset vertical stabilizer. Works okay in cruise, but in slowflight or climb a little right rudder is needed. Conversely, while diving to do a loop, (to a speed well above cruise) some left rudder is needed to acount for the offset stab.

In any case, a good pilot can get the airplane to do exactly what he pleases with very little effort. In slowflight, I can fly most single engine airplanes with my left foot on the floor, and my thumb and two fingers on the stick or yoke and a hand on the throttle. If one doesn't hold enough rudder, (in addition to not holding heading) the airplane wants to bank to the left. Too much rudder, the opposite. That's why I suggest flying with a very light touch. Does that answer your question?

Both you and Nate hit on the issue. Adverse yaw caused by P-factor varies depending on angle of attack, and the way the airplane is set up affects where the rudder needs to be to eliminate/compensate for that adverse yaw. If you've got rudder trim, you can trim the airplane for hands-and-feet-off straight and level flight in any configuration (assuming the airplane isn't mis-rigged). Without it, then you, Mr. Original Poster Pilot, get to be the rudder trim or human yaw damper.

Typically, in an airplane without rudder trim, the way it's rigged will result in being able to fly "feet-on-the-floor" in cruise, and you'll need rudder outside of that sweet spot.

If you can take the airplane on a calm day, and get it in the slow flight configuration, and trimmed for that airspeed so the stall warning is going off but your altitude is constant (adjust this with the throttle), if you take your hands and feet off the airplane will first yaw to the left and then that will normally couple to a roll as the right wing advances and generates more lift. Your goal is to use the rudder, and ONLY the rudder, to keep the wings level and the ball centered and the nose not moving. When you can do this and track a straight line, then try altering the rudder pressure gently... add some right rudder, and watch the nose skid around and then the airplane roll to the right. Release some of that pressure and the nose will come back left and the airplane will go back to level.

What I'm hoping you'll learn by this is the interrelation between yaw and roll. You can do this at faster speeds and then slow it down if that's more comfortable. If you keep your eyes focused outside and concentrate on what your body is telling you, you will develop a "feel" for coordinated flight. It doesn't come quickly, you gain it gradually as you fly, but slow flight really is the regime where it's most obvious. And it's also the regime where it's most important to be coordinated.

Once you have straight-and-level slow flight working well, you can try adding some turns. Remember that the PTS for slow flight is such that if you increase the angle of attack at all you'll stall. That means that if you're doing slow flight straight and level properly, a turn without a descent is going to result in a stall. So you need to add a little power before turning so that you won't lose altitude. Experiment - in the C172s adding 100 RPM allowed me to do reasonable turns at 10 degrees of roll or so, and 10 degrees of roll will get you around pretty quick in slow flight. Again, when you're turning, keep the focus outside and on how it feels to you. The earth should be going left or right underneath the nose - you ARE turning, but your nose should not be sliding up or down on the diagonal of your bank angle. You'll find that from straight and level you'll need to add right rudder pressure for a right turn, and just relax some of the "trim" pressure you'd put in for the left turns.

Above all, don't get discouraged, this is something that comes with repetition and correction, rather than learned in a couple of lessons. If you get a chance to do this in a glider or a Diamond (which has a similar wing), you'll pick it up faster as they really are sensitive in yaw.

Best wishes,

 

[gkaiser]

I do look outside...but I never thought of looking out the side windows for visual cues too. Usually we have such a high nose-pitch attitude that not much was visible. Next time we repeat it I'll try looking out the side windows and see if that helps at all to help me detect yaw.

Thanks Ron!

When trying to hold heading in slow flight, look outside and use the rudder to keep the nose from moving left or right. Use outside visual cues such as the ground (which, due to the high pitch attitude in slow flight, may be visible only to the sides) or clouds or anything else visible out there to detect any yaw (left/right movement of the nose), and then move the rudder opposite the movement to stop the movement. If you keep the nose from swinging like that, your heading will stay where it was.

 

[poadeleted20]

I do look outside...but I never thought of looking out the side windows for visual cues too. Usually we have such a high nose-pitch attitude that not much was visible. Next time we repeat it I'll try looking out the side windows and see if that helps at all to help me detect yaw.

Helps a lot with collision avoidance, too. :wink2:

 

[kgruber]

I do look outside...but I never thought of looking out the side windows for visual cues too. Usually we have such a high nose-pitch attitude that not much was visible. Next time we repeat it I'll try looking out the side windows and see if that helps at all to help me detect yaw.

Thanks Ron!

You should be taking quick glances out the side window when landing, as well. It helps judge height above the runway.

 

[Jaybird180]

Both you and Nate hit on the issue. Adverse yaw caused by P-factor varies depending on angle of attack, and the way the airplane is set up affects where the rudder needs to be to eliminate/compensate for that adverse yaw. If you've got rudder trim, you can trim the airplane for hands-and-feet-off straight and level flight in any configuration (assuming the airplane isn't mis-rigged). Without it, then you, Mr. Original Poster Pilot, get to be the rudder trim or human yaw damper.

Typically, in an airplane without rudder trim, the way it's rigged will result in being able to fly "feet-on-the-floor" in cruise, and you'll need rudder outside of that sweet spot.

If you can take the airplane on a calm day, and get it in the slow flight configuration, and trimmed for that airspeed so the stall warning is going off but your altitude is constant (adjust this with the throttle), if you take your hands and feet off the airplane will first yaw to the left and then that will normally couple to a roll as the right wing advances and generates more lift. Your goal is to use the rudder, and ONLY the rudder, to keep the wings level and the ball centered and the nose not moving. When you can do this and track a straight line, then try altering the rudder pressure gently... add some right rudder, and watch the nose skid around and then the airplane roll to the right. Release some of that pressure and the nose will come back left and the airplane will go back to level.

What I'm hoping you'll learn by this is the interrelation between yaw and roll. You can do this at faster speeds and then slow it down if that's more comfortable. If you keep your eyes focused outside and concentrate on what your body is telling you, you will develop a "feel" for coordinated flight. It doesn't come quickly, you gain it gradually as you fly, but slow flight really is the regime where it's most obvious. And it's also the regime where it's most important to be coordinated.

Once you have straight-and-level slow flight working well, you can try adding some turns. Remember that the PTS for slow flight is such that if you increase the angle of attack at all you'll stall. That means that if you're doing slow flight straight and level properly, a turn without a descent is going to result in a stall. So you need to add a little power before turning so that you won't lose altitude. Experiment - in the C172s adding 100 RPM allowed me to do reasonable turns at 10 degrees of roll or so, and 10 degrees of roll will get you around pretty quick in slow flight. Again, when you're turning, keep the focus outside and on how it feels to you. The earth should be going left or right underneath the nose - you ARE turning, but your nose should not be sliding up or down on the diagonal of your bank angle. You'll find that from straight and level you'll need to add right rudder pressure for a right turn, and just relax some of the "trim" pressure you'd put in for the left turns.

Above all, don't get discouraged, this is something that comes with repetition and correction, rather than learned in a couple of lessons. If you get a chance to do this in a glider or a Diamond (which has a similar wing), you'll pick it up faster as they really are sensitive in yaw.

Best wishes,

Don't have the updated PTS to refer to. Can someone post the applicable language related to this requirement?

I recall discussion when I was nearing my checkride that the requirement had changed that you didn't have to be that close to the edge of the stall such that 'any change in AoA, power setting or turning will cause a stall'.

 

[poadeleted20]

Don't have the updated PTS to refer to. Can someone post the applicable language related to this requirement?
I recall discussion when I was nearing my checkride that the requirement had changed that you didn't have to be that close to the edge of the stall such that 'any change in AoA, power setting or turning will cause a stall'.

It's unchanged:

Establishes and maintains an airspeed at which any further

increase in angle of attack, increase in load factor, or​

reduction in power, would result in an immediate stall.