Steering on final with rudder

[Yenn]

I believe that to get the full advantage of this forum you have to be able to work out what is correct and what is just rubbish. there is some of both here and probably some of the rubbish is from people giving an opinion that may be true for what they fly, but not for something else.

 

Just for those who think sideslips are dangerous I ask how you land a plane without flaps or spoilers, considering that the engine may not be available?

 

 

[Teckair]

In my view unless you are doing aerobatics, side slipping, taxing, flaring or have a control failure with the ailerons the rudder should only be used to balance the aircraft not to steer it on final or at any other time. I put the thread on the instructors forum because I found some students are taught to steer all of the final leg with rudder only and to hold the wings level with the ailerons. I wanted to find out why this was being taught as I believed it to be wrong, it turned out a fair amount of instructors were doing this but none came up with a reason for it that I thought was acceptable. If you try to steer with the rudder the aircraft will skid, you will have cross controls, if you get slow you are ready for spin entry and you will be flying inefficiently. In the event of an engine failure it will reduce the distance you can glide and increase the possibility of an inadvertent spin at low level.

 

 

[facthunter]

WHO is responsible for instructing the instructors? Getting too far from standard practice can be confusing and bloody dangerous. Newtonian physics don't vary for individuals. Some can get a weird idea and go too far with it and words from trusted sources stick in the minds of pilots. Any thing you do must be explainable and stand examination by peers who are suitably knowledgeable.

 

Pilots operating in some repetitive environments cut corners and develop idiosyncrasies and bad habits sometimes. Pilots who maintain a self discipline, might seem boring, but are much safer operators. Big noters may be covering some large need to be admired by all. If YOU know you know your stuff , that is all the assurance you require, plus doing your best to make your students good pilots, even if some of them turn out better than you. Nev

 

 

[Bob Llewellyn]

A couple of observations from a purely aerodynamic aspect:

 

1) The mass of a "conventional" aeroplane can only be moved (effectively) by its wing. In order to accelerate the mass sideways - which is what a turn is, in a particle physics sense - a lateral force must be applied (and sustained) through the centre of mass. This is achieved by tilting the wing - lowering one end and lifting the other - so that a part of the wing normal force vector acts in the horizontal plane. Ailerons do this directly.

 

There are some aeroplanes which, when yawed, develop a bit of side force from the fuselage acting as a vertical wing; but except for the Transavia Airtruck, the effect is generally very small.

 

2) A sideslip increases the drag to lift ratio - by increasing drag; an increase in parasitic drag from the yawed fuselage is intuitive, but the increase in induced drag caused by reducing the effective aspect ratio - remember, the load factor remains 1 - becomes the more powerful factor as soon as the sideslip bank reaches 15~30 degrees typically (depending upon the aeroplane...).

 

Opinion - fly the aeroplane, don't just ride in it!

 

 

[metalman]

Aviation forum survival rules

 

1: trust no one, talk to a live instructor about your flying issues

 

2:if your chosen instructor tells you something that is being taught elsewhere is 100% bad,,,,don't get mad !but do look into getting some varying training

 

3: don't argue with Motz , he knows lots and will give you a blast if needed

 

4: you have two ears and one mouth, when around other pilots ,listen twice as much as you talk ,and don't worry d1ckheads reveal themselves pretty quick

 

Matty

 

 

[motzartmerv]

Hahaha. I don't know anymore than anybody else, I'm just far less diplomatic. I'm getting better tho!!!

 

 

[facthunter]

That's true. I saw him at his first Natfly Instructor's thingo.. Always passionate about getting the message out. You can't say Andy hasn't got his heart in it. Everyone should be prepared to back up what they say. There's a few around here won't let you get away with anything, so ...... we are all different. Some things can be dangerous if people act on some things said and not fully explained or erroneous. We both try to pick up on those and I get called out for having no humour. There is a reason for that. I've lost too many friends in aeroplanes, so I probably won't change. Nev

 

 

[Phil Perry]

This is a topic close to my heart as my profession is training. So this may sound critical of instructors, but my aim is to help instructors. I can only use the experiences i had and those of the students and instructors i have dealt with.What i hypothesise they are discussing is exactly how early to put the rudder in with students that are having trouble landing and are getting confused. My father is coming out of that stage of learning right now and we have been discussing this at length. I have also discussed it with a number of other student pilots and trainers.

 

I believe many trainers are great flyers but some dont know how to correctly identify the students error and break it down to the exact problem, then design a drill to teach that. Many students ive spoken to and trainers say students get rudder use in crosswinds all wrong over and over and over. They put in the wrong amount of rudder, the wrong direction and get crossed up.

 

I believe there are a few main issues with rudder and a student pilot at landing.

 

1. With the crab method the problem is the student who kicks it straight in the hold off only gets to practice it for about 4 -5 seconds per landing and they get it wrong half the time or more at first. And even within this 4-5 seconds they get it wrong maybe 2-3 seconds. So they get to practice the skill they need (correctly) in a one hour flight of say 8 curcuits, maybe 3 or four times per 1 hour circuit session and for 1-2 seconds of correct technique. No wonder they struggle.

 

2. They fail to realise at the time that as the plane slows during the round out and hold off that the rudder needed to do the same job is a lot more. They got taught it in class , but they forget in this critical moment.

 

So the student and trainer sit there confused about why the student keeps getting the rudder wrong on landing.

 

So i believe they need to be taught to use the rudder in two different ways to the normal approach.

 

1. they need more practice then a few seconds per circuit and

 

2. they need to practice it away from the confusion of the hold off (which is when a student suffers from information overload) and thus learning is severely retarded.

 

So

 

i think the answer is the student needs to put the wing down many hundreds of meters out and start using the rudder to eliminate the crab.

 

Th

 

is has many benefits.

 

1. It allows the student to practice identifying and using the correct rudder pedal

 

2. It allows them to practice using it for a long time per circuit

 

3. It allows them to practice using rudder away from the hold off which is the area they are already struggling with

 

4. They need to dance on the rudder pedals (tiny movements) with wing slightly down on the way in, not just hold pressure on one, because that allows them to practice the landing technique prior to doing it when they have to combine it with the hold off (and more importantly the stress and overload of the hold off.

 

Then if they still cant get it , get them to fly along the runway at 50ft practising holding it straight with wing down. That way in a several circuits they get minutes worth of rudder practice.

 

See instructors need to realise that when someone starts flying every decision they make is manual and has to be thought about and then has to be compared to information the student barely knows, then they make a decision. which is why we suck at complex things at first.

 

The next stage is a few of the easier steps start to be come quicker for us to process because we have seen this situation before and we know understand it to the point we can make a reasonably quick decision.

 

The third stage is some decisions become automated or reflex. eg we recognise we are rising so we stop bulling back.

 

The fourth stage is it all becomes automated and we can then think about it, analyse it and even do other things while its happening.

 

In the two stages above the student has zero ability to analyze whats going wrong. They are so busy making decisions and mistakes that they cannot recognise what they are doing wrong or why.

 

The problem with teaching landing in crosswinds is the student has literally many many decisions to make per second. So the more decisions we can eliminate or automate for the student the better.

 

Some students i speak to say their instructor gets frustrated at this stage and asks the student why did you do that , or why do you keep doing that. But yet offer no solution and the student gets stuck in the cycle of repeating the same mistake of wrong rudder, incorrect amount of rudder, rudder too late, too much rudder, not enough wing down etc. Even if the instructor does tell them what they are doing wrong the student repeats the same mistakes, because they still cant process the information and make the right decisions quick enough.

 

The most basic solution i can offer to instructors is talk your student through it before they make the mistake. Resist the temptation to see if the student can do it. You will knwo when the student can do it. Letting a student fail in a complex task like this is very very counter productive. Because it ads to confusion, it reduces the students ability to make the decision and it shatters there confidence. Letting them fail this task repetitively and then talking to them afterwards or askign why they do it that way, is actually a failure of instruction.

 

And if they do get crossed up and information overloaded, remember your explanation will mean very little. Because they where so information overloaded that they have not committed anything to memory. They only mental picture they have of what just happened is the biggest moment of being scared and they will have little to no recollection of the control inputs that caused it. So you go ahead and give a great explanation of what happened, but they cant use this information, because they have little recollection of what just happened. In the later stages of landing practice, they will know exactly what you mean. But in the early stages they will look at you with a blank face or just nod and agree, and really they will be clueless to what you are saying.

 

A good instructor will try to identify that the student is using wrong rudder, wrong amount, wrong timing and on the next 10 or 20 circuits they will talk them through it in advance with concise verbal cues that are long enough the student knows what you saying, but short enough that they dont have to listen to a sentence to get two pieces of information. . A great instructor is there to speed up the learning process , not observe it and offer critique. That is assessment. And beginning pilots need pre-instruction to keep them ahead of the plane. Sure assess it afterwards, but what they really need is you to help them keep them thinking just ahead of the plane.

 

They need to be talked through the entire landing over and over and over before things happen. Eg with a right cross wind. A few hundred meters out remind them its a right cross wind , your going to need left rudder to straighten the plane. Try it now, put in some left rudder and put your right wing down slightly. Thats great or a bit more left rudder. Then about 100m out remind them as the plane slows you need bigger control input. etc etc etc. Keep them ahead of the plane by telling them just before it happens. And dont be afraid to do it over an over and over.

 

You need to remember the student has a very blurry mental picture of what a landing looks like, because they are so dynamic and ever changing. And students almost always fail tasks when they dont have a clear mental picture of the requirements. So your job is not to critique until the later stages, your job is to help them make faster and better decisions, until they have a better mental picture of the many types of landing scenarios and until thier own decision making can keep up with the aircraft. And the most effective way to do this is to talk them thru it slightly in advance. The exact technique a dance instructor uses.

 

Remember the crazy drama teacher out the front mouthing the words to you in advance when you had to practice a class poem performance. Well thats the perfect teaching technique, as it keeps them just ahead of the task.

Sodding hell,. . . . .

 

I've been flying cropdusters and other taildraggers for forty years,. . . .and I always thought them floor pedals was just footrests. . . . . .

 

That's what I like aobut this forum,. . . . you can learn such a lot . . . . .

 

Phil XX

 

 

[Phil Perry]

Another point is that with the rudder straight ahead it is less effectual when you move it. It has to " take up slack" against the airflow before you get a result. Whereas with a bit of rudder either way, it is already working and the response is instant.

Not strictly the case PM,. . . .I remember, ( grey years ago ) when doing my aerodynamics degree, that this subject came up, during WW2, the spitfires were updated with metal skinned ailerons and rudder surfaces, previously skinned with doped fabric,. . . his made an enormous difference to the "controllability" of the machine and the results were regarded as "Instant" . . . obviously subjective opinions ,. . . .but very important as these views were taken from blokes who were flying the things daily in mortal combat, so they had to be taken seriously. . and it is all a matter of timing,. . .ie, I quite honestly can't remember the equation but it's all about mass times angular deflection times drag times forward velocity times surface area and all sorts of weird calcs like that,. . .sorry mate, but it has been a long time,. . . .If I get really bored enough,. . .I'll have a troll through the old uni-notes and see if I can find the maths ( should you be totally sad enough to really want to know . . . .( he said - knowingly . . .) ) ./. . . .

 

Phil

 

 

[Yenn]

speaking of spitfires, there was a spit pilot in the war who attributed his lack of being shot down to always flying with some rudder on ie. he was flying out of balance and deceived the hun pilot. Obviously it didn't hurt the spit airframe.

 

 

[Old Koreelah]

speaking of spitfires, there was a spit pilot in the war who attributed his lack of being shot down to always flying with some rudder on ie. he was flying out of balance and deceived the hun pilot. Obviously it didn't hurt the spit airframe.

I too have read that, Yenn. (If 2 people saw it in print it must be true!)

 

 

[djpacro]

I recently tried to explain to some-one how a balance ball works with some high school physics but only got the usual (a pity the way this forum has deteriorated) insults for my trouble. Here is a much more complex explanation if anyone has the inclination: http://books.google.com.au/books?id=3oc9llQai5YC&pg=PA246&lpg=PA246&dq=aircraft+inclinometer&source=bl&ots=-v1L8T8y7g&sig=TKq7BHESNc8Sc8nl66dYoO1GsCE&hl=en&sa=X&ei=U6j1UorzF9CekgWiloHoDA&ved=0CHMQ6AEwBjgK#v=onepage&q=aircraft%20inclinometer&f=false

 

but all I wanted to substantiate was my statement that if the wings are level and the heading is constant (i.e. zero yaw) then the aircraft has to be in balance and the ball should indicate that too. i.e. the only forces that move the ball in steady flight are generated by angle of bank and yawing motion. (I know that is a slight simplification.)

 

Gee, if some-one doesn't understand that a slip ball simply indicates local lateral acceleration then what hope do they have of understanding stall/spin dynamics.

 

From the USA FAA's Airplane Flying Handbook "Unlike skids, however, if an airplane in a slip is made to stall, it displays very little of the yawing tendency that causes a skidding stall to develop into a spin. The airplane in a slip may do little more than tend to roll into a wings level attitude. In fact, in some airplanes stall characteristics may even be improved (p. 8-11)."

 

From Noel Kruse's Book #1, Aerodynamics and Other Stuff page 224 at http://www.flybetter.com.au/

 

"Well many instructors believe that a sideslip is a precursor to a spin (!) because the speed is low and the controls are in a similar ‘out of balance’ position. This is a misconception brought about by their lack of understanding of spinning. Let me put it simply; you can no more spin off a properly ‘set up’ side slipping approach than you can off a properly set up ‘straight’ approach."

 

From Rich Stowell's book, Stall/Spin Awareness page 335: "A properly executed slip takes us further from the critical angle of attack than even wings-level, coordinated flight. Furthermore, the yaw and roll coupling needed to drive a spin not only is missing, but yaw and roll as as far from coupled as possible during a slip. Slipping actually provides a greater stall/spin margin than even normal cruise flight."

 

Depending on the aeroplane type there may be some uncommanded roll enough to scare some-one the first time he/she encounters it nevertheless sideslips are inherently spin resistant.

 

(Of course, I and the authors above only ever refer to behaviour of certified aircraft.)

 

In addition to static behaviour of the slip ball, from Rich's book page 330, describing a simple exercise in flight: "The ball cannot keep up with this dynamic exercise, yet we can still remain in coordinated flight by using our senses of sight (nose remains on a point) and feel (no side-to-side sliding in your seat)."

 

Which, in my opinion, is the core of this discussion.

 

 

[motzartmerv]

Nev, have we met? I'm thinking you mite have me mixed up with someone else. I've not done an instructors briefing at natfly. I would like to, but I'm sure I would get boo'd off stage.. Hehe

 

 

[turboplanner]

You'd also need some plastic surgery, or a paper bag before you went on. (Hope this was helpful).

 

 

[DrZoos]

djpacro

 

Can you explain the removal of the slip and its ability/inability to produce spin if kicked in too hard too slow.

 

 

[djpacro]

djpacroCan you explain the removal of the slip and its ability/inability to produce spin if kicked in too hard too slow.

I can but not here - happy to chat in the hangar or over a bottle of red wine in the evening. I suggest that you watch the video of this webinar http://www.recreationalflying.com/threads/webinar-avoiding-the-base-to-final-turn-stall-spin-accident.50795/ (subtitle of the seminar was "Stop Ruddering the Nose Around and Stay Coordinated!!!!") When you can understand the factors there then get a bit of paper and try to work out what is different in a sideslip. i.e. in a skidded turn there are a number of factors which are pro-spin at the stall (often without the usual stall warning symptoms) but in a sideslip about half of those factors effectively oppose the spin.

 

 

[Stoney]

Recover from a stall, first thing should be unstall the wing, release back pressure, enough to reduce AOA 1 or 2 deg will unstall the wing, all the while keeping balanced with rudder, if a wing drops, still, unstall the wing first, once unstalled everything works as normal, aileron, rudder etc, The use of rudder to "pick up a wing drop" should read more like, use rudder to stop the wing drop after the wing has unstalled, if it's unstalled by 1 or 2 degrees there's a risk the effective increase in AOA by the aileron could cause a stall of the wing with the down going aileron.In a spiral dive, the wings are still flying, so use aileron to roll level, then recover from the dive with elevator, in a spin, the wings are stalled, hence aileron will not help the situation.

 

When near or very close to stall, rudder for balance only.

 

This is what can happen when using rudder instead of aileron to initiate a roll when slow and close to stall AOA. This pilot overshot the turn to final, and used rudder to tighten up the turn

 

Ultralights, thanks for putting this video up. As sad as I felt watching it, the lesson was crystal clear .

 

As much as instructors explain the need to use small bank angles when turning in the circuit and ensuring speed does not drop off on final etc. this video really hits home as to the consequences of not doing so. There is so little warning and no chance to recover at that height. This was also the cause of the Spitfire replica crash at Parafield last March.

 

All student pilots should watch this video to help it easy for them to make the decision to go around rather than tighten the turn if they misjudge the turn to final.

 

 

[metalman]

djpacroCan you explain the removal of the slip and its ability/inability to produce spin if kicked in too hard too slow.

If you have the time, money and inclination I can highly recommend having that red wine and chat with DJPacro, even go further and go flying with him

Matty

 

 

[DrZoos]

djp thanks great video.

 

Interesting at 1.26 he explains the over the top spin on final which is exactly what I was eluding to earlier if you let the nose come up and stall during a slip.

 

 

[Ultralights]

Ultralights, thanks for putting this video up. As sad as I felt watching it, the lesson was crystal clear .As much as instructors explain the need to use small bank angles when turning in the circuit and ensuring speed does not drop off on final etc. this video really hits home as to the consequences of not doing so. There is so little warning and no chance to recover at that height. This was also the cause of the Spitfire replica crash at Parafield last March.

 

All student pilots should watch this video to help it easy for them to make the decision to go around rather than tighten the turn if they misjudge the turn to final.

Actually, the lesson should be, to remain 'Balanced' in any turn you fly, don't use the rudder to turn, use the rudder to balance the turn.

 

 

[tafisama]

Forgive me folks,I think there might be something else.Its true we dont turn with rudder but ailerons and co ordinate with rudder maintaining balance.Where I feel there might be some ambiguity on the Title of this thread is at what height do we use rudder to track straight or keep aligned with the runway centre line.I think rudder may be used to make small corrections of keeping the nose aligned with the runway centre line below 50 feet.I initially interpreted the thread title to mean using rudder to align with the centre line just before and after rounding out through to touchdown keeping wings level.Cross wind operations would be something different though I think there is no continuous yaw involved.A yaw that is continuous is the one that accelerates one wing.

 

 

[Peter Collins]

Forgive me folks,I think there might be something else.Its true we dont turn with rudder but ailerons and co ordinate with rudder maintaining balance.Where I feel there might be some ambiguity on the Title of this thread is at what height do we use rudder to track straight or keep aligned with the runway centre line.I think rudder may be used to make small corrections of keeping the nose aligned with the runway centre line below 50 feet.I initially interpreted the thread title to mean using rudder to align with the centre line just before and after rounding out through to touchdown keeping wings level.Cross wind operations would be something different though I think there is no continuous yaw involved.A yaw that is continuous is the one that accelerates one wing.

"A yaw that is continuous is the one that accelerates one wing." ... and a wing that accelerates, given the "V-squared" in physics of flight generates more lift, and the resulting upward component puts the relative wind at a smaller angle to chord and so reduces AOA which takes things further from the stall region. More lift, less stall - what's not to like?

See AOPA Live: Rod Machado: License to Learn: Prevent Spin with Rudder. That depends on using the appropriate foot and force, at the right moment, for the right length of time. In every field of life you can do the right thing or the wrong thing depending on the situation. Using rudder to pick up wing is fine, but if you will hold it in you will almost certainly get a graveyard spiral - but why hold it? When you corner your car, if you don't unwind at the right time and just hold it in, you'll go off the road for sure, won't you? Flying ain't that different. Never say never. A stall turn is done at zero speed, with I have no idea what AOA, and (I gather) rudder only. Never use rudder only? Fine for commuter flying perhaps?

 

Decide why you want to fly, and what sort of flying you want to do. If it's commuting, fine - balanced, conservative AOA, and all like that: most excellent. If it's a sort of aerial moto-cross, also fine but you will have to learn a great deal more about how your plane handles in a wide range of unusual attitudes and speeds, when to use secondary effects and how much and why, and unless you are an aerobatic test pilot you must get instruction from one who is, and practice, practice, practice. My points about what works, for my plane, are my own experience and I repeat your plane may be different and you should get instruction. In my plane I have spent very many hours with instructors including a bush-fire water-bomber pilot, an aerobatics champion, and the much-vaunted Noel Kruse (whose books are great - but cockpit hours with him trumps the books big-time!)

 

For your type of flying, know your abilities and your plane, and before you try anything 'new' - check it out with an instructor who has that as their recognised speciality. All instructors are NOT equal. All are good, yes, but at different things.

 

That applies to rudder when landing, too.

 

P

 

 

[motzartmerv]

Stall turns are not done with rudder only.

 

Picking up a dropped wing with rudder can result in a spin in the opposite direction. A spiral will only be possible of you have unstalled the wing.

 

 

[Peter Collins]

Stall turns are not done with rudder only.Picking up a dropped wing with rudder can result in a spin in the opposite direction. A spiral will only be possible of you have unstalled the wing.

Oh dear! Context, context. Certainly the stall turn requires throttle, elevator AND THEN rudder only (if properly done?). I'm learning a great amount from this thread, and the reading it's leading me to. Did not Williams, Neil (2003) [First published 1975]. Aerobatics. Marlborough, UK: Crowood Press. ISBN 9780950454306. write: "Enter at full power and maximum airspeed. Pull the aircraft up through a quarter loop into a vertical climb. The speed will decay but before upward motion stops firmly apply full rudder to yaw the aircraft through a cartwheel of 180° until the nose is straight down. Dive vertically to the same altitude as the maneuver started, then pull out, exiting in the opposite direction.[1]" - quoted in Wikipedia (which I admit may have got it wrong).

Agreed that picking up a wing with rudder can result in an opposite spin - because that increases the AOA on the down-going wingtip particularly, but surely that is even more likely if the ailerons are countering the yaw-induced roll because of the aileron drag also contributing to autorotation. However, my context was not stall-flying but rudder-while-landing.

 

Agreed that the deathyard spiral is an unstalled manoeuvre. But my context was regarding a comment, some pages back, about steering (in cruise) with rudder alone (which I had asserted in my plane did result in banking from secondary effect and thus a balanced turn). We were (correctly) warned that applying down rudder would lead to a graveyard spiral. I repeat, that is true, but you have to hold in more rudder, for far longer, than is sufficient to achieve, while cruising, a gentle course correction of a few degrees. You can crash a car with over-steering or holding the wheel to the radius of a corner long after it has been turned. Same with a plane.

 

You have to know what you are doing, and do the right amount, the right way, at the right time, whatever different combinations of input you choose. It applies to driving, cycling, cooking, and most everything in life.

 

Bottom line (once more) know yourself and your plane and how it responds and fly careful and safe with expert instruction in every aspect that departs from the conventional (and I hope we all know what that means).

 

Of course you must understand how and why YOUR plane handles, using whichever control inputs, during landings with or without cross-wind, if you are on or off the centre-line, too. If your instruction leaves you wanting to ask this forum for clarification, if it were me, I'd go find an instructor who can explain the aeronautics clearly so you understand the various interactions, and who will then go up with you and help you get the techniques from learning mode to automatic mode. Fly safe.

 

P

 

 

[Teckair]

what height do we use rudder to track straight or keep aligned with the runway centre line.

Flare height.

 

Where I feel there might be some ambiguity on the Title of this thread

Read post 102.