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Skyway
23rd Jun 2003, 05:24
I am interested in hearing some different ways of explaining aileron drag. Any reasonable explanations are greatly appreciated.

Thanks.

FormationFlyer
23rd Jun 2003, 06:43
My usual tact is quite simple...'you dont get something for nothing in aviation - more lift - more drag.'

Well thats the one liner anyway - obviously then follows a more detailed explaination - the context is normally Ex 9 medium turns and a talk about adverse yaw caused by aileron drag - and this also lends itself to the concepts of differential ailerons etc...

Hope this helps,
FF

pilotbear
23rd Jun 2003, 19:55
Yes, I use a similar line to FF, I say that the wing needs energy from somewhere to create the lift, so it takes it from the speed and the wing slows down. I use this even in a trial lesson to get them to use the rudder with the Ailerons as a habit.
It has not failed yet.:ok:

justanotherflyer
23rd Jun 2003, 23:13
On a related question, which may perhaps illuminate this topic, what do you guys explain (and do you make it a demo?) about the technique of picking up a wing drop on final approach. I.e. rudder vs. aileron.

FormationFlyer
24th Jun 2003, 05:16
I never have 'wing drop' on final approach - not in the stalled sense of the word - on the other hand if it is a little lumpy I get the student to use coordinated aileron.....I NEVER advocate picking up a wing with rudder - anyway its pointless - because to pick it up with rudder you have to yaw the nose......and that means that you will no longer be straight on your runway heading....

I do an exercise on medium turns - rolling around a point - it gets the student counteracting adverse yaw with an appropriate amount of rudder - done properly this is how they should 'pick up' wings in turbulent conditions.

DANZ
24th Jun 2003, 15:31
We introduce Aileron Drag/Adverse Yaw in the Medium Turns briefing, then in the lesson get the student to look outside at the nose and see which way it yaws, then they look at the balance ball ("How much rudder we need and when?"). Before the student practises Medium Turns we get them to co-ordinate ail/rud by S-turns, turning around a point. Guess it's pretty standard everywhere else?

pilotbear
24th Jun 2003, 17:58
I find this subject of rudder/aileron fascinating in England particularly where the set way of teaching and operating light aircraft is set in stone with some people. Any contentious, challenging or interesting views are a threat to the whole meaning of life (which incidentally is 49)
Now, before someone goes off on a tangent like in previous posts, I am not trying to insult anybody, just instigating a healthy discussion as there are clearly different views - which from my analysis mean the same thing. (in general flight)
1. You cannot use the Rudder without some Aileron input.
2. You cannot use the Ailerons without some Rudder input.
3. The rudder has nothing to do with turning the Aircraft,
left aileron =left rudder
right aileron =right rudder
no aileron=no rudder
unless in a side or forward slip

Regarding the Approach;
At an aerodrome like Elstree or on rwy 18 at Cranfield it is always turbulent. The Aeroplane gets tossed around laterally and inexperienced pilots or students tend to over react with the ailerons without rudder to correct this. Now I have observed that this, as well as making the situation worse, also moves the nose side to side (adverse yaw as the inputs are usually too large and quick).

So I advocate using gentle rudder pressure; NOT to pick up a wing, but to prevent further drop and if necessary assisted with
aileron. And I can do this without the ball moving from its centre position which unless someone knows different means co-ordinated flight. The difficulty is judging how much input.

I also teach to lead turns and the rollout from turns with the rudder. NOT bootfulls of rudder, but to start the process with GENTLE rudder pressure assisted with the Ailerons for the bank angle. Then centralise everything once in the turn or when wings level. Again the ball does not move.

DANZ, I like to teach rudder and aileron together from trial lesson onwards so it becomes habit. I found if you leave it until the syllabus dictates it is too late to break the habit of just using the pedals as footrests. The first few lessons are spent just stick and rudder visual attitude flying - and nothing else.

A further point to anyone, do you teach that as well as using the good old right foot in high power low speed situations i.e. take off and climb, that you need to a little left foot when reducing power?

FF, how do you prevent or correct a wing drop at, approaching or during the stall?
I ask this because in this and the last discussion you hint at not using rudder near the stall, which I find odd as the use of aileron at near stalled conditions will surely cause an incipient spin unless the wing is unloaded.

Well, anybody got a ladder so I can get down from my skyscraper height soapbox??:D

FormationFlyer
25th Jun 2003, 07:05
Meaning of life 49? What - is that 42 corrected for inflation since the 70s/80s??? ;)

Leading turns with rudder - dont agree. As my adverse yaw - rolling around a point exercise proves to the student you coordinate the two together - different a/c require different amounts but *always* the amount of rudder is proportional to the amount of aileron input - I teach both simultaneously - and only ever simultaneously. Lagging with rudder leads to out-of-balance flight - leading with rudder leads to (no pun) out-of-balance flight - either makes the pax feel ill - especially if your new PPLs pax are not used to flight full stop.

Left foot - yep I teach adding left rudder when reducing power as well - and I also describe why it is so much less than is required when adding power....

Um...re-read my post - no intended hint of 'no rudder' usage near the stall...I personally advocate use of it - you have to maintain balance - and that will require rudder....

re: wing drop in the stall....balanced flight is all you can do to prevent it. If an a/c wants to drop a wing it will. Correct it?!?! I dont 'correct' wing drop. I advocate rudder as reqd to prevent further yaw followed by immediate stall recovery actions. To be honest C152s dont have the rudder authority to stop further yaw from a wing drop - however a PA28 is much better is this regard.

P.S. Ladder in post - although having a 'small' disagreement with Royal Mail about postage costs....you might be there a little longer!!!

BigEndBob
8th Jul 2003, 05:09
If the student is receptive i would introduce, although briefly, adverse aileron yaw and its reason on Effects of Controls.

I could never understand why we tell students that secondary effect of ailerons is yaw towards the lower wing. surely the by product of aileron application is adverse aileron yaw (yaw in the opposite direction of bank).

Secondary effect is usually explained as yaw toward lower wing after the aircraft has banked. The aircraft could become banked due to turbulence/wing drop followed by yaw/spin without any aileron application.

Yaw (toward lower wing) is the effect of being banked.

Also can anyone explain why in Piper Tomahawks when you apply left/right rudder to demonstrate secondary effect of rudder, there is very little yaw but the nose pitches down!
Could it be disturbed air from over the cockpit upsetting that T tail.
Crosswind landings?

StrateandLevel
9th Jul 2003, 05:57
3. The rudder has nothing to do with turning the Aircraft,

Have you never tried flying without using the ailerons? if you did you would find you can turn quite effectively with rudder. Anything that unlevels the wings makes the aircraft turn.

pilotbear
9th Jul 2003, 18:12
FF,
regarding the leading with rudder. I use this phrase because there is a tendency when told 'use aileron and balance with rudder' they glance at the ball as an after thought even though we say use harmonise the two together. The result often is that the rudder goes in late, during the turn when it is not needed
(i.e. the ailerons are in the neutral position).
So, I suggest to them think Rudder/aileron in that order. It usually results in the two happening together as required.
My philosophy is to prevent the adverse yaw rather than correct it, which despite the protests here, most and I mean most of the qualified pilots I fly with do.
I also think that there is a longer delay between thought to foot and thought to hand actions.:ooh:

Wing drop on the approach? At an airfield like Elstree or on 18 at Cranfield where there is always a significant amount of turbulence the aeroplane is constant lateral motion. That is what I am referring to, not wing drop due to slow speed.

Incidentally, I was having a check in a Twin the other day when an experienced multi - instructor informed me that you don't need rudder because it is a twin??:eek:

I used to fly a Seneca that had a STOL kit, full span flaps and spoilers instead of ailerons, and on that you didn't get aileron yaw, but on a normal twin???

S&L
I fly a lot without the ailerons, the rudder nothing to do with turning the aircraft. It just causes yaw.

AS you stated the further effect of the yaw- roll, causes the lift vector to be offset causing the turn.

Oh, by the way FF, the meaning of life 49. from hitchhikers guide to the galaxy - Douglas Adams.

BEagle
10th Jul 2003, 04:08
Sorry, but the Meaning of Life, the Universe and Everything from the Hitchhikers' Guide to the Universe was 42, not 49!

And personally I think that your 'rudder first' idea is utter boŁŁocks......

Mr Magoo
10th Jul 2003, 04:30
42 it is, I always use the term co-ordinated aileron and rudder when teaching. Leading with the rudder feels HORRIBLE and is wrong, (unless you want to make your passengers airsick). :yuk: I show the adverse yaw in FX of controls and my students then co-ordinate, (there's that term again), pretty well through the rest of their training.

Dan Winterland
10th Jul 2003, 16:10
My 2d worth.

Leading with rudder? Maybe in a Nimbus 3 glider with a 25M wingspan but in a light single? - No! Use enough rudder during entry, maintenance and exiting the turn to keep the aircraft in balance. Use feel/slip ball for this.

Demo adverse yaw in EofC2. Tell the stude he will need to counter this when learning med turns later in the course.

Levelling the wings with rudder on finals? No! Use the ailerons - that's what they're for.

Picking up the wing with rudder in the stall? NO! If the wing drops, you should recover from the stall and level the wings with the ailerons once the wing is flying properly again. What you should teach is to prevent yaw with rudder at the stall. As all instuctors should know, buffet with undemanded roll = incipient spin. You can't use the ailerons at the stall as the downgoing aileron will stall the wing further. So reduce your chances of entering a spin from the stall by preventing yaw.

It is quite easy to turn the aircraft on the rudder. Try it one day. In the very early days of CFS in WW1, the standard way of teaching turns was to use full rudder and keep your wings level with ailerons. Banked turns were considered 'stunting'.

The meaning of life is 42.

I hope BEagle agrees with all of the above. He's my CFI!

axill
10th Jul 2003, 23:05
With modern aircraft and differential ailerons and relatively short wingspans there's hardly any use at all in bootfuls of rudder in normal flight. Gliders maybe. When you start flynig aeroplanes that are a little bigger with a few passegers on board they certainly will not thank you for being busy on the rudder pedals.
Wing drop on finals? Ohmygawd!
If any of you C152 pilots want to know how to turn without rudder OR ailerons let me know.

FormationFlyer
12th Jul 2003, 17:46
C152 do suffer significant adverse yaw - I can prove it. If you do lookout properly in a 152 and LIFT BOTH WINGS during the lookout then failure to use rudder to counteract adverse yaw results in the nose swinging a lot and the pax feeling sick.

Is this not 'normal flight'?!?

With regard to comments about airliners....There is no such thing as one size fits all. Each a/c requires its own techniques and respect....to imply that you do not need rudder in a 152 because you dont in fast jet is ridiculous. But there again yaw dampers may just have something to do with helping you out there eh?

If you roll from a 60L to a 60R turn then you must use HUGE bootfuls of rudder....in a 152, pa28 or otherwise....that is unless you happen to have super dooper dogs nads computers to help you do the basics....hmm...all of a sudden I am hankering for more chipmunk aeros... :)

Charlie Foxtrot India
12th Jul 2003, 22:24
When I was a student I was confused when told in Effets of Controls that roll is followed by yaw in the same direction, than in turning that it yaws the opposite way :confused: I didn't really understand it until I did the instructors course despite Trevor Thom's best efforts.

Most of the trainers used these days have most of the adverse yaw designed out of them, so it is not always easy to demostrate it, as it doesn't last long before the secondary effect of aileron becomes more pronounced and it yaws into the roll.

I explain to them how the yaw is caused by a greater wingtip vortex on the upgoing wing causing it to yaw slightly in the opposite direction to the turn, and this needs to be balanced by a little bit of rudder.

Why does the Tommyhawk pitch it's nose down when you yaw? Because the thrust/drag couple is effected, which makes the nose pitch down as drag increases.

Why do people teach to pick up the wing with rudder in a wing drop? beats me. Get the airspeed back, level wings are not a priority. Some schools teach almost a full spin recovery for a wing drop. All you really need to do is relax the back pressure, and the airspeed will be back in a couple of seconds, then level the wings all you like.

FormationFlyer
12th Jul 2003, 23:01
It is very very easy to demonstrate adverse aileron yaw in any aircraft - merely reverse the aileron before the into turn yaw follows....and then reverse again...and again...and then get them to start using rudder to counteract this so the nose rolls through a point on the horizon - this technique works for every a/c ive met from microlights to twins.

Yes I do teach adverse yaw as a secondary effect of aileron - and a further secondary affect is yaw into turn....that way there is no confusion - especially when they know why the first and second yaws occur - an easier way to show into turn yaw is to raise the nose a little before applying ailerons - doesnt half make shoing yaw easy!!!

Regards.

chicken6
16th Jul 2003, 17:22
FF

We teach the second effect of AILERON (is yaw opposite to roll) at slow speed (so less directional stability) in the turn from upwind to crosswind in the departure for EOC2. Second effect of ROLL is the guts of the lesson. COMPENSATING for the 2nd effect of aileron is at the end of EOC2.

BigEndBob - I think you may have been confused by a missed phrasing - it's the secondary effect of ROLL that is yaw into the turn, the secondary effect of AILERON is yaw out of the turn.

c6

pilotbear
16th Jul 2003, 19:33
It would appear to me that there are people here who clearly do not look out of the window when flying their aeroplanes or if they do, they do not know what they are looking at.

There is a significant amount of adverse yaw during a steep turn in a 150/152, not so much in a warrior or arrow but it is still there especially in the roll out.
If you take the time to observe what happens you will see it.

Thank you for the confirmation FF.:)

Secondly the amount of rudder depends on the power setting,
eg if you are on the approach in a cross wind landing with no power in a 150 you can end up using full rudder to be straight in a wing down approach, however, if you use a higher power setting and it can be as much as 1700 rpm (speed stable at Vat) the the amount of pedal movement is half that.
I only use this example as I find amount Rudder/Power Setting co-ordination the hardest for pilots to remember do naturally.

They tend to use too much on the upwind/crosswind turn at a high power setting, and not enough on the base/ final turn at a low power setting.

These are not 'my personal views' I was taught and continue to learn from a very well known and experienced Commercial/IR/FI instructor who despite having the odd controversial view is nevertheless correct and proved this to me time and time again as I was sceptical and always followed the CAA line.
When I left the UK to fly in the Seaplanes and stuff in Canada, all the techniques I have described were confirmed by the old experienced bush and seaplane pilots who had not spent 2000hrs flying round in circles in the right seat at the same aerodrome on sunny days.
You try doing 50kt Canyon turns over a lake at 100' in a C185 or Beaver without gently leading the rollout with the rudder, you won't do it twice.

Beagle, personally if the extent of your vocabulary as a discussion contribution is using bad language, censored or not I am not surprised that you didn't understand the point I was making. A simple 'I don't agree' would suffice:yuk:
Mr Magoo perhaps you have concrete blocks in your flying boots. Use a little finesse in the co ordination perhaps.

Axill, I refer to wing drop caused by turbulance not stall:hmm: try an approach without touching the control column, it is usually a lot smoother both laterally and directionally.

BigEndBob
17th Jul 2003, 05:51
chicken6...as wot i rote, the secondary effect of use of ailerons is adverse aileron yaw.
Roll has no secondary effect, it is the motion the aircraft performs when it rotates about its longitudinal axis, whatever may cause that roll.
To demonstrate adverse aileron yaw, select reference point on the horizon, apply aileron without rudder and roll aircraft.
Aircraft nose will yaw in opposite direction to roll.
point out the effect on balance indicator.
Roll back to wings level.
Do same in opposite direction. if student hasn't yet thrown up, could continue this rolling motion to left and right. the yaw will be more evident. Also tell student to look at wing tip (should be maintaining lookout anyway).
The wing tip will magnify the effect of yaw by moving back and forward describing a oval or egg shaped passage through the air.
Rolling left, left wing tip moves forward.. rolling back to wings level, wing tip moves back.
Now repeat with co-ordinated use of rudder, show difference(Nose, wing tip, ball, stomach).
Ultimate demo, max. rate roll, collision avoidance( Watch maneouvre speed!).

FormationFlyer
18th Jul 2003, 06:03
BigEndBob Exactly. Nuff said.

bookworm
18th Jul 2003, 16:23
Roll has no secondary effect, it is the motion the aircraft performs when it rotates about its longitudinal axis, whatever may cause that roll.

I think that's going a bit far. There are other-axis effects for not only controls that are designed to rotate the aircraft around an axis, but also rotation about the axis itself. Roll causes both roll-damping (which tends to oppose the roll couple from the ailerons) and some yaw. The latter effect is small, because it is secondary.

Dan Winterland
19th Jul 2003, 06:37
Bl##dy hell! You lot have confused me - I don't know how your students cope! It's their second ever flight when they're doing this. They are only trying to get to grips with the aircraft so they can go solo after about another 10 hours or so - they haven't enrolled on a test pilot's course!

For what it's worth, the following is what I teach:

Secondary effects of controls:

Pitch - causes speed and height change - stress not realy a secondary effect in itself.

Roll - causes slip which translates to yaw which leads to a spiral dive.

Yaw - causes skid which translates to roll which leads to a spiral dive.

The above are all demos, but when demonstrating the secondary effect of roll, you teach the recovery from the ensuing spiral dive and let the student practice a recovery on the demo of the secondary effect of yaw.

Then demonstrate adverse yaw. Best done from a slow speed when induced drag is greatest and the yaw is greatest. Emphasise that it exists and he/she will have to counter it later in the course when learning turns.

I didn't invent the above - I got it from CFS. It's been good enough for them for the last 85 years, so I see no reason to change it.