More on turns....

Published by: Bryan Tuffnell on 8th Jul 2017 | View all blogs by Bryan Tuffnell

ABOUT a hundred and seventeen years ago, an obstreperous bicycle mechanic with the very United Brethren name of Wilbur was busy concerning himself aircraft control. He figured that to turn an aircraft, yaw - which at the time most people thought held the key to turns - wasn't enough; a turn had to consist of the appropriate amount of roll, pitch and yaw. The Wright's lingering contribution to aviation is the concept that a turn is not a bend in an otherwise straight line but a three dimensional carved curve, and is why to this day we have control surfaces that operate in pitch, roll, and - usually, and it's important for us to understand that as trikers we have a degree of control of this - yaw.

A hundred and seventeen years later, it seems many of us trikers have forgotten Wilbur Wright's epiphany. We insult our wings in turns by rolling at trim speed and keeping it there, counting on the wing's inherent roll-yaw coupling to convert roll into some semblence of a turn. It works - kind of - and around we go, trike wings being generally forgiving of our lack of technique. Any lack of skill tends to go unpunished until a bit of load comes on... which it does when banked and turning... and this gets exacerbated by billow shift... which means that any absence of skill is most likely felt when trying to roll the wings level. In other words, you're more likely to have trouble rolling out of a turn than rolling into a turn, which is a bad time to discover you don't know something.

If you are flying straight and level and add bank, you have commanded the wing to fly straight with bank on - nothing more. The fact that the wing cannot do that is not incidental; the wing will fall off into an uncoordinated turn. But - here's the rub - while as trike pilots we have little direct control of yaw, we absolutely do have a measure of indirect control. To convert a slipping, banked flight into a coordinated turn we must add pitch. So, some rules:

  • ROLL gives BANK and SLIP
  • BANK and SLIP both cause a bit of YAW.

Okay, if that's as far as you go, you'll get a 'turn' of sorts. But it's like shifting your weight on a bicycle while steering straight ahead: your wing is out of balance.

  • ROLL and PITCH UP (pushing out) gives a BALANCED (COORDINATED) TURN.

Now, let's add finesse at the start of the turn: 

  • PITCH DOWN (pulling in) aids ROLL

There's sound aerodynamic reasons for this. You sometimes hear that pulling in a touch increases airflow over the wings and makes billow shift more effective, but that's not all. Who can give the correct reason?

And how do we translate this into real flying? We should have our hands fixed on the bar, a fair bit more than shoulder width apart (if your hands move, I recommend a couple of wraps of electrical tape on the bar to mark where they should stay. I also vastly prefer gloves to bar mitts, which encourage you to grab the bar the way a wino holds a bottle of Chardonnay - I like to have my thumbs either on top of the bar or pointing to each other along the back of the bar, never wrapped below the bar). Try this for an experiment:

  • Take your right hand off the bar altogether. Sit on it.
  • Roll to the left with your left hand.
  • Watch what happens.

You probably pulled the bar back a little as you rolled. No? Then try doing so. By pulling into the turn with just your inside arm, it's easy to simultaneously pull the bar back. Great! Now... when you're getting close to the desired bank angle,

  • PUSH FORWARD with the heel of both hands (not the crook between your thumbs and forefinger) until
  • the BANK ANGLE stays CONSTANT
  • AIRSPEED stays CONSTANT

If you've done this correcdtly, you'll whizz around and around in cirlces with no change in airspeed or bank. You'll lose altitude - unless you ADD THROTTLE - the final factor.

Rolling level should be the reverse:

  • REDUCE POWER while
  • PULLING IN and ROLLING LEVEL

I used to preach that any time you lost control in roll, reducing power and pulling in would always allow you to roll level. I don't say that now, because there are now trike wings that require you to have a basic grasp of turns, and such wings are not necessarily bad, they just won't take an insult: if you're slipping badly, you must correct for that before you're back in control (more on that later). This is may sound challenging, but is uttely fundamental to every form of flying, and every 3 axis pilot knows and comes to grips with this.

We're not riding bicycles here, we're pilots; we kid ourselves if we think that all we need to do to turn is to roll. If we do that, we're relinquishing our control from us as pilots and relying on factors such as sweep, dihedral, airfoil section, washout, midspan twist and a whole host of factors - down to the angle of struts and the size of our windscreens - to provide the control that we do not. You know how some wings have winglets? They exist because the designer couldn't achieve the roll-yaw coupling she wanted without compromising other aspects of her design. 

I want to stress that pilots are dying because they don't have a basic grasp of this. Henry and Ken's video is a great lesson: they are alive in all likelihood because Henry knew that pulling in (and reducing power) makes roll more effective, and under the loads they were experiencing was absolutely necessary. Several Arrow pilots have discovered that you cannot overcome billow shift in turns on that wing by rolling with weight shift, and pitching up to remove billow shift is needed before you can roll out of a slipped turn; knowing that has saved lives (my own included). 

I apologise to the majority of you who know all this... but I believe this stuff, and not pilot age or refresher training or lack of maintenance, is the biggest single cause of pilots losing control of their trikes. 

So, for a pop quizz:

  • What happens to billow shift in an unbalanced turn? In a coordinated turn?
  • Where is your weight in a coordinated turn?
  • Why does pulling in increase roll rate?

Comments

43 Comments

  • Larry  Mednick
    by Larry Mednick 11 months ago
    Very well written blog on 1 of the 2 most common techniques required to fly properly in my opinion. Here is a video I did a few years ago touching on the subject of how to turn. https://m.youtube.com/watch?v=3cUl8HlcPKA&feature=youtu.be
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Thanks Philip, you can find most of my videos and others all in one place on our website video gallery page

    http://evolutiontrikes.com/gallery/

    Also www.trikevideos.com for my DVD which is $29.99
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Since very few are participating I'll answer the first part of the first question. Billow on the low wing in an uncoordinated turn is higher (less lift) than the high wing causing the wing to want to roll further into the turn. Many trike pilots counter this over banking tendency by shifting the bar towards the low wing (move bar right in a right bank slipping turn) THIS IS WRONG!

    Let's stop there if this doesn't make sense or this is the first time you are hearing this, STOP and make sure this basic concept (usually not covered in basic training) is understood now. It was someone on this list that asked why anyone would need transition training to fly some of the wings. The answer to her question is learning to make coordinated turns is 80% of the transition training. But just because some wings REQUIRE pretty much all turns to be coordinated doesn't mean that other wings that "can take the insult" as Bryan puts it won't need to be coordinated 1 time out of 999 times. It is that one time that we read about in some cases.

    Some of us looking for answers might be missing the answer they seek right here. I am 100% certain this lack of concept has taken down dozens of trikes. I can site accidents this pertains to once everyone is aware of Bryans concept he is bringing to the table.

    Perhaps a better question yet is how does one accidentally enter a heavy slipping turn compared to the regular turn that doesn't seem to be a factor that they have performed thousands of times before?
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Larry's answer goes to straight to the point of questions 1 and 2. I was expecting someone to say that if you don't push out, the lower wing keeps its extra billow - and the follow-up question would be: why doesn't the trike continue to roll, given that weight shift generates billow shift which commands roll? If the pilot gets into a tug-of-war with a commanded roll, what determines the winner?

    Question 3 was intended to cover more than rolling into turns. Pitching down a little aids roll, definitely, but flying fast with the throttle open has surprised a few pilots.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Doesn't sound like an error to me, Philip. If the amount of forward push produces an airspeed and bank angle that stays constant for as long as you continue the turn, you've got a perfect turn.

    I like to push with the heel of my hands, without my fingers or thumbs gripping the bar. That way there is pitch feedback from the bar - you're pushing forwards against bar pressure - but you're not applying any side-to-side pressure during the turn.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Here is a video showing how to slip.

    http://www.youtube.com/watch?v=evPA1h6hXfk - Video Tube for YouTube - iPhone/iPad

    My trike will not hold a slip for more than a second or so no matter how hard I try. But that's not always the case with all wings in all situations. And in some cases if the wing cannot roll fast at all I cannot slip the wing no matter how hard I try. This is what some are calling a safe wing. I don't disagree with that statement, but what a price to pay in order to be safe. I say give me a wing that slips, give me a wing that stalls let me have ultimate control.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Excellent video, Larry. Hope the one on turns will follow soon - a video is worth a million words...

    In my opinion, a safe wing is one that does exactly what it's told. It seems to me to be a sad indictment of the state of our training when manufacturers feel obligated to produce wings which override pilot inputs in turns because pilots can't be trusted to turn correctly, but I understand the reasoning - if there is a widespread lack of understanding of turns, the only options are 1) to address it in training and 2) remove some control options from pilots.

    A few days ago I was flying home as a layer of cloud was forming beneath me. It happens fairly frequently here, stratus forming reasonably rapidly between 1000 and 2000 feet AGL as moist sea air rolls inland in the evening. I was flying a new wing in a new configuration, one that coordinated beautifully, slipped nicely, and had a crisp, positive stall break. That's my kind of fun: manouvering tightly around features in the cloud tops, and dipping, diving, swooping and soaring around the edges of holes in the cloud, spiraling upwards around narrow columns of water vapour, chasing glory shadows around towers and buttresses in the clouds. When the sun set and it was time for steak and beer, getting down was a gentle pull on the bar, rolling tightly from side to side before dropping into a sustained, slipping turn to spiral through a small hole in the clouds. I'm crap on a dance floor - like Greg Brown says, I just jump around and grin - but mixing pitch and throttle in turns is a kind of dance and lets me go back to being the kid who ran around paddocks with his arms outstretched, and is about the second best thing in life. Somewhere between sex and drugs.

    For me, the art of flying trikes is about aiming for total control: finding the right amount of pitch and the right amount of throttle for whatever I'm trying to achieve with roll, and chasing the perfect touchdown.
  • Craig Dingwall
    by Craig Dingwall 11 months ago
    Hey Bryan, absolutely great discussion again. These discussions similar to the one that went on for quite some time some months ago, are just a great way to challenge the minds of low hour pilots like myself. Keep it up.

    I have a friend who is a Hangy and PG pilot that is moving to the Queenstown/Wanaka area as we speak so may head that way for a brief stay, would be good to say g'day.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Here is a link to a brief stall in a spiral.

    http://www.youtube.com/watch?v=KPhIc97z_4g - Video Tube for YouTube - iPhone/iPad


    I know what Lindsay is talking about and can do a video of exactly that. But my wing will still coordinate very quickly although many would think it's slipping longer than it actually is. Bryan has the correct wing to do a continuing side slip. Bryan, got a Go pro??

    As i have said before, is don't think we even need side slip to account for some of these accidents. Some accidents I do suspect it though. And I don't think we need a stall involved to cause some of these accidents, although some I am sure do. If you recall Henry's video we had a partial stall (and it is always a partial on a flex-wing) on the inside wing with a tremendous amount of weightshift from the pilot in the front seat fighting weight shift against the asymmetric lift on the wing. The result was a tug of war the pilot could not win.

    The big problem I believe Bryan is sighting here is pilots can enter a slipping turn at very high speeds in fact and this slipping turn can either coordinate due to the pilot or the wing or in some cases not at all which means the trike is going in the ground if the pilot doesn't know how to fix it having said that, technically the pilot caused it in most cases. The Hazzard 15 would go into a locked out spiral from a coordinated turn as the inside wing would stall way too easily at what seemed to be a relatively low AOA. And because it didn't break hard like in my video above, but broke super soft it just felt like loss of control and hard for many pilots to diagnose. It happened to me several times and I saved 3 pilots from the back seat myself.

    So the keys to safety in these cases are:

    Know how to coordinate your turns
    Recognize a slipping turn and coordinate it.
    Recognize a stalled low wing
    Know how to exit a spiral dive.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    BTW we have a configuration on our RIVAL X 14m wing that we simply removed the shifting A frame and locked up the keel with tight fixed rearcables that I cannot get to slip from any kind in normal flight conditions. The down side is the roll rate is TERRIBLE compared to what I am used to. But I honestly feel it's the only way to get a performance double surface wing to be absolutely slip proof. The billow must be limited and Roll rate must be limited to remove adverse yaw. I just see such a penalty in this approach to eliminating side slip on a performance wing. Makes me not want to bother turning and just fly straight... for some this may be a good solution... some countries that have no proper training programs will be getting this configuration from us moving forward.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Philip, I understand what you're saying and there's some validity in it.... but I don't like the approach. There is absolutely nothing wrong with slipped turns - it's a tool every pilot can safely include in their toolbox of techniques. There are times when it's a good trick to pull out of the bag. The problem is not with the turn but with the pilots who don't understand turn coordination; an item which 3 axis pilots learn on day one. If we dumb flying down, all we'll be left with Microsoft Pilot because taking off is dangerous. Besides... don't you want your trike to dance?

    I've been trying to come up with a basic way of distinguishing the two ways by which pilots get locked into turns, and it isn't easy. It's something like:

    - too much pitch up at the beginning of the turn gives a yaw led turn (incipient spiral dive) (and don't quote me on that, if only it was that simple); recovery is aided by closing the throttle and pulling in

    - not enough pitch gives a roll led turn (slipped turn); recovery is aided by pushing out

    Unfortunately the dynamics are a tad too complex to be reducible this way, and most of the time simply rolling the wings level works. And slips and spirals are not dangerous if they're controlled by the pilot.

    I guess ultimately the point is that roll, pitch and yaw all interact, and can be mixed by the pilot to produce coordinated turns, slipped turns and spiral dives, all of which should be basic knowledge taught early in flight training. They shouldn't be bogey men; they shouldn't be scarey things.

    Larry's 'keys to safety' above cover the points I want to make nicely. Some folks have said, "oh, I fly a slow single surface wing - I don't need to know that stuff". While you may be able to fly forever without needing this knowledge, there's no guarantee that you won't get caught on your next flight, whatever you fly.

    Philip, let us know how your latest flight went!
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Hey Craig, if you're heading this way let me know - there's a spare bed here, beer in the fridge and a dozen trikes in the hangar, one of which will have your name on it. Send me a message and I'll give you my contact details, and I'll look forward to a visit!
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    A factor in Lindsay's comment about high speed stalls is sometimes referred to 'g due to g', where dynamic changes occur to the centre of pressure as the wing flexes under high g, bringing the centre of lift forward, adding to pitching moments and further raising the angle of attack... an interesting aside to the discussions here.
  • Noel Clifford
    by Noel Clifford 11 months ago
    Great Discussion. Bryan, My distant recollection of my 3 axis training was to keep my focus on the top of the cockpit dash relative to the horizon to maintain altitude and as you initiate a turn add elevator and power to maintain altitude whilst co ordinating the turn with rudder so you end up with a level co ordinated turn. In my trike I use a similar principle and add power and push out slightly to maintain a level turn (all be it a standard rate turn). My question is does this technique hold true for the trike because I note you suggest pulling the bar in slightly to help initiate the turn and then push out slightly through the turn in order to maintain a co ordinated turn. Am I on the right track?.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Spot on, Noel! The goal, regardless of the type of aircraft, is to initiate roll, stop the roll when the correct amount of bank is achieved, coordinate the turn, and add power to maintain altitude. We can say the sequence, which has steps that overlaps in practice, is:

    - ROLL using ailerons or billow shift
    - CANCEL ROLL at the desired bank angle by centering ailerons with stick/equalising billow
    shift by pushing the bar forward (NOT by high-siding!)
    - BALANCE YAW AND ROLL with rudder and elevator/pushing the bar forward
    - MAINTAIN ALTITUDE by adding power.

    We can add that when rolling in or out of a turn from a position where billow is equal on each wing, reducing throttle and pulling in will speed up roll. Why?

    Sweep and billow shift couple yaw and roll for us, via... pitch! The principles are exactly the same whether it's 3 axis, rotary or weight shift; it's just the controls are different. We're aiming for a carved, balanced turn, much like a track cyclist on a banked track in a velodrome.

    A slipped turn is achieved in 3 axis with crossed controls, on a trike we achieve something similar by not pushing forward.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Noel brings up a GREAT point. 9 times out of 10 when a pilot drops his nose in the turn it has to do with where they are looking. Part of my "advanced training" is to get the pilots to stop looking at their wing tip or the ground and watch the Horizon. This one thing by itselfisually fixes 99% of their sloppy turn problem if they are experienced. Experienced pilots have the control, but if they're looking at the ground when the make the turn they have no idea what the trike is actually doing. As we saw in Henry's video looking at the ground and making the turn is a super great way to end up in a spiral.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Larry brings up a great point too: if you're looking forward at the horizon, the angle of the compression strut to the horizon readily shows bank angle...
  • Noel Clifford
    by Noel Clifford 11 months ago
    3 axis flying does tend to keep you focused on the horizon over the dash and using this view as a reference point is instinctive when manoeuvring in 3 axis however the glorious open view you get from a trike does so easily tempt the eye away from the horizon whilst flying so I guess there is some discipline required. I am happy to look around (and it is all part of situational awareness) whilst in straight and level flight but as soon as I am looking at anything beyond a shallow turn its eyes back on the horizon.
    Bryan, I assume your invitation to Craig is extended to all international trikers?. I thinks we need to all congregate on your door step for an ongoing discussion. I am sure we could help empty your fridge of beer in the spirit of safe flying.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Noel, I'm finding most trikers were never even taught to watch the horizon and reference their front strut angle to the horizon. Instead I am hearing them say in some cases they reference their wing strut to the ground!! And you don't have to stare at the horizon but you need to get back to the horizon often with your eyes. So it should go something like this:

    Looking at the horizon
    Check gauges
    Look at horizon
    Look at ground or wherever
    Look at horizon
    Etc.

    Everything needs to be done by referencing the horizon before and after you take your focus elsewhere. And it just needs to be glance, not a stare. When making a turn however I watch the horizon during the time from S+L to the time I lock in my bank angle. Then I go back to dividing my attention.
  • Gregg Ludwig
    by Gregg Ludwig 11 months ago
    As a side story, Lindsay writes: "I remember my first 3 axis full stall recovery ...suddenly the ground was in front of me and i instinctively pushed the bar out as you would in a hang glider in turbulence".
    Actually the best way to handle a hang glider in turbulence is to pull in for increased speed. Increased airspeed means increased control, but also means the sweep and twist of your wing is able to create more nose-up force. Simply put, additional airspeed means you’re less likely to get pitched over and tumble.
  • Paul Hamilton
    by Paul Hamilton 11 months ago
    This is a great discussion thanks Bryan.

    It amazes me that pilots are being thought wrong. As Larry said, it is the horizon that counts. It is clearly said throughout the FAA Weight-Shift Control Aircraft Flying Handbook starting on page 6-5. Why are pilots being thought wrong to look at the ground to coordinate turns? It would be nice if we could all use the basic aviation standards.

    FAA Weight-Shift Control Aircraft Flying Handbook page 6-4:
    Attitude Flying
    Flying by attitude means visually establishing the aircraft’s
    attitude with reference to the natural horizon. Attitude
    is the angular difference measured between an aircraft’s
    axis and the Earth’s horizon. As discussed in Chapter 2,
    Aerodynamics, pitch attitude is the angle formed by the
    longitudinal axis, and bank attitude is the angle formed by the
    lateral axis. Rotation about the aircraft’s vertical axis (yaw)
    is termed an attitude relative to the aircraft’s fl ightpath, but
    not relative to the natural horizon.
    In attitude fl ying, aircraft control is composed of three
    components:
    1. Bank control—control of the aircraft about the
    longitudinal axis to attain a desired bank angle in
    relation to the natural horizon. This can be easily seen
    in a WSC aircraft by looking at the angle the front tube
    makes with the horizon. [Figure 6-5]
    2. Pitch control—control of the aircraft about the lateral
    axis to raise and lower the nose in relation to the
    natural horizon.
    3. Power control—used when the fl ight situation indicates
    a need for a change in thrust, which at a constant
    speed raises and lowers the nose in relationship to the
    horizon similar to pitch control.

    Any and every pilot and CFI should review the basics so we are all singing the same song......
  • Lucian Bartosik
    by Lucian Bartosik 11 months ago
    Larry wrote:
    "I'm finding most trikers were never even taught to watch the horizon and reference their front strut angle to the horizon."

    Quite surprised to hear that Larry and if that is the case then the training for instructors is rather poor through the FAA. I have always taught from the first lesson, that the compression strut is your angle of bank indicator when you are flying and all those who were taught to fly by me and went on to also be instructors, I would hope were also be teaching that. Using the compression strut to reference your attitude for bank angle and pitch up or down I also included in my Trike Flight Training book "Trikes-The Flex Wing Flyers" which is on sale now if anyone is interested. It is the standard thing to do where I come from, always use the compression strut to see what your bank angle is when conducting a turn and use your pod or knees (when in a no pod aircraft) to evaluate a pitch up or down attitude. Of course I would also mention to students that they could apply two pieces of tape to their compression strut just above and below the horizon when in level flight cruising, so they could use that as a guide for pitch up or down, from their standard seated position. This would of course change if their seating position was always changing.

    Phillip left out an important part of his turn process, which I hope he accidentally left out, because with out the part he left out, he would continue to tighten up his turn into a spiral. He left out the part about neutralizing the bar after initiation of a turn, once the required bank angle has been established, then you apply slight forward pressure sufficient to keep level along with added power.

    To Turn:
    Check all around you first for clear traffic, then double check the area where you wish to turn into (you may even need to quickly raise a wing tip), pull in slightly and push your bar to the side to initiate your turn and then look at your compression strut to see the bank angle increase and when you are almost there (because there is always a slight delay from the time of implementing a bar movement to the time it actually takes affect), apply very slight opposite side pressure to neutralize the turn at the angle you wish to keep and hold that bank angle, followed by a slight forward bar pressure and added power to maintain a level altitude, assuming you wanted to remain level in the turn.

    It is rather disappointing to hear you find most pilots you have come in contact with, have not been taught that way. I think we should do a poll on here and see who has not been taught to use the compression strut as their angle of bank indicator and then find out who their instructor was, because such poor training technique needs to be eradicated and those instructors need retraining. Makes me wonder what else is not being taught out there in the real world.

    From the many pilots I have chatted with since the FAA ruling took effect from the old Ultralight training days, I was of the opinion that flight training has not been quite up to the standard that I would have expected, through the FAA, which was sadly surprising. Don't misunderstand me here though, there was a lot to be desired in the pre-Sport Pilot license days too, with a lot of poor quality instruction being given by many (not all of course) instructors.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Lucian, I like Philip's description and it works. I'd encourage you to try turning with the method he, Larry and I are describing - instead of cancelling the roll and setting the bank by opposite weight shift, set it instead by pitch alone. That's part of the point of this thread, and a key element of what's being discussed here.

    It's certainly true that there are some wings that like a touch of high-siding to keep them coordinated (so, yes, I've kind-of lied about coordinating with the palms of one's hands for some wings), but I much prefer those that don't (Tussock's Definition of Nice Handling includes great coordination: pitch pressure is the only force being resisted by the pilot when coordinated). In the ideal world, you're not getting into the situation where weight shift is opposing billow shift in order to command the wing, as it just might become a tug-of-war that weight shift loses.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Noel, you know you're always welcome. There's always a spare bed available for visitors (though you may need to share at peak times), and the fridge contains some of the finest creations of man's handiwork (tucked in among the spare body parts waiting to be peddled to back-alley Angolan surgeons). Just bring some bloody sunshine - the snow on the lawn is dissolving in the rain and I haven't flown since Tuesday...
  • Paul Hamilton
    by Paul Hamilton 11 months ago
    Lucian yes it is amazing how many are not trained properly.

    Since you mentioned it, we generally do not call the front tube a "compression strut" here in the states because it is in tension in flight. It could actually be called the "tension tube" since it is in tension during flight and effective in compression only for hard landings and sitting/slow taxing.

    I notice you use "compression strut" in your book. Do you know where it came from to be named that when it is actually in tension? This is confusing for students and pilots.
  • Doug Boyle
    by Doug Boyle 11 months ago
    We could be "engineering-neutral" and rename it to a "front strut"...which spends more time under compression on my trike than in tension! Kudos to those who enjoy it the other way around....
  • Lucian Bartosik
    by Lucian Bartosik 11 months ago
    Hi Paul, the correct terminology for that part is in fact a compression strut because it has all to do with what it does in landing, not in the air. I believe in all other English speaking countries that have a trike industry, it is called the compression strut by the trike manufacturers. Only in the USA, it seems, you call it a different name, then again I have heard it called several different things in the USA. The UK and Australia etc. it is I believe, commonly know as the compression strut. Same thing goes for drag links the part that emanates from under the seat or close to it and attaches at the end of the rear landing gear arm by the wheel. In the USA I have heard people call it various things but again, the correct terminology would be the drag link or drag link arm. Also the mast of the trike, the part that goes up from the base tube (what do you call that part?) which has the wing attached to the top. In the USA it seems people call this by various names. I feel that is what is confusing for students or new pilots over here, you don't seem to have a standard name for various parts of the trike as we do in other countries.

    In the Raven aircraft for example, it was drilled fractionally off centre at the top and bottom fittings, so that in the event of a very hard landing it would "compress" but was designed to bend outwards or at least away from the occupants of the aircraft as a safety measure. Hopefully that clears up the nomenclature part of things for you.
  • Rizwan Bukhari
    by Rizwan Bukhari 11 months ago
    Lucian, I am little off topic. But I wanted to praise your work on your book. Trikes-The Flex Wing Flyers. It was my first book about trikes. In my opinion, It is the most complete book on trikes. I own pretty much all trike training books and manuals. Your book truly is the "Bible" of the trike flying books/manuals. And I won't be surprised if other books have used your book as a reference.
  • Lucian Bartosik
    by Lucian Bartosik 11 months ago
    Brian wrote:
    "Lucian, I like Philip's description and it works. I'd encourage you to try turning with the method he, Larry and I are describing - instead of cancelling the roll and setting the bank by opposite weight shift, set it instead by pitch alone"

    Hmmm Brian, a 3-axis aircraft requires input to get to a bank angle then a cancellation of that input to neutralize the effect you initiated or it would continue rolling over.

    The same is true in a trike, if you push the bar to the side to initiate a turn and you do not release that pressure, or neutralizing the initial pressure, you will simply continue rolling until you get to a point in a trike, that it will spiral down. No amount of pitch input will stop a bank if you keep the pressure on to hold the bar from a central position, which is what you are saying to do. To tell someone to hold pressure to keep the bar out of the central position is not good advice and can be dangerous.

    All trike wings require you to move the bar out of its neutral position with pressure or movement for it to begin banking, and then releasing that pressure if you want it to stop banking and further. Maybe you are not realizing it that when you add the pitch to that bar you have then neutralized or centred the bar again and that is what has stopped your bank.

    To turn you must initiate pressure on the control bar to one side or another and then you must release that pressure or to quickly cancel any more bank angle quickly give some opposite bar pressure to what you did to get into the bank angle.

    Just to be clear I really want to say to release the pressure when you are the angle of bank you want, but you are saying the pilot must keep the bar pressure on because the releasing of pressure part was omitted in Phillips description. You are saying that you and Larry agree with that and that is a dangerous suggestion, you do not keep the bar pressure to the side the entire way around a turn or you will have the pilot entering a spiral. Pitch, as you suggest to do to stop the roll, is NOT going to stop the roll. Pitch input has nothing to do with stopping the roll of a wing.

    Is anybody else understand this, Paul for example??? Are you agreeing with keeping side pressure on the entire time in a turn and using pitch to stop the roll as Brian suggests and says that Larry agrees with and that Phillip also suggests to do, according to Brian????
  • Gregg Ludwig
    by Gregg Ludwig 11 months ago
    "....it is amazing how many are not trained properly."
    My wife often says this.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    No Lucian, that's not what I am saying. I'm saying to stop the roll and set the bank, push forward and let your weight centralize, as per Philip's description. This balances billow.

    I probably didn't make it clear, but pitching lets centrifugal force do a good chunk of the work for you.

    If i understand correctly, you're saying you cancel roll and set the bank by weight shifting sideways against billow shift before adding pitch. I'm not in favour of doing that, and it's not necessary - it's flying with crossed controls. If you simultaneously pitch and allow your body to centralize, there's no need to high-side the roll.

    Agreed?
  • Paul Hamilton
    by Paul Hamilton 11 months ago
    Lucian,
    Thanks for your perspective on the front tube terminology. More details at http://www.trikepilot.com/members/profile/273/blog-view/blog_980.html

    And yes Lucian's book is another great resource every pilot should read. It was one of many resources for the FAA Weight-Stift Control Aircraft Flying Handbook. Thanks Lucian.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Lucian, 2 points I want to clarify.

    1) The pilots I'm referring to that are looking elsewhere during the turns are from all over the world. I have flown with hundreds of pilots from Australia, all parts of Europe as well as the USA and Canada and it's pretty much across-the-board.

    2) your initial post seemed to describe "highsiding" which is opposite Roll to stop the turn. This is what we are advising not to do. If you meant to say release roll pressure/neutralize, then you are saying what Phillip described. The bar forward is not just to keep the nose up though. It is to center the keel of the wing and coordinate the turn. What you will see when Gs are created after the bank is initiated is the nose will yaw as a RESULT of pushing forward and the wing will stop rolling all at the same time. The alternative is to move the bar the opposite way to stop the roll. And in a nut shell, this is what this discussion is all about. How to coordinate your turns.
  • Lucian Bartosik
    by Lucian Bartosik 11 months ago
    Brian, Larry and others:

    I don't often comment on what I read here but when I do, I do it because I see wrong or misleading information being handed out for others to read. I comment on what has been written by the person, not what they may have left out or forgotten to say. When commenting on a subject, those who write should bear in mind that they may be suggesting to new pilots or students or not so new pilots, who have possibly not been trained very well, that they should go out and fly this way or try this etc.

    I only comment on what I see written as I have said. Brian.. you suggested that I was wrong and that Phillip was correct in what he wrote (Which I again include for you to read below) and you further suggested that Larry also agrees with flying, or better stated, doing turns the way Phillip had described. I stated that Phillip left out a crucial part of the entire turn, which if initiated just as Phillip had stated, would put the pilot doing EXACTLY what Phillip said, in danger. The part Phillip left out what the part after he moved the bar sideways and before he pushed out on that bar. Everyone, please re-read what Phillip wrote and re-read it again, none of you seem to have picked up on the fact that Phillip NEVER stated that you must also release the side pressure on the bar, to stop the increasing bank, before pushing out on that bar and also adding power. You can enter a turn/bank by doing exactly as Phillip wrote but if you do it exactly as he describes, you will enter a spiral descent because if you keep the side pressure on the bar, which is what a newbee would do if he did exactly what Phillip described, because the newbee was not told to release pressure on the bar at any point. Now please re-read what Phillip wrote and you will see that I am correct about what I am stating here...

    Phillip wrote:
    PHILIP QUANTRILL 4 days ago
    "Not being scared out putting my errors out there. I have just realised, sat here in my chair, eyes closed and going through a turn that I pull the bar in slightly then commence the turn by pulling the bar slightly to one side and then at the same time once entering the turn push the bar forwards slightly and add a little power, coming out of the turn letting off the gas and bringing the bar back slowly controlling the height with power/bar."

    Brian, you then went on to write the following:

    Bryan Tuffnell 1 day ago
    "Lucian, I like Philip's description and it works. I'd encourage you to try turning with the method he, Larry and I are describing - instead of cancelling the roll and setting the bank by opposite weight shift, set it instead by pitch alone."

    So, Brian, do you see that you have in fact again not bothered to state that the side bar pressure should be released after initiating a turn? Further more, you are telling me (and I'm sure others would be going out to try it, though I would not suggest doing what you have stated) to initiate a turn or roll and then not cancelling the roll but instead set it instead by pitch alone. Read it above again, you said "set it instead by pitch alone"

    Now by not doing anything to cancel that roll that was just initiated by a sideways bar pressure, and then ONLY use pitch, regardless if it was pitch out/up or in/down, you would be putting the potential pilot following your instructions, into a dangerous attitude because they would be speeding up by pitch change pulling in or slowing down by pitch change pushing out, in that increasing banked turn and either way will be in trouble unless they know what they are doing and know what to do to get themselves out of it.

    What ever you think you might be describing, or telling pilots to do, on here. you MUST first include the part about releasing the pressure to cancel the increasing bank, that holding sideways pressure on that bar, would induce. I don't care about the fact that you did not mean it that way, or for example, your following post to me, stating that you did not say that at all, the fact is clear that you DID say that and you also gave you blessing and added Larry's to do what Phillip had stated he does (and others who read here, may have followed on to try).

    I tried to make it clear that you would release side bar pressure once entering a bank angle, for a smooth gentle turn, or applying a bit of opposite bar pressure to stop the increasing bank (and of course then release all bar pressure by reverting to a neutral bar position, BEFORE adding pitch, bar out and power in that turn. I was not speaking about high siding or any other terminology, I was clearing stating how a pilot should enter a turn and achieve a desired angle of bank and safely continue in that turn.

    Just to complete the instructions in that turn, once you have just about reached the point that you wish to level out on, and notice I did not say once you reach the point you wish to level out onto, but just BEFORE you reach that point, the pilot would then bring the bar back ever so slightly and at the same time, initiate an opposite roll with gentle sideways bar pressure to the one they are in for the turn and immediately release that pulled back bar pressure and at the same time reduce their throttle setting back to their prior cruise throttle position, the one they had before entering that turn, and then release that opposite sideways bar pressure just as they are about to roll out level and then revert back to a neutral bar position with no pressure sideways or fore and aft and again immediately scan the sky to both sides and forward to see if any traffic is about.

    So to reiterate, the bar movement to enter a turn from level flight is almost (read ALMOST) like a question mark (?) movement starting at the top (But with a slight pull in on the bar to begin the rest of what I describe, and moving down that question mark as you progress, just flip the question mark over for turning the other direction. The bottom straight line part of the question mark would be the pushing out part of the bar in the turn, once bank angle had been established.

    Please understand that it is rather difficult to describe the movement but a lot easier to simply show the student that movement, so I hope all who read this will understand what I ma trying to describe here.

    And once more to Brian, you wrote:

    "Bryan Tuffnell 1 day ago
    No Lucian, that's not what I am saying. I'm saying to stop the roll and set the bank, push forward and let your weight centralize, as per Philip's description. This balances billow."

    Once more Brian, this is wrong, you do not push forward on the bar, as you just stated above, to set the bank, and by setting the bank I am assuming you meant stopping the bank at a desired angle. If you just initiated a roll with sideways bar movement, you will NOT stop the roll at all, by pushing out on the bar. The ONLY way to stop the roll you just initiated with a sideways bar movement, is to release that sideways pressure you are exerting on that bar and to stop it quickly you will probably need some opposite sideways pressure for a second or so, then centre the bar to stay in that bank angle, and then and only then do you push out the bar to hold you altitude, of course with added throttle/power.

    Since you did not mention releasing the initial sideways bar pressure that began your banked turn, I have to take your statement as it is written which is to say that you are saying, you initiate a bank with sideways bar pressure then you push out, as Phillip stated, and that would put you in an ever increasing roll and now a descending turn, going into a spiral. It would never put you into a level established or set angle of bank, turn. A pilot must stop the roll by releasing the initial pressure used to get the wing rolling. Any instructors on here who know what they are doing and pilots who know what they are doing in a turn, will fully understand what I am saying here and I'm hoping you will understand also Brian and Larry in order for us to not have to continue beating this point any more. I hate having these long drawn out discussion, nor do I really have the time.
  • Lucian Bartosik
    by Lucian Bartosik 11 months ago
    Hello Larry, you wrote:

    "2) your initial post seemed to describe "highsiding" which is opposite Roll to stop the turn. This is what we are advising not to do. If you meant to say release roll pressure/neutralize, then you are saying what Phillip described. The bar forward is not just to keep the nose up though. It is to center the keel of the wing and coordinate the turn."

    I can see how you thought I meant "highsiding" but I should have said to simply release the initiated sideways bar pressure, which I went on to clarify in the following post after that original one. However, I am most certainly NOT saying what Phillip was saying, because no where in Phillips description of his turn, did he mention the release of sideways bar pressure. Please go and read his post again and you will have to agree with me that he does not mention the release of that initial sideways bar pressure when entering the turn. If he had mentioned it there would be no reason for me to comment on anything. I hope you can see that, after you go and re-read what Phillip originally posted.

    Now if I am wrong here, please cut and paste the part where Phillip stated that he released his initial sideways pressure to establish a set angle of bank, before he pushed the bar out. I will then humbly apologize to you. I shall stand by while you go and find that part in Phillips post, though not very long because it is not there, and I need to get some sleep. I am pleased that you are so active on here and applaud all the help you offer to other pilots, and hope that when the dust settles each time on here, you can appreciate why I sometimes have to speak up.
  • Lucian Bartosik
    by Lucian Bartosik 11 months ago
    Rizzy wrote:

    by Rizwan Bukhari 1 day ago
    "Lucian, I am little off topic. But I wanted to praise your work on your book. Trikes-The Flex Wing Flyers. It was my first book about trikes. In my opinion, It is the most complete book on trikes. I own pretty much all trike training books and manuals. Your book truly is the "Bible" of the trike flying books/manuals. And I won't be surprised if other books have used your book as a reference."

    Thank you very much Rizzy, I greatly appreciate your kind words. The originally book went right through advance flight training but when it came time to publish, and it was self published and funded, there were far too many page for the modest money available for printing, so I had to go back and cut out a hundred plus pages to keep it to a printing cost that was affordable for the funds on hand at that time. That was hard to do. Anyone reading who does not have my book, please buy it, our baby needs new shoes. There is that 20% discount and free shipping (to the lower 48 states) until the end of the month, don't forget. Great discounts offered to flight schools too.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    Lucian wrote: I tried to make it clear that you would release side bar pressure once entering a bank angle, for a smooth gentle turn, or applying a bit of opposite bar pressure...

    Ok STOP! These are in fact 2 different suggestions. And the first one pertains to this topic where as the socond one is in fact known as "high siding" which is what in fact we are saying NOT TO DO. Had Lucien simply said release side pressure the first time I believe everyone would have agreed. Making this differentiation between the two is CRITICAL in this discussion.

    Because in Phillips description he is pulling the bar back on an angle, when he is no longer pulling and he is then pushing straight forward there is no side load on the bar when you push forward.

    Lucian your original comment was describing what we are talking about NOT doing. Whether you agree with that or not is up to you. Now you have changed that to OR which is pretty much the 2 options a pilot has and in this case only one of those options pertains to the point that Bryan is making which is probably 80% of the importance of this discussion in my opinion. And that is why you feel everyone is jumping on you. Trying to justify why you said something is beside the point. Your suggestion was contrary to the discussion and contrary to Phillips technique. You certainly can give opposite roll, and I have given opposite roll control to stop a roll, so you are not wrong. Your comment which I Think was meant to be an addition to the point, CHANGED the point.
  • Larry  Mednick
    by Larry Mednick 11 months ago
    All this discussion on the details of the coordinated turn reminds me now of the most common mistake made when pilots try switching from high siding to coordinating (opposite roll to pushing forward to stop the roll). Most pilots at first will almost morph the 2 actions by pushing forward on an angle towards the low wing. The correct action is straight forward on the bar. In fact if you use enough pull in to initiate the turn, you can just release everything and that in itself is straigh forward returning to neutral bar.

    Of course some wings roll so slow they will immediately stop rolling when Roll pressure is released. These techniques will be very hard to determine their merits on wings like this. It's kind of like practicing stall recovery on a wing that won't stall. In both cases the pilot may be using technique they can get away with on a particular wing. Then a rotor takes that once tame wing and pushes it and the pilot to a whole new level in an unusual attitude and the lack of technique can become critical.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    Lucian, I'm confused by the contradictions in your posts, so I'll just make a couple of final points:

    - Trikes are brilliant at converting roll into yaw via pitch. They aren't as good at converting bank into yaw via pitch. Relaxing the sideways pressure as you pitch forward takes you straight to the 'sweet spot'. With a little practice and sensitivity to feedback from the wing, it's easy to nail. If you cancel the roll BEFORE you pitch (high siding), you're heading more towards a pitch up with bank applied than a coordinated turn, and depending on the wing, you'll be hunting around for the sweet spot because you're undercooked in yaw and need to nudge in a little roll to find it. Try turning as we're suggesting - it works, and works better than any other method.

    - The 'second or so' that it takes to cancel roll before pitching can become the 'second or so' it takes to coordinate by pitching.

    The 'relax and push' method of coordinating turns always works, and avoids all the troubles that high-siding brings.
  • Paul Dewhurst
    by Paul Dewhurst 11 months ago
    We stopped teaching 'J turns' (bar back before rolling)in the U.K. A couple of decades ago. And we use an opposite pitch / power relationship for a turn to that which Bryan describes in the opening treatise.

    Bar back before rolling originated in hang gliders which generally ( at least in the old days) would be flown at min sink or best glide which was only a very few MPH above stall speed.

    Early slow trike wings can benifit from the same technique if they trim very slow, but we found as wings progressed up the speed scale it wasn't necessary or didn't really have any useful effect.

    For level turns we teach to select the target speed for the turn before entry and in level flight - so for a steep turn and mindful of the stall speed increase that might mean speeding up, or for turns with more modest bank angles if generally isn't necessary.

    Then from that level steady state platform we roll. We use pitch attitude as a primary reference - if we maintain it the turn will be level. So as we roll the machine will want to slip and yaw nose down. We prevent that by moving the bar forwards - so the pitch attitude is maintained. Then you get no slip and a nicely coordinated level turn.

    That brings me to the other point about pitch / power relationship. It isn't power that is added to maintain height in the turn - the procedure above will do that. Power is increased to maintain airspeed at the target value. Pitch and power combine - but the classroom briefing for turns shows that we need more lift in a turn from the wing to produce the same vertical component - and that extra lift is produced by increasing angle of attack. That then increases drag - which requires the power increase to prevent it reducing airspeed.
  • Bryan Tuffnell
    by Bryan Tuffnell 11 months ago
    The power/pitch relationship can be approached from many directions. If you're wanting a sustained, level, coordinated turn you could say that additional thrust (not power, to be precise) is needed to maintain speed, or bank angle, or lift, or drag, or yaw rate, and all would be correct because they're all related when coordinated. You could flip it around and say that the more power is added, the greater the speed or bank angle or yaw rate etc. will be required for a level coordinated turn. Given that a coordinated turn has balanced forces, we only need to know a couple of the variables of load, turn radius, thrust, lift, speed, drag and bank angle to calculate the others.

    Students learn on day one that there's a direct relationship between pitch and speed, and thrust or power don't directly affect speed. Students can readily see that adding thrust or power gives us more speed options in relationship to other factors (e.g faster speeds without altitude loss), so I feel most comfortable offering the explanation that in a coordinated turn, once certain values of speed or bank angle are increased, you need to add thrust in order to maintain altitude. It's incomplete, but so is the 'added drag' explanation - I'm not sure if there's a merit in teaching any other explanation unless it's complete.

    Less germane to the discussion here is the question of pulling in before initiating roll. It's not just that pulling in provides more authority in situations where a bit more control or roll rate is useful, it qualitatively changes the turn. I prefer a diagonal pull combining pitch down and roll, rather than an independent pitch down followed by roll. As long as we fly swept, tapered wings I see merit in teaching that pulling in aids roll.

    Paul D, you don't post here often enough! Your posts are always well considered and I get the impression you guys in the UK teach to a solid and common syllabus; something that's missing (and missed) here in NZ and many other parts of the world.
  • Bryan Tuffnell
    by Bryan Tuffnell 10 months ago
    Hey Philip, you should be in NZ. We're having a superb winter for alpine flying - best I can remember!

    A yaw string is fun if you're going all out looking for yaw, but not needed for finding the 'sweet spot' in coordination. If you can hold a constant airspeed and constant bank, you're there. It should be easy to find with the diagonal pull in/relax and push out method you describe (not a 'J' or '?' turn, more like a narrow, lopsided, uneven 'V').

    Thumbs-up needs the correct hand spacing. Imagine your arms are limp but heavy string hanging between your shoulders and hands. When you want to turn, Braunhilde, the German beach volleyball player who was acting barmaid on the last day of Oktoberfest (Monty probably pictures a strapping Merino in a French nurse uniform, freshly shawn) sits on your inside limp-string elbow, which bends and drops, causing that diagonal pull that initiates roll. Larry's video is absolutely excellent - although I'm much better looking than Larry and he doesn't talk with a proper red-blooded down-under accent, it's otherwise perfect. The only thing I can think of adding is that in turbulence you're trying to prevent billow shift with your hand squeeze. Worth watching twice, especially for getting the hand width on the bar.

    I'd guess those who fly thumbs-up are a very tiny minority. It's a personal choice, but I do think it's worth persevering with.
  • Bryan Tuffnell
    by Bryan Tuffnell 10 months ago
    Philip, I'm worried about you - if your fantasies revolve around foreign trike pilots skipping out of Paris with solutions to Korean aggression and plans for combating climate change while wearing skimpy bikinis, maybe we can pass the hat around and buy you a stack of Swedish magazines and a night in the rouge areas of downtown Paris. Hopefully that whisky did the trick and you dreamed that you were Paul Hamilton having an engine out in a sheep paddock next to a remote French convent with Miss Southern France...

    Winter here gives cloud-free days around the Alps, some hefty catabatic flows and crisp dense air, but mostly I love the soft lighting and the way colours bleed into shadows. I know what you mean by those sublime moments; guess that's why we're here.

    Everyone flies differently, and the best reason for you to change your technique is because it makes sense and works for you. The great thing about this site is that we can hold fresh ideas up to the light and see if they have merit. Maybe what works for me doesn't work for you, and that's fine too.

    Playboy Triker of the Month, Bryan
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