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Sep 18, 2013, 10:52 PM
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Stabilisers.... Hmmm, Flight Control Systems (FCS)

There are now quite a few "stabilisers" available, but that is a bit of a broad and generic term. The better ones verge on being Flight Control Systems really!!

So far I have:
OrangeRX3S V2
EagleTree Guardian
HobbyEagle A3 Super (Note: this is NOT made by Eagle Tree!)
HobbyEagle A3 Super 2
HobbyEagle A3 Super 3
Bluelight BL-3G
FRsky S6R and S8R - these are RX with inbuilt flight controlelr

So first lets see what this "Stabiliser" thing all means....
The base function is to STABILISE the plane! And this is where the generic term used for them all comes from.... and can mislead you too! Because of how much more some do!

The stabiliser part uses a 3-Axis Gyro to determine any of the planes rotational motions, and software (Firmware) calculates what is happening and what to do to the plane to 'fix' the issue.
They take your control inputs and say "This is what the pilot wants to do" and if the plane does anything different than that - like if wind blows it about etc - they adjust the control surfaces to 'erase' that 'error'. If they can.
Of course they can only do what is aerodynamically possible by the plane at any given time.

The result of this stabilising operation is going to depend on the quality of the hardware, and the quality and intelligence of the software.
Then there are also the Options/parameters that they may allow a user to dabble into so you can set it up optimally - or get lost in the complexity of that!

The OrangeRX3S is a very basic unit, and very cheap..... and you get a result pretty much in-line with that cost outlay. But it still does a job worth having! Stabilisers DO help the plane fly a lot more 'linear' and clean - especially in wind where it gets buffetted around. So the final result is a plane that flies and looks a lot more like a full scale plane would. Not a small model that is excessively affected by any motions of the air, because the aircraft is so small in relation to those air motions.

So my first comment on ANY of them is that they are GREAT little devices!
And the more you pay (generally) the more it can do! (more on that later)
Last edited by PeterVRC; Oct 03, 2018 at 06:20 PM.
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Sep 18, 2013, 11:17 PM
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Flight Control System

The more advanced/costly units probably don't really call themselves "Stabilisers", though none seem to really call themselves anything specific or higher detail.
They will almost certainly have 3-Axis Accelerometers ALSO. (with the 3-Axis Gyros). Accelerometers give the ability to "know" a mobile items exact attitude in 3D space. So with some good 'maths' used on the Gyro and Accelerometer outputs, you can do some nifty things!!

The first is "Heading Hold"
This means you can run a system that allows some attitude to be 'recorded' and maintained. eg the plane was climbing, with 10deg wing angle (bank)... and the system can just keep it flying in that attitude, whilst the pilot can do 'nothing' even hands free really! As long as the plane is aerodynamically capable of sustaining that attitude/path.

This means you can be an expert at Knife Edges, and other flying states, with fair ease!! You set the attitude and power to be able to do so, and it will keep doing it for you.
And my favourite, and very useful thing... You can preset/lock the attitude when still just holding it in your hand, then just set a throttle point required and launch it (eg hand launch) and it will fly off on that recorded attitude - path - without any pilot input needs! This is a fantastic plus for hand-launching, which can be prone to disaster out of the blue often enough!!
It can also 'lock' a tail-dragger (or any plane) onto a set steered course for the take-off run, so that it goes straight - instead of skewing off track amiss! Far more able to track straight down the runway.

And this above stuff is why I say it can be called a Flight Control System. The DEVICE flies the plane for you, over that desired period. It controls the surfaces, as required, to achieve that.
eg Even if you fly level and lock HH, it will just fly off reliably on its own - while you read your book, or whatever else you wanted to do. LOL

The next function some of them will do is take your stick inputs as angle requests, not rate requests. (huh ??)
Normally any motion you do is a RATE request. You move a stick, and the control surfaces moves to that angle, and the plane responds. But you can see that if you KEEP Left Aileron held, the plane will KEEP rolling. It will maintain the RATE your stick angle indicated. You need to centre the stick to stop the roll continuing.

In Angle request, if you move the stick to 30deg, the device will set the plane to bank at 30deg and maintain that for you ongoing (or whatever angle you put your stick to). As long as you hold 30deg the plane will do a 30deg bank. If you release the stick it thinks you want 0deg and it will level out the wings.
This is actually what Airbus commercial aircraft (and many others) use for the control systems. Rather than the traditional rate mode of a control stick in, say, a Tiger Moth or Spitfire etc.
And this system has some big pluses.... and some negatives.

The Negative is that it limits your control ability. If the system software allows "60deg at max stick angle" that is all you can do., You can never do a barrel roll etc. But its true aim is to make flying 'easy' and have those limits! eg a Commercial airliner only needs to fly around 'sedately' and no odd attitudes (loops etc), so such a process is ideal.
It is also ideal for RC model learners.... or scale flying.... Though it needs your BRAIN to understand the two different ways the sticks will act for each mode. (Rate or Angle)

The Positives are also those things mentioned above.... you CANNOT bank and crash a plane, it isn't even 'allowed' by the device. eg 40deg bank maximum limit ever.

This 'Angle' mode also tends to be called "Wing Leveling" mode, or Self Level mode, or Automatic Level mode. This is because if you let go of the sticks that means "0deg" for all axis (pitch/roll/yaw) so the plane will move to dead level flight for you!!
But NOTE, that NAMING is not truly what it is or does at all - the ability to "Self Level" the aircraft, IF the control sticks are left to be centered is only a SUB-SET of the whole control system mode!
This is another BIG Positive of the Flight Controller system..... no matter what state the plane is in - diving to crash etc!! - it will level out, and more often than not save the day for you!!
Mind you, because the device can only control surfaces to try to achieve an aim, if the plane is not aerodynamically capable of something then they can't help you either!!
Last edited by PeterVRC; Oct 03, 2018 at 06:26 PM.
Sep 19, 2013, 05:54 PM
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Orange RX3S

This is a very basic "Stabiliser" only. With only 3-Axis gyros it can't truly know exactly what attitude it is at (You need Accelerometers for that).
Its aim is to detect motions, compare them to what the RX/pilot truly requested (or didn't request) and correct/offset for any moves that they did not ask for. eg wind effect etc.
So.... it is a Stabiliser.....

At $18 it is also likely to be not as well made (parts) or software (Firmware) as a better brand. But reports say it is 'good enough', and it seems that any Stabiliser is still useful.

I tested it in a 50mm EDF... the AMX - which is a very flighty and unstable jet really! A good candidate for stabilising!
I guess the RX3S helped... a lot??... but the jet is such a terrible thing to fly, even with stabilisation, I only did two tests. And it needed the individual gains tweaked better, which I did a bit, but need to test more. Basically, to fly stable at lower speeds, it would go MENTAL at top speeds!! Because of the sensitivity causing oscillations, and the jet goes epileptic!! Lucky not to break up in flight, or crash.
This highlights a shortfall of the RX3S... it does NOT have real-time gain control !! Which is extremely useful to combat the difference airspeed makes to sensitivity/gain settings.

But I bought this unit because of OpenStabiliser, which is a replacement Firmware for this and it improves it a LOT... supposedly. It also gives the function of real-time gain too!
It even gives Heading Hold... which truly needs Accelerometers to be highly accurate, but Gyros can do a so-so job of it still. (You cannot have Wing Levelling without Accelerometers though).

I haven't done the re-flashing, as that is a bit of effort to set up for. I will eventually.
But at $18, for what will never be a great Stabiliser/FCS unit anyway, and the next in line price-wise.... the Eagle A3 Super.... at $40... is TONS better, and I recommend saving wasting the money on this little "toy" stabiliser (RX3S).

Last edited by PeterVRC; Dec 16, 2013 at 06:36 PM.
Sep 19, 2013, 05:54 PM
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EagleTree Guardian (approx $64)

With 3-Axis Gyro and 3-Axis Accelerometers, the Guardian is capable of true Wing Levelling and Heading Hold functions. $64 is a good price for it, though now the Eagle A3 Super at $40 is verging on taking over the market space!

The Guardian is SMALL and light, which is a big bonus for 1000mm and smaller aircraft! It also has probably the best programming interface, via PC, to set it up.
When you have the Gyros and Acc's, the Software does the rest... and when you have software that means 'programming', and when you have programming that means - it can be - FLEXIBLE... Dynamic.... IF the programmers give you that ability.
And in the Guardian they DO.
Thus a reasonably complex, yet intuitive, programming interface for your PC to set up the Guardian in finer detail.
The A3 Super did NOT have this, until its recent V2.0 Firmware upgrade.. so now the A3 has eaten into the Guardian's prior reasonably dominant territory.

I have used the Guardian the most and it has been solid, reliable, easy to use. And one of the keys to these units is TRUST!! Trust that it WORKS and will not somehow crash your plane instead! You are going to have to trust that it does not do something NUTS and crash the aircraft it is controlling! And so far, my two units, used in various planes, have been flawless and thus I consider them totally TRUSTWORTHY!

I definitely recommend the Guardian!! But the current challenger, the Eagle A3 Super V2.0, is looking like it will take the lead!!

Last edited by PeterVRC; Dec 16, 2013 at 06:38 PM.
Sep 24, 2013, 01:03 AM
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Eagle A3 Super (Approx $40)

The non-Accelerometer A3 PRO has been around a while, but the SUPER is what you really want! because it does have the 3-Axis Accelrometers.
An edge the A3 Super has over the Guardian is the price.... it is $40 for the unit itself.
Another edge is the programming box that can be plugged into it to fully program it on site - though you could program it via plugging into a notebook PC (eg on site) too. That was what I did at first, but a notebook is still quite a big item to cart around, turn on, and use, versus a little programming box!

Yet another edge is the ability of the A3 Super to allow dual Aileron AND dual Elevators - which the Guardian cannot do dual elevators. This is useful for many modern jets with tailerons or one servo per elevator (left and right sides) etc. BUT, if you use the new V2.0 functions of allowing in flight GAIN, and/or the MODE (2D, 3D, off) you lose the dual elevator option - they just don't have enough I/O pins to do it all (in this model anyway - maybe the next one will)
But at least the dual elevator ability is there, versus none at all for the Guardian.

Before the new V2.0 Firmware, the A3 Super did NOT have in flight Gain control - and that is a really useful, important, ability to have! But now the A3 and Guardian are on level footing with that.

The A3 Super is in a plastic case, which is very robust BUT a bit heavier and larger than the Guardian. So this compromises fitting into smaller aircraft, a bit. Enough to matter sometimes. I have used the Guardian in an 800mm plane, but would not be able to fit the A3 Super in there. The A3super can even struggle to be fit into a 70mm EDF jet. I would say that most 70mm EDF jets can not fit it viably, seeing they are typically quite limited in space availabe! Remember, you also need all the WIRING to run and ft viably too!
So between the two units, one is useful for certain cases, the other suited to other cases.... and both suited to most cases!

To buy the full A3 Super set of item - with programming box - is $69. A fraction more cost than the Guardian, but you only need that ONCE... if you even get it at all. The A3 on its own is $40... so any further buys are that price.
So at one unit they are pretty well equal, but at 2 or more the A3 zooms ahead in value!!

With Accelerometers, the A3 Super does the same "angle" (2D) or "rate" mode control as the Guardian.
The A3 has a few extra, useful, programming options (another Edge!), and it does its 3D heading Hold job in a slightly different manner - which 3D pilots seem to know more about. To me they seem effectively the same.
"3D mode" does NOT mean you have to fly 3D actions!! It is very useful for a number of other reasons, that ANY pilot can make use of!! Namely take-offs or hand-launches. As well as in-flight use.

So whilst I liked the Guardian the most before.... the V2.0 update on the A3 Super very likely leaps it onto a lead - but needs some USE to see that all is truly well in the A3 Super! On paper, better..... in use... yet to be seen!
If you can only buy one... I would pick the A3 Super without hesitation - unless it is for a SMALL plane. I would also buy the full program box kit up front too (I didn't for the first one).

NOTE: The A3super now has a V2.1 Firmware which add even more features and fixes some shortfalls it had too!!

Last edited by PeterVRC; Oct 03, 2018 at 06:28 PM.
Nov 14, 2013, 06:32 PM
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Eagle A3 Super - Updates - Firmware V2.1

I have been having some quirky results with the A3super, and it has not been anywhere near as 'nice' to use as the Guardian.
The Guardian... plug it in and go, and it WORKS fantastic!
The A3super.... some flight paths quirks on changes from 2D, DEACT, 3D... not as nice 'tracking' flight as the Guardian. I find I flies nicer with it OFF than any mode On!

V2.1 Firmware came out, and this seems to have fixed some of the issue of flight path 'changes' per change of mode selection as you fly. BUT, because updating Firmware Resets all settings, it is not impossible I somehow 'messed up' values across modes that made it unhappy....
But anyway, that aspect is fixed now.

As for overall use... I left in totally default, and it is still nowhere near as nice as the Guardian. And the Initialisation "where is level?", or supposed to be, remains.
You power on the aircraft and must leave it stationary and "level" until the initialisation is completed. But nothing explains what this 'level' means or is used for. I tried various Pitch attitudes but the flying result of what the unit thinks is level flight always seems the same - amiss.
Versus the Guardian which takes that static initialised position as the plane's attitude required for level flight.
This suggests the A3super ONLY initialises itself as far as working out where 'vertical' is and NO reference to what level flight is is arrived at from this, The level flight seems to only come from setting the Offsets manually in the unit, but even that didn't seem to help me achieve a true level flight - but maybe if you fly, test, set the offset manually, a LOT of times you could arrive at that aim!
It still remains a nuisance point versus the Guardian's seemingly best way for the unit to learn what level flight is. Though BOTH units would benefit from being allowed to record level flight WHEN FLYING!! DERR... of course that would be the best time to SEE and KNOW what Level Flight really is! And then have the unit record that then and there - not statically on the ground.

So the A3super is still ending up a pain to use, for lack lustre results. I still believe it is USER SETUP created.... but it is quite hard to work out HOW to set it all up to work well and properly.... which I can't achieve so far!
And when flying with it OFF is better than any form of ON..... well, that is not a good sign! I mean, the plane feels like a plane should fly... not 'impeded' and distorted by their interventions. And again, especially when the Guardian DOES what it should, and in a nice flying and controllable manner, for all modes.

I am persevering..... in hope.....
But the Guardian remains the leader with ease for now!


NOTE: I still believe the A3 super is... should be... great!! Something is not right. If it can be worked out it should move ahead to be the clear winner in functionality and abilities - just never in size terms.

1) In Wing Levelling (Angular control) mode, I can't get it to bank 'enough' to turn an EDF in any more than a LONG SLOW turn. Hopefully I can find how to alter, control, that better.

2) If you switch from OFF or SBAL (Wing Levelling) to 3DAL (Heading Hold) the plane dramatically alters course/attitude - which suggest some trimming, stick calibrating, level offset etc issue. But I can't remove the issue so far. This means I set up to use only ONE of them.... as a transition means that erratic flight change.
I believe I will eventually work out WHAT is amiss - and believe it is MY fault.... but it seems it is a un-intuitive setup manner that makes it elusive to get right.

So all in all I still hold great hope for the A3super!! And it is still great when used within those limitations - which is fine for many/most cases you will use it.
Last edited by PeterVRC; Dec 16, 2013 at 06:59 PM.
Nov 14, 2013, 06:36 PM
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Bluelight 3G

Still no use of this item by me.....
Not having Accelerometers, and thus "Wing Levelling" level flight ability, means I don't see a great use for it. I don't really need a Stabiliser Only device in anything - at least not one that is a big as this item is.
And the A3super's more complex settings range, versus the Guardian's more simplistic yet adequate settings range, makes me worried about the Bluelight's MASSIVELY more complex settings abilities!! It means there are masses more permutations and combinations of settings to interact and MESS UP results, more than Fine Tune them perfectly. LOL.

But I will find something to use it in and test it eventually.....
Maybe my 1600mm P-51, seeing I don't really intend/need to have any device in that, and it is a big plane that can carry the extra item for testing without even knowing it is there (weight and size and room).
Hmm, yes.... good idea... I will do that.
Last edited by PeterVRC; Dec 16, 2013 at 06:48 PM.
Jan 29, 2014, 09:34 PM
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A3 Super - WORKING properly!

FINALLY... I got the A3 Super working properly!
Pre V2.5 Firmware had an issue when switching from DEACT (Off) to 3DAL... it would do a sudden erratic move. That was corrected in V2.5
But then after upgrading to V2.5 I shifted one A3 into my SBach 1400mm and in the process of setting it up I set the Elevator Gyro direction to the wrong way!! Even though I checked many, many times!!

Because the Sbach has Elevators that use the tailplane portion at the tips, I somehow managed to look at that LEADING edge motion of the Elevator every time I tested/checked the travel direction! DOH.
Today was the first time I did the check and it hit me!! Oh dear....

And then it all worked PROPERLY and totally fine!!
Perfect Knife Edges, with ease! As easy as flying inverted un-assisted... or even flying upright! LOL. The SBach did it easy even at 50% throttle.

So now I need to do a few more flights, and tune it better, and test all functions.
But it looks GOOD!! So far doing exactly as it should!
SBAL (Wing Levelling) worked fine too.
Feb 15, 2014, 05:18 AM
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A3 Super V2.6b Firmware

Well I HAD it all working great.... for a few days. Then V2.6c came out, with some new additions - mainly AUTOMATIC Stick Calibration at every power on !! That is very useful!
You can fly, trim a plane, land, power-off then power-on and your new Stick Calibration is all done....

But since then, I have had some odd quirks again.....
Too bad I crashed the SBach shortly after - NOT the A3's fault!!! - so I have not been able to investigate the issues further yet.

But even better news!!!
The NEXT A3 Firmware will include a TX Switchable Offset Level Setting ability! Which means you will be able to FLY the plane LEVEL and then flick a switch (twice) to teach the A3 Super what Level Flight is! Not a static guesstimation on the ground!

So soon the SBach will be flying again, and I will check out the V2.6b issues - which in theory can be 'erased'....... I will see.
But maybe a V2.7 is not too far away anyway!
Jun 18, 2014, 04:31 AM
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Stabilisers in "2D" mode (A3 Super "SBAL")

It seems that very very few people really understand how these 'stabilisers' work in "2D", "Wing Levelling", "SBAL" mode - all various names for it.
I will say "2D" mode to cover them all for now.....

"2D" mode is a pretty bad term.... as are ALL the namings really! But there is no easy way to name it anyway....
The reason they name it "2D" is because the method it prevents a plane from ever turning over - thus not able to do 3D. Ummmm... I guess it is sort of right.
"SBAL", Self Balance.... meaning the same things as "Wing Leveling"...another poor term - yes it can "Self Balance", but that is only part of the story.
That is a RESULTANT of what the mode does. A sub-set.... or sub-function... of what the whole system is really doing and able to do.
So let's get down to the basics of it all.....

These modes are really an "Angular Control Mode".
The way most real planes are controlled is via RATE Mode - but some real planes do use Angular mode!

So let's first explain RATE mode....
That is where you move a control stick, yoke, column, and the surface(s) move as per your motion. Lean the stick to the right and the Ailerons move X amount - directly linked to what you did with the stick. If you leave the stick at 45deg then the Ailerons will stay at the angle also and the plane will Roll incessantly - at the RATE of Rotation according to the angle you had the stick at. Move the stick a bit, and the plane rolls slowly. Move the stick a lot, and it Rolls FAST. Your stick motion controlled the RATE of Roll.

Angular Mode operates by taking your stick ANGLE and using that a reference as to what ANGLE you want the plane to be at. If you move the stick to 45deg and keep it there the plane will Roll over to 45deg and STAY at that angle. Not keep rolling as per a 'normal' plane in Rate mode. To have Angular Mode a control system must have a device in between the stick and the surfaces - not a cable, pushrods etc, direct connection because a 'computer' with sensors (gyros and accelerometers) is needed to create the required Aileron/Elevator motions to achieve the angle requested. The 'device', computer, has to use sensors to determine the state/attitude of the aircraft and then calculate and control the surfaces to achieve what the input goals are.
The device controls the surfaces HOWEVER it needs to, to achieve that requested angle.

"6 Axis" Stabilisers.... (again, a bad naming system!)
They have the 'computer' and the Gyros and also Accelerometers, so all you need is the programming code in Firmware to be able to use those sensors to achieve this Angular Control Mode.
"2D", "Self Balance", "Wing Leveling". This ais a SUB-SET of what the system is really doing to control the plane.
When the control stick is neutral, this means you request ZERO Angle. For the Roll Axis this means the Ailerons will do WHATEVER they need to do to make the planes wings horizontal = level. The same goes for the Pitch Axis and Elevators.
Move the Roll stick to 45deg and it control the Ailerons to make the plane Roll over to 45deg and maintain that for as long as you keep the stick there. etc etc
So "2D", "Self Balance", "Wing Leveling" is just a RESULTANT of what happens if the sticks are left neutral... the PLANE will be LEVEL then.... in Roll and Pitch. It has nothing to do with some 'special' system they invented to achieve this, it is just what Angular Control Mode DOES.

To fly around you in this Angle Mode of Control you need to KNOW how this system works and control the plane accordingly! This is because it is quite a different way that the control sticks need to be used to achieve expected results. (versus the far more common Rate Mode of Control).
Flying around using an Angle mode of Control has it has its uses, but is mostly 'boring' and too simplistic. Ideal for scale flying, or very 'sedate' flying though!

In Rate mode you Roll the plane for X seconds, to get a bank, and then release most of the stick so that the plane stays at that approx bank angle. In Angular Mode you move the stick to the ANGLE you want, and need to HOLD it there.
The device will have programmable LIMITS, and they are the link between the TX Stick and the Angle. For example, if the max bank angle allowed is set to 45deg then FULL Stick is 45deg.... and any fraction of stick movement is a fraction of that 45deg. Note that with a 45deg limit that is ALL you can ever go to! Impossible to continue further, thus it can never do a Roll, or a Loop. But that is the AIM of Angular Mode!!! To LIMIT control, so you can only do 'normal' safe things!
Airbus (eg A320, A380 etc) use Angle Mode control in ALL their aircraft! Meanwhile Boeing use the more traditional Rate Mode in all theirs! But you can see how Angle Mode is a far safer and more useful mode for Airliners - all they do is fly 'normally' at all times! No loops... rolls... severe angles etc. Mind you the Airbus system does still have OTHER modes they can be switched into also.

So now, in Angle Mode, you have a very sedate and limited aircraft!! That was the aim.... but someone might also want to exceed the limitations, to have some extra control....

In the Guardian they have a Center Stick Stabilisation only Mode. This mode expands the controllability of the system by changing it back to Rate Mode when the sticks move MORE than a pre-set amount. The values form a "box", or rectangle really, around the mid stick position and if you move outside the "box" then the mode changes to Rate... slowly. So then a plane CAN Roll and Loop, and have more full control.
Its problem is knowing WHERE that box is when you are flying - thus why they made the transition overlap from one mode to the other to be a slower process. And it is also important that you CHANGE your thought process to suit the change in the control method that you will be causing!
Imagine this: You are flying along and think "I want to rocket up vertically!!" So you pull back hard on the stick, to get it to turn to vertical sharply.... and what would you do next? Normally you would see the plane go to vertical and then CENTER the sticks because you don't want any more rotation. But now if you did center the sticks the device will think you want ZERO DEGREES = level!!! So your vertical climb will never eventuate if you go back to center stick! For any amount you get closer to mid stick region, X amount of Angle Mode will be added in and mess up your aims! With careful control use, within that 'grey' range of both Angle and Rate mode, you could get it to go dead vertical - but it is hard and messy to do!

Best is to have a VERY SMALL "Box" so that you are really flying in Rate Mode almost all of the time, and the center area is only for getting the plane back to level flight.
Basically I dislike CSMM totally!!!
A better option is fly with the device OFF, or in 3D mode, and only go to 2D mode for specific tasks that it is well suited for!

So leave CSMM OFF !!! To remove its grey, messy, fairly useless, operation result.

Main "2D" uses:
1) Levelling a plane - probably only if you are out of control, or lost orientation etc.
2) Creating some useful ANGLE situations - like for setting a guaranteed landing AoA angle (relative to the ground!), or maybe a guaranteed take-off angle.

The Auto Leveling use is simple - just LET GO OF THE STICKS!! DO NOT USE THEM!! Let the device do what it has to, without your own now generally useless intervention! It KNOWS what to do to get it level... YOU POSSIBLY DON'T! And the controls are NOT in Rate Mode, so all your prior experience is just detrimental to it!

To create a take-off or landing AoA... think about it.....
Having the Pitch Stick at "10deg" means the plane will move to a "10deg attitude", as per the device will make it do.
So for a take-off you could just HOLD the stick at that angle, even when stationary.... then increase power and as the Elevators gain more authority the device will eventually achieve its goal and the plane will go nose up to 10deg. No more.. no less.. no matter what. As long as you hold that 10deg....
Even better... create a MIX in your TX, with a value that sets that "10deg" offset in the Pitch Stick channel. Thus you flick a switch to activate that MIX and do NOTHING!! The device will do as per above and make the plane go to 10deg.....
Note: The device will TRY to MAKE the pane go to 10deg nose up from the moment you set the angle request (via Mix or stick moved), but because the plane is stationary, or when moving too slow still, there is no, or little, elevator authority so it can't achieve your request. But it will TRY and thus will move the Elevators to FULL UP !!! This is not a problem at all, because the device ALTERS the control surfaces to ACHIEVE the goal.... so as the Elevator Authority increases to actually Pitch the plane up, they will reduce what is needed to suit. So it will just go smoothly JUST to the 10deg you requested! By that 10deg, there will probably be a small amount of Up Elevator to achieve that ongoing. You yourself do not need to know, or care, about what they did at all... they just do it right, whatever is required!

For landing you can do the exact same thing......
Though there is a slight difference in how you have to fly it! If the plane is flying 'fast'... fast enough and with enough Power in use.... going to 10deg nose up will make it CLIMB!! But you want it DESCENDING with 10deg nose up. This means you need to slow it down BEFORE going to 10deg Stick Angle (or Mix Switch), so that it CAN'T climb... and to do this is a very Dynamic thing that you will need visual queues and practice to do well. You can still ALSO use the TX Pitch Stick, so at first you might need to use Down Elevator to offset any speed/energy that would otherwise make it climb then. And once you do get it to the slower state than can fly descending in at 10deg nose UP you can RELEASE the Pitch stick totally and all further plane control is via THROTTLE. More throttle (speed) to reduce the descent slope, or less throttle to make it steeper. The device will assure the plane stays at 10deg nose up all the way down to landing.

NOTE that using CSMM will totally stuff this ability up!! So... don't set it at all !! (It is NOT on by default in a Guardian).
Last edited by PeterVRC; Oct 03, 2018 at 06:45 PM.
Jun 18, 2014, 05:05 AM
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"3D" mode - and Heading Hold

3D mode, and heading hold, are actually different things - they may, or may not, be used together.
Heading Hold just means it will maintain the compass heading you "locked in".
"3D" Lock means it will maintain the ATTITUDE that you "Locked in". Attitude meaning any/all of the 3 Axis/Dimensions it can move around to point to.

The "3D Lock" is triggered when the TX Sticks are centered - with some area/range usually being a setting to set how 'tight' a range that is. So while you move the sticks around to fly 'normally', it just flies as per a normal plane - in a RATE Mode!!
The moment you release the Sticks to center, the device memorises the plane's ATTITUDE, in the 3 Axis, and takes over control of the surfaces to do whatever it needs to so that the plane maintains that 3 axis Attitude - if aerodynamically and physically possible to do so!
If Heading Hold was on, it will also maintain the overall heading it was on. If not on, then it could drift or blow off the initial course.

Some Stabilisers release that "3D Lock" totally if EITHER the Roll or Pitch stick is moved away from center. The Guardian does this. So if you use ANY of the Pitch, Roll or Yaw sticks then all three axis will release the 3D lock.
The A3 Super does NOT do this - it maintains Lock for any stick NOT released away from center.
There is a difference in both these results.... but in general I find I am always using either a full 3D lock, or none. Though I think technically the A3 Super method is of more use.

So this system is all pretty simple..... Roll to 90deg, go Full (high) opposing Rudder, so it is a Knife Edge and RELEASE the Sticks! It will "3D Lock" and keep flying along in the Knife Edge attitude for you! Though you will find that in practice it is not quite as simple as just that, to get it working perfectly....

Another great use of 3D Lock is Hand- launches!!!
If you hold the plane to an appropriate "Flying away slowly Angle Of Attack", then move Pitch or Roll and then RELEASE the sticks, it will lock in that Attitude you held it at. DON'T move the sticks again, so the Lock is not released!
Then throttle up and throw the plane..... it will fly off perfectly, under the 3D Lock control that maintains that nice 'Flying off AoA' attitude!
It is so good that you can do the 3D Lock, then even put DOWN your TX..... it doesn't matter what you do with the plane in this meantime.... reach down and throttle up... stand up again.... throw the plane.. and it will fly off perfectly under3D Lock control once again! Indefinitely, climbing away stable into the distance. Pick up the TX at your leisure (more or less)!!

If Heading Hold is on (by default it usually is) the plane will even fly off in the exact same direction as the Lock was set at. So you can throw the plane 90deg amiss, and it will immediately turn the plane back on course! You main thing to be wary of is that it is a plane that CAN do a turn at this slower speed ok, without stalling/crashing!

For a plane on a runway, the Heading Hold can assure it will travel DEAD STRAIGHT down the runway.... especially useful for Tail Draggers!! But don't use a Stick and RELEASE the 3D Lock too soon!
With the A3 Super, using Pitch and Roll won't unlock the Rudder still..... and from memory the Guardian also does not release Rudder if you use Pitch or Roll. The main difference in those two units is that the A3 Super will also not unlock Pitch if only Roll is used, and vice-versa. The Guardian will unlock BOTH if either is moved.

So you can see that "3D Mode" has some handy uses!!!
It is a bit 'weird' to fly around all the time in 3D mode, so I tend to fly OFF mode and then change to 3D (or 2D) if I want to use something they can do, then switch back to OFF once done.
Mind you, I find doing most 3D flying stuff (like Knife Edge etc) 'nicer' when just done myself, not using 3D mode at all really.
Last edited by PeterVRC; Oct 03, 2018 at 06:52 PM.
Oct 03, 2018, 07:21 PM
Registered User
Thread OP

FRsky S6R and S8R

Quite a while ago FRsky released Receiever (RX) versions that INCLUDE a 6 Axis Flight Controller also.
These are extremely good value, as they only cost "$2" more than the plain RX versions!
They have software to support, Stabilisation, Automatic Leveling (Angle Mode of Control!!), Automatic Knife Edge, Automatic Hover. And of course "OFF" (do nothing).

Stabilistion Mode - the usual Rate Mode of Control, and they correct for un-commanded attitude changes of the aircraft.

Automatic Level Mode - in this mode the Flight Controller actually works far more like it NAME suggests (than other brands) because it uses an Angle Mode of Control for a fair range of input (Stick) control, but reverts to RATE Mode after that amount. Just like the Eagletree Guardian does in 2D Mode if the CSSM is enabled.
By doing this it means that centering sticks will Level the aircraft, but using a 'lot; of stick control will move it into the Rate Mode and a Loop or Roll can be completed still too. Which a pure (full stick range) Angle Mode could not do.
As with the Guardian, this has the grey transition area that can make control though that region a bit 'odd'.
It would have been nice if the SXR settings allowed a 'tick box' to enable FULL Angle mode, or this dual/transition Angle/Rate mode they use.

The SXR's do NOT have any "3D", Attitude Lock, mode. So that was disappointing! But, they do only cost "$2 more" than a plain RX, so......

The Knife Edge mode, and Hover Mode, do those two tasks. They use the Angle Mode of Control system, that they use for Automatic level, but they control the different flight control surfaces required to achieve each of those tasks. eg Rudder and Elevator for Hover, and Aileron and Rudder for Knife Edge. They basically just change those two controlled surfaces required, and the reference calibration base - which you set up during the device setup and calibration process.
One issue with these two modes is the TRANSITION process they implemented. When you switch to that new mode they just go "They have requested Knife Edge" and WHAM, they drive the surfaces to the MAXIMUMS to get it there 'instantly'. Which is very harsh, and usually has overshoot due to that high speed and inertia of the change. You are far better off GETTING the plane to the attitude YOURSELF, that you are going to switch to as then it can be a smoothly controlled transition. eg for Hover, reduce power in level flight, arc up to vertical and THEN switch on the Hover Mode.
Also, the Knife Edge only supports ONE wing down attitude - I think it is the Left Wing down attitude. But at least it allows someone who can't do a Knife Edge manually at all to do one!

In Automatic Level mode the Angle Mode of Control range, before it changes back to Rate Mode for larger command values, means it can still be used totally fine for various "Automated Flight" modes, such as Semi Auto Take-Off and Landing setups. Or Semi Auto High Alpha set ups.

So the SXR's have some great features, and some "shortfalls" too, but overall for "$2" they are fantastic devices to use instead of the plain RX versions!
Oct 03, 2018, 07:45 PM
Registered User
Thread OP

HobbyEagle A3 Super 2 and 3

There have now been a Version 2 and a version 3 of the A3 Super Flight Controllers.
The first thing of note added was SBUS support. This allows a single RX lead connection to fully control it. Not a bunch of PWM leads.
The processors (power) was improved (upgraded, increased) so it can do calculations faster and more precise.
A few changes to modes of operation, but overall the same basis across them all.
The Version 3 had some serious flaws when it was released, but that was corrected and now it is the one you would buy. So really only the Version 3 matters now.

It is a "Full Function" Flight Controller, so it is quite highly detailed in what it can do, and the variations you can set up.
It is WAY better than the FRsky SXR devices, but it is an EXTRA Device you need to fit/install into an aircraft so you really want to weigh up the extra COST of it (About USD$40), and that extra SPACE required, versus the extra things it can DO. Usually the things you need/want to be able to do make the decision of which to use a simple choice. (eg SXR or A3 Super3)

The A3super3 also includes an Auto Hover mode (but not Auto Knife Edge).
In terms of DEVICE it is clearly the best one - but at its COST and SPACE differences.

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