General Dual Rates Expo & Stabilisation

[Heliman450]

Hi all, I was pondering where to put this and think general chat is the best option.

Recently, I've been engaged in quite deep and meaningful stuff on this subject with Harford. It's resulted in me doing some testing with various, somewhat extreme settings by recommendations and chat I heard in the past. So here's a summary based upon function. All this was carried out using the stabilisation function in my Spirit Pro activated.

Throttle: D/R 100% Expo 0% - I see no benefit to making changes here for an electric motor.

Elevator: D/R 30% Expo 30% - This results in very gentle, more 'real' behaviour, which for a relative novice like me is much more controllable. The heli can still be flown forwards/backwards very fast but still within the capability of the pilot to make moves without panicking. This is reinforced by the stabilisation feature of the gyro.

Aileron: D/R 60% Expo 30% - This results in very stable flight and enough travel to give a realistic, gentle banking turn.

Pitch: D/R 100% Expo 30% - I was wondering why I might use any change here and tried some D/R but came to the conclusion that one can already create pitch curves to produce a suitable reaction from the heli. However, the Expo surprised me enormously. The main benefit was that the tendency for my dumb thumb/finger to give a very slight up and down movement on the stick as I use the rudder function has just disappeared. I will definitely do some more work on this newly discovered benefit. When I turn the heli on its 'Yaw' axis there is almost no change in the altitude and the pitch curve I use gives me very fine control to correct it.

Rudder: D/R 80% Expo 10% - This has resulted in very smooth reaction of the tail to stick inputs rather than the very snappy reaction I had from the previous setting of 70% D/R and 0% Expo.

To give a bit more background. My T-Rex 550 has a full pitch range of 24 degrees (-12 to + 12). The cyclic ring tuning in the Spirit Pro gives almost exactly 11 degrees each way in the Aileron axis. The tail has a tip to tip measurement of 5cm with left and right rudder inputs. The gyro is set to -70% ('Normal (Rate) Mode'). This keeps the stabilisation feature of the Spirit Pro active during flight.

I look forward to any discussions arising from the feedback.

 

[Heliman450]

P.S. I have a one-eyed friend who I 'mentor' and tried the above settings with my left eye closed. It was very new to me and I must say quite frightening, too. Despite slowing the heli down and taming its naturally wild ways, I'm of the opinion that I should try to discourage him in his quest to fly helis. If anyone has experience how I might help him despite his limitations then I'd appreciate any feedback.

Many thanks in anticipation.

 

[Tony]

The thing to remember, with only one eye, you have absolutely no depth perception. However, if you are forced (lose an eye) to only use one eye for the rest of your life, then you become accustomed to it and you can gauge pretty well (from what I have heard) where things are. Because of this, I don't think it's such a bad idea. Just have him start out on something small that won't really hurt if it hits him. Like a fixed pitch heli or something. The 911 would be good I would think to get his feet wet.

 

[Heliman450]

Hi Tony, I've heard similar things myself and had another friend years ago who also had one eye. Yesterday was the first time I tried it for myself so it was probably ten times more frightening for me. My own (two-eyed) depth of field perception is giving me some issues and I'm using my test/training gear to help (see photo Spirit Pro Set Up). This is mainly at a distance of greater than about 80m away in altitude and linear, too. If I can overcome it then at least I'll be able to do my 'scale' flying objective but never the crazy stuff I see in videos on the Internet. Sometimes one just has to accept certain boundaries.

 

[Tony]

lol, I accepted that boundary a LONG time ago lmao.

 

[Heliman450]

I'm working on it by trying to steer my focus on scale flying but my main buz comes from the building and setting up. Line up a constant stream of helis to build and I'm as happy as a pig in the dirty and smelly stuff

 

[Harford]

Hi Heliman,
An ongoing learning experience ! I can see with my Tx that it is possible to activate Expo against a pitch curve although I am not sure how you set a value for it . I cannot see where D/R is an option for pitch, at least where my Tx is concerned. More thorough reading of the DX9 manual required. In any event, I am content to firstly experiment with some D/R on the Aileron and Elevator as a starting point, just as we have discussed. It is clear you have got a very good result from your experimentation and I hope I can emulate it.

 

[Heliman450]

Hi Harford,

Good luck. I think you've picked up lots of ideas to go forward with. Don't hesitate, any further questions just post them up and someone will always get back to you.

 

[Smoggie]

This is interesting, I don't really experiment anymore because I've settled on a setting that generally works for me which is expo in the range 20-30% on cyclic. Rudder expo varies over a wider range in order to get similar 'feel' on all my helis. Rates always at 100%. I've never even tried the stability option as I'm sure it would limit the flight envelope too much for the type of flying I do, but I totally understand why some would use it.

One point to note is that if you activate 'stability' (or rescue) in the Spirit then the tail gyro goes to heading hold mode. Negative gyro % in the Tx only activates rate mode if stability and rescue is disabled.

 

[Smoggie]

Hi Heliman,
I can see with my Tx that it is possible to activate Expo against a pitch curve although I am not sure how you set a value for it .

Harford,
Expo is really a misnomer in this context. All pitch curve 'Expo' does is draw a smooth curved line joining up the points you set in the pitch curve. If you disable 'expo' you get a series of straight lines joining the points. This is why you cant set a value, it's either 'on' or 'off'.

For me it makes no difference because I always use a governor so all my pitch curves are flat straight lines... I like to keep things simple.

 

[Harford]

Thank you Smoggie. I understand what you are saying about the expo effect on a pitch curve. I have never activated it.
I am very sorry to labour this point but I am still not sure about what I should do differently in the DX9 after I have activated the stabilisation function in the Spirit software. Do I simply select rate mode by using the switch I currently have for switching between HH and rate, or do I do something different ?
I know this is in the wrong thread, for which I apologise.

 

[Smoggie]

Yes, if you have a switch that makes the gain go to a negative value then that switch will work as a stabilisation on/ off switch. I'm wondering how you actually made the gain go negative with a switch? It can be done using mixes but it took me ages to figure out how. The tricky part is exactly mirroring the gain so that the numeric value remains the same but the sign changes.

 

[Harford]

Clearly I am on the wrong track. I am referring to the Gyro menu in the DX9. This operates via the Gear channel (5). Position 0 is set at +50% (and therefore is HH) and position 1 is set to -50% (and therefore is rate).
I intended to allocate another switch on the DX9 to activate Stabilisation.
You will see from the above that I have not grasped yet how to set a negative gain in the DX9 which operates in conjunction with the Stabilisation function in the software.

 

[Heliman450]

Hi there you two, I was at the field again today quite late and I'm still convinced of a beneficial reaction to me inputting an Expo value in my Jeti Tx. However, I didn't spend much time there so will continue tomorrow morning as early as I can get there without setting an alarm.

Steve, you use the expression 'misnomer' above. Is this something unique to the Spektrum transmitters?

 

[Heliman450]

Hi again,

I managed three batteries' worth of checking this morning and I gradually increased the Expo setting in my Jeti until I reached 100%, which I suppose is equivalent to you throwing a switch for on/off. It actually works better for how I'm currently flying and any tendency for me to give the slightest increases in pitch command when using the rudder command, is now gone. The heli still seems to respond to the up/down movement and adjusts the altitude exactly as before. The settings are 100% D/R and 100% Expo. This means that if I increase the range of the pitch curve from what I have it will still achieve the -12/+12 degrees that are set for the full range.

I intend to continue with my practising with this setting.

 

[Smoggie]

Steve, you use the expression 'misnomer' above. Is this something unique to the Spektrum transmitters?

It's only a misnomer in the context of the collective pitch curve. On cyclic and rudder 'exponential' really does give an exponential shaped curve.
In the pitch curve on the other hand the shape of the curve is defined by where you place the points. All the 'expo' function does in this case is draw a smooth curved line between the points rather than a series of straight lines. The curve created doesnt necessarily have any resemblance to an exponential curve.

 

[Heliman450]

Up to now, the curve drawn in the display of the Tx. shows the stick response moving away from the centre and 'feels' like this in flight. I use the stick mostly in the 52% to around 60% position and the heli climbs and falls quite satisfactorily in the field. I'll take some screen shots from the Jeti tomorrow to show you what's happening with the Expo activated.