Rudder Control Rate or HH Setup

[waveydavey]

Hey buddy.

Be good to see the results and I think you'll see a stop improvement.

No, you're right the Vbar doesn't require an actual rate mode trim flight, but asks the user to set 3 degrees tail rotor pitch against the torque on the tail setup stage/tab. So this is doing the rate model setup of adding pitch at the neutral stick position, but on the bench with a value known to be enough to work effectively, rather than an actual trim flight where you adjust the pushrod length.
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It may say that but I've set my back ends up the same way for a number of years since 2 Clicks educated me. So thats bang on in the centre, I even take the first set of figures for stops add them, divide by 2 set them to the figure I end up with and then adjust the control rod so that they are the same both ways. In fairness the torque reaction may be different with leccy and you may need to setup differently but I've never had a problem with it.

[Mike Sanders]

2 Clicks = Anjki on here.

[dszabo]

I always set up my tails in HH until i had a chat with Wavey at MK back in the summer, i now set them up centre with equal travel each way and can say i cant tell the diffference.

[Peteski]

I always set up my tails in HH until i had a chat with Wavey at MK back in the summer, i now set them up centre with equal travel each way and can say i cant tell the diffference.

How have you got your OXY tail set up? Centre position on the tail bellcrank actually gives 3.5 deg counter pitch. So it's effectively pre-trimmed for you. I might try mine in rate mode just to see if there is any rotation.

[myxiplx]

Bear in mind guys it depends on the FBL unit. Some like the Vortex work better if the tail is neutral, it's just the way the code is designed. Others don't need it as the code automatically adjusts. Ultimately if your helicopter is flying well enough for you there's no need to mess with things, and with the quality of FBL systems and speed of tail servos these days the discussion is largely academic as the differences are pretty minor unless you're really pushing the model hard.

I only looked into this in detail as I have a Trex 250 which is fiddly as hell to get the tail performing well, that little bird really does need every ounce of help you can give it!

[myxiplx]

Hey Buddy.

Ah no, not necassarily, as you then move onto another form of tail control which can in it's simplistest term be called "revolution mixing".
On the Vbar for example, if you input collective pitch (or cyclic for that matter) tail rotor pitch changes are introduced to counteract the impact of these controls on the models ariframe, so on collective pitch inputs as you describe, a throttle to tail rotor mix is introduced to help keep the tail in check. Simply put tail rotor pitch is altered by the FBL controller with collective inputs.

Those who have not been in the hobby long, will probably not know what "revolution mixing" is, but may have seen it in their transmitter menus. Basically this is a mixing parameter that can be fine tuned to automatically input yaw/tail commands alongside collective pitch inputs made by the pilot, thus keeping a better hold of the tail during aggressive pitch changes as the tail rotor is automatically adjusted to compensate. Of course along came heading hold gyros and this feature wasn't really needed, but that is because it's built in already.
The last time I used Revo Mixing in the transmitter was when I flew for CenturyUK and we had fun with the FP Hummingbirds, as we could tame the tail even more with finely tuned Revo Mixing.

We then move onto other gains available within most FBL units, P Gain, I gain etc etc to help smooth out any other tendancys.

The bottomline is that there is benefits for most tail gyro's/FBL units out there when setup in rate mode, whether the pilot is at the point in his flying skill to notice the improvement makes this setup procedure a do or don't do affair, but if you're at a level that can benefit from it I'd say do it, as it takes minimal time.
What I have found in my training is that most people are frightened to fly in rate mode for fear of what will happen, experience helps one to set a pretty close neutral pitch position off the build bench, thus minimising any tail swing in rate mode. As Peteski has said above, some models even have this neutral tail pitch position designed into the controlling arms, making it even easier for the builder to set.
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Ian is spot on with pretty much all his posts. His explanation of why some units benefit from rate mode setup is spot on, and same here with the mixing.

Again I'm talking Vortex as that's the one I know, but once you have done the full tail tuning you should have it pretty darn good. And for me that full setup is rate mode setup, tail gain, stop gains, decceleration and I gain. Those get the gyro code working as well as it can, and what I'll then do is tune the "collective to tail" and "cyclic to tail" parameters on the vortex. Just like the rate mode setup they're giving the tail a helping hand, and helping to predict the load required, which reduces the amount of correction the PID loop needs.

It's just like running your governor in the FBL, the more proactive you make it, the less work the PID control loop has to do, and the smoother and more locked in it can be. It means your tail gyro is spending the majority of its time doing fine adjustments to keep it dialed in, it's not having to really fight to keep it in position.

[waveydavey]

Well, my findings and apologies for the lack of video but for some reason the focus on my camera wouldn't so they are of little value.

First setup was my normal centre slider with tail limits equal and using the whole travel available and set the tail parameters to standard out of box apart from piro speed. Then a quick test flight as I'd had a little tumble last week. Hover, exactly what I expected, not bad, no drift, no wobble. Piro speed left to right the same, I run 530 degrees per second, piro stop consistency not very good overshoot and bounceback, exactly what I was expecting. In flight it's okay, no blow outs, no wags just a nice controlled tail in backwards hurricanes, piro moves, tail slides etc and what I have become used to. From here I would normally then start adjusting accelerations and stop gains with tweaks to the travel on the slider. I didn't though as this was an experiment to see if setting hover in rate mode actually makes any difference to tail performance.

So, leaving everything else as it was above I set idle up 2 to rate mode so I was using the same headpseed. Set the tail rod so little to no discernible drift was evident, very light wind so an ideal day for it. Once this was achieved I returned to the bench and set the tail limits so I wasn't binding. Out to the peg again and up into the hover, nice, no drift, no wobble. Out into the field a little and piro speed was the same with nothing noticeably different to above. I was surprised to find, yes you guessed it no difference whatsoever in the stops, overshoot and bounceback. Flight performance the same except I got a little wag now and again and it wasn't consistent, sometimes in a tail slide and sometimes even in forward flight. Not sure why and I couldn't see anything binding mechanically, will take a look through the week.

So my conclusion, a rate mode setup on the tail with my setup is 100% pointless. This is with Vortex out of the box settings (which I wouldn't use but had to be the same for both setups) my Raptor e700 MJ nitro conversion and Align 105 tails. Servo is the Align BL750Hv with 2S LiPo. So a common or garden setup nothing exotic these days.

[myxiplx]

But nobody said a rate mode would dial in the stops or make an automatic improvement. You seem to be expecting something totally different.

When you have the tail tuned, and you're at the point of fine tuning to get the best performance and crispest stops and eliminating that bounceback, having the rate mode set helps get things more even and that little bit sharper. If you don't tune the stops at all there's obviously no benefit to rate mode.

You can get the tail 90-95% perfect without doing this anyway. Rate mode really just gives you the last few percent of performance on the tail, it's not a massive thing that's going to jump out at you.

[GIXERMAN]

mmm are you missing something then Dave !

[waveydavey]

You seem to be expecting something totally different.

No I'm not, you're missing the point of the original post. I will repeat it, what is the point of a rate mode setup on a model. My experiment was to use both setups and with an out of the box set of parameters to see what could be achieved by the tuning of the mechanical geometry required by a rate mode setup as suggested by various members to a relative beginner on another thread. My question there was what is achieved by doing this, the answer with my setup is not a sodding thing.

Nobody has been able to answer the question, only theorise as to what could be achieved. I'll give it that my experiment was done with my old thumbs and probably inconsistent stops but the overall experience was that it doesn't matter how the rudder is setup, on my machine admittedly but I suspect it wouldn't matter who's machine it is or what gyro. Heading Hold is just that.

Ignore the stops part of the trial, ignore the fact it was my FBL unit of choice, they were just a coincidence. I have the stops as good as they're going to get on my machines, I accept that they need tuning out of the box and I know how to do it. The point is a rate mode adjustment whatever you want to call it is a waste of your flying time, or it is in my setups

[waveydavey]

mmm are you missing something then Dave !

Missing loads of things Brian, always have it's part of being a Northerner

[Peteski]

No I'm not, you're missing the point of the original post. I will repeat it, what is the point of a rate mode setup on a model. My experiment was to use both setups and with an out of the box set of parameters to see what could be achieved by the tuning of the mechanical geometry required by a rate mode setup as suggested by various members to a relative beginner on another thread. My question there was what is achieved by doing this, the answer with my setup is not a sodding thing.

Nobody has been able to answer the question, only theorise as to what could be achieved. I'll give it that my experiment was done with my old thumbs and probably inconsistent stops but the overall experience was that it doesn't matter how the rudder is setup, on my machine admittedly but I suspect it wouldn't matter who's machine it is or what gyro. Heading Hold is just that.

Ignore the stops part of the trial, ignore the fact it was my FBL unit of choice, they were just a coincidence. I have the stops as good as they're going to get on my machines, I accept that they need tuning out of the box and I know how to do it. The point is a rate mode adjustment whatever you want to call it is a waste of your flying time, or it is in my setups

I guess you've confirmed that it isn't important for most pilots and most models in the real world. Kind of what it says in my BeastX user manual! But it's probably something to do IF you are having issues with inconsistent piro rates or stops that you can't iron out with the control loop. A centre mechanical setup is probably good enough in most cases and especially so if there is counter pitch designed in.

Thanks for doing the test, always useful to know.

[myxiplx]

No I'm not, you're missing the point of the original post. I will repeat it, what is the point of a rate mode setup on a model. My experiment was to use both setups and with an out of the box set of parameters to see what could be achieved by the tuning of the mechanical geometry required by a rate mode setup as suggested by various members to a relative beginner on another thread. My question there was what is achieved by doing this, the answer with my setup is not a sodding thing.

Nobody has been able to answer the question, only theorise as to what could be achieved. I'll give it that my experiment was done with my old thumbs and probably inconsistent stops but the overall experience was that it doesn't matter how the rudder is setup, on my machine admittedly but I suspect it wouldn't matter who's machine it is or what gyro. Heading Hold is just that.

Ignore the stops part of the trial, ignore the fact it was my FBL unit of choice, they were just a coincidence. I have the stops as good as they're going to get on my machines, I accept that they need tuning out of the box and I know how to do it. The point is a rate mode adjustment whatever you want to call it is a waste of your flying time, or it is in my setups

Aaah, but that is the wrong experiment to see the difference, on an untuned setup it's going to have little to no effect, I wouldn't expect you to see anything at all there.

And I do agree, that for most people, it probably isn't needed, you're as well just to get out and fly and ignore all this faffing about

The benefit of rate mode setup is a subtle effect and you are only going to see it if you're pushing the limits of tail performance and trying to get the absolute best out of the tail. What definitely isn't true is to suggest that the helicopter won't fly well unless you do this. A modern 700 size machine with just stock settings on the Vortex (or any FBL) is pretty darn good, and just as you say, you can get it flying great with nothing more than a few tweaks. In fact you can get it to the point that it's pretty hard to see any benefit at all, and for the vast majority of us that's more than good enough.

But if you need that extra edge of tail performance, then you definitely can get it to perform a little better if you do all the fine tuning. For me I spent a lot of time tuning the tail on my Trex 250 and I absolutely did need to do the rate mode setup on that helicopter. It's such a small helicopter, and so twitchy in the air that the stop gains are a real pain to nail down, and setting it up in rate mode to even out the CW and CCW stops really helps you get those few extra points on the gains. On that particular helicopter unless you get the tail performing really well you get a shudder in tic-tocks that's extremely noticeable, and it took every bit of tuning the Vortex offers to get that tail to the point where it will take anything I throw at it.

[George J]

I'm with you on this Dave, it makes no difference what so ever on modern helis and FBL systems if you set up the tail in rate. In theory setting up in rate will ease the work of the gyros but in reality makes zero difference imho.

As for stops etc you always have to sort them however you choose to set up the tail or if you use Vbar just do a tail optimise and then forget about it!