ZYX short first impression and V-bar comparison

[Vinger]

Originally Posted by Dr. M

Thanks for the tips, Vinger. The tail geometry is actually very good and well tested. This is not a new setup, I just pulled off the ZYX (over 200 flights) and mounted the VBar. I was planning to tune the stop gain on the mushy side manually to get it close and then run the Optimizer.

The VBar can be a bit difficult to get the tail to behave properly. You have to make sure center is approx 3 deg to the right, AND not use full mechanical throw on the right side, set left and make the numbers equal. That is what I meant by geometry, actually should have said SETUP GEOMETRY!!

Happy setup....

[Dr. M]

I did another driveway test to fiddle with the tail. It's actually not that bad. The CCW stop are just a touch hard, and CW piro stops just a bit soft. A few more points tweaking to the stop gains and I'm sure it'll be good.

Today I'm taking it to the field in the hopes I can get the cyclic sorted out. As I said before, it feels a bit doughy around center, even though max rates are pretty high. It might just be a matter of turning down the expo on the radio (currently 30%); I already zeroed expo on the VBar.

[ZuvieleTeile]

Looking forward to your next flight test.
30% expo is a lot for my taste and I am not a hard 3-D flyer.
I have about 10 for cyclic and 15 for elevator. All in TX and nothing in the V-bar.

[RedOctobyr]

Thanks for all the info in this thread, really interesting, and educational.

I'm curious- why would you choose to use Expo/DR in your FBL, rather than your TX?

There's probably a good reason, I'm not just getting it. To me, if it's in the TX I can easily tweak it at the field, etc, and I can check the setting easily.

Doing it in the FBL, whether BeastX, VBar, etc, just seems more limiting. I'm not sure what the benefit would be. I'd probably set nothing in the FBL, and do it all in the TX. But if that were perfect, the FBL wouldn't even give you the option, so....

One thing I can think of is that my DX6i doesn't provide any real means of doing collective expo. With 5-point pitch curves, there's only so much I can do, if I wanted to tweak it. I suppose the FBL could give me more control there?

[Dr. M]

Well, expo is really a very personal feel thing. I like my setups to be precise in the center, and quick at the extremes, so I tend to run high rates and a lot of expo. The VBar seems to function differently than ZYX here, as I run 35% expo to tame down that one, but for the VBar I think I settled on 20%. The sluggish feel around center was most likely caused by expo... BTW, I've got expo set up on the Tx, not on the VBar.

I did fly today, 4 packs of tuning and tweaking. Ended up with 70 on the Style, 90 Agility, 100% D/R and 20% expo for cyclic. Now it feels pretty good and I did some very nice piroflips. The crisp collective will take some getting used to, but I do like it. The heli was also very stable in FFF into the wind, with no nose-up tendency even approaching VNE at full collective in a shallow dive.

Tail tuning did not go so well. I pretty much used all 4 packs trying to get stops equal, and tuning out a rapid wag in extreme moves (fast tail down funnels). I gotta say this is turning out to be as much of a chore as it was on the ZYX. Tuning the tail on that one was pretty onerous as well, but I did succeed in the end. VBar tail is still in progress...

Quite apart from that, I did take the opportunity to do some tail hold (precomp) test moves - rainbows, continuous flips/rolls, tic-tocs, tail slides, backwards hurries. No problems. The VBar holds the tail very well (it's not 100% yet), even though the CCW stop is bouncy and it wags in funnels. Interestingly it does not wag in FFF into the wind.

Other comparisons:

• VBar accurately maintains attitude in FF rolls, whereas ZYX tends to pitch up
• VBar cyclic feels just a touch more solid than the ZYX. This is particularly noticeable when doing continuous flips/rolls - VBar appears to drift just a bit less, and requires less off-axis corrections
• FFF piros smooth and symmetric (both VB and ZYX)
• VBar tail hold slightly better than ZYX in tic-tocs, rainbows, hard stops = less sideways drift
• VBar tail has a weird hunting in the hover - almost as if the deadband setting for the servo is too large (this is not adjustable on VB, but it is on the ZYX). The tail kinda wanders about 1 in side to side, in a random and lazy fashion. I noticed a similar effect on the ZYX, but it was much less pronounced.

So far I'm quite surprised by how similar the VBar and ZYX fly. The ZYX has definitely grown in my eyes because of this experience.

VBar has the edge on cyclic, and a big plus on collective. ZYX has the edge on tail for now.

But in their comparison so far, I'd have to give the win to the MSH Brain. The tuning of that system was by far the easiest, both on cyclic and tail (provided, it was on a different heli, so that might have been a factor). Basically the Brain was done with tail tuning in one flight; cyclic took another 2-3 packs, and I haven't touched that part of the setup software since.

[beenflying]

The tail optimizer is definitely your friend, especially when it comes to symmetry. Just start off with 75/75 (also try 70/65) for P & I, stop A/B at 20 (also try 20/30) and enable the optimizer. Do lots of hard piro stops in both directions, at your preferred idle up, and you should find the tail gets remarkably better. Once you're happy with it land and disable the optimizer.

[Dr. M]

Thanks, beenflying.

That's exactly what I did. P-I at 75-75, Tail stops A/B at 26/19 and ran the optimizer until the stops felt OK. Values came back at 32/72 and I'm still not happy with the CW stop. On top of that I get aggressive wag in right-rudder funnels. Left-rudder funnels didn't seems to wag, but that's my weak side, so I can't fly them quite as aggressively as the right-rudder ones...

[beenflying]

Unusual to have the A stop more than B. Try reducing the I gain to stop the sideways wag.

[Dr. M]

Time for an update on my progress... I've gone on vacation and took the Protos with me, so I have ample time to tune this vbar. Today I got to fly on a beautiful beach under overcast skies, 10kt winds (steady) and a balmy 62F.

Dropping tail I gain solved the wag in funnels. Thanks BF. Why do you say it's unusual to have A stop higher than B? My CW piros stop soft, and CCW have an angry double tap. The manual sems to suggest A side is for CW and B for CCW.

Next I'm gonna tune these darn stops, then focus on finetuning the cyclic, which still has a slight odd feel.

OTT, the tail still does an uncertain hunting in the hover. No vibe alerts in the logs. I'm not quite sure what to make of it.

[Dr. M]

The VBar is 95% tuned. I decided to leave the tail stops alone and just fly and enjoy it. I gotta say it flies pretty well, very locked in and precise. I noticed today while doing aileron tic-tocs that the elevator precomp is misbehaving and causes drifting nose-towards-disk. I think it might be too high, but that's what the 4 banks are for...

Cyclic still feels a bit strange to me, almost as if there's too much expo. I tried tuning the expo on the Tx, but that's not the answer. I might have to play with the paddle sim and/or Style settings to get back the ZYX feel.

In terms of comparison, there really doesn't seem to be much difference between the vb and zyx V4, imo. Vbar cyclic seems just a touch more locked in and true to the inputs. The zyx had some slight off axis interactions sometimes, most noticeable in looong, drawn out rainbows. VBar rainbows appear more true to the input axis, and the crisper collective helps make the stops cleaner.

Finally, I also tested the auto behavior, and everything went well. I probably did more than a dozen autos with the vbar so far, and they all turned out just fine. No tipover tendencies, no head wobbles during the flare (overspeed or not), perfect tail hold. Very much in line with the zyx again.

[beenflying]

Great to hear you have the v bar flying well enough to have some fun with it.

Re the A/B stops. I see what you mean in the online manual. I had reached the conclusion that the B Stop was the CW stop, after looking at a lot of other peoples setup files and screen shots, which only showed the B stop increased. Not once, to date, have I seen the A stop higher (except yours).

I've found the optimize has evened out the stops on 3 out of my 4 v bar helis anyway. Interestingly this same heli (with the uneven stop) has quite a high value in the second optimize box. It also uses the MKS 760us mini tail servo that the ZYX doesn't like.

Re the ZYX feel, try style at 90. You wont notice a few counts different in style, so go 5 to 10 steps at a time.

Also paddle sim is a bit like cyclic burst coefficient in the ZYX v4. Interestingly they both default to 20.

[ZuvieleTeile]

Nice to hear some more about the two units.
In regards to the cyclic, did you try and up the cyclic number?
When you've done your binding test in the swash tab, just give it 5 or 10 more and feel the difference.
How about your agility setting? I am not an aggressive 3-D flyer, but I have mine at about 90 for the Logo-400 and 100 for the TDR.

[Dr. M]

Thanks for the tips guys. I've already started to suspect the manual is wrong about the meaning of the A/B stops.

For cyclic, I have Style at 70, Agility 90. The max rates are not a problem, it's plenty fast when I jam the sticks to the ends. It's the finesse stuff that bugs me, including piro flips, transitions, small corrections during funnels etc. I was actually considering dropping the Style parameter, rather than increasing...

I'll play with it some more and see how it fares.

[Dr. M]

Check out this comparison of the ZYX to the MSH Brain/ikon.

https://www.helifreak.com/showpost.p...7&postcount=42

[Dr. M]

Many won't believe this, but I've made a decision that the ZYX tail is better than VBar. Even after all this tuning, the VBar tail still drifts in high-power moves, such as tick-tocks and power loops. I was doing some HUGE figure 8 power loops today and I kept noticing it takes a whole lot more effort to keep them tracking parallel to the flight line. They were truly easy with the ZYX, but VBar just kept drifting with torque (nose left)... I'm starting the tail tuning over from Mr Mel's suggestions with PI at 75-75 and we'll see if it gets better. But clearly it's far more painstaiking to get a perfect tail with VBar than ZYX, not that the latter was easy by any means, but still.

Second observation: I turned off elevator precompensation, as it was seriously cramping my style in sideways tick-tocks, causing a constant and visible drift nose-towards-disk. This is probably related to my tendency to use slightly more negative pitch than positive when alternating in tick-tocks (I'm working on it, but for now, that's how I do them).

Finally, I'm experimenting with paddle sim. tomorrow I'm flying the 4 banks at different settings to see if I can get that elusive cyclic feel I'm after; paddle sim values to test range from 20 to 50.

[RedOctobyr]

Wow, interesting. Thank you for sharing your experiences, this is great info for comparison.

I decided not to go to v4 FW on my ZYX before trying VBar. I know 4 flies better, but I figured redoing my ZYX just to remove it was asking for trouble, and maybe a crash :rolleyes: Leaving the ZYX as-is until I switch.

Sent using Tapatalk.

[Dr. M]

Success! I figured out the tail and now it's perfect. Also found out I like paddle sim at 40. Will post my settings file later.

[beenflying]

The suspense is killing me.

[Dr. M]

sorry for the delay. Bank 3 is the one.

[RedOctobyr]

Originally Posted by Dr. M

Success! I figured out the tail and now it's perfect. Also found out I like paddle sim at 40. Will post my settings file later.

Thanks for posting the file. But can you describe what you did to fix the tail?