Can't hold bank angle (and pitch)

[BronzeYardNo11]

Description: When rolling or pitching the aircraft, there seems to be quite a bit of lag when returning the stick to center. It just keeps rolling/pitching in the direction you gave it, again despite that fact you returned to center!

 

DCS Version: 1.5.4.56500

 

Reproducible: Yes.

 

Step to Reproduce: Open the controls indicator, roll the aircraft a bit then return to center. Turn SAS off to really feel it. It happens when SAS is on too, just not as noticiable.

 

Screenshot/Video available:

 

Controllers: Homemade, leobodnar controller, no saturation or curves.

 

Any Additional Information: If this is a real "feature" of the Gazelle, I would love to know what and how it happens! However I think this is just a bug in programming, as many helicopter flight manuals/handbooks and other simulators talk when turning the aircraft you roll to your desired angle and return cyclic to center to hold. Just like an airplane!

[Spacehamster]

Getting the exact same problem.

[Pikey]

Are you talking about phase lag https://en.wikipedia.org/wiki/Phase_lag_(rotorcraft) or just the expectation that the helicopter should level out by itself somehow?

[Spacehamster]

It's a bug, not some highly sophisticatesd feature of the flightmodel. The bank input runs away long after the bank input is held in place.

[drPhibes]

Helicopters aren't dynamically stable. In order to arrest a roll or pitch momentum, you need to compensate in the opposite direction. Centering the controls does not prevent you from "tipping over" in one direction or the other.

[BronzeYardNo11]

Are you talking about phase lag https://en.wikipedia.org/wiki/Phase_lag_(rotorcraft) or just the expectation that the helicopter should level out by itself somehow?

 

"As a consequence of the phase lag, to turn the rotorcraft to the left or right would theoretically require a forward or backward cyclic if there was no mechanical correction. The rotor control system is mechanically shifted up to 90 degrees to compensate for phase lag"

 

Did you even read the wiki article you sent me? lol

[Pikey]

You mentioned lag? So you mean a delay in moving the stick and the resulting effect? I can't see your bug, It looks like intertia from throwing it 45 degrees in bank violently. I just tried with normal 15-30 degree bank and the helicopter settled normally.

[Penshoon]

Helicopters aren't dynamically stable. In order to arrest a roll or pitch momentum, you need to compensate in the opposite direction. Centering the controls does not prevent you from "tipping over" in one direction or the other.

That shouldn't be the case in forward flight right, only in hover?

Edited September 16, 2016 by Penshoon

[M]

Thanks for posting the video! A couple of observations:

 

The first few manoeuvres you perform show the helicopter exhibiting static instability. After your roll input the helicopter doesn't show any tendency to want to roll back to the original attitude. Dynamic stability is irrelevant here since the aircraft is statically unstable.

 

The manoeuvre at ~1:40 shows the helicopter returning to the original attitude without pilot input, i.e. it's statically stable. It appears to return to "wings level" with only minor overshoot and is hence exhibiting dynamic stability also.

 

It's difficult to determine exactly what's happening in the remaining manoeuvres since these involve quite drastic pilot inputs.

 

It would be interesting to see:

1. A comparison between SAS on and SAS off

2. The aircraft response with shorter, sharper pilot inputs to mimic, say, a wind gust

3. Control inputs during coordinated turns (with SAS off, applying in-to-turn pedal seems to fix the issue for me)

 

I don't know enough about the Gazelle's stability system to determine if it's working as designed or not. From what you've posted, it seems to be a question of static - rather than dynamic - stability.

[BronzeYardNo11]

I'll make another video when I get home :)

[drack]

NixNB and spacehamster are right.

 

I bought this module yesterday and spent quite a bit of time with it.

 

It's impossible to fly an accurate circuit. I can not hold bank angle or pitch on the ball.

 

I tested it against other DCS world and xplane Heli's.

 

Im sure this module is going to be the best of the best when you get to the stage of bringing it out of Beta.

Edited September 20, 2016 by drack

[docWilly]

I flew the Gazelle for quite a long time with "easy controls" (setting set in main menu...maybe you want to try that first to get your hands on?) - no issues in handling it after TRAINING (and I crashed the bird often at the beginning after my transition from the huey in DCS). Then I disabled easy controls (after 50+ hrs or so) and it took me some time to get used to the more sensitive FM (it´s all about musccle memory and training).

But I have to state: she´s not killing me, she has a superb handling, TO/Landings without problems (FARP, hard surface, grass), I get her into hover as I did with "easy controls", I fly procedures as intended.

 

I read a lot of posts about a "faulty FM" that is "crap". Guys...really I can not state this findings. And I fly it without curves/saturation whatever, just plain warthog stick/throttle (no extension) and Saitek rudder pedals.

 

Are you really sure it´s the flight model that is causing the issue and not your sticks (oszillation, profiles etc), settings or training? I do not know how many hours I have in the gazelle but it´s for sure more than hundred or so.

And I guess we all have the same Gazelle, right?

 

@drake: no offense...but you bought it yesterday and you are not able to fly a circuit??? I believe it´s not possible to fly a circuit after you bought it yesterday and I was not able to do so either (especially with "realistic mode").

 

Polychop did an amazing job with this little bird and I can not say if it´s realistic or not (because I am no helo pilot but fixed wing and I do not fly Gazelles IRL), but to me it feels like it shoud (i.e. light attack helicopter).

And I am able to peform the maneuvers she is able to do IRL doing her job.

 

The Huey is easier to fly in DCS (and it feels close to reality of a HUEY as I know because I flew in the back for years with the german airforce SAR IRL). Don´t compare the Huey to the gazelle or the KA-50. All are helicopters, yes...but all are different.

I do not say that there´s not room for improvement with the module (the FM) but she´s not what I have to read about in many posts.

 

I am i no way affiliated with Polychop.

[BronzeYardNo11]

2 days late, but here is part 2:

 

I've included more comparisons because some of you can't test these out for some reason?

 

@docWilly I'm not saying it's hard to fly, I'm just saying it doesn't feel right compared to other flight sims. Mostly Dreamfoil's AS350 (x-plane), which I imagine is similar to the Gazelle IRL, but in the sim, it's not the same at all.

 

Polychop did everything extremely well, just not the FM :(

[Penshoon]

Thanks for taking the time making the videos NixNB, hopefully Polychop can respond to this.

[0xDEADBEEF]

But I have to state: she´s not killing me, she has a superb handling, TO/Landings without problems (FARP, hard surface, grass), I get her into hover as I did with "easy controls", I fly procedures as intended.

 

I read a lot of posts about a "faulty FM" that is "crap". Guys...really I can not state this findings. And I fly it without curves/saturation whatever, just plain warthog stick/throttle (no extension) and Saitek rudder pedals.

 

Are you really sure it´s the flight model that is causing the issue and not your sticks (oszillation, profiles etc), settings or training? I do not know how many hours I have in the gazelle but it´s for sure more than hundred or so.

And I guess we all have the same Gazelle, right?

 

@drake: no offense...but you bought it yesterday and you are not able to fly a circuit??? I believe it´s not possible to fly a circuit after you bought it yesterday and I was not able to do so either (especially with "realistic mode").

 

 

And I am able to peform the maneuvers she is able to do IRL doing her job.

 

The Huey is easier to fly in DCS (and it feels close to reality of a HUEY as I know because I flew in the back for years with the german airforce SAR IRL). Don´t compare the Huey to the gazelle or the KA-50. All are helicopters, yes...but all are different.

I do not say that there´s not room for improvement with the module (the FM) but she´s not what I have to read about in many posts.

 

I am i no way affiliated with Polychop.

 

You are misinterpreting something. I never ever ever claimed it is hard to fly. I always claimed: "it does not fly like a helicopter". It simply does not do things a helicopter does, like nosing up with increasing airspeed, nosing up when lifting collective/down when dropping collective, adding a roll component when you press pedal in any direction. It does not do those things at all, despite them being fundamentals of helicopter-flying. In fact, I find pitch and roll is exclusively controlled by cyclic-input. I am still waiting for a helicopter-expert to confirm this is how the gazelle behaves IRL and why, because I am really willing to learn something new, but ever since the gazelle is out and explained my view on this, nobody has stepped forward and brought up an explanation (it is not due to its size, the fenestron or the SAS, yes the SAS would make these effects lesser, but not even the super sophisticated systems in the EC-135 reduces those effects to zero). IMHO the gazelle is defying physics.

 

It is great that you are able to takeoff, land and fly a circuit, but please understand that this does not mean the flightmodel is accurate. Please let me emphasize this again: I NEVER EVER complained about it being hard to or me being unable to fly, it is no problem to adapt to the quirks and fly it, but this does not make it more realistic.

 

I just happen to have spent a lot of time investigating how helicopters are controlled. I learned it in sims, and I got to confirm my findings in real helicopters on the controls, and I can tell you, it is fascinating to sit in the real thing the very first time, take off without help of the PIC and fly away, and you see your hands moving by themselves due to the things you learned in simulators. Taking off the gazelle every time is the complete opposite experience.

 

I just recently got to fly co-seat on a R44 on a photo mission, on the way back the pilot let me take the controls, had to decend 5000ft into a tight valley, I reduced collective to start sinking, put cyclic aft to prevent a complete nose-down attitude (you dont want that in a robinson/low-g pushovers prohibited) while making sure the rotor would not overspeed, performed two circles to bleed altitude and line up for final, as speed decreased I gradually added more collective and eased out the sinking, Once at about 25kias I had to apply forward collective in order not to stop, as the landing spot the pilot wanted me to land at was still 50m ahead. It was not much, a couple of millimeters, barely feelable. Now I expect people to step up and say: "dude, you are comparing a Robinson to a Gazelle!". Yeah you're right, but guess what, the first helicopter I flew IRL was the Bo105, and I think there's few helicopters with a more similar rotorhead to the gazelle. Admitted, it's not fitted with SAS, but: IT WAS THE SAME PROCEDURE! Sure, the Bo is way more direct on input, any input on the stick gets DIRECTLY translated into attitude, very fascinating. But still: Doing an approach works the same, collective down, cyclic aft (the more aft cyclic the faster yo bleed speed), before you come to a hover a tiny little bit cyclic fwd. Now please go and try in the gazelle: Approach at full speed, apply a little bit AFT cyclic to slow down, and hold it there, now to prevent the nose from rising slowly drop collective (this is how you do it in real helicopters, all of them). You will be surprised you will find collective NOT having ANY effect on your nose moving up, even though your cyclic is just a tiny little bit aft.

 

Oh and btw, in the Bo105 if you rise collective, the helicopter will also roll a little to the right, as a result you cannot get out of a high-bank right turn without bleeding massive amounts of altitude, while a 90°-bank left hand turn is no problem (see crash of Siegfried Hermann, on youtube incorrectly labeled as Charly Zimmermann)

[docWilly]

Ok,

 

I think I got your point about the physics. I never thought beyond SAS..

 

Did some comparison flights with Uh1/Gazelle and yes...the behaviour described is very present in the Huey, not in the Gazelle. The question for me now is....who can confirm the FM vs RL, effect of SAS IRL.

Polychop claims testing by RL Gazelle pilots, who can confirm that the FM is close to reality beside that.

 

Thanks for the look insight.

[Holbeach]

I made this for other reasons, but it might have some relevance here.

 

I'm redoing some stuff with the Gazelle, I tried some time ago. Full cyclic deflection, then return to center and see where it goes and how it returns to a stable condition. No other controls are touched. Then a hands free, 125 kph grass landing (for fun). Certainly the skids are stronger and landings are far more predictable, especially on grass.

 

The stable rotation, seen at the beginning and the return to stable flight condition, without using controls, are the suspect parts, which I can't believe a real Gazelle, (or any helicopter), can do.

 

 

..

Edited September 26, 2016 by Holbeach

[0xDEADBEEF]

Ok,

 

I think I got your point about the physics. I never thought beyond SAS..

 

Did some comparison flights with Uh1/Gazelle and yes...the behaviour described is very present in the Huey, not in the Gazelle. The question for me now is....who can confirm the FM vs RL, effect of SAS IRL.

Polychop claims testing by RL Gazelle pilots, who can confirm that the FM is close to reality beside that.

 

Thanks for the look insight.

 

 

 

It is indeed *very* present on the Huey, which is mainly due to the bell-hiller mixer on the rotorhead (if you look at it, the control-links dont go directly onto the blade-, but first on the paddle, then down again to the blade, which makes it very easy to control). It is much less present on the Mi8, but it's there, and even if you try the Ka50, it noses down if you lower collective just as well as it lifts the nose with increasing speed.

 

Polychop is looking at it, but at the moment they are focussing at multicrew and the mistral, which is good as well. Also those testpilots are not available all the time. They did promise to look at the things I have reported, and I am fine with being patient. After all, I don't want that chopper fast, I want it to be good, and this is the only reason I am speaking up. Please let me also emphasize that I do not blame anyone, I am just trying to provide constructive feedback. If I ever become emotional in my response please accept my apologies, I've just pointed this out many times, and I have heard "I can fly it fine, you only need to practice" too many times.

 

After all, I think Polychop does a great job, and I am sincerely looking forward to the day when both Gazelle and 105 are finished, apart from the FM they did an absolutely incredible job so far, and even the competition needs a couple of tries till the FM is right, so this is NO blame at all towards Polychop.

Edited September 20, 2016 by 0xDEADBEEF
added quote

[Penshoon]

Remember that the Gazelle is AFM and not PFM like the rest of the Helicopters in DCS.

Edited September 20, 2016 by Penshoon

[0xDEADBEEF]

Remember that the Gazelle is AFM and not PFM like the rest of the Helicopters in DCS.

 

I never read about that. But it was/is being advertised as "as realistic as possible", and I disagree. There was even a video where Roie said: "we are happy with the FM and apart from a few tweaks we consider it finished", that was before I went deeper into my investigations and tried to explain myself in better detail.

[Penshoon]

It's right on the purchase page:

[LazerPotatoe]

Remember that the Gazelle is AFM and not PFM like the rest of the Helicopters in DCS.

Are you trying to say that because it is more Advanced, it should handle differently than other DCS choppers in normal flight regimes?

[Spacehamster]

That roll is a bug. We just need to keep making noise so the developers will fix it

[BronzeYardNo11]

[myHelljumper]

That roll is a bug. We just need to keep making noise so the developers will fix it

 

It does not work like that...