Cyclic - can't maintain attitude?

[FragBum]

I am not certain. Something aint right with this thread. Its like I have fallen into alternate universe.

Granted I don't fly helicopters in real life. However in DCS I am fairly allright with UH-1H and KA-50. Getting Gazelle under control.

In DCS UH-1H. Lets say I want to test hover or hover taxi. To do that with properly loaded and started helicopter. Pedals deflection to the left, cyclic deflection back and to the left, as that is where UH-1H (2 blade) rotor disk center of lift. Add collective smoothly helicopter rises about 3 meters off deck, and I hover with minor corrections. Cyclic cannot be brought to center. If it is UH-1H will fly forward as expected. Cyclic has to be held at that sweetspot, adjusted for headwind, it is not centered. I can activate cyclic trim, in which case the current held cyclic deflection becomes a center, and allows me to re-center cyclic. This is for pilot releif, and is not required for safe flight or safe hover.

To fly fwd, from hover, in UH-1H,allow cyclic fwd, and maintain height with collective and maintain heading with pedals as helicopter transitions into forward flight. Translational lift begins to take effect at above 20 knots, with slight shaking of the rotor disk. To achieve maximum fwd speed, cyclic forward of center as needed, reducing collective as speed increases. As speed increases torque pedals deflection is reduced until not needed at all. To maintain fwd speed, cyclic has to be held at the deflection forward of center. This is how H-1H is flown.

KA-50 is flown similarly, except that deflection amounts are different, and there is less pedal work, but is still required.

In both, in stable forward flight, without use of cyclic trim, if cyclic is centered the aicraft will pitch up.

This, I believe is how DCS and real world helicopters are flown. Many YT videos of vertical instructors (real world) show that. So when I am being told that to achieve and maintain fwd flight in Gazelle, a pilot has to cyclic fwd and then once fwd flight is achieved, re-center the cyclic, and gazelle will continue fwd flight with same attitude. This is counter to every lesson of helicopter flight I have watched, and read, and practiced, and counter to UH-1H and KA-50 control in DCS. Gazelle is small and light, but it is a bit underpowered for its weight, and it is still a helicopter. So yclic fwd then return to center for sustained forward flight is not what am not experiencing. But perhaps I am, because the cyclic deflection is so tiny, it is hard to tell.

In Gazelle, the deflections in cyclic are so tiny , I can only describe them as pressure on the cyclic and not really a deflection. On visible control indicator, from stable IGE hover to VNE forward flight, tight banked turns, any aircraft maneuver that uses cyclic, the usable cyclic deflection area is no more then the little diamond indicating control position of cyclic. If cyclic deflection is larger then area of diamond, it result is severe helicopter control. Great for snap turns, I suppose, but you can easily find yourself with out of control helicopter.

I tried the "Easier Control" option , but find no difference, and have it turned off. I am not certain what it does.

 

More to it you missed a reply where I said, *I'm not sure why it's like that." Link here.

 

This is just an observation,.. I am not a pilot IRL, Okay. But the Gazelle's cyclic is centric in nature.

 

The inputs may well be correct, actually they feel like the other heli's but there seems to be no need to counter/correct for changes in CoG or other effects like Blow Back etc, within the cyclic input.

 

I'd beg to differ with usable cyclic area/input, I use a lot of cyclic at times in all Heli's including the Gazelle, as with all heli's less input is more control. :pilotfly: :D

 

There have been many discussions re PA and SAS, What it means is it Electrical (Electronic) control or Hydraulic control or some combination? I suspect but don't now for sure but they operate to hide some detail from the pilot, maybe maybe not, I don't know.

 

If this is how they come from the factory, I'm fine with that. :thumbup:

 

Welcome to the conundrum. :)

[Gunnars Driver]

I am not certain. Something aint right with this thread. Its like I have fallen into alternate universe.

Granted I don't fly helicopters in real life.

 

...and I hover with minor corrections.

Cyclic cannot be brought to center.

 

Well, I am a pilot, since close to 30 years. Both aircrafts of different types but mainly helicopters.

I have around 200hrs Bell 206( teetering rotor like the Huey), around 2000 on Bo105 and also a bit more than 2K on the As332 Super puma an now active on NH90, around 1000hrs so far.

Im instructor on all profiles we fly, Im a maintanence test pilot on NH90( and was for long time on AS332 and Bo105). Have a few other types also, not important to this thread.

 

There are some basics that is known to all real helo pilots, disregarding on the helicopter type.

When someone clearly states things that just can not be true, I think its the time to make sure the module malers dont get lured in the wrong direction.

 

 

Very well then, it is very different to control a helo with teetering rotor with a bell hiller stabilization bar like the Huey and some other helos that have fully articulated rotors like the SA342. ( I dont have the SA342 module yet, due to some of the flight model issues heard of).

The Huey is litterally hanging under the rotor center like in a center mounted joint. When cyclic is centered the rotor only provides a lifting force in line of the rotor mast. If cyclic is moved the rotor will tilt in the same direction causing the force to the mast to no longer be in line with the mast. This force will move the upper part of the rotor mast in the same direction as the controls was moved as long as the control is not recentered. If in forward flight this will give the helo a bank angle that increases as long as the stick is hold at this position. Remember, displaced stick causes a constant rotor tilt angle from the rotor mast and thereby a constant rolling rate.

 

When in hover the perceived center stick position is determined of center of gravity only( if no wind).

If the helo is back heavy it will tend to hang tail low and because the rotor is perpendicular to the mast if stick is in ”normal center position” the rotor would also lean backwards making the helo move backwards. Stick will be needed to move forward until the rotor is horizontal. This is the reason why the stick is not in the marked middle position in the DCS Huey.( the tail rotor causes drift sidewards to the right, this causes the need to have the cyclic a small bit to the left to give the rotor a left tilt = left force to counter the tail rotor.)

 

The teetering rotor has a built in slow reaction for cyclic input: first stick is moved, then the rotor tilts, and after this the rotor makes the rotor mast/helo react slow. In hover, the huey ”hangs” under the middle of the rotor and there is less need for quick corrections than with a fully articulated rotor like the SA342 has. Stick position in hover will also depend on wind. The rotor will be needed to be tilted against the wind direction to counter the wind drift, this also changes the stick position at hover.

 

The following part is the same for all types of helis/rotor systems:

In forward flight, stick need to be forward to keep the speed, but in roll axis it will be close to center. When stick is moved sidewards there is a rolling moment on the helo as long as stick is still hold in that position. For a turn, when bank angle is reached, the stick need to be centered. For rolling back to wings level the stick need to be moved in the other direction and held until the wings is level again and then the stick can be recentered. Id did post a link recently in the same

Question of a Bo105, where tou could clearly see the stick vs helo movements.

 

The part below is the post which is not right. The Huey is a very well built DCS module but it is not the same thing as flying the real huey because it doesnt work like the real one in every aspect. Its very good though. Its has way better collective stick feeling than one of the Bell 412 Full flight simulators I did fly some years ago( and they where real, you actually could count the flight time as flight time( civilians do, I think). Still the Huey isnt perfect( again, very good) so you can not take every behaviour as a proof for the real Huey characteristics. And, because the very different rotor system you cant use this to draw conclusions of how the SA342 should fly and react to inputs.

 

For the part below, how many hours do you have in a real helicopter? And how many in the Huey? How would you be able to judge correct behaviour if you did not fly the Huey, or not a helo at all? I have the experience to know how some stuff work, and to know the wider possibilities of for example the teetering rotor system of the Huey. I have some hours in the Huey, I was not type rated on the Huey but I flew a number of flights as left pilot and then got some hours at the controls, I also wanted a few hours in the log book before my employer stopped flying it so I managed to get a couple of hours in ”dual command” with a huey flight instructor, so then I also could try autorotation and other stuff. Still, its > 15 years ago so I cant remember the feeling in detail. I could maybe judge the feeling in flight charecteristics quite close but to say whats is exactly right we need a pilot that flew the huey a lot and also not burnes the memory afterwards with a lot of hours in other helos. ( Not that it would need a lot of tweaking, but for reference to the statement below.)

I dont have the KA-50.

The small cyclic, in forward speed you most often use a very smal part of the stick range. The stick is around 50 cm (-ish) above the floor and you most often do corrections that are a few millimeters. If you use a regular PC joystick this would transfere to very small stick movements due to the very much shorter stick. Maybe a correct beaviour is made unflyable if you use a shorter stick than IRL.

 

 

QUOTE=DmitriKozlowsky;3811764]That is not right. Even in DCS. Deflection of cyclic places certain attitude of helicopter. If cyclic is re-centered, so would attitude. Its just that in DCS: Gazelle, the deflection is very small, and most overreact, requiring counter cyclic motion

UH-1H and KA-50 modules have correct cyclic behavior.

[Deezle]

Well, I am a pilot, since close to 30 years. Both aircrafts of different types but mainly helicopters.

I have around 200hrs Bell 206( teetering rotor like the Huey), around 2000 on Bo105 and also a bit more than 2K on the As332 Super puma an now active on NH90, around 1000hrs so far.

Im instructor on all profiles we fly, Im a maintanence test pilot on NH90( and was for long time on AS332 and Bo105). Have a few other types also, not important to this thread.

 

Very well then, it is very different to control a helo with teetering rotor with a bell hiller stabilization bar like the Huey and some other helos that have fully articulated rotors like the SA342. ( I dont have the SA342 module yet, due to some of the flight model issues heard of).

Please do not take this the wrong way, many of us are not real pilots but have substantial sim time and appreciate what real pilots such as yourself have to say. Maybe we are not accurately describing the issues we're seeing and it is leading to confusion, on both sides, about what's going on. You yourself acknowledge you do not own the Gazelle because of flight model issues you've heard about, yet you're trying to comment on it's characteristics the rest of us have actually experienced by owning it. To me, the cyclic feels weird, I can't really describe it any better than that. I'd really like if you can actually fly it and comment on it.

 

 

I have some time in a very highly regarded Bell 407 simulation in another sim that shall not be named, and it's more what I'd expect the Gazelle to feel like, perhaps you have experience with that sim as well? It's fairly popular.

[Gunnars Driver]

Please do not take this the wrong way,

 

You yourself acknowledge you do not own the Gazelle because of flight model issues you've heard about, yet you're trying to comment on it's characteristics

 

No problem, discussion’s welcome :)

 

No, I dont comment on the actual characteristics of the DCS Gazelle. I never did, and I hope its clear, reading my posts. I might comment the part of the real SA342 where I know enough about how it works, to be sure I`m not wrong.

 

I comment other comments that just can not be true:

 

first one, a few weeks ago, another thread:

First problem: the DCS Gazelle is never stopping rolling when you move your cyclic and maintain a steady position, for example 3cm left from neutral position). In the real Gazelle (and in most part of French helicopters) a displacement of the cyclic of x cm is corresponding to a steady x degrees roll angle of the helicopter.

 

And in this thread:

Deflection of cyclic places certain attitude of helicopter. If cyclic is re-centered, so would attitude

 

The idea of for example putting the cyclic x mm to the left and after finding it in a 30 degree bank is fundamentally wrong, regardless of helo type. The idea that recenter the stick would take the helo out of bank in to wings level is also wrong. This isnt the case for aircrafts either.

 

In most helos, the cyclic is a bit displaced during forward flight wings level( to the left for conterclockwise rotors and right for clockwise), after putting a helo in a bank, when recentering the stick it will go back to this position( slight displaced) to keep the bank. This means, in a continous right turn the stick might be a bit to the left( counterclock turning rotors) and in left turn it will be slighly tomthe right( clockwise rotors).

 

Look at the right turn at 8:00, right turn, stick to the left.

[FragBum]

As I have said before the guys at PC are working on their new Helicopter and are also accessing/revising the Gazelle. Great news.

 

Currently the cyclic is centric in action which feels different to the other DCS helicopters, this could be correct for the real deal I don't know. I have no problems with the sensitivity of the cyclic but I also have essentially a "modelled" cyclic for input no center detent or springs etc, I did find it difficult to fly with a "joy stick" input but that's another story.

 

 

For the DCS Gazelle flight control is very direct and controllable once your used to using mostly just slight pressure on the cyclic to provide input and of course it is more responsive then the Huey different rotor designs and the Gazelle is also less than half the weight of the Huey.

 

I used to run saturation down somewhere around 28 for cyclic until I got some time in an R44 (4.8 hrs logged) where I had to deal with you got it sensitive cyclic input the take home from that was I needed much better input controls then what I had at the time and way more spare money than I have. :D

 

One stark difference is transitioning into forward flight as the helicopter gains forward speed the nose will lift due to increased relative airspeed over the rotor at 90deg left or right side depending on rotational direction of the rotor which asserts lift at the front (gyroscopic precision) requiring more forward movement of the cyclic to maintain attitude. The first time I experienced this it was a real eye opener set power for climb at 60 KTS and gradually move the cyclic more and more forward to maintain 500Ft/min at 60KTS.

 

This does not happen with the DCS Gazelle indeed if you apply any forward pressure on the cyclic whilst accelerating forward it will push the nose down.

 

Interestingly if you carefully pretend and slightly allow the nose to come up a little the climb rate seems correct but there simply isn't a requirement to move the cyclic forward to compensate for blow back.

 

Now if anyone has a Gazelle and their IP ratting I'd be up for some instruction time in one. Just putting it out there. :thumbup:

 

Looking at videos of Gazelle and other small Helis cyclic input for control is usually (mostly) fairly small, watch some of those guys doing crop dusting etc.

 

Aside I do consider Chuck Aaron's videos and others as instructional content. :joystick: :D

[DmitriKozlowsky]

The post is great. The amount of stick deflection I see in video is amount of cyclic I use in DCS: UH-1H and KA-50 or about that. If I could film my cyclic motion when flying DCS: Gazelle , it would appear static. This is my #1 issue with DCS: Gazelle module.

[swatstar98]

You can make a video and posting it with the info of the controls, like the UH with the red box. You now what I mean?

[Deezle]

You can make a video and posting it with the info of the controls, like the UH with the red box. You now what I mean?

Here's a video I made comparing the Gazelle cyclic behavior to the Hip (I know, vastly different helos), even without the Hip to compare to, looking at the control indicator, you can see it's just weird. You can see an obvious deadzone, and once you pass it, any input you give will continue to roll or pitch the helo in that direction until the cyclic is centered again.

 

 

[Gunnars Driver]

Here's a video I made comparing the Gazelle cyclic behavior to the Hip

 

For the Mi-8 flight: No, that behavior doesnt seem possible. I cant swear of it tough but Id say it is less than 1% chance being possible. The cyclic stick if held left or right of center will make the helo to roll continous. I actually went by another nations mi-8 flight like 15years ago, on the 3rd crew seat but of course I didnt think about cyclic i puts that day.

 

[Edit]Didnt find any clear view of the Mi-8, nut this is from a Mi-171 Full flight simulator, and at 1:00 minute there is a left turn, after achieving bank the stick is centered to keep the bank, and at 1:24 there is a roll out to wings level, using opposite cyclic deflection. (Mi-171 is a civil version of the Mi-17, which is a more modern version of the mi-8):

[End Edit]

 

For the DCS Gazelle the first things that comes to mind is that the cylic doesnt need to be further forward the faster you fly. This behaviour is not possiblewith normal mechanical flight controls, the aerodynamic forces on the rotor ( togheter with gyroscopic precession) will set the laws so you need to have the cylic futher forward the faster you fly. It would only be possible to construct a behaviour like this with a Fly By Wire-system( which the Gazelle does not have).

I fly the only operative helo with FBW and it also has the stick movement further with speed.

 

To make life harder for the ones that might think of protesting;

Here is the US Army test of the SA-342:

https://apps.dtic.mil/dtic/tr/fulltext/u2/a016921.pdf

Page 17:

The variation of longitudinal cyclic stick position with airspeed from 50 to 150 KIAS was stable and nearly linear. The stick moved forward from 43 percent to approxi- mately 75 percent of the total displacement (0 percent was full aft and 100 percent was full forward cyclic) between 50 and 150 KIAS.

The DCS Gazelle cyclic is not correct in position vs airspeed. Edited February 28, 2019 by Gunnars Driver

[Deezle]

For the Mi-8 flight: No, that behavior doesnt seem possible. I cant swear of it tough but Id say it is less than 1% chance being possible. The cyclic stick if held left or right of center will make the helo to roll continous. I actually went by another nations mi-8 flight like 15years ago, on the 3rd crew seat but of course I didnt think about cyclic i puts that day.

 

[Edit]Didnt find any clear view of the Mi-8, nut this is from a Mi-171 Full flight simulator, and at 1:00 minute there is a left turn, after achieving bank the stick is centered to keep the bank, and at 1:24 there is a roll out to wings level, using opposite cyclic deflection. (Mi-171 is a civil version of the Mi-17, which is a more modern version of the mi-8):

[End Edit]

 

For the DCS Gazelle the first things that comes to mind is that the cylic doesnt need to be further forward the faster you fly. This behaviour is not possiblewith normal mechanical flight controls, the aerodynamic forces on the rotor ( togheter with gyroscopic precession) will set the laws so you need to have the cylic futher forward the faster you fly. It would only be possible to construct a behaviour like this with a Fly By Wire-system( which the Gazelle does not have).

I fly the only operative helo with FBW and it also has the stick movement further with speed.

 

To make life harder for the ones that might think of protesting;

Here is the US Army test of the SA-342:

https://apps.dtic.mil/dtic/tr/fulltext/u2/a016921.pdf

Page 17:

The DCS Gazelle cyclic is not correct in position vs airspeed.

So what you're saying is normally, bank is induced by some roll input with the cyclic and is more or less centered through the turn to maintain that bank. So the Gazelle is correct in that you cannot maintain roll in the cyclic through a turn without continuing to bank, which also conversely means the Gazelle is wrong in that when centering the cyclic in a bank results in the helo rolling back to level, which it should not do without counter roll in the cyclic.

 

 

 

The DCS Mi-8 is pretty highly regarded and one of the lead devs is or was an M-8 pilot IIRC, to me it sounds hard to believe FM could be so far off of what you say it should do and what that other simulator video appears to show, but without a control indicator on the screen it's hard to make precise comparison.

[Gunnars Driver]

So what you're saying is normally, bank is induced by some roll input with the cyclic and is more or less centered through the turn to maintain that bank. So the Gazelle is correct in that you cannot maintain roll in the cyclic through a turn without continuing to bank, which also conversely means the Gazelle is wrong in that when centering the cyclic in a bank results in the helo rolling back to level, which it should not do without counter roll in the cyclic.

 

 

The DCS Mi-8 is pretty highly regarded and one of the lead devs is or was an M-8 pilot IIRC, to me it sounds hard to believe FM could be so far off of what you say it should do and what that other simulator video appears to show, but without a control indicator on the screen it's hard to make precise comparison.

 

 

For the DCS Gazelle question, yes if I understand the q correct.

 

 

For the FFS Mi-171 I think its easy to se, just because they don't fly the mi-8 like a lady in that clip.

I actually can not see a solution to how the rotor system with controls could make the stick be needed to kept deflected during the turn, or more exakt I can not se how the cyclic stick could be kept deflected during a forward speed bank without the helo continue to roll.

If the mi-8 is modelled like that what happens if you do a for example 150km/h( I guess its km/h on the airspeed) and keep the cyclic maximum to the left or right ? It should continue to roll infinite, and not stop at a level of bank.

Cyclic deflection should be seen as a roll rate funktion. 100% deflection, 100% roll rate, and 40% = 40% roll rate.

[dahlgren]

Here's a video I made comparing the Gazelle cyclic behavior to the Hip (I know, vastly different helos), even without the Hip to compare to, looking at the control indicator, you can see it's just weird. You can see an obvious deadzone, and once you pass it, any input you give will continue to roll or pitch the helo in that direction until the cyclic is centered again.

 

 

 

Good video, was thinking about doing one myself, but am up in the alps away from my computer for some time. When banking in the gazelle if you engage the magnetic brake (trim), keeping the cyclic left, but centering your joystick you get a similar result as keeping the cyclic left in the mi-8. No rolling over.

[Deezle]

For the DCS Gazelle question, yes if I understand the q correct.

 

 

For the FFS Mi-171 I think its easy to se, just because they don't fly the mi-8 like a lady in that clip.

I actually can not see a solution to how the rotor system with controls could make the stick be needed to kept deflected during the turn, or more exakt I can not se how the cyclic stick could be kept deflected during a forward speed bank without the helo continue to roll.

If the mi-8 is modelled like that what happens if you do a for example 150km/h( I guess its km/h on the airspeed) and keep the cyclic maximum to the left or right ? It should continue to roll infinite, and not stop at a level of bank.

Cyclic deflection should be seen as a roll rate funktion. 100% deflection, 100% roll rate, and 40% = 40% roll rate.

Thanks.

 

 

Back to the aforementioned Bell 407 simulation that I earlier posited the Gazelle should feel more like. I just took her for a spin, and despite never having consciously noticed this before, the cyclic behaves just like I believe you described in this thread. It's a counter clockwise rotor so in a left bank you maintain just a little left cyclic to maintain the bank and in a right bank you actually give it a little counter cyclic to the left to maintain the bank.

 

 

So the Gazelle is correct in one aspect, in that if you maintain roll in the cyclic it will keep rolling, however the fact that it rolls back to level with neutral cyclic is incorrect. This same roll behavior is seen in the pitch behavior, which is also incorrect. Also there is something like a 5% deadzone in the cyclic, after which it feels like a light switch when the cyclic actually begins to respond, which also cannot be correct.

 

 

It's funny that I've never noticed the difference in the cyclic behavior between the 407 and the DCS Huey/Mi-8 (the Huey which you say is correct to need roll input to maintain a bank because of the teetering rotor if I understand you correctly), but the Gazelle immediately felt completely unnatural to me.

 

 

I am encouraged to hear that the FM is being worked on, because I really do like what the Gazelle has to offer, I just wish I enjoyed flying it more.

[FragBum]

 

 

So the Gazelle is correct in one aspect, in that if you maintain roll in the cyclic it will keep rolling, however the fact that it rolls back to level with neutral cyclic is incorrect. This same roll behavior is seen in the pitch behavior, which is also incorrect. Also there is something like a 5% deadzone in the cyclic, after which it feels like a light switch when the cyclic actually begins to respond, which also cannot be correct.

 

A couple of questions,.

 

I have never used the input device you have however I just consciously did perhaps the same test however I find that once a bank angle is set bringing the cyclic to center (as per the controls display) does not result in the Gazelle levelling. As I have effectively 25CM extension for cyclic input in theory I have finer physical control of input. I'm just thinking here is it possible with the short throw of your joystick that you are actually inputting a slight correction as and I presume your joystick has a centering mechanism?

 

Just observing if I set up a bank angle and bring the cyclic back to center, yes that center area of cyclic where not much happens the Gazelle remains more or less at the set bank angle. To bring it back to horizontal I only really need to blip the cyclic in the required direction to level the Gazelle.

 

When you say the cyclic feels like a light switch like an almost digital on/off that action reminds me of what I get if force feedback is enabled in DCS->Options->Misc.

[Deezle]

A couple of questions,.

 

I have never used the input device you have however I just consciously did perhaps the same test however I find that once a bank angle is set bringing the cyclic to center (as per the controls display) does not result in the Gazelle levelling. As I have effectively 25CM extension for cyclic input in theory I have finer physical control of input. I'm just thinking here is it possible with the short throw of your joystick that you are actually inputting a slight correction as and I presume your joystick has a centering mechanism?

 

Just observing if I set up a bank angle and bring the cyclic back to center, yes that center area of cyclic where not much happens the Gazelle remains more or less at the set bank angle. To bring it back to horizontal I only really need to blip the cyclic in the required direction to level the Gazelle.

 

When you say the cyclic feels like a light switch like an almost digital on/off that action reminds me of what I get if force feedback is enabled in DCS->Options->Misc.

My extension is in the 20cm region, I have also reduced the Y saturation of the pitch and roll to 70%, so my stick setup should have plenty of precision, and yes it has spring loaded cam centering.

 

 

Great call on the force feedback option, I found that was enabled despite me not having a force feedback stick. The deadzone in the center is now gone, overall the helo feels much better, however it still rolls back to level with neutral cyclic for me, and the pitch behavior is still obviously wrong. But overall, it's much better with that deadzone gone.

[swatstar98]

My extension is in the 20cm region, I have also reduced the Y saturation of the pitch and roll to 70%, so my stick setup should have plenty of precision, and yes it has spring loaded cam centering.

 

 

Great call on the force feedback option, I found that was enabled despite me not having a force feedback stick. The deadzone in the center is now gone, overall the helo feels much better, however it still rolls back to level with neutral cyclic for me, and the pitch behavior is still obviously wrong. But overall, it's much better with that deadzone gone.

The most common problem with the gazelle

[Gunnars Driver]

(the Huey which you say is correct to need roll input to maintain a bank because of the teetering rotor if I understand you correctly), but the Gazelle immediately felt completely unnatural to me.

 

No, that is nit the case.

 

All helicopters should have the same ”cyclic in center” behaviour* during a stable turn.

 

When in forward speed and in a turn, the sum of all G-forces is perpedicular to the helicopter floor. If you shut your eyes, you cant really know that hou are banking left or right or going wings level. This is a fact, not an opinion. This also means that the helo ”can not feel” what is horizontal or what is wings level**. Because the helo can not know whats horizontal it of course can not roll back by itself. Logical if you think about it.

This also leads to the conclusion that if the helo can not detect the difference between horizontal flight or in a banked turn it also will have about the same stick position for horizontal flight and a banked turn.

 

From wikipedia(for reference check):

”The helicopter is statically stable because each oscillation will take it through its original position, but it is dynamically unstable because the amplitude of the oscillations progressively increases”

 

The ones here that actually did fly real helos understand this. A helicopter is not stable and it will not go back nice and easy to the original position if you release a cyclic that is trimmed for level flight. ( if you have a stab system like SAS or ATT it can, but as we talk the basics of flight controls we should consider the stab system -OFF. If it was on, it anyway have to use the same stick inputs we are talking about to keep it in a banked turn or bring it wings level).

 

This is info about helo stability: I did not read it but it looks like a good start to learn from:

http://helicopterblog.com/?p=986

If you dont already know( know you know not think you know) you need to read it begore it is any idea to continue.

 

*) As said before, stick is most often a bit displaced sidewards during forward flight( left or rigt depending on rotor direction).

 

**) Without a gyro feeding an stabilisation system/autopilot. If you have a flight control system with attitude mode you can get into a turn by not pressing the force trim release/mag brake and when your turn is done, you release the stick and it will automatically bring the helo back to the set attitude(could be wings level or another bank angle). Still, to maintain a steady bank angle you need to recenter the stick and the ”autopilot” need to use opposite stick to bring the helo back to wings level.

[FragBum]

@Gunnas Driver.

 

Ignoring the Gazelle for the purpose of this question and I may well be incorrect. :)

 

Could you advise the terms for conditions for cyclic position for non trimmed flight.

 

a) Mechanical center this is simply physical center of the cyclic action.

 

b) The cyclic position that brings the aircraft into equilibrium taking into account CoG and other forces acting on the aircraft.

 

I very rarely use trim in DCS so for me the notion of center is really the cyclic position (that attempts) to keep the aircraft in equilibrium as per b) above and this position is usually not the physical mechanical center of cyclic travel.

 

I understand for a joystick the use of trimming to move the balance point to mechanical center makes it physically easier to deal with the action.

[Gunnars Driver]

@Gunnas Driver.

Could you advise the terms for conditions for cyclic position for non trimmed flight.

 

Im not sure I understand what the question is. I leave the a) and b) out ti begin with.

If we describe ”trimmed flight” first, then all other control positions is non trimmed flight.

 

First, the basics from helicopter stability most be understood( must read and understand my link in former post).

 

Second, because of the fact that a helicopter is ’statically stable but dynamically unstable’ we must understand that a really trimmed control position only exist in that fraction of a second just when the force trim release/mag brake button was pressed. Immediatly after the cylic should be needed to be moved to the new position where it has to be for sustained flight in the desired way( straight and level or turning etc). This is the reason why helicopter pilots continously move the cyclic in flight. One might think that the movement of the stick comes from nervousity or parkinsson but thats only partly true :).

(Look at youtube for reference of cyclic movement during flight).

 

You can not release the cyclic for any longer period even if perfectly trimmed because that cyclic position no longer correlates to trimmed position. The helo will start to raise or lower the nose and it will start to bank right or left. How quickly this happens is depending on the type of rotor system and helicopter size etc.

 

For a real cyclic the trim always moves the stick.

A FFB gamingstick might do the same( never seen one).

Normal gaming joysticks can’t move the center giving a few options to the developer of the module how to simulate this. Either make the model not needing the cyclic hold forward for forward flight. This seems to be the case in the DCS Gazelle. Or make it possible to simulate the trim movement by moving the joystick center to correlate with the stick position where the stick is when pushing the mag brake / force trim release button. This is the case of the DCS Huey. It doenst stretch the joystick ”other side” making the joystick no longer able to use the full range.

Power changes like when dumping the pitch which need bigger corrections can put the gamer in a position where the actual cyclic range is not enough if not trim resetted( this happens on the DCS Huey.)

[FragBum]

Im not sure I understand what the question is. I leave the a) and b) out ti begin with.

If we describe ”trimmed flight” first, then all other control positions is non trimmed flight.

 

First, the basics from helicopter stability most be understood( must read and understand my link in former post).

 

Second, because of the fact that a helicopter is ’statically stable but dynamically unstable’ we must understand that a really trimmed control position only exist in that fraction of a second just when the force trim release/mag brake button was pressed. Immediatly after the cylic should be needed to be moved to the new position where it has to be for sustained flight in the desired way( straight and level or turning etc). This is the reason why helicopter pilots continously move the cyclic in flight. One might think that the movement of the stick comes from nervousity or parkinsson but thats only partly true :).

(Look at youtube for reference of cyclic movement during flight).

 

Yes,.. :thumbup:

 

 

You can not release the cyclic for any longer period even if perfectly trimmed because that cyclic position no longer correlates to trimmed position. The helo will start to raise or lower the nose and it will start to bank right or left. How quickly this happens is depending on the type of rotor system and helicopter size etc.

 

IP instructed me on that said it was important. :)

 

I'll rethink the question/context ok. :(

[Gunnars Driver]

I'll rethink the question/context ok.

 

 

No problem, just did'nt know exactly what to answer :)

 

Did it answer the q's ?

[Deezle]

No, that is nit the case.

 

All helicopters should have the same ”cyclic in center” behaviour* during a stable turn.

Damn, my reading comprehension has been terrible in this thread.

 

 

I do notice after trying again that the Huey does handle similarly to how you state it should, it's weird how I can spend so much time with these helos and never notice that until I looked for it.

 

 

 

I will also say, the I've tried the Mi-8 with the autopilot system off and the cyclic also behaves much more like you say (and that other sim video shows) it should. :joystick: Although it appears the autopilot is indeed on in that video. So that's an interesting discrepancy between the two sims.

Edited March 2, 2019 by Deezle

[Gunnars Driver]

I will also say, the I've tried the Mi-8 with the autopilot system off and the cyclic also behaves much more like you say (and that other sim video shows) it should. :joystick: Although it appears the autopilot is indeed on in that video. So that's an interesting discrepancy between the two sims.

 

For stab systems/autopilots they have one thing common IRL: They have to use the sticks exactly as the pilot have to. If you are using SAS or ATT mode or similar( stabilisation modes that makes the helo more easy to fly) and release the stick you will se the stick moving in the same maner you had to do to stabilize it. The stick is mechanically connected to the rotor system.

This is also the same for the automatic flight modes( ALT: keeping set altitude, Heading: keeping heading etc.) so you will see the stick move. If turning the heading knob making the helo turn will make thecstick do exactly as you would have to do.

 

From you post it looks like DCS Mi-8 simulation of the stick when autopilot is on is not correct.

[msalama]

when autopilot is on is not correct

 

The Mi-8 development lead was a professional pilot with thousands of hours on the type and several RL transport chopper drivers have praised the product too, and not one of them has ever said a word about this being wrong in any way, shape or form. So I'm willing to believe they're right and you're wrong, unless you've got some tangible and unequivocal evidence supporting your claim.

Edited March 2, 2019 by msalama

[FragBum]

The Mi-8 development lead was a professional pilot with thousands of hours on the type and several RL transport chopper drivers have praised the product too, and not one of them has ever said a word about this being wrong in any way, shape or form. So I'm willing to believe they're right and you're wrong, unless you've got some tangible and unequivocal evidence supporting your claim.

 

Or there in another explanation. Some of this discussion is theoretical as for the 'AP" in the Mi-8 we don't know.

 

As for the discussion of a helicopter being put off level and into a bank by pushing the cyclic and returning it to the "neutral" position the aircraft wont bring it self back unless correction input is subsequently applied. Which seems to be the aspect being discussed.

 

It may also be more polite to enquire as to the person making the claim before berating them, he could be an actual pilot also with thousands of hours of flying. Just saying. :)