Axis input delay - huge

[Bucic]

Why there is so huge delay between actual game controller movement and in-game helicopter controls movement? Especially rudder and collective. It takes more than a full second (if not two) for the helicopter rudder pedals to go from full left to full right deflection. Are there such heavy dampers on those axes in real helicopter?

[astrospud]

Are you using Saitek Direct Output? Refer to this thread I posted a wee while back...

 

I hope this helps...:)

[Bucic]

I don't think it's relevant. FirstI see no lag. Second - I use non-Saitek controller for rudder pedals. Try it yourself:

- push your rudder pedal all the way right and observe in-game Ka-50 pedals (or pilot legs RShift+P)

- now kick the left pedal as fast as you can all the way left

- you have your left pedal fully pressed in less than 0.5 s

- it takes ~1.5 s for the in-game controls to catch up

 

Also the RCtrl+Enter Controls indicator indicates in-game controls positions, not player's joystick etc. positions like I previously thought.

Edited September 24, 2010 by Bucic

[AlphaOneSix]

If I had to guess, I would say that the flight controls in the actual aircraft are just not able to move that fast, probably because of the hydraulic boosters. But I don't know for sure.

[Bushmanni]

It's a general feature of hydraulic controls that they have a certain maximum deflection speed. The hydraulic pump is able to pump only limited flow of fluid through the system. Having bigger valves, hydraulic lines and a pump would make it faster. I don't know how it's actually set up in Ka-50 but there's certainly some limits that are imposed by laws of physics. Usually the controls are set up so that the control stick isn't able to move faster than the actuator which speed is limited by the hydraulic pump output.

Edited September 24, 2010 by Bushmanni

[sweinhart3]

Can I ask why you would want instantaneous deflection? Im not an aeronautical engineer so I'm just guessing but I would think that instantaneous movement in such large proportions in a fast moving aircraft could disrupt airflow enough to cause an unstable condition. Of course that wouldnt be the case at slow speeds, but aside from stunt aircraft designed for those stresses, Im not sure of any aircraft that can instantly deflect from one extreme to the other.

[Bucic]

If I had to guess, I would say that the flight controls in the actual aircraft are just not able to move that fast, probably because of the hydraulic boosters. But I don't know for sure.

That was my first guess too.

 

It's a general feature of hydraulic controls that they have a certain maximum deflection speed. The hydraulic pump is able to pump only limited flow of fluid through the system. Having bigger valves, hydraulic lines and a pump would make it faster. I don't know how it's actually set up in Ka-50 but there's certainly some limits that are imposed by laws of physics. Usually the controls are set up so that the control stick isn't able to move faster than the actuator which speed is limited by the hydraulic pump output.

That I know but I doubt/didn't realized that they are so slow / there are such huge limits. Now I wait for a bloke in a shiny armor who can tell me what are the force=f(deflection rate) characteristics. I really could use such info. AlphaOneSix :smilewink:

 

Can I ask why you would want instantaneous deflection? Im not an aeronautical engineer so I'm just guessing but I would think that instantaneous movement in such large proportions in a fast moving aircraft could disrupt airflow enough to cause an unstable condition. Of course that wouldnt be the case at slow speeds, but aside from stunt aircraft designed for those stresses, Im not sure of any aircraft that can instantly deflect from one extreme to the other.

See my response to Bushmanni. I don't 'want' it. I suspect the delay is too high OR I'd like to hear some technical explanation.

 

"Im not sure of any aircraft that can instantly deflect from one extreme to the other"

Tell it to X-Plane plane makers, hahahahaha :megalol:

http://forums.x-plane.org/index.php?showtopic=46060&st=0

Edited September 24, 2010 by Bucic

[AlphaOneSix]

Now I wait for a bloke in a shiny armor who can tell me what are the force=f(deflection rate) characteristics. I really could use such info.

 

Well I can try, but I have to make some assumptions: First, I have to assume that the Ka-50 uses KAU-115 hydraulic boosters. Second, I have to assume that the control of the rudders on the tail is controlled in a linear fashion by the differential pitch (i.e. directional/yaw) booster (i.e. if the booster's actuator rod is fully extended, the rudders deflect fully in one direction, when fully retracted, rudders are full deflection the other way).

 

If those assumptions are correct, then I have the following helpful information...otherwise, I have the following useless information:

 

The output rod total travel for a KAU-115 hydraulic booster is 74mm. The fastest the outpost rod can move (that I've found) is 40mm/s. That means that moving from full deflection one way, to full deflection the opposite way would take 1.85 seconds, assuming the rod moves at its fastest rate.

 

EDIT: As a side note, I should mention that the KAU-115 is the hydraulic booster used in current models of the Mi-8/17 and Mi-24/35. I find it very likely that the Ka-50 uses the same boosters, but I could always be wrong. We'd need AirTito to correct me, as he used to be an engineer on the Ka-32.

Edited September 24, 2010 by AlphaOneSix

[ericinexile]

^^^

 

What he said.

 

 

But more simply, the visual representation doesn't necessarily correspond with actual control movement. Controls flopping around inside the cockpit are animations. What's important is aircraft response. And that has never been mentioned as a problem.

[Bucic]

Well I can try, but I have to make some assumptions: First, I have to assume that the Ka-50 uses KAU-115 hydraulic boosters. Second, I have to assume that the control of the rudders on the tail is controlled in a linear fashion by the differential pitch (i.e. directional/yaw) booster (i.e. if the booster's actuator rod is fully extended, the rudders deflect fully in one direction, when fully retracted, rudders are full deflection the other way).

 

If those assumptions are correct, then I have the following helpful information...otherwise, I have the following useless information:

 

The output rod total travel for a KAU-115 hydraulic booster is 74mm. The fastest the outpost rod can move (that I've found) is 40mm/s. That means that moving from full deflection one way, to full deflection the opposite way would take 1.85 seconds, assuming the rod moves at its fastest rate.

 

EDIT: As a side note, I should mention that the KAU-115 is the hydraulic booster used in current models of the Mi-8/17 and Mi-24/35. I find it very likely that the Ka-50 uses the same boosters, but I could always be wrong. We'd need AirTito to correct me, as he used to be an engineer on the Ka-32.

Thank you very much. That's very useful information. Imagine me absorbing it like a junky ;)

So on the forces subject - if pilot tries to push the rudder pedals faster than the whole coupled control elements displacement the force he experiences can rise to infinity.

 

Now, what do you think, what would be the controls behavior on releasing the force acting on them e.g. pilot puts rudder pedals in maximum deflection and then quickly takes both of his legs off the pedals? That would tell me about the amount of free damping on the controls. Goes back quickly => no damping. Goes back slowly => some damping. I would put my money on the latter.

 

I would also welcome a guess on rudder pedal behavior near neutral position during slow movement. Force close to linear?

 

But more simply, the visual representation doesn't necessarily correspond with actual control movement. Controls flopping around inside the cockpit are animations. What's important is aircraft response. And that has never been mentioned as a problem.

I truly despise such gimmicks on the simulator developers side (AFAIK it's Il-2 case). Animation should always be 100% simulation data driven. Otherwise I want my 15 bucks back. Fortunately I know of no such dirty gimmicks in DCS series. In fact I recently learned that DCS A-10C Warthog control stick wobbles when engine starts due to hydraulic pumps kicking in!

 

Besides you can confirm it any time using controls position indicator.

Edited September 24, 2010 by Bucic

[Frederf]

There are several flight sim that represent pilot pulls instead of control movements directly to prevent unrealistic deflection rates and introduce the human element.

 

Like you're blacking out in a dive in a P-40 pulling back on your joystick but the game actually says "hey, maximum pull from a weakened pilot against this huge stick load is not going to cut it."

 

FSX's elevator trim axis changes at its maximum rate even if your joystick axis can slam from limit to limit in a blink of an eye.

[Bucic]

There are several flight sim that represent pilot pulls instead of control movements directly to prevent unrealistic deflection rates and introduce the human element.

Yay for those sims then :thumbup: Please don't take this topic as 'hey, my Ka-50 in-game pilot jumps on his rudder pedals slower than I can - look!' This topic's subject is quite different.

[AlphaOneSix]

Hydraulically-assisted flight controls in a helicopter are non-reversible. That is, no amount of force applied to the control surfaces will cause them to make the flight controls in the cockpit move. In other words, if you jam the left pedal to the floor (well, it will only go as fast as the hydraulic booster can push) and then suddenly release your feet from the pedals, the pedals will stay right where they are, they will not move at all until the pilot pushes on them again.

[Bucic]

Hydraulically-assisted flight controls in a helicopter are non-reversible. That is, no amount of force applied to the control surfaces will cause them to make the flight controls in the cockpit move. In other words, if you jam the left pedal to the floor (well, it will only go as fast as the hydraulic booster can push) and then suddenly release your feet from the pedals, the pedals will stay right where they are, they will not move at all until the pilot pushes on them again.

No centering spring or anything? :shocking:

Same for the cyclic stick?

Edited September 24, 2010 by Bucic

[AlphaOneSix]

No centering spring or anything? :shocking:

Same for the cyclic stick?

 

If the aircraft in question has force trim with feel springs, then the controls would "center" to the last position where the trimmer was released. If you had the pedals centered, and then without holding the trimmer switch, pushed them completely to one side or the other, and then released them, yes...they'd return to center. I don't normally consider that alternative, since I am so used to automatically holding in the trimmer button whenever I move the controls. For example, one of our pilots let me hover for about 30 minutes the other day and practice picking up to a hover then sliding around then landing, etc. Once I got the aircraft into a stable hover, I'd let go of the trimmer and only make very small adjustments. However, whenever I wanted to reposition the aircraft or land or anything, I'd hold the trimmer button in for the duration of the maneuver, only releasing the trimmer once I'd reached a stable hover or had landed.

[Bucic]

If the aircraft in question has force trim with feel springs, then the controls would "center" to the last position where the trimmer was released. If you had the pedals centered, and then without holding the trimmer switch, pushed them completely to one side or the other, and then released them, yes...they'd return to center. I don't normally consider that alternative, since I am so used to automatically holding in the trimmer button whenever I move the controls. For example, one of our pilots let me hover for about 30 minutes the other day and practice picking up to a hover then sliding around then landing, etc. Once I got the aircraft into a stable hover, I'd let go of the trimmer and only make very small adjustments. However, whenever I wanted to reposition the aircraft or land or anything, I'd hold the trimmer button in for the duration of the maneuver, only releasing the trimmer once I'd reached a stable hover or had landed.

Ah, ok, so not shocking after all :)

I have to repeat my question - how does it feel to press against control boosters? Just don't say 'NICE' :D

[AlphaOneSix]

Ah, ok, so not shocking after all :)

I have to repeat my question - how does it feel to press against control boosters? Just don't say 'NICE' :D

 

I have never ever (and never ever will I) come even close to pushing the controls anywhere near the max rate of movement of the boosters. That being said, if you do no have the trimmer button pressed, you feel the increasing spring tension of the feel springs (this tension depends on the aircraft, I only have hard data for the Mi-8/17 at this time, but the values are roughly standard throughout all aircraft that I've ever worked on that use feel springs). With the trimmer button pressed, you feel virtually no resistance at all, the only resistance is the natural mechanical resistance of moving the flight controls through a series of rockers as they snake through the aircraft on the way from the control stick to the hydraulic boosters (which is extremely light).

[Bucic]

I have never ever (and never ever will I) come even close to pushing the controls anywhere near the max rate of movement of the boosters.

OK, so I get it that at rates required for small adjustments during hover you feel centering springs only OR nothing, when trim button is pressed.

[AlphaOneSix]

Right on.

[Bucic]

Right on.

Thank you for your time!

[Slayer]

Having to recenter the pedals in the game while having a FFB stick is hard to get used to since you dont recenter the stick. I would mod my pedals in a sec to hold position if it would work like that in the game :/

 

Seems all you would need are a few cheapo hydraulic dampers and to just adjust the pedals so there is no centering spring...but then this would make the pedals terrible for fast movers since the pedals would no longer return to center.

[Frederf]

I have had problems with extremely laggy controls using my X-45. Axis inputs were 5-10 seconds late. The problem I think was with some oddly-programmed advanced profile macros that had very short loops. A reboot or a reprofile would fix it but definitely ruined all your flight planner planning (which isn't save-able :( ).

[Bucic]

Having to recenter the pedals in the game while having a FFB stick is hard to get used to since you dont recenter the stick. I would mod my pedals in a sec to hold position if it would work like that in the game :/

 

Seems all you would need are a few cheapo hydraulic dampers and to just adjust the pedals so there is no centering spring...but then this would make the pedals terrible for fast movers since the pedals would no longer return to center.

It's OT but can you make BS not waiting for recentering rudder pedals - just the stick?

 

I have had problems with extremely laggy controls using my X-45. Axis inputs were 5-10 seconds late. The problem I think was with some oddly-programmed advanced profile macros that had very short loops. A reboot or a reprofile would fix it but definitely ruined all your flight planner planning (which isn't save-able :( ).

I haven't had any problems like that. You can investigate macros from my profile anytime.

[Bushmanni]

I have been using many kinds of hydraulically assisted work machines that have had several different kinds of hydraulically assisted steering systems. The ones that have the same kind that is found in helicopters generally have no feel other than very light resistance like in a fluid dampener and when you try to turn the wheel too fast the resistance feels like the resistance in brake pedal. It gives in a little bit but pushing harder doesn't make it go faster. I would suspect the helicopter controls feel pretty much like this?

[Bucic]

I have been using many kinds of hydraulically assisted work machines that have had several different kinds of hydraulically assisted steering systems. The ones that have the same kind that is found in helicopters generally have no feel other than very light resistance like in a fluid dampener and when you try to turn the wheel too fast the resistance feels like the resistance in brake pedal. It gives in a little bit but pushing harder doesn't make it go faster. I would suspect the helicopter controls feel pretty much like this?

Thanks for your input. Definitely a legitimate guess.