Dampening definition

[Havner]

Just get me right, I'm not asking about basics of autopilot/trim control.

 

I'm asking what is dampening and dampening only. I don't exactly get this term and I didn't manage to find it anywhere. The only mention I found is that it help with player induced oscilations. What is it?

 

To put things into perspective. Per flight manual: pitch, bank and heading channels have two options, dampening and hold. The hold part I get very well. But when you leave them on and enable FD the hold part is turned off. Dampening stays.

 

My question would be: What is the difference between FD and a situation where all the channels are turned off completely? I can't see any and in theory they differ by this dampening.

 

Also what exactly is turned off when you hold the trimmer? Dampening, hold, both? Or just the heading hold? The last one is definitely turned off.

[Flagrum]

My question would be: What is the difference between FD and a situation where all the channels are turned off completely? I can't see any and in theory they differ by this dampening.

Try it out and you will notice the difference very quickly. :o)

Dampening smoothes the pilot inputs. Without dampening the helo is very very sensitive to your inputs and quite instable.

 

Also what exactly is turned off when you hold the trimmer? Dampening, hold, both? Or just the heading hold? The last one is definitely turned off.

While the trimmer button is depressed, only the dampening is in effect. That is the same as if you turn on the FD. That both is different to all channels turned off completely. As I said above: try it and you will see.

 

Tie a rope loosely between two trees, then get onto that rope and balance from one end to the other - that is hold mode and dampening turned off completely.

Replace the rope by a steel cable, pull it a tight and firm, and then try to balance on it again. That is dampening.

Now get two friends to hold both of your arms while you balance along the cable. That is hold mode on. :o)

Edited September 23, 2013 by Flagrum

[zaelu]

dampening means attenuation.

 

your inputs may be too steep or too jerky for helicopter to handle well so the dampening attenuates them. also the controls will feel stiffer and harder to move so your brain gets used easier not to overcontrol.

[Suchacz]

This might help: http://www.simhq.com/_air13/air_429a.html

[Havner]

Thanks guys. This has been really helpful.

[Hunden Ynk]

[...] The only mention I found is that it help with player induced oscilations. What is it?

To my understanding it's similar to trying to balance a cup of coffee, walking down the corridor. Your continuous corrections will just make the liquid more and more unsettled. Now replace coffee with aircraft controls, and things get more dangerous.

[Flagrum]

To my understanding it's similar to trying to balance a cup of coffee, walking down the corridor. Your continuous corrections will just make the liquid more and more unsettled. Now replace coffee with aircraft controls, and things get more dangerous.

You just must stop watching the cup. :o)

That's at least my experience. If you look at the cup, you try (unconsciuosly) to keep it stable - and thus, as you already said, unsettling the contents of the cup. Our motoric skills seem just to be too coarse ... :o)

But if you don't look at the cup and just keep on walking, we hold the cup much more relaxed and thus just letting physics take care of not spilling the coffee (center of gravity, etc).

 

Well, but how or even if at all this relates to your example of dampening ... I don't know. I leave that to you to decide. :D

[Hunden Ynk]

Is the coffee example all wrong? I'm thinking pilot induced oscillation is the same (unconscious) behavior of micro correcting, where the pilot ends up correcting the corrections in an escalating loop. Wrong?

[zaelu]

Is not wrong. But my corridor is usually dark. :D

[Flagrum]

Is the coffee example all wrong? I'm thinking pilot induced oscillation is the same (unconscious) behavior of micro correcting, where the pilot ends up correcting the corrections in an escalating loop. Wrong?

No, in regards to induced oscillation it is a good example, i think.

 

My doubts refered more to my own example of not watching the cup ... I found it interesting, but it might not really relate to "dampening" :o)

[St3v3f]

Well try flying with a blindfold on and we'll find out ;)

[BBQ]

Awesome analogy -- well done :)

 

Try it out and you will notice the difference very quickly. :o)

Dampening smoothes the pilot inputs. Without dampening the helo is very very sensitive to your inputs and quite instable.

 

 

While the trimmer button is depressed, only the dampening is in effect. That is the same as if you turn on the FD. That both is different to all channels turned off completely. As I said above: try it and you will see.

 

Tie a rope loosely between two trees, then get onto that rope and balance from one end to the other - that is hold mode and dampening turned off completely.

Replace the rope by a steel cable, pull it a tight and firm, and then try to balance on it again. That is dampening.

Now get two friends to hold both of your arms while you balance along the cable. That is hold mode on. :o)

[BBQ]

The word that seems to be missing from this thread: oscillations

 

So when I'm constantly making micro adjustments to the cyclic, it would soon get hard to manage as without dampening, nothing would be prevent my input corrections and over-corrections from adding up (e.g., I pull back, but went too far, so push forward, when actually I should have waited a second or two for helo to respond to initial back pull, instead, end result was that I was pushing forward when helo was also pitched forward, etc., ad infinitum, until someone in a village below you calls the local radio station and reports some "porpoise-like" object flying through the sky. It's much easier when the inputs are dampened and the oscillations cancel each other out, or are lessened in some way. Not sure how it actually works mechanically or electrically or pneumatically, or hydraulically, however it may be in the Ka-50.

 

From an article about tight-rope walkers:

 

He designed a means of safely anchoring both ends of the cable both at Niagara Falls and the Grand Canyon where no suitable infrastructure existed. Perhaps most notable, he designed an innovative means to stabilize the cable and dampen oscillations. Highwires in a circus tent or at an amusement park are only 30-50 feet above the ground, and are stabilized with a system of guy wires attached from the main wire to the ground below. This is clearly impractical at the heights of Nik Wallenda’s stunts. “Michael designed a solution wherein the cable is stabilized with a system of pendulums made of weights suspended by smaller cables attached to the main cable. The engineering problem was to determine the number, spacing, length and weight of these pendulums needed to counter the effects of wind and the vertical oscillations created by Nik’s steady cadence as he crossed the wire.”

Edited September 23, 2013 by BBQ

[P1KW]

damping = a cup of puree

no damping = a cup of coffee

 

You will not care about the content, only cares that this does not spill.

 

Yes, a good waiter / pilot does not spill neither of them ... :music_whistling:

 

Greetings!!

[Bushmanni]

I tested this just now. I turned the AP channels off and gently lifted to a hover and trimmed the chopper. After that I let go of the controls and observed what would happen. As the weather was dead calm there was only a slight oscillation in pitch axis (+-2 degrees, 0.1Hz). I then turned on the channels and FD (while not touching the stick) and the oscillation kept going. I then tried some rapid 10 degree pitch ups and downs and observe what would happen. With channels off the chopper would keep going the direction it was moving before centering the stick and after reaching a high point would swing back like a pendulum. With channels and FD on the chopper would gently but quite quickly stop moving after centering the stick and then very slowly start to drift towards the level attitude. The same behavior was happening on both pitch and roll axis. When channels were off rolling would cause also yawing and make the chopper start turn slowly but with channels and FD on the nose would pretty much keep its heading while making short and fast roll maneuvers but it would still drift very slowly when chopper was kept tilted.

 

Having AP channels on or off didn't have any noticeable effect on roll or pitch rate or how quickly the chopper would respond to control inputs. The only effect was that when you suddenly stopped the maneuver the chopper wouldn't start oscillating like a pendulum but it would stop (or greatly reduce the angular speed) itself instead.

[Hunden Ynk]

Achievement unlocked: Kamov Test Pilot :thumbup: