Trimming the Ka-50

[Esac_mirmidon]

Thanks AlphaOneSix.

 

I am also doing test and trials with my brand new russian version downloaded today. No words to express how happy i am.

[EvilBivol-1]

...input is immediately transfered to the simulation resulting in a pitch, bank or yaw change.

Incorrect. The sim gives you a moment to recenter the stick before assigning the new trim setting to the FCS. You can even increase this delay if you wish, through the LUA files. See the User FAQ.

 

Trim settings are assigned when the trim button is released. For simulation purposes for users with non-FF sticks, the simulation then gives you a moment to recenter the stick before applying the assigned trim. Holding the trim button down while maneuvering to your new desired trim setting is fine, but holding it down while you recenter the stick will not work, because when you release the trim button after your stick is centered, that will become your new trim setting.

Edited November 19, 2008 by EvilBivol-1

[Prophet]

So as I was doing before, if I moved the cyclic and then hit the trim and then recentered, it does in fact destabalize the helo from the input of the stick returning to center.

 

But if you hold the trim before moving the cyclic, and release when you have it where you want, then return to center. There is no issue's. Works marvelously.

 

Definately have to learn to hold the trim when using the cyclic.

[mckee14]

it's a little bit strange first, the whole trim-thing...

 

yesterday i tried different methods. if you don't hold down the trim button when maneovering, it works best if you only HIT the trim button and immediately release the stick. do not press it longer than for a fraction of a second.

otherwise, hold it down while steering, then release the trim and immediately release the stick.

 

if you hold down the trim longer than a fraction of a second, but not long enough (i don't know the time, maybe something around 2-3 seconds) it seems to turn my shark into a gogo-dancer, shaking like crazy.

 

btw, maybe it depends on the stick?? i'm using a x-52...

[JimMack]

Covered in the manual which has just come out in English. Trim is going to have to be a reflex action to fly this ac properly. Trim often.

 

Somewhere there is an excellent video (produced I believe by Kamov) of a pilot flying a Ka-50. It has 4 windows: text, HUD, external view, and in-cockpit. You will see by looking at his hand on the cyclic, that he is frequently trimming and untrimming when maneuvering.

Edited November 20, 2008 by JimMack
sprlling

[Stalintc]

In order to fly with some degree of control, when I want to change direction or manuver I have been holding in the trim button, performing flight manuvers (change course, low level obstacle avoidance etc etc) then resettling my course and pitch to a stable position for speed etc. Then releasing the button and letting the stick centre.

 

This has been working a treat.

 

Thanks for starting this discussion I am now better able to understand the trimming mechanism thanks to this.

[Acedy]

Somewhere there is an excellent video (produced I believe by Kamov) of a pilot flying a Ka-50. It has 4 windows: text, HUD, external view, and in-cockpit. You will see by looking at his hand on the cyclic, that he is frequently trimming and untrimming when maneuvering.

 

That video can be found here:

http://www.virtual-jabog32.de/index.php?section=downloads&subcat=30&file=807&lang=en

[deviletk]

Ok good, it appeared to me like you almost needed FF from Urze's FF demo. Guess I won't make any more stupid posts like this until I get my hands on the game and can speak from experience ;)

 

It was not a stupid post at all. It had me worried as well. ;)

 

Regards

Alex

[V1Rotate]

Also it should be noted that once trimmed for say nose-in forward flight and you are stable in that flightpath, you shouldn't need to retrim if you are just making small corrections to your flightpath trajectory: Eg low level avoiding trees/buildings/terrain etc.

 

Instead use the collective and cyclic controls to maneuvre until you are clear of the obstruction, at which point your heli should return to the previous "hands-off" stable condition at more or less the same height and speed. Clearly if you've made big corrections you will need to trim again.

[Esac_mirmidon]

And waht happens if you fly with the trim button pressed ?

 

What systems are working while trim pressed? No FCS or decressed stability augmention until trim released?

 

This question is because while you are correcting your attitude or position certainly it would take several seconds before you are in the desired position until trim release. Because when i press the trim button i feel totally different the control and stability of the Ka-50, much more stable and controlled than if i cancel the autopilot stability modes pressing each blue buttons.

 

Who and how is taking control when the trim is pressed this seconds?

Edited November 20, 2008 by Esac_mirmidon

[EvilBivol-1]

Added some trim information to the user FAQ.

[Esac_mirmidon]

Thanks, reviewing now..

[Slayer]

Thanks for all the replies, looks like I wasn't the only one confused. It's all new to me since no heli sim I've ever played modeled the trim realistically.

[hitman]

Trimming BS--How does it work?

 

I understand what buttons to trim the heli...what I dont understand is what it does. The manual is kind of light on a description on how to properly trim it. It doesnt trim like it would an aircraft...and from what I understand in the manual, you press T and your aircraft is trimmed. You hold down T, your aircraft is trimmed more.

 

What is the point Im missing here?

[crazysundog]

The question is a lot easier to answer if I know you've flown it! Then I can tell what to take notice of; and what not to do...

[EvilBivol-1]

Hitman, try the User FAQ sticky, if you have not already.

[hitman]

Hitman, try the User FAQ sticky, if you have not already.

Thats not what Im asking...Im not asking on how to make it work, Im asking HOW it works. Whats posted in the FAQ is even more brief than in the manual.

[AlphaOneSix]

Okay, I'll try not to make this into a book...

 

The trimmer button does two things, first, it removes spring pressure from the controls so that they are easier to move, and second, it temporarily interrupts the autopilot.

 

First, the springs. On the way to the hydraulic servos, the flight controls go through a set of springs that are attached to a rod that is held in place magnetically. When the trim button is PRESSED (turning OFF trim), the magnets are deenergized, and the rods are allowed to move freely with the controls, so the springs basically float freely and offer no resistance to the pilot moving the controls. When the trim button is NOT being pressed, the magnets are energized (and trim is considered ON), so that the rods that attach to the springs no longer move, meaning that moving the flight controls will require additional force to overcome the springs. This is used to keep the controls in one place without having to keep your hands and feet on them at all times. Making small adjustments with the trim on is fine, but in most cases, when a control movement is needed, you would press the trim button, make your adjustment, and release the trim button. In heavy maneuvering, you would be pressing the trim button a lot. I have hovered an Mi-17 a few times, and I just keep the trim button pressed the entire time.

 

Second, the autopilot. With the autpilot channels on, the autopilot send control inputs to the servos in addition to your flight controls. The autopilot sends control inputs that try to keep the aircraft generally pointed where you left it when you last trimmed. When the trim button is PRESSED, it interrupts the autopilot, so that it will not try to hold anything, allowing you to make your adjustment. When your adjustment is complete, RELEASE the trim button, and the autopilot goes back to trying to hold it where you left it.

 

When you take these two together, it means that if you are flying along straight and level (for example), you could take your hands and feet off of the controls without worrying that the aircraft is going to try to tie the low altitude record as soon as you let go, and will continue just flying along straight and level.

Edited November 22, 2008 by AlphaOneSix

[hitman]

So using the trim is done purely in conjunction with the autopilot, and the only true way to adjust trim is to trim it [not using trim tabs or control surfaces like on fixed wing aircraft], but by putting the rotor disk in the plane you want?

 

(basically speaking, trimming the aircraft is done by holding the trim down and maintaining the forward velocity and vertical speed at the desired setting)? Ive never gone too far in depth in helis, so you can understand if I sound a little confused...

[RvETito]

One basic principle you have to understand- it's called force trim system, by pressing the trim button all you do is to set new neutral position of the cyclic and pedals in terms of force caused by the artificial force devices (springs). It's only purpose is to make pilot's life easier so he doesn't get tired fighting with the springs all the time. It's completely independent system.

 

The rigging of the flight controls is such that in the neutral position (cyclic and pedals centered) all springs are relaxed and there is no tension on the controls. When you move any control you have to overcome the tension of the corresponding srping (there are 3 of them in total- one for pitch, one for bank (on the cyclic) and one for yaw (on the pedals)). If you let go on the stick (or pedal) with the tension still present the spring will bring it back to the neutral hence giving the oposite command. So what the pilot does is to move the cyclic (pedal) the way he wants, press the trim button and that will cancel the tension, he has now set new neutral position in terms of force.

 

You may ask why the heck we need those srpings to make poor pilot's life miserable. :) Well, the servo actuators are irreversible- they take all the load and don't give anything back, so all the force the pilot must apply to move a control is just to overcome the weight and friction of the mechanical linkage to the servo which is so small that you can do it with one finger. The pilot needs feedback for aerodynamic forces and that feedback is given by the srpings.

Edited November 22, 2008 by =RvE=Tito

[RvETito]

I have hovered an Mi-17 a few times, and I just keep the trim button pressed the entire time.

 

Funny thing- I've worked with ex-Mi-17 pilots on Ka-32 and they've told me the same- often in hover they've used to fly with trim button pressed in the Mil. They don't do that in the Kamov anymore, although the loading mechanism and the solenoids (electro-magnetical brakes) are identical. I guess it's the autopilot that makes the difference.

[hitman]

Well, the servo actuators are irreversible- they take all the load and don't give anything back, so all the force the pilot must apply to move a control is just to overcome the weight and friction of the mechanical linkage to the servo which is so small that you can do it with one finger. The pilot needs feedback for aerodynamic forces and that feedback is given by the srpings.

 

Thats because hydraulics doesnt send pressure back to the stick, its dampened due to all the hydraulic pumps etc.. within the system. So this is a type of system that would have to rely on something else to recieve artificial signals to the controls? I didnt know helis had this kind of system.

 

So the practice here, is to hold down the trim button while in the plane of motion you want your aircraft trimmed to and let trim work on its own?

 

The question is a lot easier to answer if I know you've flown it! Then I can tell what to take notice of; and what not to do...

You can pretty much assume Im flying it.

Edited November 22, 2008 by hitman

[RvETito]

So the practice here, is to hold down the trim button while in the plane of motion you want your aircraft trimmed to and let trim work on its own?

 

No, if you hold down the button it's not a trimming anymore- you're losing all artificial feedback, the controls become light as air and you may pretty easily overcontrol the helicopter. It may be common practice for some helicopters to hover with holding down the trim button but not in the Kamov. I guess it's because of different autopilots.

 

In BS the practice is to press and release, during manuvering- in every 1-2 sec and since most of us don't have FFB sticks you need to quickly bring the stick back to neutral after releasing the trim button. Note- the cyclic and the pedals won't be in neutral in your virtual pit.

[hitman]

No, if you hold down the button it's not a trimming anymore-

Well I forgot to add release the trim button obviously, but technically thats how its done, right? :D

So the practice here, is to hold down the trim button while in the plane of motion you want (and release afterwards) your aircraft trimmed to and let trim work on its own?

[Amraam]

I understand what buttons to trim the heli...what I dont understand is what it does. The manual is kind of light on a description on how to properly trim it. It doesnt trim like it would an aircraft...and from what I understand in the manual, you press T and your aircraft is trimmed. You hold down T, your aircraft is trimmed more.

 

What is the point Im missing here?

 

My way of understanding the trim function is by not strictly thinking of it as trim. Instead, you position the heli where you want (be it a stationary hover, or just flying forward) then press the trimmer immediately before releasing the controls.

 

A good way of thinking of it is that the computer tells the autopilot to continue doing what you were doing with the contols, allowing you to take your hands off the HOTAS to flick switches, or concentrate on firing weapons etc. Without it, it would near impossible to fly the KA50 like a tradition helicopter AND control all of the systems.

 

That's why when you use auto hover, you hit the trimmer button again, as soon as it settles into a stable hover. This way your neutral stick position matches the 'saved' cyclic position on the autopilot.

 

In real life, when you press the trim button, the stick doesn't return to centre - instead it is held in place where you left it. Obviously (unless you have a force feedback joystick) our sticks can't be held in position, so our trimming function is really a "close as it can be" trim emulation.

 

Hope that made sense. It took me a while to get my head around it, so I hope my above post is clear and helpful!