Trimming the Ka-50

[Bucic]

Kamov's coaxial helos are quite stable W/O AP.

Dedicated to some of my opponents :devil_2:

[haigotron]

so, before doing a hover check, I should trim before taking off the ground? would that keep the helicopter from moving wildly?

[Yo-Yo]

so, before doing a hover check, I should trim before taking off the ground? would that keep the helicopter from moving wildly?

 

Surely yes.

[haigotron]

oh excellent, I never did it, and I was having a dickens of a time, trying to just keep it from moving back while pitching up :D

 

thanks yo-yo :D

[GGTharos]

You are perhaps taking off too fast :D

 

Pull your chopper into a hover 'on the main landing gear' ... trim it. Add a little collective...trim it. At some point the main landing gear will come off the ground and you'll be trimmed in hover :D

[DaWu]

finally figured out how to fly this beast. just flew my first night mission with zero sight and managed to find the destination airfield. crashed at landing though :)

 

one question besides trimming. I had 6 waypoints which worked fine in the abris. but why couldnt I select wp 5 and 6 on the ins? only 1-4 worked here.

[Reticuli]

Because the PVI-800 doesn't get nav information from the ARBIS. Turns out they are two separate systems that work in parallel, but independently. As EvilBivol-1 described it, it's an aftermarket add on. If it was designed with it from the get-go, you'd have the PVI-800 and ARBIS routed to a selector switch/knob for choosing which one you want the autopilot getting its nav information from. I have yet to actually program them ahead of time in a mission editor, but I assume the sim loads them into both before hand. I would love if they could talk to each other or be selected between, mostly because the ARBIS is such a powerful system and who doesn't like a nice GUI? Heh heh.

 

***

 

One thing to remember, I think, is we're not letting go of a non-tensioned cyclic in the real bird. If you let go of a real heli cyclic, usually the cyclic and corresponding rotor disc will tilt over on its own, right? I think someone said the newer Apaches don't actually allow you to get rid of the cyclic tension/trim setting, but let's disregard that one.

 

With this sim, though, we are controlling a virtual cyclic, which you can see when the control display is up. The sim pilot's hand never actually comes off this virtual cyclic. Try this at home on DCS:BS. Fly strait and level at a speed of 100. Trim it out for that. Turn off all the hold channels, now come in on a 60 degree down angle. Even with the hold channels all off it will still always come back up...messy, but it does. So right now the Bank Hold and Pitch Hold functions are not really turning off. You're just losing some AFCS dampening ability.

 

In contrast, Heading Hold is no real dampening feature at all right now, rather it's effectively or functionally dampening-like. What it's really doing is just, well, holding the heading. Good. Like I said, I don't know whether the real helo has yaw dampening or not when the Heading Hold channel is off. For all I know, it works just like this right now where it will mostly continue to rotate until you apply counter-pedal.

 

The big issue with the yaw, though, and I am sure it's giving people much more trouble than anything else, is the fact that the pedals are affected by the cyclic trim button AND the heading hold reset feature that this trim button also produces. Do the following: put Heading Hold and Trim Button both on your HOTAS. Go fly. Set your airspeed for low or hovering. Now, trim the helo out only in the pitch and slightly in the bank to be level, but no pedal trim on the control display. With Heading Hold off, you rotate pretty much freely, and pedal input is pretty imprecise and requires some counter-pedal to stop. Fine, let's assume the Ka-50 does not have yaw dampening.

 

Next, make sure the heading selector for the autopilot is on neither Desired Heading nor Desired Course. Leave it in the middle. It's right next to the Flight Director Button. Don't turn Route Autopilot on, though. This frees up the heading diamond in the HUD to properly reflect the Heading Hold setting at any moment. That's always happening in the background when the autopilot is not on, but this makes it easier to see what is happening since otherwise it will show your next PVI-800 waypoint. Assuming you're not rotating too quickly, tap Heading Hold on your HOTAS. The caret will realign to this new heading and the AFCS will slowly move at or close to it. Again, the pedals should show no trim on the control display.

 

O.k., now pitch, bank, and rotate yourself moderately with the stick & pedals and tap the Trim Button on your HOTAS and release pressure on the controls. Now you have a problem. The system has trimmed the pedals *and* it has a new Heading Hold position. The latter is fine. The Trim Button should absolutely be resetting your Heading Hold to a new point. If the Ka-50 doesn't have a yaw dampening feature, this reset is necessary.

 

However, the trimming system should not be affecting the pedals and that's what it has just done. Your virtual pilot now has his pedals stuck to one side while the AFCS is also attempting to realign to the new Heading Hold point you just set...which causes you to errantly rotate away from the desired heading. The Trim Button should be a function of the virtual cyclic only, not affecting the pedals at all.

 

A coaxial rotor design does not require steady trimming in the yaw, since we don't have to worry about the imperfect tail-mixing/crosscoupling of conventional designs. It instead requires constant small, variable yaw input from either the pilot (if the Heading Hold is off) or from the AFCS (if Heading Hold is on), but it does not require a specific yaw trim. Instead in the sim now, we have the Heading Hold reset to this new spot AND a pedal trim added by the Trim Button. I guarantee this is 90% of people's control problems, the other 10% or so probably being the trim delay & the necessity to release the controls.

 

Get rid of the Trim Button trimming the pedals, but leave the Heading Hold function unchanged: it is reset to a new heading by both turning Heading Hold on/off quickly and by tapping the Trim Button. But you wouldn't get the conflict and doubling up of inputs in the yaw. Now, I've become very proficient dealing with this issue in the sim. I often turn the heading hold off when I am not trying to actually hold a heading (duh!), and when I hit trim I always make sure the pedals/twist is not being applied at that moment. If I do accidentally trim the pedals, I immediately correct it with counter-pedal & another trim tap. But I would bet money this is not the way the real Ka-50 works. ED has been emphatic that the hold channels are kept on all the time, though they *can* be turned off (hence the reason the buttons are there). However, ED has already stated their trim arrangement is altered for home use, and my guess is they goofed up and applied it to the pedals, too, even though the Ka-50's Heading Hold function already entirely serves that purpose.

 

Easy mistake. Easy fix for them. Totally understandable.

Edited December 30, 2008 by Reticuli

[Yo-Yo]

I often turn the heading hold off when I am not trying to actually hold a heading (duh!), and when I hit trim I always make sure the pedals/twist is not being applied at that moment. If I do accidentally trim the pedals, I immediately correct it with counter-pedal & another trim tap. But I would bet money this is not the way the real Ka-50 works. ED has been emphatic that the hold channels are kept on all the time, though they *can* be turned off (hence the reason the buttons are there). However, ED has already stated their trim arrangement is altered for home use, and my guess is they goofed up and applied it to the pedals, too, even though the Ka-50's Heading Hold function already entirely serves that purpose.

 

Easy mistake. Easy fix for them. Totally understandable.

 

I know the best solution - you have to use rudder pedals with FFB. An all will be as real Ka-50 does.

And finally - don't you think if you have your autopilot down only rudder pedals trim would help you?

[DaWu]

Because the PVI-800 doesn't get nav information from the ARBIS. Turns out they are two separate systems that work in parallel, but independently. As EvilBivol-1 described it, it's an aftermarket add on. If it was designed with it from the get-go, you'd have the PVI-800 and ARBIS routed to a selector switch/knob for choosing which one you want the autopilot getting its nav information from. I have yet to actually program them ahead of time in a mission editor, but I assume the sim loads them into both before hand. I would love if they could talk to each other or be selected between, mostly because the ARBIS is such a powerful system and who doesn't like a nice GUI? Heh heh.

 

thats right I knew this but why was wp1 on my abris wp2 in my ins?

the numbers didnt match.

why were not all my 6 wps loaded in to the ins on mission load? sry for offtopic..

[Aser]

I know the best solution - you have to use rudder pedals with FFB. An all will be as real Ka-50 does.

And finally - don't you think if you have your autopilot down only rudder pedals trim would help you?

 

Can I get the name of those pedals?? :joystick:

 

I want to add that in another helicopters below 60knots AP will work in heading hold and above it will keep the ball centered. I assume not in kamovs...

 

Another cool feature in the 139 is that we have got a pressure switches in the pedals , and:

one force trim on/off switch (the same in the 109 and 412).

and another Collective/Yaw force trim on/off.

I think it would be great to have those switches (yes I know it isn't real in the Ka50).

 

Regards

Aser

[haigotron]

You are perhaps taking off too fast :D

 

Pull your chopper into a hover 'on the main landing gear' ... trim it. Add a little collective...trim it. At some point the main landing gear will come off the ground and you'll be trimmed in hover :D

 

hey Tharos, you're right, I think I really am taking off too fast...since im not giving it time to properly hover on the main gears.

 

I assume if I press trim before the EKRAN signals "Flight", the trim will not have any affect? In that case, I understand now that when I push trim and then pull on the collective that nothing is trimmed :P

[EvilBivol-1]

thats right I knew this but why was wp1 on my abris wp2 in my ins?

the numbers didnt match.

why were not all my 6 wps loaded in to the ins on mission load? sry for offtopic..

Your INS stores the departure/arrival points separately under Airfield Points. The ABRIS does not do this. In other words, for your INS, a typical route will include one or two Airfield Points (one if the take-off/landing airfield is the same and two if it isn't) and up to 6 Nav Points in between. In the ABRIS, the entire route, including the take-off/landing points, will be numbered as waypoints. So where as on the ABRIS waypoint 1 is your take-off point, in the INS, waypoint 1 is the first route point.

 

Note, if the mission does not have a departure point, i.e. it starts you off in mid-air, the waypoint numbers will match.

[DaWu]

Your INS stores the departure/arrival points separately under Airfield Points. The ABRIS does not do this. In other words, for your INS, a typical route will include one or two Airfield Points (one if the take-off/landing airfield is the same and two if it isn't) and up to 6 Nav Points in between. In the ABRIS, the entire route, including the take-off/landing points, will be numbered as waypoints. So where as on the ABRIS waypoint 1 is your take-off point, in the INS, waypoint 1 is the first route point.

 

Note, if the mission does not have a departure point, i.e. it starts you off in mid-air, the waypoint numbers will match.

 

 

ahhh got it now. thx for the help and sry for offtopic

[Reticuli]

I know the best solution - you have to use rudder pedals with FFB. An all will be as real Ka-50 does.

And finally - don't you think if you have your autopilot down only rudder pedals trim would help you?

 

Seriously, if the autopilot is down in Blackshark, you might as well land there and quit the mission, because it's unlikely you're getting home in one piece without the pitch and bank hold channels. Why would Kamov even apply the trim to the pedals? Very little pressure is needed even in a hover to prevent the chopper from continuing to rotate with hover hold off. And the amount of pressure is not necessarily fixed, so trim becomes a less than steller solution.

 

Seems to cause far more problems than it helps, especially with the heading hold point being reset at the same time you've retrimmed...causing a conflict. I don't see how FF pedals would improve things much, because you'd still have to look down at the control window, recenter them, and trim again each time you've actually set them off center. Having to hold down the pedals in a hover in a conventional light helicopter without tailmixing/crosscoupling and no heading hold autopilot is not uncommon. A coaxial design needs far less pedal in hover, so it's a terrible design choice.

 

The more I'm flying the Ka-50 here, the more its design is seeming a disaster. Poor integration of aftermarket & thirdparty modules/systems, screwy yaw trimming you can't turn off that conflicts with the heading hold system, poor low light performance of the TV sensor, no flir (even police & boarder helos have that in the US), and on and on. It's cheap and not susceptable to being taken out by a single shot to the tail boom, but those are about the only positives worth mentioning. From a purely game-play standpoint, its negatives certainly make things dynamic and interesting, though.

[Airway]

:megalol:

Funny how amateurs see things :megalol:

[GGTharos]

Then I suggest you write a letter to Russian Army Aviation telling them that you'll design a better attack helicopter for them :D

 

And while you're at it, point out to them you might as well go take the top seat in Kamov :D

After all, they could certainly benefit from someone who has decades of experience designing and flying helicopters!

 

The more I'm flying the Ka-50 here, the more its design is seeming a disaster. Poor integration of aftermarket & thirdparty modules/systems, screwy yaw trimming you can't turn off that conflicts with the heading hold system, poor low light performance of the TV sensor, no flir (even police & boarder helos have that in the US), and on and on. It's cheap and not susceptable to being taken out by a single shot to the tail boom, but those are about the only positives worth mentioning. From a purely game-play standpoint, its negatives certainly make things dynamic and interesting, though.

[Reticuli]

It's amatures the US Army went to in the ADOCS program to find out how to create the next generation of helo control interfaces, precisely because of how stuck in their ways pre-existing pilots are. When you're trying to reduce casualties and crashes, sometimes you have to tell the real pilots to shut up. So ditto.

[Airway]

Is "requirement specification" and "functional specification" a term for you, Reticuli?

 

First that, then the design.

[GGTharos]

The only one stuck here is you :)

 

It's amatures the US Army went to in the ADOCS program to find out how to create the next generation of helo control interfaces, precisely because of how stuck in their ways pre-existing pilots are. When you're trying to reduce casualties and crashes, sometimes you have to tell the real pilots to shut up. So ditto.

[Prophet]

I really don't have a problem....

[scatter]

Has anyone else noticed the "bump" that occurs when trimming using non force feedback gear?

 

I've made a (very) short video to demonstrate it. In the video I'm holding the trim button while moving the cyclic back to get the trim centered. When I release the trim button the joystick output is set back to the centre by a script (to prevent human factors). You can clearly see the onscreen control overshooting before settling back to the trimmed point.

 

Eliminating this bump might be a good idea for improving trimming on non ffb controls. After all it can't be anything to do with realism as in the real aircraft there's no need to re-center controls.

 

[Reticuli]

First version of my solution to DCS Blackshark's trim. You can download it at the lower link to AVSim Online.

 

Here's the Readme:

Note: Always reset your trim within the sim itself (ctrl+t) each time you start a mission that gives you a non-centered trim state, such as missions where you start out flying.

Put the Blackshark 1 in your saitek software folder.

Put PIE file in your GlovePIE profile directory. Obviously you need to download GlovePIE.

Both LUA files go in your internal DCS profiles directory, which is somewhere inside of config/aircraft/ka-50/joystick, I think. I'm actually not totally sure if these are the correct ones, since I don't know where they saved. This is what was in the folder.

You also need PPJoy installed. See the other uploads under my name if you want further details.

Pinkie trigger single tap resets to slow flight trim or somewhere around the lower detent.

Pinkie trigger double tap (quickly) resets to fast flight trim or somewhere around the upper detent.

Holding the pinkie trigger for over a second will engage ground trim. When landing, you can choose to keep this held or not.

The current "capture" value is 62. If you have very high fps in the sim, you can lower this to 50 if you'd like in the GlovePIE script.

I currently have the y.rot (top of throttle) on the x52 as a 50% authority trim range, which is nice to suppliment the twist axis or pedals (if you have them).

The three keys under the x52 MFD are the channel hold buttons. Reset is the all important Heading Hold. The middle is pitch. The right most is bank. Switch the Desired Heading/Desired Track switch to the middle when autopilot and weapons are not selected to see where the FCS is trying to realign you slowly to (limited to 20% authority).

Yes the X52/DCS profiles are simple, but I've been mostly just using the keyboard and cockpit clicking for other commands. Not sure how much I want to program.

I'd also like to plug, for a moment, the first commercially available stereoscopic driver set which actually works.

Go to www.iz3d.com to download it. They already have a dcs profile for it. Please support this company if you have an interest in true 3D...especially if you have an ATI card.

Here is the PIE script itself:

 

PPJoy1.Analog2 = Joystick1.z

if singleclicked(joystick1.Button6) then begin {

var.y = -0.2

var.x = -0.1

}

if doubleclicked(joystick1.button6)then begin {

var.y = -0.5

var.x = -0.1

}

if helddown(joystick1.button6, 1) then begin {

var.y = 0

var.x = 0

}

var.y = EnsureRange(Joystick1.y / 62 + var.y, -1, 1)

PPJoy1.Analog1 = var.y + Joystick1.y

var.x = EnsureRange(Joystick1.x / 62 + var.x, -1, 1)

PPJoy1.Analog0 = var.x + Joystick1.x

if (abs(var.x) = 1) and (abs(Joystick1.x) > .0001) then BeepDefault

if (abs(var.y) = 1) and (abs(Joystick1.y) > .0001) then BeepDefault

PPJoy1.Analog5 = Joystick1.zrot + (Joystick1.yrot * .5)

[Yo-Yo]

Seriously, if the autopilot is down in Blackshark, you might as well land there and quit the mission, because it's unlikely you're getting home in one piece without the pitch and bank hold channels. Why would Kamov even apply the trim to the pedals? Very little pressure is needed even in a hover to prevent the chopper from continuing to rotate with hover hold off. And the amount of pressure is not necessarily fixed, so trim becomes a less than steller solution.

First of all: KA-50 DOES NOT REQUIRE HOLD CHANNELS TO BE SWITCHED ON. IT IS STABLE WITHOUT IT. IT IS A REAL FACT. And your thoughts "how it would be" are off target very often.

 

All Russian helos have all three channels trim. It's a fact too regardless of your opinion.

"If it's stupid but works - it's not stupid" though I do not consider it stupid.

 

 

 

The more I'm flying the Ka-50 here, the more its design is seeming a disaster. Poor integration of aftermarket & thirdparty modules/systems, screwy yaw trimming you can't turn off that conflicts with the heading hold system, poor low light performance of the TV sensor, no flir (even police & boarder helos have that in the US), and on and on. It's cheap and not susceptable to being taken out by a single shot to the tail boom, but those are about the only positives worth mentioning. From a purely game-play standpoint, its negatives certainly make things dynamic and interesting, though.

 

Don't forget it's early 80's design...

[Reticuli]

Here's a better script. And sorry for having the slider axis not inverted. I will fix that. Not sure yet if I like 45 or 50 capture rate better, but you can put it at whatever you want. A higher number will have more bobbing/wobbling, but be less prone to overcontrol. The available trim needed some limiting added and has reduced the tendency to continue rolling or pitching.

 

if singleclicked(joystick1.Button6) then begin {

var.y = -0.2

var.x = -0.1

}

if doubleclicked(joystick1.button6)then begin {

var.y = -0.5

var.x = -0.1

}

if helddown(joystick1.button6, 1) then begin {

var.y = 0

var.x = 0

}

var.y = EnsureRange(Joystick1.y / 45 + var.y, -0.85, 0.0)

PPJoy1.Analog1 = var.y + Joystick1.y

var.x = EnsureRange(Joystick1.x / 45 + var.x, -0.575, 0.275)

PPJoy1.Analog0 = var.x + Joystick1.x

PPJoy1.Analog5 = Joystick1.zrot + (Joystick1.yrot * .5)

[4c Hajduk Veljko]

Has anyone else noticed the "bump" that occurs when trimming using non force feedback gear?

Yes, there is definitely a “bump” (kick) in the stick when trimming is activated. It was very pronounced in the Logitech FF joystick I've just returned because I was not satisfied on how it worked with trimming.

 

I wonder where does the “bump” come from? And what can be done to eliminate it?