Central position trimmer problem

Haven't we already established that the bump is autopilot induced (no aircraft controls movement on controls indicator) so it should be submitted as a bug report for dev team?

It models the real system correctly, the Pilot does not get feedback of the autopilot position through the stick, I feel the same way as you do about the Autopilot and trim system and I have had many debates about it on the forum. But it has been explained to me that this is how it does in fact operate.

As far as I'm concerned Kamov got it wrong :)

Nate

It models the real system correctly, the Pilot does not get feedback of the autopilot position through the stick, I feel the same way as you do about the Autopilot and trim system and I have had many debates about it on the forum. But it has been explained to me that this is how it does in fact operate.

 

As far as I'm concerned Kamov got it wrong :)

 

Nate

To be honest I don't know what you're talking about. I don't 'feel about the autopilot and trim'.

I have the 'bump' after each trim and Viper don't. I'd like to solve it and I need any help I can get.

To be honest I don't know what you're talking about. I don't 'feel about the autopilot and trim'.

I have the 'bump' after each trim and Viper don't. I'd like to solve it and I need any help I can get.

It is quite clear in your video that it is the way you use the trim that is causing uncommanded control input from the autopilot/stabilisation system. I.e the Bump you describe. Don't forget that the trim is 2 buttons in one, on release it sets the Cyclic centre position and commands the autopilot to maintain that pitch, bank and heading.

As I said previously if you don't trim often enough (and ideally with press, hold, manoeuvre, release), it is quite possible the Autopilot/stabilisation system will use its full authority to try to maintain the pitch, bank and heading originally set. When the trimmer is then pressed in this situation, instantly 20% of the control input is removed (this is your Bump).

You always want to be in a position where the autopilot isn't near the limits of its authority to maintain the pitch, bank and heading you have commanded. The only way to assure this is to trim constantly.

Nate

It is quite clear in your video that it is the way you use the trim that is causing uncommanded control input from the autopilot/stabilisation system. I.e the Bump you describe. Don't forget that the trim is 2 buttons in one, on release it sets the Cyclic centre position and commands the autopilot to maintain that pitch, bank and heading.

 

As I said previously if you don't trim often enough (and ideally with press, hold, manoeuvre, release), it is quite possible the Autopilot/stabilisation system will use its full authority to try to maintain the pitch, bank and heading originally set. When the trimmer is then pressed in this situation, instantly 20% of the control input is removed (this is your Bump).

 

You always want to be in a position where the autopilot isn't near the limits of its authority to maintain the pitch, bank and heading you have commanded. The only way to assure this is to trim constantly.

 

Nate

Thanks for you reply. I'll have to watch Viper's track again to investigate if he were using the trim button any different than I do.

The bump also occurs as soon as you press (not release) the trim, so it's definitely the disengaging of the authority, it's like letting go of a stretched elastic band that were holding the controls back from exercising their full output.

With heading hold on, it also means if you trim whilst turning that the elastic band will instantly reappear again too. When flying a circle with heading hold enabled, half the circle is flown with the heli's nose inside the circle, and half the time it's flying with its nose outside the circle, all the while trying to pull itself back on course. It's a rare time that the nose is actually following the circle and you're flying the course 'straight' without input from the AP.

Tacview shows this quite well, but you notice it if you fly the circle without tacview because during the transition from nose-inward to nose-outward and vice versa, there's a noticable drop in pitch for a short while whilst the craft ceases pulling either side.

All in all, it seems better/smoother than the old trimmer method which I'm used to using anyway, since for me that's having no discernable delay allowed to getting the stick centered before it starts adding my input when I release trim (even with the tauinverse delay set). That produces so much bump for me that I don't even really notice the one incurred by the AP disengage :) I will have to try the new method some more.

Thanks topdog for your input. To be honest I don't get the 'the bump comes from AP's 20% authority'. Not a bit. And I'll have to grab piece of paper (or Inkscape:)) and crack that one out. Give me some time, please. Or send me some links if you think it will speed things up.

Also (very important!) quick trim button press and release IS recommended on the forums as a method real Ka-50 pilot's use by ED devs, among others. I highly doubt that real pilots get the bump. If not that it directly implies a bug in DCS BS. No matter how many workarounds there are. Also note that holding the trim button while maneuvering disables some damping functions of AP which greatly increases the risk of rotor blades intersection.

Also (very important!) quick trim button press and release IS recommended on the forums as a method real Ka-50 pilot's use by ED devs, among others. I highly doubt that real pilots get the bump. If not that it directly implies a bug in DCS BS. No matter how many workarounds there are. Also note that holding the trim button while maneuvering disables some damping functions of AP which greatly increases the risk of rotor blades intersection.

I apologise in advance as all I seem to do in this thread is contradict you :)

The quick button press is not the recommended method, however this is not your specific problem you are having. EDIT:- Apologies, it seems I am wrong, it is the desired method, however, it is still unrelated to your problem.

Real pilots trim every few seconds, or more if manoeuvring a lot, to avoid the scenario of over-stretching the autopilot..

Also holding the trim does not disable any Damping at all, it merely shuts off any Autopilot input to the control surfaces. Holding the trim is the same as the Flight Director mode, Damping on/Autopilot off.

Have a read of IvanK's excellent description of the AFCS system on the Shark.

http://forums.eagle.ru/showthread.php?t=36246

Try flying with the Flight Director for a while, you will not get the Bump with that at all.

Nate

I apologise in advance as all I seem to do in this thread is contradict you :)

 

The quick button press is not the recommended method, however this is not your specific problem you are having. EDIT:- Apologies, it seems I am wrong, it is the desired method, however, it is still unrelated to your problem.

 

 

Real pilots trim every few seconds, or more if manoeuvring a lot, to avoid the scenario of over-stretching the autopilot..

 

Also holding the trim does not disable any Damping at all, it merely shuts off any Autopilot input to the control surfaces. Holding the trim is the same as the Flight Director mode, Damping on/Autopilot off.

 

Have a read of IvanK's excellent description of the AFCS system on the Shark.

 

BS Auto Pilot description and operation

 

Try flying with the Flight Director for a while, you will not get the Bump with that at all.

 

Nate

Oh please do contradict me :) as long as it will be getting me closer to solving the problem. Thanks for the article. I will aid my pencil and paper method for sure!

Bucic, I'll give you my own procedure, perhaps you can avoid the 'bump' this way?

(Sorry, I havent watched your vidoes or anything)

Assuming you have all damper channels aneabled except. And no FD.

1. Before I commit attitude change, press and hold trimmer.

2. Perform attitude change. Keep trimmer pressed.

3. Wait until the chopper 'settles' in the new direction. Still Holding the trimmer.

4. Controls center & chopper settled - release trimmer within a 0.5 second of centering the controls.

This way I counteract any yay / oscilations at the end of the manouver.

All that energy needs to settle and I have to smooth out the transition so the AP can cope with the new attitude.

PPS, if there's alot of manouvering, several changes one after another, I wont release the trimmer until I've established a path I can hold.

This means, sometimes, I can end up with trimmer pressed for 2-3 minutes when avoiding missiles and such.

Panzertard,

Thanks, I know the procedure and I did use it sometime ago until I've stumbled upon many mentions that 'it's not recommended and real Ka-50 pilots use short presses'.

This means, sometimes, I can end up with trimmer pressed for 2-3 minutes when avoiding missiles and such.

I'm sure there is more than one ED dev/tester that would bash you for that :D

All in all the fact remains that witnesses confessions are contradictory :smartass: Both regarding holding down the trim button and using FD to overcome the bumps. Me being me thinks that that subject should be settled once and for all and pinned up in the FAQ.

Minding that I haven't read that comprehensive article on AP yet I see no explanation nor excuse for bumps occurring when using real life short presses-releases of the trim button. Also, going ahead of those who really like excuses, the fact that we do not have a real control sticks with real trim mechanisms at our homes is irrelevant. Basically in my understanding a proper trimming (real=short) should set new neutrum for cyclic stick as well as send a 'BUG OFF!' signal to the AP. Or to put it differently - what I observe is not a bug only if real Ka-50 pilots get the bump too.

OK, I'm out to read the article. Rest assured that I will ask more inconvenient questions ;)

With permission from Frazer

At first there doesn't seem to be a problem to me, a little bounce when trimming is not unusual.

 

What I did notice is that you are not flying symmetrical. The "ball" is out of the center and it looks like the more it is, the greater this bounce is.

 

This could be eigther the flightmodel, or a little bug in the flightmodel. Besides the a-symmetric flying, I don't think you do anything wrong.

 

Will need to test this myself.

 

Greets,

Fraz

 

PPS, if there's alot of manouvering, several changes one after another, I wont release the trimmer until I've established a path I can hold.

This means, sometimes, I can end up with trimmer pressed for 2-3 minutes when avoiding missiles and such.

Yup, same for me. Sometimes, I will hold the trimmer down for even longer than that if flying NOE in hilly areas. What I did is assigned trim to my X52's middle mouse-like button on the throttle. Since that button takes alot of pressure to hold down normally, I rolled up some masking tape into a little cylinder, taped it across the face of a quarter, and then taped the quarter across that button with the little rolled up wad of masking tape pressing against it. I put some tension on the tape, and now it only takes a light force to depress the button, and it's much bigger. So now I have an easy-to-activate trimmer button that is pressed by fingers that cannot be used for anything else- basically, I just grip my throttle a little harder and I am holding down the trimmer. I can operate all my other buttons on the HOTAS setup regardless of whether or not I am holding down the trimmer. Works great, but is pretty crude.

I'm sure there is more than one ED dev/tester that would bash you for that :D

 

You're wrong, they wouldn't dare touching my delikate skin. :D

Besides, finding a workaround for a problem is not considered as bad practice. If it is a problem in the first place I mean ;)

If not, then it is a perfectly legal procedure.

:)

I'm reading the comprehensive article again. Beware! :D

I've read the article few times and I'll have to stick with the following

I see no explanation nor excuse for bumps occurring when using real life short presses-releases of the trim button. Also, going ahead of those who really like excuses, the fact that we do not have a real control sticks with real trim mechanisms at our homes is irrelevant. Basically in my understanding a proper trimming (real=short) should set new neutrum for cyclic stick as well as send a 'BUG OFF!' signal to the AP. Or to put it differently - what I observe is not a bug only if real Ka-50 pilots get the bump too.

I've read the article few times and I'll have to stick with the following

It does send a BUG OFF to the autopilot, that's what causes "the bump". The AP suddenly removes up to 20% of the control input on pressing trim. If a real Ka-50 pilot flies like in that video, he will get "the bump" too.

Nate

It does send a BUG OFF to the autopilot, that's what causes "the bump". The AP suddenly removes up to 20% of the control input on pressing trim. If a real Ka-50 pilot flies like in that video, he will get "the bump" too.

 

Nate

Remember the Ka-50 real display footage, in-cockpit? IIRC the pilot very rarely used a longer trim press than a tap.

Edit:

Got it. I was right. Tick-tick and no bumps in the real footage.

Hahaha, 3:15 right in your face! I swear the video was made before I started the topic :megalol:

In my face huh? :)

Well now, that's a non-standard HUD for start - doesn't look like the Autopilot heading hold is engaged (the caret doesn't move when he trims), how do I know the other attitude holds are engaged?

Looks remarkably similar to flying in DCS with the FD on (hard to prove with the non-standard HUD). Unless you think he was doing aerobatics with autopilot engaged after 3.15?

Nate

In my face huh? :)

 

Well now, that's a non-standard HUD for start - doesn't look like the Autopilot heading hold is engaged (the caret doesn't move when he trims), how do I know the other attitude holds are engaged?

 

Looks remarkably similar to flying in DCS with the FD on (hard to prove with the non-standard HUD). Unless you think he was doing aerobatics with autopilot engaged after 3.15?

 

Nate

In everyone's face, to be fair :) But it looks like it was a false start ;) So, I'll check it out. Namely - I'll try to mirror the HUD symbology from the vid in DCS and then try it out. What setup would you recommend to start with?

In everyone's face, to be fair :) But it looks like it was a false start ;) So, I'll check it out. Namely - I'll try to mirror the HUD symbology from the vid in DCS and then try it out. What setup would you recommend to start with?

You won't be able to replicate that HUD in DCS to be honest, it looks like the one in the video is from older type & didn't have any information from the Autopilot/Stabilisation system on the HUD at all.

Nate

You won't be able to replicate that HUD in DCS to be honest, it looks like the one in the video is from older type & didn't have any information from the Autopilot/Stabilisation system on the HUD at all.

 

Nate

If so then we're back to

what I observe is not a bug only if real Ka-50 pilots get the bump too.

again. On short trim tap that is.

If so then we're back to

 

again. On short trim tap that is.

Only IF heading and attitude holds are engaged. As I said, the way he was flying suggests to me he only had damping on, but we can't be sure either because there is no information on the HUD.

With just damping on (FD equivalent), short trim tap is all you use, as you aren't attempting to set attitude and heading at the same time.

Edit:- Ideally we need AirTito in here to give you a definitive answer.

Nate

Only IF heading and attitude holds are engaged. As I said, the way he was flying suggests to me he only had damping on, but we can't be sure either because there is no information on the HUD.

 

With just damping on (FD equivalent), short trim tap is all you use, as you aren't attempting to set attitude and heading at the same time.

 

Edit:- Ideally we need AirTito in here to give you a definitive answer.

 

Nate

AirTito you say. I think he's just got himself his own personal stalker :) If there's a risk that the Ka-50 from the vid is not the same as modeled in DCS then let's forget about it.

Nate, I've watched the second video of that performance and there seems to be differences to the KA50 modelled by ED...

Any ideas?

EDIT: Had a closer look and there are more differences to the left forward panel, namely the Caution lights panel are different...

The >whats this< looks like something for Temprature Control maybe for the laser :)