What does HKTB in screen control mean?

[jozeffff]

Hi guys!

 

Absolute noob here.

 

I cannot for the love of God find online what the white HKTB characters mean in the upper right corner of my screen.

I know that it has something to do with trim settings but I don't understand it.

I looked it up in the 400+ page manual but I cannot figure out the pictures.

 

I know this is absolutely beginners question and probably has been answered a 100 times .

 

Thanks for your help!

 

Cheers Jozeff

[shake307]

Heading, roll, pitch, and altitude channels for "autopilot".  It is more like a Stability Augmentation System (SAS).  Roll and pitch are generally always on (unless rotor rpm drops too much, more on that later).  They move around according to how much they are adjusting flight controls to hold the helo at trimmed attitude.  They only have so much authority, as they are only trying to hold the helo in the last position it was trimmed to.  I dont think I have ever seen the Roll and Pitch go yellow N (which is out of limits), but heading will with a lot of collective adjustment as you are fluctuating rotor torque with collective, therefore requiring pedal adjustment.  I try not to use altitude hold as it gets a bit wonky and has caused me to crash.

 

Finally, with all that said, the center console actually has the indicators showing what this system is doing (the white lines moving).  The indicator in the upper right of the screen is just a representation of those indicators.  

 

One last thing.  Map your autopilot switches your flight controls.  When you get the inevitable Generator failure, the helicoptor will lose its damn mind and try to kill you as your autopilot just died.  And it doesnt automatically come back on when you get power back.  You dont want to be wrestling the flight controls while looking for the switch turn Roll and Pitch back on.  I have it all mapped to some buttons on my throttle.

 

I know that was a long explanation to your question.  I hope it helps

[jozeffff]

Wow!

 

Thanks a lot for your help.

 

Appreciate it a lot!

[Rudel_chw]

3 hours ago, shake307 said:

Heading, roll, pitch, and altitude channels for "autopilot".  It is more like a Stability Augmentation System (SAS).  Roll and pitch are generally always on ...

 

Thanks a lot for the detailed explanation, I'm learning the Mi-8 too and didn't knew about this extension of the Controls Overlay. I don't like it very much because it hides the corner of the screen where trigger messages are displayed.

[scoobie]

Just one clarification, if I may: pitch and roll are SAS (engaged together with the middle green button on the center pedestal and disengaged together with a red button on the cyclic), but heading and altitude channels are real "HOLD" autopilots.

If you're interested in some peculiarities of Mi-8 autopilot in DCS - here's some I've learnt.

Provided that there have been no changes introduced to Mi-8 autopilots in DCS, you may encounter altitude oscillations after engaging ALT HOLD.
Sometimes it just works - you turn on ALT HOLD and it just "snaps". As expected.
Some other times, however, you may see that she starts to oscillate in altitude, as on a rollercoaster. The longer you allow it, the bigger the oscillations get.
It seems to be a clash of two autopilot channels - pitch (controlling your cyclic) and alt hold (contolling your collective). Sometimes they feel like having a little fight and work against each other.
If it happens to you, here's what I do with it:
1. Don't engage ALT HOLD if your vertical velocity isn't small. If you trim her first, ALT HOLD seems to "snap" nicely more often.
2. If oscillations do occur - I counteract with the stick, looking at the ALT HOLD channel. When VVI goes up or down towards zero and I can see that silly ALT HOLD channel tries to ruin it ("overreact"), I counteract with the cyclic. After 1, 2 or 3 such counter actions, ALT HOLD should finally give up and settle down.
Once oscillations stop, they seem to never reappear, so you don't need to worry (i.e. until you disangage and re-engage ALT HOLD again).
3. Another quite good option: don't use ALT HOLD if your cruise is not going to be long - she trims so well that you may simply trim her for straight and level. There seems to be few aircraft in DCS that trim so nicely (Huey is not one of them).

 

Lastly: HDG hold is very attractive for cruise in windy conditions (or for long cruise), especially when you're navigating with the DISS system or you're homing on an NDB. If the drift gauge shows some drift, you may engage HDG hold and tune the heading very precisely. Then you observe that DISS navigation panel (or NDB bearing change tendency) - correct, check, correct, check and you will get home every time (in a more or less straight line, not a spiral ). Very handy!
I have a separate (ON)-OFF-(ON) toggle switch for tuning HDG channel (well I have such switches for all autopilot channels, but I'm crazy).
Two notes for HDG hold:
Make sure you understand that touching pedals temporarily disengages HDG hold. Takes a bit of patience to get used to. During cruise it's great, but on approach/landing - less so, read below.
If you moved your pedals off the center position (and temporarily disengaged HDG hold), you now cannot turn HDG HOLD off with the red button on the center pedestal! I suspect it may be a bug. First center your pedals, then turn off HDG hold, then fly. This may cause a lot of trouble if you have HDG HOLD on and you think it's OFF... and you approach LZ, at some point center the pedals (because you retrimmed her) and BANG - the big lady suddenly tries to rotate, e.g. 3 meters above ground. Not very funny, it's good to remember about it

 

[Rudel_chw]

1 minute ago, scoobie said:

.. If you're interested in some peculiarities of Mi-8 autopilot in DCS - here's some I've learnt...

 

 

Thanks a lot for sharing your experience 

[jozeffff]

Thank you guys!

 

Great information. Appreciate it!!

[TomChaai]

For autopilot altitude hold, if it starts to go phugoid, you are flying too fast. adjust your baseline pitch attitude to stabilize in slower airspeeds.

The real Mi-8 autopilot has a speed stabilization mode  that are turned on together with altitude hold, it pitches up when the airspeed increases and vice versa, it does not seem to have been modelled in the sim. Combined with the autopilot's control response and the helicopter's high speed stability characteristics, it may end up going phugoid or even loop.

If the autopilot "B" channel starts skipping immediately when engaged, it is a bug, disconnect and immediately reconnect it.

The pedal switches are not properly simulated in game. In real aircraft, putting the feet's weight on triggers the yaw channel into override mode, the heading hold and the pedal force trim disconnects, allowing the pilots to maneuver in to new heading and stabilize it, when the aircraft is in new heading and pedals are manually positioned to stabilize it, the pilot lift the feet off, so heading hold and pedal force trim re-engages, holding the aircraft in new heading.

The game does not simulate "feet-on, feet-off" properly and instead takes "feet push" as "feet on", so when you push the pedals to turn the aircraft and are about to stabilize it in new heading, the pedals may move across neutral point, which updates the autopilot yaw channel with wrong heading, and because the yaw rate is not yet stabilized, the yaw channel swings heavily to try to stabilize the aircraft, causing great problems during hover/power change.

There is a bug that randomly prevents the yaw channel heading hold to be updated properly with pedal movement, further complicating the matter. You can end up dancing all over the place with these factors combined.

[AlphaOneSix]

On 2/17/2021 at 7:32 AM, TomChaai said:

For autopilot altitude hold, if it starts to go phugoid, you are flying too fast. adjust your baseline pitch attitude to stabilize in slower airspeeds.

The real Mi-8 autopilot has a speed stabilization mode  that are turned on together with altitude hold, it pitches up when the airspeed increases and vice versa, it does not seem to have been modelled in the sim. Combined with the autopilot's control response and the helicopter's high speed stability characteristics, it may end up going phugoid or even loop.

If the autopilot "B" channel starts skipping immediately when engaged, it is a bug, disconnect and immediately reconnect it.

The pedal switches are not properly simulated in game. In real aircraft, putting the feet's weight on triggers the yaw channel into override mode, the heading hold and the pedal force trim disconnects, allowing the pilots to maneuver in to new heading and stabilize it, when the aircraft is in new heading and pedals are manually positioned to stabilize it, the pilot lift the feet off, so heading hold and pedal force trim re-engages, holding the aircraft in new heading.

The game does not simulate "feet-on, feet-off" properly and instead takes "feet push" as "feet on", so when you push the pedals to turn the aircraft and are about to stabilize it in new heading, the pedals may move across neutral point, which updates the autopilot yaw channel with wrong heading, and because the yaw rate is not yet stabilized, the yaw channel swings heavily to try to stabilize the aircraft, causing great problems during hover/power change.

There is a bug that randomly prevents the yaw channel heading hold to be updated properly with pedal movement, further complicating the matter. You can end up dancing all over the place with these factors combined.

 

I know I'm a month late to the game, and I don't mean to be nitpicky, but I just wanted to post a couple of clarifications.

 

Older Mi-8's don't have a speed stabilization mode. I'm assuming that you're referring to the KZSP indicated airspeed controller. This was never installed on any V1's I ever saw (I know the game is modelling the V2), and I also only occasionally saw it installed in V5's. I'm pretty sure it was optionally installed based on customer requirements, since not even all brand new aircraft I'm seeing have it installed (Mi-171E). So it seems fairly likely, and certainly consistent within the game, that the airspeed controller is not installed. Note that it would have its own separate cockpit switch labeled "V HOLD".

 

Also, placing the feet on the pedals and engaging the pedal microswitches does override the yaw channel of the autopilot, but it does not disconnect the force trim. You'd still need to disengage the force trim with the cyclic button to do that.

 

Thanks!

Edited March 11, 2021 by AlphaOneSix

[TomChaai]

Thanks AlphaOneSix. It's always good to have someone with real-world experience on the subject matter to input.

 

With so many production changes and customer options available for the Mi-8 family, probably not many people have a whole picture or consistent opinion about it. Probably the game developers themselves can't agree on how to implement some of those differences.

 

I did see this manual mention that when the pedals are used to override the yaw autopilot, pedal force trim is temporarily disengaged. Maybe it is just another obscure production variant?

It's page 2-46 of this manual. TSMO Dash 10 (TM 1-1.. (yumpu.com)

[AlphaOneSix]

4 hours ago, TomChaai said:

I did see this manual mention that when the pedals are used to override the yaw autopilot, pedal force trim is temporarily disengaged. Maybe it is just another obscure production variant?

 

The TSMO manuals are pretty good, but the only thing you can trust 100% are the pictures.  We have copies of the TSMO flight and maintenance manuals at work, and my coworkers and I have found several inaccuracies and contradictions in those manuals, albeit mostly in the maintenance manuals. While I wouldn't rule out the possibility, I have never seen and Mi-8/17 where putting your feet on the microswitches disengages the force trim. Nor have I ever seen that referenced in any Russian-produced document.

[virgo47]

Just chiming in with some translations from the Russian cockpit (HKTB is in fact more like NKTV):

H=N направление (~napravleniye = direction)
K=K крен (~kren = roll, bank)
T=T тангаж (~tangazh = pitch)
B=V высота (~vysota = altitude)

Of course, the meaning was covered by the previous replies, but I was really curious what those letters mean (seeing H and B I guessed these are really N and V but in Cyrillic) - and I wanted to know the words in original. As I couldn't find it anywhere else, I'm just adding the info here.