Autopilot: ONLY altitude stabilization?

[Rhinox]

How can i activate autopilot so that ONLY altitude is stabilised? I mean, so that I could still turn left/righ (using roll-axis on the stick)?

 

Before Su-27 switched to this advanced flight model, I could simply use "H" which stabilized altitude, but I could still change direction of flight. Now when I use "H", both altitude and heading is "locked"...

[Nedum]

You have to read the manual. ;)

"H" does it right as you say.

But you have also RALT+1, RALT+2, RALT+3 -> RAlt+6 and RALT+9 for a resett. This are the other Autopilot Modes. Sometimes you must activate 2 Modes so you follow the route and holde the route hight. :pilotfly:

Edited November 27, 2014 by Nedum

[JulienBlanc]

You have to read the manual. ;)

"H" does it right as you say.

But you have also RALT+1, RALT+2, RALT+3 -> RAlt+6 and RALT+9 for a resett. This are the other Autopilot Modes. Sometimes you must activate 2 Modes so you follow the route and holde the route hight. :pilotfly:

 

The "H" doesn't do it ^^', exactly as described it locks the direction as well. Banking to one side will cause a violent counteraction from the auto-pilot to bring it back on track.

 

Post a track and report it as a bug :)

[sigzegv]

Same issue here, any autopilot modes lock altitude and pitch. No way to only have altitude only.

[Fouga]

The answer is : there is no more altitude holding (only) autopilot.

[karambiatos]

the H and recover autopilots, work the same right now, even though the options say they are different.

[amazingme]

Autopilot is rekt at the moment.. I often use trim reset to make it work. Idk if this is intended behavior.. but I strongly doubt. We wait and see..

[Bourrinopathe]

From what I've understood, it seems the current autopilot implementation is close to the real Su-27.

 

While trying to bind and make sense of the autopilot modes, I had to dig in the "autopilot" part of the Su-27SK Flight Manual (and I barely understood what I found :huh:)

I think all the different modes we have in the key configuration options are inherited from the common Flaming Cliffs autopilot modes.

 

I might be wrong, but the Flanker autopilot modes are pretty similar to the Ka-50 "channels logic" as you can add different flight assistance modes.

 

 

Based on the Su-27SK manual, the barometric altitude mode keeps the bank value if it's superior to 7°.

There should not be any "altitude + roll" mode as the radar and barometric altitude modes both include the roll/bank conservation.

 

Some specific modes are still missing but we don't have the chance to pilot a DCS-level Su-27.

 

The current available modes and functions should cover the essential functions, though.

 

• Attitude hold = АВТОМ (pitch + roll)
  
• Route = НАВИГ (pitch + roll, following the different waypoints (?))
  
• Barometric altitude hold = Н БАР (roll + baro alt)
  
• Radar/radio altitude hold = Н РВ (roll + rdr alt)
  
• default autopilot (default key: A) = НАВИГ+Н БАР
  
• RESET = СБРОС (cancels any mode)
  
• And the specific "level flight" which has a very special place on the Su-27's stick (ПРИВЕД К ГОРИЗ).
  

 

Nevertheless, I had some difficulties with the radar altitude autopilot as it was constantly climbing instead of stabilizing the aircraft (from a stable 120-150m rdr alt).

The radar altitude autopilot is supposed to be functional between 100m and 1000m (Su-27SK Flight Manual).

It may struggle with the new PFM (or I'm doing it wrong, or something else).

 

At least the DCS Su-27 manual tells us 'H' is an alternative to Alt+4 (baro hold) (and similar to Alt+2 (baro+roll))…

 

If it's not too much trouble, ED should modify the Su-27 key bindings to remove the useless and confusing modes.

In any case, it's still WIP and we should have a more polished autopilot.

In the meanwhile I should go back testing that AP…

Edited February 11, 2015 by Bourrinopathe

[Bourrinopathe]

the H and recover autopilots, work the same right now, even though the options say they are different.

 

I'm not sure how it's modeled right now but the "recover" autopilot has a specific behavior (Su-27SK Flight Manual (which could very well be different from what we have, of course) - please grab the salt ;) ):

- with a roll angle inferior to 80°, the autopilot recovers the pitch and roll angle simultaneously.

- with a roll angle superior to 80°, [EDIT:the autopilot recovers the pitch angle first, then the roll angle.<<< WRONG! (the AP reduces the roll angle first (<80°) and then recovers the pitch and roll angle simultaneously)]

 

Time to test "H" and "Level Flight" modes ;)

 

[EDIT: "H" and "Level Flight" autopilot modes act differently here: "H" just tries to lock and stabilize the baro altitude and "Level Flight" achieves to recover the aircraft with more than 90° bank, inverted flight, high positive and negative pitch.

Did I understand you correctly? ]

Edited February 13, 2015 by Bourrinopathe
wild spelling tamed + huge mistake whipped

[Azrayen]

I'm surprised. I would think first wings level (roll) then pull (pitch) with max aerodyn performance is more efficient to "recover". That's how it works on F-16, Rafale...

[karambiatos]

 

[EDIT: "H" and "Level Flight" autopilot modes act differently here: "H" just tries to lock and stabilize the baro altitude and "Level Flight" achieves to recover the aircraft with more than 90° bank, inverted flight, high positive and negative pitch.

Did I understand you correctly? ]

 

I had it wrong the first time, i just found it strange that the same lights turn on for both the recover and the when pressing the "H" and both locked the roll.

[Bourrinopathe]

- with a roll angle inferior to 80°, the autopilot recovers the pitch and roll angle simultaneously.

- with a roll angle superior to 80°, the autopilot recovers the pitch angle first, then the roll angle.

 

I'm surprised. I would think first wings level (roll) then pull (pitch) with max aerodyn performance is more efficient to "recover". That's how it works on F-16, Rafale...

 

Indeed. :doh:

My mistake. I was too hasty and made a sloppy translation (I must have been really tired, because I try to be careful about those details).

Sincere apologies.

 

Here's the original text from the Su-27SK Flight Manual:

 

В процессе приведения самолета к горизонту контролировать параметры полета и в соответствии с их значениями изменять режим работы двигателей.

Приведение к горизонту происходит в следующей последовательности:

 

− при углах крена менее 80° самолет приводится к горизонту по крену и тангажу одновременно;

 

− при углах крена более 80° самолет приводится к горизонту сначала по крену, а после достижения угла крена 80° приводится по крену и тангажу одновременно.

 

So, when the roll angle is superior to 80°, the AP first decreases the angle to a value inferior to 80°, and then achieves a simultaneous correction (roll + pitch).

 

 

Thanks for spotting the error, Azrayen :thumbup: