BS Auto Pilot description and operation

[pbsmgm]

This is why I avoid the use of the term "axis" when referring to helicopters. For example, pushing the cyclic to the left causes a lateral movement of the aircraft, but if you are referring to the axis, then it creates movement about the longitudinal axis, not lateral. Some would say this is nitpicking, but the hydraulic booster that rolls the aircraft left and right is called the lateral servo. The pitch servo is called the longitudinal servo (it causes longitudinal movement, even though, again, using the axis term it would be movement about the lateral axis). The other two servos are collective and yaw (or directional). So yeah, if you are stuck using the term "axis", then the pedals would be used to move the aircraft about its vertical axis.

 

Actually, what you are saying here is no different than what I was saying, so you are totally correct and it does not change anything from being a chopper. A lateral movement with a cyclic or yoke whether its a chopper or an aircraft is a roll, which is on the longitudenal axis. A pitch movement is a longitudinal movement, yes, but it is on the lateral axis...and of course the yaw on the vertical axis. So everything you have stated is exactly what it is...whether on rotorcraft or not. So whether it is a chopper or aircraft, the AUTO TURN ON TO TARGET does in fact pivot on the vertical axis. So per this beautifully written autopilot description, we still need to change the lateral to vertical per my note above.

Edited April 23, 2009 by pbsmgm

[andysim]

This helped me so much. I watched alot of vids and the developers videos but only when I read this post did i really grasp it.

 

Before I was always pressing T once or twice during a turn but mostly cause I didnt know you could hold the T (mapped to Joystick now) button down do a direction change and then let go.

 

My flying is much smother now. :smartass:

[Harry Cockpit]

There should be a "Guides sub-forum". would be awesome. Im trying to learn auto-pilot, as far as auto-pilot flying the waypoints. Still cant get it though.

[FOXFIRE TWOONE]

Autopilot ( confused )

 

In a mission I created just to get familiar with the AP I set different altitude levels for each way-point in miss editor. When I fly the mission I choose to fly the course line in the rout mode but when I turn on the AP switch the K50 goes off in different direction from the course. As long as I leave the AP switch off it fly's and auto turns at each way-point. What am I missing here. ?

 

And should the K50 auto clime to the ( preset ) ALT, or is it a non function in BS. I know it will hold at present ALT when the ALT hold is engaged. :pilotfly:

 

Thanks

 

 

 

Never mind just saw the lengthly post on the AP

Edited April 24, 2009 by FOXFIRE TWOONE

[LastRifleRound]

The only thing that stinks about holding trim down to change settings is that the dampeners go off for as long as you have the trim button held down, and you can get some erratic behavior when that occurs.

 

The autopilot drives me bonkers when I'm trying to land, but if I go flight director or trim held down, it's very difficult to arrest lateral movement. Someone should do an in depth take-off/landing tutorial. I still don't quite understand how Wags gets the bird off the ground without forward movement pre-takeoff, yet no pitch-up on lift-off.

[AlphaOneSix]

The only thing that stinks about holding trim down to change settings is that the dampeners go off for as long as you have the trim button held down

 

The dampening function of the autopilot is still operating when the trimmer button is held down. Only the attitude hold functions are temporarily disabled.

[LastRifleRound]

Hmmmm....then i must be really jerky with my rudder inputs, as without heading hold on (trimmer depressed) i yaw all over the place, and with heading hold on (Trimmer release) sideslip becomes difficult to deal with. It must all be in smooth rudder input. I'll try tweaking my twist axis and see where that gets me.

 

I still think this way off from the real bird's operation. Normal autopilot behavior (i.e., no route or hover mode activated, the 3 recommended channels engaged pitch, bank, and yaw) behaves EXACTLY as the manual describes the behavior of "route without task" autopilot, which is basically route autopilot activated with the toggle swtich for DT-DH set to the neutral position. It would seem in real life this would be an awfully redunant choice, since this is how the helicopter behaves anyway.

 

It seems to me the previous posters' description are more accurate, wherein pilot input OVERRIDES autopilot input when route mode is deactivated, regardless of the 20% control range. That range should only be relevant if the pilot maneuvers the chopper in such a way that the FCS would have to shift the controls more than 20% of their current state to hold/stabilize whatever the pilot did.

 

In its current state, it is impossible to make fine adjustments for rocket attacks, etc. with the FCS on, meaning you must run contrary to the manual ("It is recommended to leave these on at all times") to successfully perform these maneuvers. This is because unless i make a control input of more than 20% of the current state of the controls, the autpilot will actively engage an opposite control input to what i'm trying to do. I.e., I engage rudder 15% left, the autopilot counters with rudder 15% right. "Heading Hold" should be renamed to "Yaw hold" meaning whatever yaw RATE wheter zero or 5 deg./sec the pilot set will be stabilized for easier maneuvering.

 

I guess it's all moot as ED knows what the heck they're doing and are already on top of this one, I just want my dang rockets to hit something :music_whistling:

[AlphaOneSix]

In its current state, it is impossible to make fine adjustments for rocket attacks, etc. with the FCS on

 

Hold the trimmer button down while lining up for a rocket attack. The attitude/heading hold functions will go away, leaving you with only dampening, until you release the trimmer button.

[Esac_mirmidon]

And remember rocktes are zone weapons not pinpoint ones. Salvos are your friends, best friends with the new fragmentation warhead of the S-80 ones coming with the patch.

[Topgun505]

I have been tinkering with all the various AP modes. FD on or off, Hdg hold on and off. And combinations thereof. I have noticed that when Hdg Hold is on and FD off that the system not only appears to attempt to hold the course, but if there is ANY rudder input at the time I hit the trim it snags that setting as well and pretty soon after a couple of trims it appears to build up and I'm practically flying along sideways unless I turn off Hdg Hold or hit Trim Cancel. Am I to assume the standard practice when using Hdg Hold and turning that when you finish the turn you level out and zero the rudder and IMMEDIATELY hit the trim before your helo has a chance to yaw very far off course? Or am I missing something?

[warden]

Covering all eventualities

 

Here's my understanding of it assuming no FFB (I'll edit in any corrections you have):

 

With FD mode off

 

In this mode the autopilot will always use up to 20% authority to dampen any motion that isn't due to pilot input (to stop the heli swinging like a pendulum due to shifts in momentum during by manouvering, or spinning to face wind direction).

 

Blue pitch button:

On - Default pitch for centred joystick is calibrated according to heli attitude when trimmer is tapped or released. Up to 20% authority used to return to this attitude as well as dampen any motion not due to pilot input.

 

Off - Default pitch for centred joystick is calibrating according to cyclic pitch input when trimmer is tapped or released. Up to 20% authority used only to dampen any motion not due to pilot input.

 

Holding the trim button down effectively flicks this to off, so manouvres should relate more closely to cyclic position.

 

Blue roll button:

On - Default roll for centred joystick is calibrated according to heli attitude when trimmer is tapped or released. Up to 20% authority used to return to this attitude as well as dampen any motion not due to pilot input.

 

Off - Default roll for centred joystick is calibrating according to cyclic roll input when trimmer is tapped or released. Up to 20% authority used only to dampen any motion not due to pilot input.

 

Holding the trim button down effectively flicks this to off, so manouvres should relate more closely to cyclic position.

 

Blue heading button:

On - Default heading for centred pedals is calibrated according to heli heading when trimmer is tapped or released. Up to 20% authority used to return to this heading as well as dampen any motion not due to pilot input.

 

Off - Yaw for centred pedals is calibrating according to rudder input when trimmer is tapped or released. Up to 20% authority used only to dampen any motion not due to pilot input.

 

Holding the trim button down effectively flicks this to off, so the heli shouldn't try to return to default heading under small rudder input.

 

With FD mode on

 

In this mode the autopilot will only use up to 20% authority to dampen any motion that isn't due to pilot input when the blue buttons are switched on (to stop the heli swinging like a pendulum due to shifts in momentum during by manouvering, or spinning to face wind direction).

 

Blue pitch button:

On - Default pitch for centred joystick is calibrating according to cyclic pitch input when trimmer is tapped or released. Up to 20% authority used only to dampen any motion not due to pilot input.

 

Off - Default pitch for centred joystick is calibrating according to cyclic pitch input when trimmer is tapped or released. No dampening so you'll have to manually correct for any pendulum-like swinging.

 

Holding the trim button down effectively flicks this to off, so you'll have to manually correct for any pendulum-like swinging while manouvering.

 

Blue roll button:

On - Default roll for centred joystick is calibrating according to cyclic pitch input when trimmer is tapped or released. Up to 20% authority used only to dampen any motion not due to pilot input.

 

Off - Default roll for centred joystick is calibrating according to cyclic pitch input when trimmer is tapped or released. No dampening so you'll have to manually correct for any pendulum-like swinging.

 

Holding the trim button down effectively flicks this to off, so you'll have to manually correct for any pendulum-like swinging while manouvering.

 

Blue heading button:

On - Yaw for centred pedals is calibrating according to rudder input when trimmer is tapped or released. Up to 20% authority used only to dampen any motion not due to pilot input.

 

Off - Yaw for centred pedals is calibrating according to rudder input when trimmer is tapped or released. No dampening so you'll have to manually correct for the effects of wind direction.

 

Holding the trim button down effectively flicks this to off, so you'll have to manually correct for the effects of wind direction while manouvering.

[Fakum]

Nice break down,, thanks for the effort

[Tucano_uy]

Hi guys!!!. I have one question that I couldn't answer reading the manual or this thread. Both DH/DT and RD/BR switches have 3 positions. Please correct me if I'm wrong.

 

DH - Flies straight heading to steerpoint

Neutral - Flies set heading when trim was released

DC - Flies course as planned

 

RD - Keeps radar height up to 300m

BR - Keeps baro altitude

Neutral - What does this position do? It's not mentioned in the manual or in this topic.

Also, is there any way to automatically fly a programed altitude and/or speed as you would do in a fixed wing aircraft? (programmed in the mission editor or on the navigation equipment)

 

Thanks

Edited July 28, 2009 by Tucano_uy

[Arclight]

I think the neutral position for the "altitude input" switch turns off input. As a result, the AP won't be able to hold an altitude at all.

 

To fly at a steady altitude, climb manually to desired altitude, level off and engage "ALT HOLD". There's no way to program an altitude beforehand, like you would in, say, a Boeing 737 (use dial to set desired altitude for AP). To change altitude, press and hold the collective brake, adjust collective to climb or descent, level off at desired altitude and release collective brake. (at least that's how I do it; it may not be nescessary to hold the collective brake, just press it once at desired altitude to send this new data to AP)

 

Same thing for speed; either trim the aircraft to a specific attitude that gives you desired speed (make sure HOLD functions are active instead of dampening, ie FD off), or get up to desired speed and engage AP ROUTE mode. It will keep the desired speed to the best of it's capability. To change speed, press and hold trim, change pitch to change speed (adjust collective to maintain desired VS) and release trim to send new speed to AP.

 

I think in the second case you need to trim close to the desired attitude like you would with the first method, or the AP won't have enough authority (20% max) to properly control speed by adjusting the pitch. Remember that any adjustments to the collective change the pitch, requiring a re-trim to make sure the AP still has enough authority to maintain desired pitch/speed. (when going into steady climb or descent, for example)

Edited July 28, 2009 by Arclight

[EinsteinEP]

Warden,

 

Holding down the trim button disables autopilot control feedback, but does not disable stability augmentation, so not exactly the same thing as turning the autopilot channel off.

 

Tucano_uy,

 

The middle position of the altitude input switch is "automatic" - if you're low enough (<300m) for the radar alt to pick up a reading, the system uses that altitude. If you're higher than that, it uses baro.

 

Arclight,

 

In the real chopper, the collective brake keeps the collective from moving during maneuvering or accidental bumps, so the pilot doesn't always have to keep a hand on it. To release the brake to make a collective input change, the pilot has to squeeze the brake handle on the collective grip. It's spring-loaded so it pops back once it's let go. In the sim, of course, you can fly all day and never touch the brake, but the method you described is the most representative of the real thing.

 

Also, I wanted to second your last point, about trimming close enough to the desired attitude/airspeed/altitude so that the autopilot isn't exercising the majority of its control authority: it seems that many of autopilot "problems" reported are due to pilot controls or trim settings forcing the autopilot to use most or all of its 20% margin, which can result in unexpected behavior if the flight conditions change. Also, all that autopilot control feedback gets temporarily disabled if the pilot holds the Trimmer button down, which may cause the chopper to suddenly move, just as if the controls were bumped. Keeping trim updated for all flight conditions is important for stable, smooth, and predictable control, especially when using the autopilot control feedback functions.

[JG14_Smil]

I think so much confusion could have been avoided by better labeling of the controls mentioned (not really an ED issue) :)

 

The pitch, heading and bank 'AP' buttons are really just Flight Control System (FCS) buttons that stabilize the helo. Same for the FD.

 

The ''alt hold' button is more of an AP funtion button and the route and descent modes are true "auto-pilot" functions, although without 100% control of the helo.

 

thank you EinsteinEP, I did not know the middle position was auto for the altimeter.

[Tucano_uy]

Thank you all for the quick answers

[Arclight]

thank you EinsteinEP, I did not know the middle position was auto for the altimeter.

Indeed, a valuable peice of information, much appreciated. :thumbup:

In the real chopper, the collective brake keeps the collective from moving during maneuvering or accidental bumps, so the pilot doesn't always have to keep a hand on it. To release the brake to make a collective input change, the pilot has to squeeze the brake handle on the collective grip. It's spring-loaded so it pops back once it's let go. In the sim, of course, you can fly all day and never touch the brake, but the method you described is the most representative of the real thing.

This is part of the reason I do it like I do. The other part is because it is similar to how the trim function is used; hold it down while making changes, release when at desired attitude/speed/altitude.

 

I'm not sure, but it seems to override the altitude hold behaviour untill released, much like holding down the trimmer overrides hold functions untill released. :unsure:

 

And if it doesn't, it should. ED, next patch please. :D

Edited July 28, 2009 by Arclight

[EinsteinEP]

I'm not sure, but it seems to override the altitude hold behaviour untill released, much like holding down the trimmer overrides hold functions untill released. :unsure:

It does. You can put something else on your Patch 1.0.2 wishlist now... ;)

[Arclight]

That's easy! Button to cancel only rudder trim. :)

 

And maybe a "destroy all enemies" switch. :music_whistling:

[achoice]

Fly to?

 

Hi all, my first post here.

I've been flying BS for a week or so - enjoying the challenge.

 

I've read this thread and been trying to understand/master the "auto pilot". I grasp/understand the basic features.

 

However - still I don't understand how to use;

Route mode switch and the DH/DT switch.

 

Currently I use "default settings" (as it is in campaign missions, warm started). And I manually direct the chopper roughly pointing to target point, with speed & altitude - and making small changes as time passes by to destination. (I guess it is "heading hold" function that keeps me on track to the heading when I release the trim)

 

However - reading here it seems that the auto pilot is capable of "automatic flight to track/destination". I don't understand how that is done.

I would like a step-by-step instrutcion how to "autofly" to a target point;

 

1) At liftoff - I ascend right up - say 200 m.

2) Now what - how shall I set up auto pilot to auto-turn and auto-fly to next target/nav-point?

 

my current technique - manually pointing ship to target, releasing trim, flying away - I need to correct heading now and then.. and watch altitude. A 50 min flight to target area gets boaring... and dangerous at high time acceleration...

 

regards all, thanx for a great forum!

 

/David

[159th_Viper]

Hi all, my first post here.

I've been flying BS for a week or so - enjoying the challenge.

 

I've read this thread and been trying to understand/master the "auto pilot". I grasp/understand the basic features.

 

However - still I don't understand how to use;

Route mode switch and the DH/DT switch.

 

Currently I use "default settings" (as it is in campaign missions, warm started). And I manually direct the chopper roughly pointing to target point, with speed & altitude - and making small changes as time passes by to destination. (I guess it is "heading hold" function that keeps me on track to the heading when I release the trim)

 

However - reading here it seems that the auto pilot is capable of "automatic flight to track/destination". I don't understand how that is done.

I would like a step-by-step instrutcion how to "autofly" to a target point;

 

1) At liftoff - I ascend right up - say 200 m.

2) Now what - how shall I set up auto pilot to auto-turn and auto-fly to next target/nav-point?

 

my current technique - manually pointing ship to target, releasing trim, flying away - I need to correct heading now and then.. and watch altitude. A 50 min flight to target area gets boaring... and dangerous at high time acceleration...

 

regards all, thanx for a great forum!

 

/David

 

Welcome :)

 

For a good intro, watch the first tutorial in the following post:

 

http://forums.eagle.ru/showpost.php?p=714119&postcount=1

[achoice]

Welcome :)

 

For a good intro, watch the first tutorial in the following post:

 

http://forums.eagle.ru/showpost.php?p=714119&postcount=1

 

Exelent, thanx! I have missed the "R" button - I bet that it is the magic i need to auto-fly to way points.

 

Now watching the other vids too to learn more about other stuff too.

 

//David

Edited August 5, 2009 by achoice

[Oldflyer2]

excellent thread and artical on the AutoPilot and FD systems of the Ka-50

 

I not only feel that it should be made sticky or regular main thread topic.

 

I feel it should be revised if needed and be part of the DCS Manual.

 

I feel that everyone would better understand the flight systems of this heli if they did! Avoid alot of traffic on this forum for sure.

 

Awesome!

[slug88]

I still think this way off from the real bird's operation. Normal autopilot behavior (i.e., no route or hover mode activated, the 3 recommended channels engaged pitch, bank, and yaw) behaves EXACTLY as the manual describes the behavior of "route without task" autopilot, which is basically route autopilot activated with the toggle swtich for DT-DH set to the neutral position. It would seem in real life this would be an awfully redunant choice, since this is how the helicopter behaves anyway.

 

It seems to me the previous posters' description are more accurate, wherein pilot input OVERRIDES autopilot input when route mode is deactivated, regardless of the 20% control range. That range should only be relevant if the pilot maneuvers the chopper in such a way that the FCS would have to shift the controls more than 20% of their current state to hold/stabilize whatever the pilot did.

 

 

Sorry for the thread necromancy, but I've been flying BS regularly since the release of the Russian version, and I've been reading these forums regularly for at least twice as long, and I still haven't figured out the answer to this question. Why is it that the current behavior with the 3 standard AP channels ON, flight director OFF, route switch OFF seems to exactly follow the "route without task" description in the manual? Why is it that I *have* to retrim once I've banked, or once I've turned to a new heading, to prevent the AP from returning me to the previous trim point? Why do I have to hit the trimmer to update the heading caret when I change my heading? Again, I understand completely why I would have to trim in these instances if I had Route mode engaged without a navigation task selected, as described on page 365, 10-29, of the extended flight manual. As AlphaOneSix stated on page 3 of this thread, I believe that when route mode is not engaged, any control inputs should update the AP with new hold parameters. Currently this is not the case; you have to hit trim to update the desired attitude and heading parameters.

 

The only channel where the autopilot will fight you if you move the controls without trimming is the altitude channel (which isn't technically part of the normal "trim" system since it has its own seperate button for setting altitude).

 

...

 

It has commonly been noted that in the normal autopilot mode with the three normal autopilot channels on, the autopilot will fight you if you move the controls. This is not true. It is true that absent any control inputs from the pilot, the autopilot will attempt to hold the aircraft's heading and attitude. However, if the pilot moves the cyclic or the pedals, the autopilot is aware of that and makes no move to interfere, although it continues to provide control input for the purpose of dampening (stability augmentation is the term typically used in the West).

 

In a more technical way of saying it, if the aircraft's attitude or heading changes (without any input from the pilot's controls), the autopilot receives a signal proportional to the amount of change (from the attitude indicator, typically) and the rate of change (from a gyro). It uses these signals to generate an input to the controls that restores the original attitude or heading.

 

If the pilot moves the controls and causes a change in the aircraft's heading or attitude, the signals mentioned above are still sent to the autopilot. However, in addition, a signal is sent that corresponds to the movement of the controls, effectively cancelling out the signals from the attitude indicator and gyros. This results in the aircraft's heading or attitude changing, although changes caused by instability or turbulence are still being corrected.

 

Pressing the trimmer button "re-centers" the input from the autopilot and helps keep it from reaching it's 20% limit of authority.

 

In prior posts I have mentioned that I personally like to hold down the trimmer button while moving the controls, while AirTito has explained that this is not normally done on Kamov aircraft, and instead, the pilot moves the controls to establish a new heading/attitude, and at that point presses and releases the trimmer button. My method comes from being taught by American helicopter pilots. Maybe it's because Americans are wimpy and don't have the strength to fight the force trim springs. Maybe it's a difference in piloting philosophy, I don't know.

 

What I do know is this: When flying in the game, if I move the stick, even just a tiny bit, the aircraft moves, I am not fighting the autopilot.

 

For what it's worth, I currently fly with FD off and 3/4 AP channels selected at all times. I hold down the trimmer while making large adjustments to flight profile, and incrementally tap the trimmer when making small adjustments. I can fly the BS very precisely, and am quite proficient at maneuvering, engaging with rockets, etc. But I'm still not absolutely convinced that the behavior we have in game is the same as in the real helicopter. Once again, my primary question is, in game and in real life, what is the difference between flying in Route Without Task mode, and flying with route mode disengaged, but the 3 standard AP channels activated?

Edited November 11, 2009 by slug88