Autopilots and Flight Directors and Trim, Oh My!

[kingfish]

Let me preface this post by saying that I am an airplane guy through and through, so I am learning both how the heck helicopters even work at the same time as trying to figure out all the systems.

 

I bought BS and have been trying to learn how to effectively fly it for some time now. I am still in the "make it go where I want it to" phase of learning, but I feel like I'm missing something, because the auto-functions don't seem to do what I want or what I would expect them to do, and half the time it feels like they're actively fighting me.

 

So without further ado:

 

Autopilot Functions: From what I understand, the heading, pitch, roll, and alt hold buttons activate some kind of stability system on the helicopter for the indicated channel. But they do not seem to do all that much. The manual says that they only have 20% authority over the stick, but even trimmed out as well as I can get and with the stick at zero, my helicopter likes to drift up and down and roll. If I am moving forward (trimmed) and I let go of the stick, it immediately pitches me way up, often past 30 degrees. I'm not sure why that happens. I have to trim my helicopter nearly half my control range nose-down just to keep it from making me do backflips.

 

The only thing that works well is the heading hold, and that seems to work way too well and is always yanking me around left and right. Is the only way to get the hdg hold to settle on a new heading to hit the trim button at the new heading? Is there a mode where it simply holds whatever heading you leave the helicopter at? Exactly what is the purpose of the other autopilot buttons, seeing as they have apparently very limited control authority? What is the practical use case for these buttons?

 

Flight Director: Ok, this one I have read forums and manuals and I'm still not sure what it does. As far as I can tell, turning FD on disables all the autopilot functions and replaces them with an indicator on the screen. Is this accurate? If so, what is the purpose of this mode, and what is the purpose of autopilot+FD rather than just turning off the autopilot?

 

Auto Hover: From what I understand, you bring the helicopter to a near-hover, and hit the auto-hover button, and then...what, exactly? auto hover on and off, my helicopter likes to drift in all directions (albeit slowly), so I have to be constantly tweaking cyclic and collective position to keep from slowly drifting into the ground, or into trees, or towards the enemy. It feels like about the same amount of effort to hold position as it takes with the AH fully off. What does this function do exactly? I read somewhere on the forums that it is supposed to hold you in place while you hover. Assuming I'm doing something wrong and it does do this well, how would I then change my location set point? Turn off auto-hover and move? or does pilot input to move also move the AH setpoint?

 

 

Anyways, I figure most of this is just gross misunderstanding of the systems. Any help would be greatly appreciated.

 

Peace

Kingfish

[winz]

Autopilot has two functions

1)Stability augmentation - to make the helo more stable overall and prevent things like pilot inducted oscilation

2)Hold mode - Which is what you descibed in Autopilot function. It is there to hold the helo in the attiude/heading it was in when the trim button was released.

 

Flight direction disables the hold mode, but keeps the stability augumentation. So the helo will not become the suicidal mess of rotating parts that it by design is.

 

Auto hover: If you're trimmed correctly and already in hover when you engage this mode, then it will keep you in hover, stationary. Helicopter is unstable, so there no hover without constant inputs (especially irl when the weather is much more lively), auto hover provides the constant inputs instead of the pilot.

 

All these system are there because helos are unstable, they require constat input and correction. Unlike fixed wing aircraft they don't have a stable attiude, all these system are there to lower pilot load by making the helo more stable.

 

I would suggest the UH-1 module, it will show just how unstable and how much work flying a RAW helo is and it will make you appreciate the stability systems in Ka-50 much more ;)

[dburne]

Autopilot channels:

I typically fly with three of these channels on, the exception being altitude hold. Trim the aircraft for the direction and speed you want, holding in the trimmer as you do so. When it stabilizes to where you want it, release the trimmer button. The helicopter will hold this attitude. You can adjust altitude with the cyclic.

Anytime you change direction, hold the trimmer in whilst doing so, and release when you are in the heading and pitch you want and stable again.

Btw, I use the " central position trimmer". That option is located in the " special" tab of the control menu for the Ka-50.

 

Flight Director - yes disables autopilot channels and allows complete control, personally I rarely use it.

 

Auto Hover: Be stable and not moving. When engaging, I think ideally you want to be less than 15 kmh when engaging - the closer to 0 the better.

When you decide to move, disengage the AH. ( also note engaging auto hover also engages altitude hold).

 

Practice, practice, practice. Work on using and getting used to that trimmer button. It is your best friend. Use rudder input with your banking for co-ordinated turns, watch your climb/descent rate on the gauge as you turn, practice turns without gaining/losing altitude.

 

There are others with much more experience in the Shark than I that will chime in as well. I am still learning, mainly how to navigate and fly combat now.

Edited October 28, 2015 by dburne

[ricktoberfest]

It is definitely a learning curve on trimming the ka50. Like someone said above me- the easiest way is to hold the trimmer until you stabilize on a new heading/pitch/roll and then release. Not realistic from what I hear, but without force feedback it seems to work the best. Most other helos use repeated presses of the trim but not the ka50. Also- there is a switch below the autopilot stability buttons that changes from DT/neutral/DH. In DT mode it will try and fly the track towards your next waypoint, DH mode try's to fly the heading towards your next waypoint, and neutral (middle position) will keep the heading from the last time you released the trimmer. This is not the route following- it's more subtle than that. If I feel I'm fighting the autopilot too much press and hold the trimmer and stabilize before releasing

 

 

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[StrongHarm]

I have the AP channels set up to the CM hat on my HOTAS. I keep pitch and bank on at all times except when evading, in that case I can press the hat down to do quick all channel AP disable. As for trimming to change heading, I've never really understood this logic. I simply push forward on my CM hat to disable heading AP, go to the desired heading, then turn it back on. It zeros to that new heading without altering my pitch and bank trims. Alt AP is useful for popups: if you keep the alt AP off and zero out your Vertical Velocity Indicator (VVI), then turn alt AP on and give just a little up collective you'll still stay at the same altitude.. BUT when you're ready to do a popup turn alt AP off.. you'll increase alt nice and steady, take your shot, then turn alt AP on again and return to your original altitude. Also concerning alt AP; you'll notice that if you turn alt AP on while moving fast, then change altitude with it still on, the bird will fight the collective and your nose will oscillate. Don't fight the APs with the controls, it's a common mistake. Just turn them off, make the change, then turn them back on.

Edited October 29, 2015 by StrongHarm

[Frederf]

It is important to remember what Winz says: autopilot channel (3, altitude is different) is two components: stabilizing and hold. When the light is shining the stabilization part is always on. It can be said the second part of each channel may be "suspended" by certain actions (trim, FD). When the hold function resumes it captures a value and applies it addition to the pilot input.

 

Stabilization in all 3 channels are used at all times except in emergency. Flying with raw input (no stabilization) is distinctly difficult. Hold component is optional for pilot convenience. They are suspended while "Flight Director" (loose translation from Russian) is on or trim button is held.

 

Flying with "FD" is flying with the stab. layer but not the hold layer. This is not getting the "money's worth" from the full autopilot but it is good at least to learn one layer at a time. Once the flight dynamics are understood in stabilization only flight the changes that hold component makes is less mysterious.

 

Trim button is an important control because it is two functions in one. It is a change in the mechanical spring feel and also it is for capturing autopilot values. It must be understood that the control of cyclic is hydraulic without natural feeling for the pilot. It takes normally no effort to move cyclic to any position. To improve control a spring is introduced so the pilot feels a pull toward some center position. When the trim button is pressed the anchor for the spring is released and the pilot feels no resistance to motion (like the spring is broken). When the trim button is released the spring is again anchored and this new anchor location is the next center of the spring feeling. It is up to pilot technique if the button is held for a significant time during a maneuver or if it is quickly tapped when the new flying state is reached.

 

Electronically the trim button held down suspends all channel hold input. When the trim button is released the autopilot captures the next working values of pitch, bank, speed, heading, turn rate, etc. as appropriate for the working mode of the AP.

 

Because it is possible to trim a new position of the cyclic more quickly than the helicopter can stabilize into a new flight state is it very likely that hurried trimming will cause a mismatch between cyclic input and captured electronic value. It is therefore recommended that input for a new direction of flight be held by the pilot steadily until it is confirmed that this input produces steady and desired direction of flying. It is often found that the input made to begin a change of flying quality is greater than needed to maintain it. When steady input produces steady flying satisfactorily, press the trim button and release control pressure.

 

At this time is good to notice the collective has an AP channel and a trim button of its own. This is named collective brake and is normally squeezed each time the collective handle is moved. If the altitude channel is on (optional) it will alter the collective blade angle if configured to hold radio or barometric altitude. Holding the brake suspends the hold and releasing the brake resumes the hold while capturing a new altitude. Maneuvers by the cyclic and rudders while the altitude hold is functioning will produce a significant sluggish feeling. It is recommended to disable altitude channel or hold collective brake except when requiring its function. All altitude functions are entirely separate from cyclic/rudder both physically and electronically.

 

With "FD" on it can be seen through HUD symbols only values that the holds would use if they were active. But in "FD" the holds are suspended in actual function, providing no input. In "FD" the hold components are displaying advice only visually and the pilot is responsible for following.

 

With no navigation task set the captured heading value is shown as a diamond on the HUD. If a navigation task is active the captured value is not shown (but it is still captured) and the diamond shows the navigation flying instead.

 

Without "FD" it can be felt the capturing of values of pitch, bank, and heading (or heading rate if captured when fast changing). Again it is reminded that only cyclic/rudder and electronic value captured during steady flying are guaranteed to continue steady. Maneuver can be done by applying enough input to achieve new flying condition without regard to hold and then trim in new condition or trim can be held from beginning of maneuver so holds are suspended during.

 

For autopilot "route" instead of pitch, bank, and heading it is instead speed and track direction. If no navigation system task light is illuminated then route will be "without task" capturing current speed and track. If task is illuminated then turning will happen according to task needs. Trim works in a similar way with route, suspending when held and resuming/capturing when released.

[Slazi]

From my experience, the main thing I learned was to trim everytime I do anything. Start by trimming all the time and you will eventually learn when you don't need to.

 

What you learn from the shark will transfer to all helicoptors. The Huey and the Mi-8 are totally different to fly, but the basics are the same.

[Slazi]

Oh, and if you know where the offshore oil rigs are, these make for great landing an maneuvering practice areas.

[StrongHarm]

I would recommend not getting into the bad habit of trimming anytime you do anything. The only time I use trim is if I need to change the speed I'm maintaining or for wind affects, and I find flying much more enjoyable than before. Before you decide which method you want to use, take 30seconds to test it for yourself:

 

TRIM METHOD:

- Get in level flight at 50kph heading 000

- Hold your trim and make a 90deg turn to 270

- Release your trim and get back into level flight

- Retrim if necessary to maintain 50kph at heading 270

 

AP METHOD:

- Get in level flight at 50kph heading 000

- Disengage heading AP and make a 90deg turn to 270

- At the precise moment you hit 270, turn your heading AP back on

- Allow the helo to stabilize itself, no retrim necessary (high winds not withstanding)

[ricktoberfest]

I would recommend not getting into the bad habit of trimming anytime you do anything.

 

Strongharm, I appreciate your many contributions to the community, but what you're telling him to do is not at all realistic.

 

Although the trim system can be a lot to begin with, if you intend any kind of "realistic" flying you need to learn it (yes it's a computer program- I get that)

 

The ka50 was built as a single person helicopter and the autopilot system allows the pilot to concentrate on weapons delivery instead of flying at crucial points in the mission. Turning on and off the stability system is adding more work overall- not less. While I will sometimes switch on the flight director while evading fire, turning off the stability/autopilot system simply to make a turn is not realistic at all.

 

There is a great video on the forums somewhere of a helo landing on a ship (commercial simulator) and you can hear the pilot constantly re-trimming. Trimming in a helicopter should become second nature.

 

Now of course as this is a game- to each his own. But unless someone says otherwise, I aim to give fairly real life procedures. In real life the stability system is on whenever the helicopter is flying unless it's an emergency situation (damage)

 

 

 

 

 

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[StrongHarm]

I'm not saying don't trim.. I'm saying not to use trim in place of fighting AP channels. Look at my last post and try what I said before you make any conclusions. I just finished a very successful mission and only used trim when changing speed and entering new wind patterns. When I change heading I simply turn heading AP off... go to the new heading and turn heading AP back on (which does the same thing as trimming without changing all your other trim axees). To be clear this is just heading and alt AP; the only time I turn all channels off is in an emergency evasion (i.e. I notice a missile headed at me .5k out).. this is most likely why it's called emergency AP override.

 

Really I know it's far outside what you're used to, but do me the courtesy of not dismissing it until you give it some thought and actually try it. I don't believe it's unrealistic.. in fact, I would venture to say it's more likely what's done in real life (or some combination), and I can assure you it works a hell of a lot better for me. Hope it helps.

[Reaper6]

Strongharm, I appreciate your many contributions to the community, but what you're telling him to do is not at all realistic.

 

Although the trim system can be a lot to begin with, if you intend any kind of "realistic" flying you need to learn it (yes it's a computer program- I get that)

 

The ka50 was built as a single person helicopter and the autopilot system allows the pilot to concentrate on weapons delivery instead of flying at crucial points in the mission. Turning on and off the stability system is adding more work overall- not less. While I will sometimes switch on the flight director while evading fire, turning off the stability/autopilot system simply to make a turn is not realistic at all.

 

There is a great video on the forums somewhere of a helo landing on a ship (commercial simulator) and you can hear the pilot constantly re-trimming. Trimming in a helicopter should become second nature.

 

Now of course as this is a game- to each his own. But unless someone says otherwise, I aim to give fairly real life procedures. In real life the stability system is on whenever the helicopter is flying unless it's an emergency situation (damage)

 

 

 

 

 

Sent from my iPhone using Tapatalk

 

I would have to agree, you most certainly need to be familiar with trimming the KA50. Normally you don't really need to trim all that often because of the AP dampeners, as in other rotary aircraft. I use the trim for long level flights(over 30km), or for Hover Hold. After that you can concentrate on spotting targets and destroying them.

 

Reaper6

[StrongHarm]

Again, I'm not saying trimming is not important. What I am saying is that retrimming all axees for the sake of changing heading requires a lot more effort than turning heading AP off, going to the new heading, and turning it back on. Yes, stabilization is important but not 'heading stabilization'. The bird will not be destabilized by turning off heading AP. I don't turn pitch and bank AP off to change heading.

 

I encourage standing by what you know, but progress is considering that there might be a better way. Take 30sec to try changing heading with heading AP off (LSHIFT+H I believe, but I suggest mapping it to your HOTAS). You might just be surprised.

[Reaper6]

Again, I'm not saying trimming is not important. What I am saying is that retrimming all axees for the sake of changing heading requires a lot more effort than turning heading AP off, going to the new heading, and turning it back on. Yes, stabilization is important but not 'heading stabilization'. The bird will not be destabilized by turning off heading AP. I don't turn pitch and bank AP off to change heading.

 

I encourage standing by what you know, but progress is considering that there might be a better way. Take 30sec to try changing heading with heading AP off (LSHIFT+H I believe, but I suggest mapping it to your HOTAS). You might just be surprised.

 

I agree. I use the same method from time to time for resetting my heading. I have also used the HMS and TOT for resetting my heading, each person knows what way is best for them.

 

Reaper6

[StrongHarm]

I should mention, if I know I'm going to do a forward velocity change and heading change at the same time, I re-trim instead of messing with heading AP. If I know I'm going to maintain the same speed I'll turn off headingAP, turn to the new heading, then turn it back on to lock that new heading in.

 

One major clear example where re-trimming to change heading is bad for me: When I'm unsure of a manpad threat and I need to get in close enough for them to be a danger, I'll put myself into a funnel maneuver and circle the target at about 3k out. I trim to maintain the side slip and lock my alt in. I'm then a very difficult target for anyone to hit and I can blast away at the target area indiscriminately. I'll use turn to target, but sometimes the weapons threshold is outside of my nose vector. In this case I'll turn heading AP off, make the correction, then turn it back on.. because re-trimming in a funnel maneuver is hell.