APFD Logic

[bluepilot76]

I now see why I have never really been able to fly this beast safely in the past: The APFD switch operates in the opposite sense to how I expected....

 

Why does the BS attempt to follow a trajectory when the APFD switch is not selected- ie it is unlit. If you release the controls the helicopter will slowly turn back to the trajectory it was when you last pressed the trim button.

 

When the APFD switch is lit, the trimming simply operates to release continuous pressure off the controls and is (to me) much more intuitive. Completely gone are the sensations of fighting against the AP system.

 

So why is the APFD switch operating when the switch is not lit, and not when the switch is lit which would indicate “on”- as it does for the roll / pitch/ hdg channel selectors to its side.

 

Could this be why so many people struggle to control this machine? Could this be why some people have developed the habit of holding the trim button through complicated maneuvers? If you are fighting the flight director the temptation is to hold the trimmer. In my case I developed the habit of turning off the Rol/Pitch/Hdg channels and flying it the old fashioned way. The lighting logic seems incorrect to me.

[Arclight]

Nope, logic is just fine. Normally the channels are in a "hold" mode, with the FD active they only dampen.

[Kite]

i never understand well this point.

"Flight director mode button. Disengages autopilot automatic angular stabilization (except for dampener function) and enables flight director mode on the HUD. [LCTRL + A] "

 

This disegnage angular stabilization , ( bank correct ?) except for dumpener funcion. ( what this mean? Disengage roll or not? what is the meaning of dumpener? )

thanks

[Luigi Gorgonzola]

FD OFF -> Attitude HOLD

 

FD ON -> Input Dampening

 

Attitude HOLD means it will attempt to keep the flight attitude as found on latetst trimmer usage.

 

Input Dampening means it will only dampen (soften?) your input on Cyclic, Collective and Rudder but it will not alter your flight attitude.

 

FD != AP this is important to keep in mind. In fact, you actually do switch between FD and AP usage instead of switching on/off any one of FD and AP. One of both is always in command (as long as you have those shiny blue buttons lit, that is)...

Edited November 30, 2011 by Luigi Gorgonzola

[Arclight]

The difference is that the auto-pilot no longer tries to keep the helicopter to a set attitude.

 

Normally, when you release the trimmer in a wings-level condition, the AP holds the pitch and heading, keeping wings level and correcting for heading deviations.

 

In a turn, I believe bank angle 15 degrees or greater, the bank angle is held instead. Rather than trimming it to hold a heading, you're trimming it to hold a turn.

 

 

With the FD active, all that goes out the window. There's is no hold functionality in those 3 channels at all. What the AP does in that case is dampen, ie. "smooth", pilot inputs only. This dampening, to the best of my knowledge, is mainly there to prevent pilot induced oscillation.

 

Try flying with all the channels turned off (as compared to pitch/bank/heading active with FD enabled). I think you'll come to appreciate the dampening rather quickly. ;)

[Kite]

didn't ever experienced. Should try.

You mean try all AP off and only turn on the APFD?

[wess24m]

The difference is that the auto-pilot no longer tries to keep the helicopter to a set attitude.

 

Normally, when you release the trimmer in a wings-level condition, the AP holds the pitch and heading, keeping wings level and correcting for heading deviations.

 

In a turn, I believe bank angle 15 degrees or greater, the bank angle is held instead. Rather than trimming it to hold a heading, you're trimming it to hold a turn.

 

 

With the FD active, all that goes out the window. There's is no hold functionality in those 3 channels at all. What the AP does in that case is dampen, ie. "smooth", pilot inputs only. This dampening, to the best of my knowledge, is mainly there to prevent pilot induced oscillation.

 

Try flying with all the channels turned off (as compared to pitch/bank/heading active with FD enabled). I think you'll come to appreciate the dampening rather quickly. ;)

 

+1 :thumbup:

[bluepilot76]

Good knowledge - thanks for your input.

 

I have been confused by the term "Flight Director" in this instance. To me, a "Flight Director" is a system usually used to control a flight path through visual cues to the pilot or to the autopilot system. With FD "on" in Ka50 it actually frees up the controls for the pilot to manoevre the helicopter without any predetermined flight path. It actually seems the free-est method of flying the machine, apart from turning off the Pitch/Roll/Heading channels which is not reccomended. Now that I have realised the difference I find KA50 much more enjoyable to fly! I will only use the FD "Off" if I am in transit somewhere and need to setup the cockpit for the next phase.

[Luigi Gorgonzola]

With FD "on" in Ka50 it actually frees up the controls for the pilot to manoevre the helicopter without any predetermined flight path.

 

Near miss ;) The FD is actually meant to direct (guide) you along the selected flight path.

 

Give it a try by setting up a route (ME or in the cockpit, use the PVI-800 for the latter case) and switching to ROUTE mode (DT or DH doesn't matter). The FD will visually guide you along the predefined flight path.

 

Without a programmed route (i.e. PVI-800 neither in WP, IP nor Airfield mode), it will provide you a visual guidance to reach the flight attitude as given/determined when the trimmer was released the last time.

 

It actually seems the free-est method of flying the machine, apart from turning off the Pitch/Roll/Heading channels which is not reccomended. Now that I have realised the difference I find KA50 much more enjoyable to fly! I will only use the FD "Off" if I am in transit somewhere and need to setup the cockpit for the next phase.

 

As far as I understood, that's one of the ways it's meant to be used. FD is fine when flying along a route (or freeflight), e.g. scanning for threats. AP is cool when used in transit.

 

For further reading I highly recommend the following link. It's way better than the (cluttered) information in the flight manual:

 

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

Edited November 30, 2011 by Luigi Gorgonzola
fypo tixing, yeah!

[bluepilot76]

Hi Luigi, thanks for the link to that, I look forward to reading it properly. Hopefully only the 1st post will suffice as its an 11 page thread.

 

If I was designing the shark I would get rid of all these FD route visualisations from the FD mode, and just let it be a freeflight, smooth, no worries aerobatic mode, and put all those route following functions onto the AP mode.

 

Anyway presumeably once I read that thread I will discover there is actually a really good reason for it to be the way it is.

 

I wish it had been in big bold letters on the HUD:

 

Beginner ? TURN THE DAMN FD ON! Its not what you think!

[Speed]

I've got a question:

 

Should the helicopter fly the EXACT same way with the trimmer button held down as it flies with FD AP enabled?

 

Anyone? Because to me, in Black Shark 2, it doesn't feel like it does.

 

In Black Shark 1, however, I think that it felt like it did.

 

This could solely be my imagination, but I'm still suspicious of Black Shark 2's flight and autopilot modelling. I'm aware that human objectivity sucks, so I'll readily admit I could be wrong... but I just can't shake the feeling that something is wrong with my helicopter in Black Shark 2.

[bluepilot76]

Hey Speed, Im obviously a bit of an amateur to the Shark. But just a thought on this;

 

If you hold down the button, presumeably there is no trim on the control, Pilot would be feeling unassisted controls.

 

In FDAP mode, using the trimmer, there is feedback. for example I trimmed it for 250 and was manoevering at that speed, but then I did some serious slowing down without retrimming. It was apparent that my stick was now near the end of its travel and it required retrimming for the new slower speed. Presumeably the RL KA50 pilot would have been feeling some serious pressure on the control to hold the stick that far off trim.

 

Whether its changed sionce BS1, I dont know. I do know I can now fly the sucker, but obviously thats because prior to now I was using AP not FD so the damn thing kept trying to fight back to the previously trim button trajectory.

 

Didnt think you would be in the Shark, must seem very low to you!

[GGTharos]

^^^^

 

Bluepilot is onto something there, but not quite correct. With the trimmer pressed down, there is certainly assistance/damping, but there's no trim/force effect on the stick. It moves pretty freely.

 

With FD ON, you still have the trim forces affecting the stick and bringing it back to the /trimmed/ position.

 

@bluepilot: Put the FD OFF and learn how to use the AP instead of fighting it, you'll live a longer (virtual) life ;)

[bluepilot76]

Hey GGTharos,

Thanks for the tip! At the moment I am like a spring lamb in the field, bouncing around enjoying my new toy. Maybe one day I will grow up and use the horrible AP. But not yet! I just hate the feeling of the AP pulling me away from the manoevres I am flying.

 

In IL2 terms (long time since I been there...)

FD on = Spitfire

AP on = Spitfire with massive hole in one wing.

[Luigi Gorgonzola]

Hi Luigi, thanks for the link to that, I look forward to reading it properly. Hopefully only the 1st post will suffice as its an 11 page thread.

 

Oops - never followed the thread, the first post says it all ... :wub:

 

Anyway presumeably once I read that thread I will discover there is actually a really good reason for it to be the way it is.

 

I wish it had been in big bold letters on the HUD:

 

Beginner ? TURN THE DAMN FD ON! Its not what you think!

 

:thumbup: Full ACK!

[GGTharos]

Certainly the FD on will help you learn how to fly a heli - much like any training heli, and I'd reccomend that ... but if you're flying just fine with FD ON and having issues with FD OFF, then you're experiencing one or both of the following problems:

 

1. You're massively over controlling.

2. You don't understand the AP functionality.

 

Hey GGTharos,

Thanks for the tip! At the moment I am like a spring lamb in the field, bouncing around enjoying my new toy. Maybe one day I will grow up and use the horrible AP. But not yet! I just hate the feeling of the AP pulling me away from the manoevres I am flying.

 

In IL2 terms (long time since I been there...)

FD on = Spitfire

AP on = Spitfire with massive hole in one wing.

[bluepilot76]

1. You're massively over controlling.

2. You don't understand the AP functionality.

 

I am sure your right. I am sure I will improve. I just struggle to see why AP seems to be the most popular mode.

 

How it seems to me just now (no doubt this will develop as I learn) that there are two types of flying that one might generally partake in, in the KA50, and there are 2 modes of control.

 

(1) flying legs, or gentle and stable orbits. e.g. either in transit or on targetting runs. In this case AP is most suitable. Allows heads down activities.

 

(2) Nap of the earth / aerobatic /evasive manoevres / dogfights. In this case FD is most suitable.

 

Previously whenever I tried to do (2) I was not in FD because to me FD sounds like it is supposed to be for (1). Then I could feel the AP interfering and didnt like it, or in extreme case all the blades would fall off. Its just a relief to fly the thing in FD now. More like what Im used to as Im mostly a A10 guy. I think a lot of people have had problems with this aspect of the shark and wonder if more would be enjoying better it if they used the FD mode.

 

Incidently when I first got BS1, I remember totally struggling and looking for help on the internet. I remember reading an article (sim HQ I think) where the author had also struggled and reccomended taking off, setting the trim for hover at 50 feet or something, then flying round the whole mission never touching the trim again so that when needed he/she could let go of the controls to easily attain a new hover! wow what a way to carry on! And I was thinking, thats a good idea, that must be the key, because I sure as hell wasnt having a lot of success with my methods!

[GGTharos]

Combat, aerobatics, all this fun stuff is flown with AP on and frequent trimming. This includes NOE. Most people don't realize that NOE, however, is as high as 200'. Regardless, the heli is actually capable of flying itself in a NOE profile as long as the terrain is reasonably smooth - since it doesn't have a TFR, it only know what's below it.

 

The reason you are having trouble with the AP is that you're probably thinking various maneuvers need to be more violent than they are in reality. In reality -everything- is smooth and 'gives you heads down time', except perhaps when flying low and - at that point, what you want is a very predictable heli, and AP gives you this.

 

It's just a matter of knowing what the AP does, when it does it, frequent trimming, and /using/ the AP.

 

Previously whenever I tried to do (2) I was not in FD because to me FD sounds like it is supposed to be for (1). Then I could feel the AP interfering and didnt like it, or in extreme case all the blades would fall off. Its just a relief to fly the thing in FD now. More like what Im used to as Im mostly a A10 guy. I think a lot of people have had problems with this aspect of the shark and wonder if more would be enjoying better it if they used the FD mode.

 

Yeah, and in reality you'd stop flying 10 minutes later, because your hands and arms would be cooked. The trimming mechanism puts a LOT of force into holding the stick in its trimmed position :)

 

Now, all that said, there's a third problem, and that is the problem of your controls not being realistic. That one isn't easily solvable, and it may indeed cause you to prefer FD ON. I can't tell if that's the cause for you though, or if it's just because you have a more let's say, movie like expectation of what you should be doing with the heli vs. what you should be doing realistically speaking.

 

Frankly, I think realistic flying can be somewhat boring - a lot of it is navigation in long stretches for example, and even combat runs that may seem fast and furious are actually done meticulously, sticking to procedure and giving yourself enough setup time to execute your maneuvers.

 

Defensive maneuvers are procedure, too - there's really not much to do with 'instinct' in real life combat flying - not in a highly trained air force.

 

To conclude, though - it's your game, play it the way you enjoy it. It provides you with all the things that the real vehicle does if you want to learn to 'do it right', but there's nothing saying that you can't play the way you want to. As for me, I'm just the guy who'll always poke you and say 'Hey, you have a great realistic flight sim, why aren't you using it to find out how they do stuff for real?' :)

 

Incidently when I first got BS1, I remember totally struggling and looking for help on the internet. I remember reading an article (sim HQ I think) where the author had also struggled and reccomended taking off, setting the trim for hover at 50 feet or something, then flying round the whole mission never touching the trim again so that when needed he/she could let go of the controls to easily attain a new hover! wow what a way to carry on! And I was thinking, thats a good idea, that must be the key, because I sure as hell wasnt having a lot of success with my methods!

[bluepilot76]

OK, Im going to stop buggin everyone about this, time to go and get some airtime and maybe read that good post I was told about earlier,

 

just a tiny point before I bug out, because I know that everyone of the experts agrees that frequent trimming is good trimming, as it is in real life. Whilst flying in FD I was trimming LOTS. I just mention this because it sounds from your post that you think I am not trimming. I dont advocate that at all!

 

Oh, I add the track I recorded of my experiments with the two modes this morning, just in case it is interesting to anyone. You can see I am checking the mode and then flying various manoevres to see whats happening. During this flight the penny dropped for me.

 

Thats the end of my 12 hour shift, now Im glad to go get back in the Shark to try the second mission in the medevev campaign! Wish me luck!

 

Thanks everyone for the useful input. I will be rereading a lot to make most use of the advice!

FD AP testing.trk

[GGTharos]

Is this a BS2 track?

[bluepilot76]

Yes

[GGTharos]

What are you trying to demonstrate by turning FD on and off? :)

[bluepilot76]

Good morning. Watching that Kamov KA50 (cockpit view, real) on You Tube it looks to me like the pilot changes from AP to FD at about 2.42 - there is a wobble - possibly where he swaps hands to change the switch, he then starts to trim for speed rather than course. His last trim is just before he says something (love to know what) and at that point he has trimmed for a stabilsed hover. Through the whole of the aerobatic sequence there is no trimming. No way is he using AP through this in my opinion.

[GGTharos]

No, he doesn't. Do you see any FD symbology on the HUD? He's flying with FD OFF.

[bluepilot76]

Im sorry GG, I can tell I am getting on your nerves and it must be annoying to have a beginner come on here and say this doesnt seem right. I am just trying to think logically, and outside of the box. It is an unfortunate trait of mine...I want to understand why using the AP is the accepted norm, I promise I am not trying to be a pest!

 

Bear with me;

An AP is supposed to assist a pilot. Having a spacial-reference-position-hold-stabilisation-system (or whatever..the KA 50 mode AP) is not going to help a pilot perform airshow aerobatic manoevres.

 

It is EASY, even for me- a mere beginner! to perform manoevres like that if I am in FD mode. I tried it in AP and could not do them. It makes sense to use FD; the damping functions are there, but not the position hold functions.

 

WHY would you choose the AP function over the FD function in this situation. People keep saying to use AP its better, but nobody has given me a reason why yet.

 

Meanwhile there seems to be a major issue going on on this forum because people are getting trim bumps because they are flying manoevres with the AP engaged. Of course there is; the helictoper is trying to do its own thing. It "thought" you wanted to fly in a certain trajectory, but you are pulling it away from that. Try it with FD I promise its easier!

 

If you have a chance, and are not totally bored of this topic, could you please post a couple of tracks. One doing these airshow manoevres with the AP engaged, One using FD. Show me the advantages of one over the other..Try and replicate the airshow part of the YT video.

 

As for the missing FD symbology, I would be very VERY surprised if you cannot turn that off. DCS is good, but its not perfect.