APFD Logic

[159th_Viper]

....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....

 

Have a look at the following track - flew with Pitch, Bank and Lateral dampener engaged and Flight Director off with absolutely no trim input apart from the very beginning -

 

Hooligan.trk

 

Whilst I am the first to admit that I am no aerobatic pilot, I think the vertical manoeuvres are close to similar enough for the purposes of comparison.

[GGTharos]

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!

 

You're not getting on my nerves, you are actually not thinking logically:

 

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.

That symbology is the flight director, and there is no way to turn it off in the cockpit.

 

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.

Because it increases situational awareness in an already overloaded work environment and allows the pilot to concentrate on doing something else, safely.

 

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!

Yes, which means you didn't tell the heli what you really wanted it to do. As far as the bumping is concerned, as I mentioned before, one issue centers around the fact that you don't have the same controls as the helicopter, and there is a compromise in simulating those. I'm not the first nor last person to trim rudder into a disastrous position for example.

 

As for tracks, do look at Viper's.

[bluepilot76]

That symbology is the flight director, and there is no way to turn it off in the cockpit.

 

Actually thats not what is significant. You could turn the HUD off. What is significant to this discussion is that the FD mode allows the pilot unimpeded access to the helicopter. The positional stabilisation provided by the AP is absent.

 

I understand that the AP mode is good for holding a course or a regular turn or a spatial position, I understand that that can be a useful aid. but I also understand that AP can also be a barrier between the aircraft and the pilot. At times the pilots NEEDS to be 100% in control of the aircraft. Like at an airshow display or a dogfight.

 

When we fly A10C, are we impeded by NOT having the autopilot on all the time? No. Are we helped by having the SAS on all the time? Yes! This is the same. FD is like SAS, makes the helicopter easier to fly. AP is an extra layer on top it allows the aircraft to fly predictably whilst you are eating your sandwiches. But if you are not eating your sandwiches and are actually showing off to your girlfriend then you probably want to be the one flying the machine.

 

Thanks for the track Viper I will check it out later. Got another 8 hours at work first.

 

I see significance in that you state the Trim was not touched. This would have the effect of reducing the annoying aspects of the AP from the routine. Unfortunately the general consensus on here seems to be that you should trim trim and trim again, no matter what you are doing. And definately not to hold the trimmer down, which is actually what a lot of people are doing in order to escape the annoying stabilisation aspect of the AP (and I do not mean annoying full stop, just in certain situations)

[GGTharos]

Actually thats not what is significant.

 

It sure is when you're making a claim that is untrue.

He's flying exactly like procedure says you should fly the heli: Stabilization on, FD off.

 

 

I understand that the AP mode is good for holding a course or a regular turn or a spatial position, I understand that that can be a useful aid. but I also understand that AP can also be a barrier between the aircraft and the pilot. At times the pilots NEEDS to be 100% in control of the aircraft. Like at an airshow display or a dogfight.

And yet the pilot performing the air show is flying with the AP on as normal. You could claim that the AP isn't modeled entirely as well as it should be, and you might be on to something as opposed to claiming he's flying it with FD on.

 

When we fly A10C, are we impeded by NOT having the autopilot on all the time? No. Are we helped by having the SAS on all the time? Yes! This is the same. FD is like SAS, makes the helicopter easier to fly. AP is an extra layer on top it allows the aircraft to fly predictably whilst you are eating your sandwiches. But if you are not eating your sandwiches and are actually showing off to your girlfriend then you probably want to be the one flying the machine.

Two completely, utterly different airframes with two completely different flight procedures. The FD is very rarely turned on in RL practice in the Ka-50 (testimony from one of the pilots, no less!) and certainly not for 'dogfights' or air shows. It is simply not needed, required, or desired. On the contrary, the flying with AP on is preferred.

 

I see significance in that you state the Trim was not touched. This would have the effect of reducing the annoying aspects of the AP from the routine.

How so? The 'annoying aspects' can only be worse without trimming. The significance is to demonstate that you don't have to fight the AP.

 

Unfortunately the general consensus on here seems to be that you should trim trim and trim again, no matter what you are doing.

It isn't 'general consensus', it's the way it is done. This is real pilot technique.

[bluepilot76]

How so? The 'annoying aspects' can only be worse without trimming. The significance is to demonstate that you don't have to fight the AP.

 

Because the annoying aspect to me is that when I turn the machine the machine wants to go the other way. Unless I trim trim and trim again!. It is jumping from one small flight path to the next, not a smooth transition.

 

It isn't 'general consensus', it's the way it is done. This is real pilot technique.

 

Except for the guy in the video.

[GGTharos]

This video? You can hear the trimmer going all the time when he's doing anything other than flying straight and level:

 

eq1kkvxAsd0

[159th_Viper]

Except for the guy in the video.

 

He's flying the Heli like I did in the track - AP on, as per the norm. I'll post the track on youtube later.

[GGTharos]

^^^^

 

Yep, you're right. He's trimmed to hover and then does his show without touching the trimmer until he levels off and exits in the end.

[159th_Viper]

Aye - it's quite easily spotted too as he recovers from the manoeuvres.

 

In-SIM I reckon we are at a disadvantage as the type of 'hooliganism' I portrayed as per the track relies inter alia on sensitive rudder-input. With CH pedals at default and no spring to boot I find I tend to over-correct easily and thus the Helo 'wallows' ever-so-slightly, dependant on attitude - that is easily noticeable in the Vid too during the routine. Now you do not really get that with FD IIRC - always felt to me as if you are 'on rails', the reason I dislike utilizing FD mode.

[bluepilot76]

Yes I mentioned that he wasnt trimming on my first post of the day.

 

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.

 

Just in case noone wants to go back that far!

[bluepilot76]

Now you do not really get that with FD IIRC - always felt to me as if you are 'on rails', the reason I dislike utilizing FD mode.

Viper do me a favour and go and try again with FD on (blue light on). Maybe its a while since you tried it. I swear it is easier than AP mode. Of cours it should be, all it seems to do is lose the AP modes positional stabilisation, NOT the helicopters stabilisation.

 

Going back to my first ever post on this thread. FD mode sounds like it should "put you on rails" it sounds like a heavy duty autopilot mode. In fact you are left with the helicopter unburdoned with the APs clunky course holding every time you press the trimmer.

 

Go an fly some crazy aerobatics with the FD on, and trimming. I swear it will be as smooth as silk!

[159th_Viper]

Viper do me a favour and go and try again with FD on (blue light on). Maybe its a while since you tried it. I swear it is easier than AP mode.

 

In my instance I think it's more of a 'Can't teach an Old Dog new tricks' scenario :)

 

Started with a rudimentary 'Split-S' of sorts, turned about, climbed and did it all again with FD on. Felt more 'in-control' with FD off, probably due to the fact, as stated previously, the controls sensitivity, which is even more pronounced with FD on.

 

In any event, herewith track: FD.trk

 

Disclaimer: Crash at end intentional and not indicative of FD-interference in any way.

[bluepilot76]

Thanks Viper I will check it after work, still 5 hours to go.

 

Incidently it might be fun to have a blackshark airshow online, or blackshark races around some course in a city somewhere. Maybe you guys are doing that already.

 

I know its not by the book, but it would be good practice and a lot of fun.

 

Im going to see if I can replicate that guys airshow lator.

[Speed]

^^^^

 

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 ;)

 

Thanks GG.

 

Here's how I control my helicopter:

 

During significant maneuvers where I am constantly applying stick, or applying a lot of stick corrections and movements, I will hold down the trimmer button for much of the maneuver. Often, I will release the trimmer at a certain attitude that I will need to hold for a while, then go back to holding it down again. This way, I do not have to fight the 20% control authority.

 

For small adjustments, and for fine maneuvering, I will use the trimmer in short presses.

 

I never use the flight director.

 

I can't think of a better way to use the AP channels and the trimmer than the above method. If you are anyone else has some way I could approve upon that method, however, let me know.

 

Anyway, the point is, a few weeks ago, just after BS2 release, I tried the flight director for the first time, really. It felt like the helicopter actually move more freely in FD mode than with the trimmer held down- for example, if I were to hold down the trimmer and push my nose down, when I release stick pressure, my nose will tend to try to return to the previous nose elevation. It felt like with the flight director mode, the helo might also return to the previous nose elevation when stick pressure was released, but much more slowly. I will have to test this tonight.

[GGTharos]

Sounds like it works fine for you. I know -some- RL pilots use the 'hold trimmer down' method for certain things, but I believe this is individual training/technique, and I don't really know the ins and outs of the whole deal in this case.

 

We have people who are more of an authority on that subject, perhaps they'll see this thread and comment.

 

As to the specific difference you're perceiving, I'll try to ask around a little.

[bluepilot76]

It felt like with the flight director mode, the helo might also return to the previous nose elevation when stick pressure was released, but much more slowly. I will have to test this tonight.

 

This is how it seeems to me. It seems more analogous to an aeroplane elevator trim.

 

I find in FD mode I feel like I am trimming for a specific speed. I can trim for 250 and fly around like that. . I can then slow to 200, but I can feel that the chopper wants to fly at 250..because that is whats its trimmed for. You can trim for 250 and slow down to 50. you are stuill perfectly incontrol but near the end of your sticks travel so you feel like re trimming..

 

Its the same in a Cessna. I can trim for 100, but fly at 75. Its uncomfortable, the plane wants to fly at 100. So I retrim for 75. Now I am flying at 75 with the plane in trim.

 

But this is the important bit.. I can fly in any direction at 75...

 

I dont need to retrim for North if before I was flying South.I am trimming for speed.

[Luigi Gorgonzola]

We have people who are more of an authority on that subject, perhaps they'll see this thread and comment.

 

As to the specific difference you're perceiving, I'll try to ask around a little.

 

That'd be great (both). I'm very much interested in getting a little more insight into the training phase since I find it very difficult to get more information about (in the net, I don't know any helicoter pilot IRL).

[GGTharos]

As far as learning to fly the heli goes, you should start learning with FD on. It will operate like a training helicopter.

 

Real Ka-50 pilots learn on such a helicopter first, probably (obviously not on the Ka-50 itself). Later they might learn on a heli that operates like a Ka-50, such as a Ka-27 with an instructor on-board, and there operational flights require the use of the AP.

 

Unfortunately I'm not familiar with instruction techniques for helis - I wish I was, then I could help explain things better.

[Luigi Gorgonzola]

This one already helps:

 

As far as learning to fly the heli goes, you should start learning with FD on. It will operate like a training helicopter.

 

Thank you very much, GGTharos! Just when I began to think I would have understood the FCS principles and thought I'd have an idea how to use it, all these trimmer threads drove me mad ;)

[bluepilot76]

Viper, checked your tracks thanks for posting them,

 

Both seem to confirm that you can manoevre the shark freely in AP if your last trimmed position was a stable hover. You can manoevre the shark freely in FD no matter what your last trimmed position was, because the angular stabilisation will not try and return the shark to your last trimmed position.

 

However, against the AP method: Your last stable position is a stable hover and a heading. so your are manoevering fairly freely but the shark still wants to return to the last trimmed heading. I reckon that will be why so many people are turning off the HDG channel. Surely that is not reccomended.

 

Its all about cockpit resource management. Most pilots are actually competant at flying a plane safely without crashing into a mountain whilst doing other things. The autopilot can help with that, but only in safe airspace. Not where there is obstacles such as buildings, missiles, other aircraft, birds. It seems only suitable to me in navigational phases.

 

Summary:

AP has a time and place where it can be helpful

FD has a time and place where it can be helpful

 

People who are struggling to enjoy smooth flight with a feeling of complete control should look again at flying with the FD mode ON

 

I am a near beginner and have been repeataedly told not to fly in FD. Its dangerous for some reason. Or AP allows you to concentrate on other tasks. To be honost, the BS weapons systems are not very complex. Realistically theres ATGM and a gun. Big deal. A10C it aint! Theres not that much to do with your head down.

 

A pilot in complete control of his aircraft does not even notice his hands and feet are moving, same as driving a car. Your brain can cope with more than that.

 

And to finish on a lighter note, attached my airshow practice. it aint pretty, but theres no blood spilt!

[bluepilot76]

Couldnt attach as got logged out. FD all the way of course!

manoevres.trk