Flight Director Mode and Auto Hover

[Lange_666]

One thing I do notice is that sometimes all AP buttons are turned off seemingly by themselves--I dont' have emergency disengage mapped right now.

I noticed the same thing. Does this happen when you switch Hover Off?

[Frederf]

You should be able to switch auto hover off while keeping the AP channels on. The only thing that I know of that should disable the AP channels is pressing the buttons (obviously) and the emergency AP disconnect button on the cyclic. However I wouldn't be surprised if there's a way for AP to turn itself off if it gets overloaded or something.

[Reticuli]

I've always wondered what the middle setting on the DT/DH switch did! Does the yaw channel do heading-hold if not in Route mode?

 

If Head Hold is on, it's doing it all the time...that's my point. It's also the reason people are constantly trying to trim out some damn yaw component they constantly can't get rid off, even though Head Hold is on. This is because it's always running in the background when the autopilot-proper, Route Flying, is off. Head Hold is Kamov's solution to not having true yaw damping. That's all the yaw channel does here, in fact, on this model of the Ka-50 (and I assume the real deal): hold a heading. It does not dampen rate, Heading Hold simply attempts to realign to the heading hold diamond, but has available to it only 20% authority at any moment. Route Following so much more quickly changes heading, of course, because it also has the pitch and bank channels available to it, by the way.

 

If you switch the DH/DT switch to Desired Track, it will change the heading tape diamond, but it's still only using the original Heading Hold setting that is now invisible if Route Flying is Off. If you put it on the up position, you get in the HUD either the manual HSI heading bug or (and this is a guess) what seems to be the waypoint directly, and not the strict course track. I need to check on that, though. The only time the AP will follow anything OTHER than the middle position's diamond's setting, as far as I can tell, is when Route Following switch (the autopilot-proper) is set to On...located on the collective.

 

The Head Hold diamond itself (whether you see it or not) is constantly reset whenever you hit trim or whenever you turn On (or off/on) Head Hold. Problem is, most people don't have things set up so they know what the current Head Hold setting is, so they can't see it's not what they want. Instead, they're just blindly trimming the yaw all the time even though they've got Head Hold On already. Since they usually are tapping trim when they are applying yaw, the pedals get trimmed AND a new Head Hold spot has just been selected. Then they start a cycle of successive (and seemingly unending) trimming again to stop the bad yaw.

 

There are three solutions: 1) turn off Head Hold (momentarily or for an extended period), 2) apply counter pedals/twist to center the yaw trim in the control display and tap trim again to make a new heading hold spot after doing a major trim change, or 3) find a way to remove the primary trim function from acting on the yaw. I originally used the second, but since creating my GlovePIE script, I use the first and third, now. Or more precisely, I always have yaw trim totally separate, but from time to time I also turn off Head Hold when I don't need it...my manual yaw trim still available, by the way.

 

Regardless, there's no reason to have main trim acting on the yaw all the time (I disagree with that decision by Kamov) and manual trim is ALWAYS nice to have for minor adjustments. Even the Head Hold function is often short or over by a degree, and in a long weapons shot that may be enough to prevent a launch authorization. And I think we all know how imperfect the hover hold + auto turn to target modes are in concert. Sometimes you're drifting over different terrain and the altitude hold feature is giving you grief as it and hover hold battle to keep you steady with only a 20 degree authority, which shutting it off or resetting altitude hold can certainly help. But often some very slight & continuous yaw tweak is necessary in these situations. And your wrist/feet will thank you.

 

As for the rest of you, I often feel like you're flying a different sim. All this talk about how great it is to fly in Flight Director mode and how peachy it performs has got me confused again. Are all of you using force feedback sticks? Does trim and FD mode work THAT differently with an FFB stick? Does the tension dynamically shift as you work a FFB stick in FD mode without even hitting trim, or something?

 

Otherwise, it almost sounds like you guys are flying with the course/track Route Following mode of the autopilot On and are trimming against it most of the time, suddenly thrilled that Flight Director has magically freed you of some monkey off your back. That monkey is the autopilot-proper. Just turn off Route Following on the collective. Right? I feel like I'm in the Twilight Zone, here, though if FD suddenly turned out to give you dynamic trim updating-like results without needing GlovePIE, then hell, sign me up! Is there some tutorial you guys originally followed that had you turning Route Following On and you just never learned how to shut it off, or is there something about FFB and FD in combination I haven’t been exposed to?

Edited January 3, 2009 by Reticuli

[uhoh7]

I noticed the same thing. Does this happen when you switch Hover Off?

 

yes I think that's usally when.

 

Now how do you turn off heading hold?

[Reticuli]

HAH! I did a load of testing and tweaking with GlovePIE. Finally was able to show that in Flight Director Head Hold goes from following the bug, to instead just yaw dampening. Very hard to see, but it's there if you tweak out the shark's instability first. If you turn Head Hold off completely in Flight Director mode, you lose yaw dampening, too. Flight Director does indeed turn off the reorienting/wings-leveling feature of the autopilot. The problem is you also need to trim it slightly to get rid of the pre-existing instability that the 20% authority available to each dampening channel (that can't help each other out) will still push past. Got a solution with GlovePIE, but not sure if I want to include a manual mode, too. Thank goodness it wasn't some forcefeedback issue that was preventing me from seeing the benefit of flight director.

[Rob2222]

I have the same question like Reticuli.

What is the point using flight director?

Lets forget the altitude for now.

 

When you follow a route, waypoint selected, Route-Follow-Mode-ON:

FD-OFF/Pitch-Hold-On/Bank-Hold-On/Heading-Hold-on and the Shark follows the route automatically.

FD-ON/Pitch-Hold-On/Bank-Hold-On/Heading-Hold-on and the Shark shows you how to fly/trim to follow the route.

 

When you want to "go afk" and fly a straight course, NO waypoint selected, Route-Follow-Mode-ON:

FD-OFF/Pitch-Hold-On/Bank-Hold-On/Heading-Hold-on and the Shark holds speed and course automatically.

FD-ON/Pitch-Hold-On/Bank-Hold-On/Heading-Hold-on and the Shark shows you how to fly/trim to follow the route.

 

When you want to maneuver in fight you just disable the Route-Follow-Mode to OFF and disable the Heading-Hold. If I understood the manual right, with Route-Follow-Mode-OFFand Heading-Hold-OFF you just have damping on the PITCH and BANK axis, no stabilisation.

So I can't see where the point is for using Flight-Director to have more control over the chopper cause Route-Follow-Mode-OFFand Heading-Hold-OFF should behave exactly the same.

 

Can someone enlighten me?

 

BR

Rob

[ericinexile]

Here's how autopilots work in my experience (which is considerable but never in large helicopters):

 

---When pilot and autopilot agree on desired attitude and flight path then it usually helps to have the autopilot on. (explanation to follow)

---When they disagree then the autopilot should be off.

 

Put to practical use: Lift off to a 3 foot skid-height hover with FD off (AP on). Now, unless the trim is depressed, the instant you begin to apply inputs that do not agree with the helicoptor's current attitude, you are FIGHTING the autopilot. Let's say you now wish to translate (fly) sideways. Your choices are 1) fight the autopilot which is trying to maintain level flight, 2) Hold trim while you maneuver, effectively temporarily disengaging the autopilot, or 3) Push and release the trim to command the autopilot to hold the new attitude--which, as with "2", you will need to trim out once the sidewards manuever is complete. These are all cumbersome choices when all you really wish to do is apply slight sideward cyclic and relocate to your new desired hover position. Again, any time the pilot is applying a control force with the autopilot on he is FIGHTING the autopilot or he his applying trim when he doesn't really desire it. Let's not forget that trim isn't always desired. There are times where the pilot is perfectly happy with the current neutral positions of the stick and rudder but wishes to make a tiny temporary input only to have the helo settle back to its original trimmed position when the input is removed. With the autopilot on (FD off), this freedom isn't really possible without FIGHTING the autopilot.

 

Where the autopilot works perfectly (in game) is: Route mode, Autohover, and turn-to-target. I LOVE the autopilot in these situations because the autopilot and I are in perfect agreement and I have no need to counter the autopilot with a control input (unless I wish to "trim" the autopilot to a new speed or heading).

 

The above observation obviously only applies to the game. I am convinced that the real Ka-50 senses pilot control input in a way that makes manuevering with the autopilot engaged a much more natural experience. In DCS, the AP works and most players do fine without ever feeling a need to use the FD. But if you ever do find yourself either constantly applying stick forces against the AP input OR holding trim, the FD is a godsend.

Edited July 6, 2009 by ericinexile

[ericinexile]

No, there is not. If you are in auto-hover and you need to fly freely, hold down trim/emergency AP disengage until you get yourself out of hot water...

 

The Trim and Emergency AP disengage are two separate buttons. The Emergency Disengage will not only disengage the AP but also kills all axis dampening. Hit that button and you better be prepared to fly.:)

[GGTharos]

.. apparently by flapping my arms a lot, too.

 

Thanks for the correction :D

[ericinexile]

I have the same question like Reticuli.

What is the point using flight director?...

 

...So I can't see where the point is for using Flight-Director to have more control over the chopper cause Route-Follow-Mode-OFFand Heading-Hold-OFF should behave exactly the same.

 

Can someone enlighten me?

 

BR

Rob

 

The FD allows you to keep dampening in all axis AND simplifies the trim button to one function: TRIM <<----THE PRIMARY FUNCTION OF THE FD---<<<. The moment you are satisfied that the autopilot will do what you wish it to do, then you click the FD off (hopefully mapped on your hotas) and the autopilot does your bidding.

[Rob2222]

Hmm,

 

when I have:

Route-Follow-Mode-OFF/Pitch-Hold-On/Bank-Hold-On/Heading-Hold-OFF

 

for me there is almost no noticable difference between FD-ON or FD-OFF. I have no problems to maneuver the helicopter. Only when switching Heading-Hold-ON it gets annoying. (I have no Force Feedback).

 

BR Robert