Controls guide for helicopters... Or: Why you should avoid using curvature - ED Forums
 


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Old 02-13-2018, 08:45 PM   #1
henhag
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Post Controls guide for helicopters... Or: Why you should avoid using curvature

For all the old and new rotorheads:
DO NOT USE ANY CURVATURE FOR HELICOPTER CONTROLS!!!!!111!


--> Detailed explanation below

So... why is curvature a bad thing for helicopter controls? It works so good on the fixed wing aircraft...
Yeah, but on a trimmed fast mover you will have your stick centered most of the time.
Curves are always applied regarding to the center position. And this is where we have a problem...
As you already know, a helicopters cyclic stick is off-center most of the time during flight.
The cyclic position where your helicopter will fly in a straight line might be 40% forward and 30% to the right... but as soon as you increase collective it can be 45% forward and 25% right...
I hope you understand what I'm trying to explain here... Your stick is almost never in the center position from which all curves are being calculated in DCS.
In the attached drawing, the green dot represents the currently required cyclic position to maintain your flight attitude, on an axis that has a very strong curvature applied.
The horizontal red lines represent an equally strong joystick movement to either the left or the right side, something you permanently need to adjust your flight attitude.
In normal flight or hover, you apply small corrections, but you always stay near the sweet spot (green dot)



If you take a closer look on the vertical red lines now, you will see that the left line is much shorter than the right one.
This indicates that moving the stick to one side will have a much stronger effect on your helicopter, than moving it in the opposite direction!
In a hover situation where you need precise and really small movements on the cyclic, this will lead to oscillation, unintended movement and failure.


So... what can we do, if a curvature is actually making it worse? We have to find a way to reduce control sensitivity, but keep the in- and output as linear as possible.
Fortunately, there is another axis setting called "Y-saturation" - that's the one you should try if the cyclic feels too sensitive
It will take the full deflection of the joystick on your desk and limit it to whatever percentage you have selected.
A roll axis Y-saturation of 50 means that you can only move the ingame cyclic stick 50% to the left and 50% to the right.
But you get these 50% deflection when your real joystick is already fully deflected, so you might have just increased your input accuracy by the factor of 2???
There is a downside.. as always...
50-80% cyclic Y-saturation is enough for most normal flight operations, especially if you are new to helicopters and struggle keeping the bird in a stable hover.
⚠️ ATTENTION: On the Huey and Mi-8 (maybe Ka-50, too), you might not be able to reach maximum airspeed or maneuverability, as this sometimes requires a cyclic deflection near 100%. ⚠️
But this setting is a great pair of training skids! ????
It will limit you in speed and performance, but it really helps you improve your flight skill and hover precision!
Once you get more familiar with the flight behaviour of your rotary wing aircraft, increase the Y-saturation step-by-step back to 100%.
You don't need to start as low as 50%, even 80% will give you a noticeable improvement for training.
The setting you feel comfortable with depends on several parameters like joystick type, spring strength, stick length, hotas mount/ desktop use,
how you sit in your chair and lets not forget about the DCS helicopter module itself

On the Sa-342 Gazelle, you may want to keep it at 60-80%, as this bird is very, VERY sensitive on the cyclic and keeping the Y-saturation reduced will have no real disadvantages at all.
On all the other helicopters (Huey, Mi-8, Ka-50), there is no point in keeping the Y-saturation lowered forever. It is a great method for flight training, but as mentioned above, it comes with a price.




I really hope you liked this guide, if you have any recommendations or comments, please post them below Feedback is always welcomed
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Old 02-13-2018, 09:35 PM   #2
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Thanks, I will give it a try!
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Old 02-13-2018, 09:38 PM   #3
=Pedro=
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Seems it's a bit different with Gazelle though. Anyways, nice guide

"This indicates that moving the stick to one side will have a much stronger effect on your helicopter, than moving it in the opposite direction!
In a hover situation where you need precise and really small movements on the cyclic, this will lead to oscillation, unintended movement and failure. "

You wouldn't believe how good human muscle memory is

S!
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Old 02-13-2018, 09:50 PM   #4
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Interesting consideration.
But wouldn't this only apply to force feedback joysticks?

My understanding from my own setup experience (and I may well be wrong!) is that the curvature applies to the physical joystick only, not the virtual cyclic.

So when flying with my physical (non force-feedback) joystick, when I hit 'trim' (e.g. to match the green dot in your figure), then the virtual cyclic locks to that position and my joystick returns to center.

If I then make a post trim adjustment to the left or right, then the sensitivity is the same in both directions, because the starting point for the adjustment is from a centered joystick (coinciding with the curvature inflection point in the middle position).

Similarly, in your example with 50% Y-saturation, I can move my physical joystick fully up and hit trim and I get 50% forward locked in the virtual cyclic. After centering my stick, I can move my physical joystick all the way up and hit trim again, and I've now got 100% forward locked in the virtual cyclic. You can clearly see this with the controls indicator turned on.

I fly the Ka-50, Huey an Gazelle with both curvature and saturation set and it works very well for me, enabling super fine adjustments from the centered joystick (wherever the virtual cyclic happens to be offset to) and still providing sufficient precision for larger stick movements (without becoming over sensitive). Trimming multiple times is however required for fast forward flight, but in a heli you're always trimming anyway, and with my set-up it can now be done with much greater precision (and with the full range of the virtual cyclic still being accessible)!

Hope that makes sense!
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Old 02-13-2018, 10:04 PM   #5
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uhm, this only applies if you keep your stick in place. I'm guessing most people will use the center-trimmer option so that once you've trimmed, you let the stick go back to the center and you're back to where you started, curve wise.

Your guide is fine for FFB sticks or ones like the VKB (with brake) which will stay put where you leave them.
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Old 02-13-2018, 10:25 PM   #6
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@Kestrel @lemoen

I barely use the trim function, only if I need both hands to write in the chat or sth. I'm used to reset the trim right after I take back the controls
When flying in VR, my hand position on the joystick nearly matches the "virtual hand" on the cyclic.. this is absolutely fantastic for immersion and 'not getting VR sick'.
If I'd use the trimmer, my hand wouldn't be where I (virtually) see it.. And I know my brain doesn't like it that way

With the 12cm extension, the warthog stick is extremely smooth, and the recentering is barely noticeable. It does recenter, but fighting the spring is absolutely manageable.
I prefer to manually keep it in place, instead of having it trimmed and centered. The most important aspect for me is that I always 'feel' the current cyclic position,
centering the stick using a trimmer could make this less intuitive. Flying the Huey is an amazing experience, and you can do some really tricky maneuvers with it
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Old 02-13-2018, 10:59 PM   #7
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Quote:
Originally Posted by henhag View Post
Flying the Huey is an amazing experience, and you can do some really tricky maneuvers with it
Check this out:

https://forums.eagle.ru/showthread.php?t=200655

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Old 02-13-2018, 11:19 PM   #8
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Well henhag, all I can say is that you must be a much stronger person than me, the warthog spring is very heavy, Salute!

I have a 7.5cm extension on my warthog and still find it hard work even though I use trim all the time!
If I was doing it over again, I'd definitely go with a floor mounted stick (biggest regret for sure). Perhaps when my warthog wears out (if that will ever happen).

I think the KA50 would be too difficult (and tiring) to fight in effectively if had to manhandle the warthog stick the whole time, but you have got me thinking about the Huey now ... that might indeed be doable (for short flights), so might give it a go!

But if you very seldom use trim, wouldn't it actually be quite feasible to use curves in that case (if the key concern relates to trimming as per OP)? Each to there own I guess, and I am glad DCS provides so much flexibility for users to tailor the experience according to hardware limitations and personal preference.

If it wasn't for the fatigue factor, I agree that your setup does sounds the ideal way ... otherwise it is very easy to lose track of where the cyclic is really at (and while the control indicator helps immensely, I do have to admit that it does reduce immersion in VR).
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Last edited by Kestrel; 02-13-2018 at 11:40 PM.
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