Force Feedback Settings Discussion

[Phantom12]

Seeing as a few people in the discord have been confused or having trouble with FFB I figured Id open a thread so we can compare settings or maybe ask some questions abot how exactly things are implemented in the F-4. Do any of the devs actively fly with an FFB stick and have any settings recommendations?

The FM seems very nicely done, and I can already tell where the bellows and bobweight forces are coming into play  But I did run into a few things that left me a bit unsure about whether everything was working correctly or not. Some of the below are more observations than questions, but maybe they will get the conversation started.

Firstly and most obviously: sitting on the ground the virtual stick seems to lag behind the Joystick considerably in pitch. Even with stick force blending off. If I understood correctly turning this option off is supposed to give 1:1 displacement between the virtual and real sticks. Its much less noticeable in the air, where the stick is generally not moved as far or as quickly. Am I misunderstanding this option or is something not working correctly?

Stick forces in the pitch axis also seem to be very light with the blending option turned off. I turned gain up to 250% and the aircraft flew much better, certainly at higher speeds. In the landing pattern forces are still quite light.

In general the aircraft seems to require very little stick displacement per G (especially at combat speeds etc). With the higher gain settings I mentioned above the forces build up quickly though, even with very little displacement. The aircraft is much more controllable with a higher gain so you can feel the change in forces. From what Ive seen/read this is correct but I mention it as it gives the airplane a very different feel to things like the tomcat.

I need to test it more but I think turning down or removing the AFCS pitch breakout force might make things a little easier as well. I have read somewhere that the stick force transducer introduced some amount of slop in the controls in the real airplane, and I think it might be doing the same in our virtual plane. Or worse since our sticks will move even before the breakout point.

Would love to hear what other FFB users have figured out so far. 

[some1]

I've looked into FFB telemetry on my joystick and yeah, my conclusion is that the stock settings are pretty much unusable on most force feedback devices. At 100% gain in the special options, the pitch axis works like this:

• 1% force when stationary.
• less than 5% force at 150 kts.
• 12% force at 200 kts.
• 50% force at 300 kts.
• 100% force at 470 kts, give or take. 

Roll axis does not have the dynamic feel system, so it's fixed at 25% force.

This may be mathematically correct if you have a stick capable of producing 30-60 kgf at 100% force, but for most of consumer devices, the stick is basically limp at traffic pattern speeds. You can crank the gain up, but a small number remains a small number even if you multiply it 250%. And the joystick will saturate quickly below 300 kts. 

A more practical solution would be something that Aerges did for their module, which lets us set the minimum force, and then the force increase is scaled on top of that baseline to match 100% at the intended target.

Or just bring the force build-up with airspeed more in line with other DCS modules from ED, like warbirds. Right now it does not feel like any other aircraft in DCS, and I don't say it as a compliment.

Edited May 23 by some1

[Super Grover]

8 hours ago, Phantom12 said:

Firstly and most obviously: sitting on the ground the virtual stick seems to lag behind the Joystick considerably in pitch.

The stick position in the cockpit when stationary on the ground isn't directly related to your physical stick position, as high friction in the real aircraft cannot be applied when combined with the joysticks we use.

8 hours ago, Phantom12 said:

Even with stick force blending off. If I understood correctly turning this option off is supposed to give 1:1 displacement between the virtual and real sticks. Its much less noticeable in the air, where the stick is generally not moved as far or as quickly. Am I misunderstanding this option or is something not working correctly?

Stick force limit and stick force blending are applied only to non-FFB joysticks and ignored for FFB joysticks. Their purpose is to emulate more feedback from the stick for non-FFB joystick users.

8 hours ago, Phantom12 said:

Stick forces in the pitch axis also seem to be very light with the blending option turned off. I turned gain up to 250% and the aircraft flew much better, certainly at higher speeds. In the landing pattern forces are still quite light.

Pitch stick forces vary greatly with the airspeed in the real F-4 and are considered weak below 250 kt. For more detailed information, I recommend reading this report: https://apps.dtic.mil/sti/citations/AD0881743

8 hours ago, Phantom12 said:

I need to test it more but I think turning down or removing the AFCS pitch breakout force might make things a little easier as well. I have read somewhere that the stick force transducer introduced some amount of slop in the controls in the real airplane, and I think it might be doing the same in our virtual plane. Or worse since our sticks will move even before the breakout point.

The AFCS breakout deadzone for the pitch axis only applies when using the AFCS mode (autopilot). It has no effect in all other states.

[Phantom12]

Its normal that the forces are pretty light in the landing patter/approach speeds. I believe this is correct for the F-4. Stability and stick forces decreased alot in this area.

I tried some stick curves of about 10 like victory suggested in his post. They seem to help with blending off, but not necessarily with blending on.

Also blending didnt really behave the way I expected it to. Commanding a constant force in a decelerating turn the virtual stick didnt seem to move at all. FFB forces were higher than with it off though...? Unless the gains change with airspeed or the blending only kicks in at supersonic speeds where the forces really increase Im not sure whats going on here? Not sure why the FF forces would be higher if the blending isnt active yet.

 

Edit: Grover posted as I was writing this.

 

@Super Grover Thanks for responding. Ill definitely check out that link. I understand that the big change in forces is expected. So far everything ive seen in the FM in that regard makes absolute sense and seems to be working very well.

Is the "friction" effect reduced at higher speeds or just less noticeable since the stick isnt thrown around as much? If its the red diamond in the controls indicator I guess its the latter. I guess you could apply some constant friction on the ground to mimic this but I see how it might hurt things with the limited amount of force available in a consumer stick.

I guess the AFCS thing is placebo on my part.

If stick force blending is ignored with FFB sticks I guess that explains what I wrote above. But the feel and  at least the magnitude of the forces are definitely noticeably different with those settings on and off.

Is turning those off only recommended for spring joystick users who (for whatever reason) want to fly without the added feedback/with 1:1 displacement?

Edited May 23 by Phantom12

[DummyCatz]

21 minutes ago, Super Grover said:

Pitch stick forces vary greatly with the airspeed in the real F-4 and are considered weak below 250 kt. For more detailed information, I recommend reading this report: https://apps.dtic.mil/sti/citations/AD0881743

Thanks for the explanation. There're also some diagrams of the feel system from Page 65-67 of NASA CR-2144, and I'd like to know if it is correct to say that, the stick force variation is largely caused by the Bellows Spring, whose spring force (pulling the stick forward) varies based on dynamic pressure and other coefficients (like q-B and P-BF), and the Bellows Pressure creates a push force that pushes the stick back?

The Bobweight seems to just function as pulling the stick forward based on normal acceleration of this object.

 

Block diagram of the pitch feel system:

 

Variation of parameters like q-B and P-BF:

[Super Grover]

49 minutes ago, Phantom12 said:

 

@Super Grover Thanks for responding. Ill definitely check out that link. I understand that the big change in forces is expected. So far everything ive seen in the FM in that regard makes absolute sense and seems to be working very well.

 

Is the "friction" effect reduced at higher speeds or just less noticeable since the stick isnt thrown around as much? If its the red diamond in the controls indicator I guess its the latter. I guess you could apply some constant friction on the ground to mimic this but I see how it might hurt things with the limited amount of force available in a consumer stick.

I guess the AFCS thing is placebo on my part.

If stick force blending is ignored with FFB sticks I guess that explains what I wrote above. But the feel and  at least the magnitude of the forces are definitely noticeably different with those settings on and off.

Is turning those off only recommended for spring joystick users who (for whatever reason) want to fly without the added feedback/with 1:1 displacement?

 

I might have been imprecise in my words. In real aircraft, the friction forces are pretty high (and above the threshold to open the gate inside the force transducer for the pilot stick). However, we can't simulate them because that would disconnect your physical stick input from the aircraft controls position, and it would be highly disorientating for you. However, we had to find a way to make the stick stay around where it should be when you're stationary - so we enabled another slightly simplified model when stationary, which prevents the stick from falling fully forward.

We spent a lot of time understanding and modelling the flight controls system, including the bellows and the feel trim. This allowed us to prepare a physical model for the neutral stick position, where the net force from the feel trim system is zero. This position is the centred position for the non-FFB sticks and the zero-force position for the FFB sticks. However, on the ground, this position is often beyond the physical limits for the aircraft stick position - which is exactly why we have that special on-ground mode.

The options to disable force limits and force blending are for non-FFB users who, for any reason, prefer a more "traditional" relation of the joystick position to the aircraft stick position. Yet, I'd try to convince everyone to try force blending first.

 

9 minutes ago, DummyCatz said:

Thanks for the explanation. There're also some diagrams of the feel system from Page 65-67 of NASA CR-2144, and I'd like to know if it is correct to say that, the stick force variation is largely caused by the Bellows Spring, whose spring force (pulling the stick forward) varies based on dynamic pressure and other coefficients (like q-B and P-BF), and the Bellows Pressure creates a push force that pushes the stick back?

The Bobweight seems to just function as pulling the stick forward based on normal acceleration of this object.

This is 100% correct, and we modelled the pitch controls to include all those elements: the bobweight and the bellows. The point where the forces (moments) from these two cancel each other is the neutral stick position.

 

Edited May 23 by Super Grover

[Phantom12]

Yeah the bellows and bobweight forces are definitely modeled and you can see the Zero force position move the way it should in the controls indicator.

 

The stick very easily falls fully forward for me on the ground but perhaps its because the sidewinder only generates very small forces in general. If this model turns off as soon as you start rolling I guess its not a big deal though.

 

I guess the default gains are changed somehow with the blending option on or off. Idk why else it would feel so different if it isn't applied to FFB sticks.

 

Anyway thanks for taking the time to explain it to us Grover.

[kablamoman]

1 hour ago, Super Grover said:

We spent a lot of time understanding and modelling the flight controls system, including the bellows and the feel trim. This allowed us to prepare a physical model for the neutral stick position, where the net force from the feel trim system is zero. This position is the centred position for the non-FFB sticks and the zero-force position for the FFB sticks. However, on the ground, this position is often beyond the physical limits for the aircraft stick position - which is exactly why we have that special on-ground mode.

Reading this I am a bit worried the behavior I am seeing in the sim with my non-FFB stick is by design.

I am experiencing some pretty heinous lack of control at lower speeds, like when on approach, where pitch inputs on my real stick end up being directly opposed with a slight delay by the in-game stick simulation, which makes it atrociously easy for it to develop into an oscillation with increasing amplitude making the thing next to unflyable.

At these speeds it should be trivial to hold the stick at a steady deflection and make small adjustments, but the simulation seems to induce instability by taking direct control of the stick away from me entirely. I am still hoping this is a bug of some sort. Is it possible that a pitch and roll curve has induced the problem somehow? I have made sure "use force feedback" is unchecked in the MISC options.

 

[some1]

5 hours ago, Super Grover said:

Pitch stick forces vary greatly with the airspeed in the real F-4 and are considered weak below 250 kt. For more detailed information, I recommend reading this report: https://apps.dtic.mil/sti/citations/AD0881743

What is considered weak in real world applications is still very strong by flightsim hardware standards. According to the linked document, a change in airspeed of 50 kts in landing configuration still results in a force change of several kgF on the stick.

Meanwhile in Heatblur's implementation the change in these conditions is something like 0.15 kgF on a VPForce Rhino... when measured at max deflection, and much less at neutral trim position as measured in the real test. It's basically a limp stick. Even the strongest FFBeast hardware will not produce realistic forces with FFB inputs like that.

Here's a comparison of how FFB works in practice. Blue line is DCS F-4 at stock settings. Red line is DCS F-4 at 250% gain, even when scaled it is still very weak at approach speeds. Yellow line is how other ED aircraft with aerodynamic forces on the stick are implemented. Not great either, as FFB spring saturates quickly, but at least the stick is centring nicely at low speeds and feels more like a real airplane. 

A green line is a possible compromise solution that would both provide decent centring force on takeoff and landing, while also retaining the effects generated by F-4 Phantom control system.

*The lines are drawn from a few data points so they may not be fully accurate, it's just for illustrative purpose.

 

[Super Grover]

@some1, thank you for your messages. We're here to provide the most realistic simulation ever, yet, of course, we understand the needs of the users who value more of the gameplay aspects and have fun with the module on their rules. We will look for a solution enabling you to tailor the force feedback response to your needs. However, please note that using such settings may degrade your experience with the module, as it may create centring forces that are not present in real aircraft.

[Hiob]

Hi all, I can't detailed technical descriptions like some of the above posters - my impression(!) is, that, yeah, in pitch at slow speeds it's rather weak - but that doesn't matter so much to me. What I find more irritating is the rather limb and feedbackless roll axis. The forces doesn't seem to change with airspeed as well. Is this due to servo-augmented actuation in the real AC?

Not judging (because I don't have a clue how it 'should' be), just explaining my experience.

Thank you!

[Super Grover]

Yes, there is only a sad, plain and a bit weak centering spring for roll.

[Bazz_Mulder]

Cześć Krzysztof,

Thanks for the great insights on how these systems work together!

Is there any chance that you can share your settings? I'm struggling to find a baseline with my Rhino. 

Thanks!

Edited May 23 by Bazz_Mulder

[Jayhawk1971]

Yes, for those of us who'd rather spend time in the cockpit than of forums reading about the cockpit (), could we please get a TL;DR version of which settings would be recommended?

I, for example, use a G940, and whatever I did, the Tomcat right now has FFB to my liking (I did use the Logitech profiler, I believe I kept DCS ffb-settings off?). What would be the recommended FFB-settings for that stick to get "the most" out of the F-4?

To quote Lt. Cmdr. Matt T. Sherman (Cary Grant's character from Operation Petticoat): "It's like watching a strip tease. Don't ask how it's done, just enjoy what's coming off."  

Edited May 23 by Jayhawk1971

[Super Grover]

19 minutes ago, Bazz_Mulder said:

Cześć Krzysztof,

Thanks for the great insights on how these systems work together!

Is there any chance that you can share your settings? I'm struggling to find a baseline with my Rhino. 

Thanks!

 

I'm sorry. I wish I could help, but I don't have the Rhino. Yet. I guess it's about time to line up in the queue for one. I'm still using the old MS Sidewinder FFB 2 for my testing. Nevertheless, I'm sure that we have testers using Rhino who might want to share their settings.

5 minutes ago, Jayhawk1971 said:

I, for example, use a G940, and whatever I did, the Tomcat right now has FFB to my liking (I did use the Logitech profiler, I believe I kept DCS ffb-settings off?). What would be the recommended FFB-settings for that stick to get "the most" out of the F-4?

With DCS FFB set to off, you won't get the correct neutral position from the F-4E, and probably, the joystick will revert to the default centring force only.

[Hiob]

33 minutes ago, Super Grover said:

Yes, there is only a sad, plain and a bit weak centering spring for roll.
 

… got it! Thank you!

then it is simulated perfectly! 

25 minutes ago, Bazz_Mulder said:

Cześć Krzysztof,

Thanks for the great insights on how these systems work together!

Is there any chance that you can share your settings? I'm struggling to find a baseline with my Rhino. 

Thanks!

 

If it is any help - I used the Mirage F1 profile as baseline, but increased the spring force in the roll axis.

[amadeus]

54 minutes ago, Super Grover said:

@some1, thank you for your messages. We're here to provide the most realistic simulation ever, yet, of course, we understand the needs of the users who value more of the gameplay aspects and have fun with the module on their rules. We will look for a solution enabling you to tailor the force feedback response to your needs. However, please note that using such settings may degrade your experience with the module, as it may create centring forces that are not present in real aircraft.

One question I have about the real aircraft, is it true then that even after take off, the stick would be basically completely dead in the Y axis? Meaning it could fall forward under its own weight alone?

The sense I got from some1’s posts are that the current forces being applied might accurate in terms of force percentages, but no force feedback stick today is capable of the force profiles of the real thing, which would have provided enough force to straighten out while hitting takeoff speeds.

[Super Grover]

4 minutes ago, Hiob said:

… got it! Thank you!

then it is simulated perfectly! 

[Phantom12]

7 minutes ago, Super Grover said:

I'm sorry. I wish I could help, but I don't have the Rhino. Yet. I guess it's about time to line up in the queue for one. I'm still using the old MS Sidewinder FFB 2 for my testing. Nevertheless, I'm sure that we have testers using Rhino who might want to share their settings.

With DCS FFB set to off, you won't get the correct neutral position from the F-4E, and probably, the joystick will revert to the default centring force only.

Are the default settings what you use/recommend using for the Sidewinder? I also use this stick.

The 3D printed DIY kits for the Rhino seem like a very attractive way to go if one has access to a printer. But I havent taken that step myself yet either.

https://github.com/protomaker964/Rhino-FFB-Clone-3D_Printed

[Hiob]

1 minute ago, amadeus said:

One question I have about the real aircraft, is it true then that even after take off, the stick would be basically completely dead in the Y axis? Meaning it could fall forward under its own weight alone?

The sense I got from some1’s posts are that the current forces being applied might accurate in terms of force percentages, but no force feedback stick today is capable of the force profiles of the real thing, which would have provided enough force to straighten out while hitting takeoff speeds.

Hmm…. the stick (in pitch axis) is rather weak at slow speeds, but at TO speeds mine has enough force (barely) to center itself (even with the heavy TM grip) from there the forces increase gradually up until 400-450 knots IAS or so……

1 minute ago, Super Grover said:

Frickin‘ great! Perfect! 

[Super Grover]

It wouldn't fall because the friction forces are quite high. Yet, I think it's still a step too far for the current FFB tech to simulate friction.

[Hiob]

4 minutes ago, Super Grover said:

It wouldn't fall because the friction forces are quite high. Yet, I think it's still a step too far for the current FFB tech to simulate friction.

Au contraire, mon amis! Friction, Stiction, Inertia, Damping, Spring and constant force can all be set individually and tuned endlessly with the Rhino. Its software is great.

Problem is, that the control over those effects is usually handed over to the application. But each effect on its own can be set to „sticky“, meaning the application can‘t override it.

Edited May 23 by Hiob

[Lt_Jaeger]

7 minutes ago, Super Grover said:

It wouldn't fall because the friction forces are quite high. Yet, I think it's still a step too far for the current FFB tech to simulate friction.

So you basically say, if I add some friction, I would be close(er) to the real thing? 

As Hiob said, friction can be introduced with a click or two in 10sec.

[slowmover]

I just broke my VPForce ffb on the F4. So be careful

[Super Grover]

OK. I'll rephrase it. Currently, we have no direct way to control friction from the module in any FFB stick. Nonetheless, we will keep looking for options here.