fixed F-16C wheel brakes braking mostly left or right (normal behavior or bug?)

[Ithronwise]

Hi ED team, hi pilots,

 

if I hit the wheelbrakes (no matter if I use the keyboard key, a button on my Thrustmaster Warthog or the both toe brakes of my Logitech/Saitek rudder pedals) the F-16C brakes almost ever only with one wheel (sometimes with the left one, sometimes with the right one). This also happens right after landing and results in a breakout of the plane to the left or to the right, which is difficult to catch by the rudder. Only very rarely both wheelbrakes will be activated at the same time by hitting the key/button/toe brakes (like you can see in the background of the first picture).

Is this a normal behavior identical  to the real life viper or a bug?

 

Best regards,
Rene

[BIGNEWY]

Hi,

 

please attach a track replay showing the issue and I will run it by the team

 

thank you

[GoodHope]

I've noticed this too--thanks for looking into it.

[Florence201]

So if you’re using rudder pedals, ensure you have both L/R assigned

 

i also notice from your pics that you’re locking up a wheel. This will cause the nose to slew towards the locked side

[Ithronwise]

51 minutes ago, BIGNEWY said:

Hi,

 

please attach a track replay showing the issue and I will run it by the team

 

thank you

Hi BIGNEWY,

here is the track. Every time the plane runs out of line, I have hit the wheel brakes. Especially right before the plane stops (last part of the track) it breaks out dramatically to the right or left.

Best regards,
Rene

F-16C Wheel brake issue.trk

[BIGNEWY]

sorry, I can not use the track replay as I do not have the unofficial mods. 

 

can you do a test without the user mods?

 

thank you

[Ithronwise]

17 minutes ago, Florence201 said:

So if you’re using rudder pedals, ensure you have both L/R assigned

 

i also notice from your pics that you’re locking up a wheel. This will cause the nose to slew towards the locked side

Hi florence,

 

no, I didn't locking up a wheel. I just uses the wheel brakes command "W" (by keyboard and by Warthog button), not the commands for left wheel brake and the right wheel brake. Normally this should brakes both wheels simultaneously, not in one moment the left wheel and some seconds later the right wheel. Both toe brakes of my rudder pedals are set to the same wheel brakes command, too.  I also tested it with setting left wheel brake to the left toe brake, right wheel brake to the right toe brake, but even if I hit both toe brakes the plane breaks out to the left or right randomly. This behavior of the F-16C I already noticed long before I bought my rudder pedals, but I haven't flown the Viper for a longer time and so I forgot it.

 

Best regards,
Rene

[Ithronwise]

30 minutes ago, BIGNEWY said:

sorry, I can not use the track replay as I do not have the unofficial mods. 

 

can you do a test without the user mods?

 

thank you

Arrgh, sorry BIGNEWY, I forgot to delete the unoffical mods from the mission. Here is a track without them.

F-16C Wheel brake issue.trk

[Ithronwise]

Here is another short track that shows the strange behavior after touchdown.

F-16C Wheel brake issue 2.trk

[Florence201]

1 hour ago, Ithronwise said:

Hi florence,

 

no, I didn't locking up a wheel. I just uses the wheel brakes command "W" (by keyboard and by Warthog button), not the commands for left wheel brake and the right wheel brake. Normally this should brakes both wheels simultaneously, not in one moment the left wheel and some seconds later the right wheel. Both toe brakes of my rudder pedals are set to the same wheel brakes command, too.  I also tested it with setting left wheel brake to the left toe brake, right wheel brake to the right toe brake, but even if I hit both toe brakes the plane breaks out to the left or right randomly. This behavior of the F-16C I already noticed long before I bought my rudder pedals, but I haven't flown the Viper for a longer time and so I forgot it.

 

Best regards,
Rene

 

The wheel brakes are locking up as you brake, hence the black skid marks on the runway. Set rudder toe pedal wheel brakes in the assign axis menu, then they will be incrementally applied as you apply pressure, rather than digitally on/off

[BIGNEWY]

Hi,

 

 you do have to be a little easier on the brakes and gradually brake.

 

If you check your fuel load, left and right tanks you should see the fuel load is heavier on one side which also has influences.  

 

thanks

[Ithronwise]

3 minutes ago, Florence201 said:

The wheel brakes are locking up as you brake, hence the black skid marks on the runway. Set rudder toe pedal wheel brakes in the assign axis menu, then they will be incrementally applied as you apply pressure, rather than digitally on/off

This was my old setting ...

 

This is my current setting ...

 

There is no difference in its behavior, no matter how i set the wheel brakes axises or I use the wheel brake command key "W".

[Florence201]

I have no such issue with wheel brakes with my toe pedals set up. Try adding a dead zone of 5 to each keybind, such that you have a little "wiggle room" before the brakes are applied. Plus, with the Viper, you Aero brake to <100kts, then slowly apply wheel brake. If you're trying to wheel brake from 160Kts, you'll struggle and things like what you're experiencing will happen.

[Ithronwise]

37 minutes ago, BIGNEWY said:

Hi,

 

 you do have to be a little easier on the brakes and gradually brake.

 

If you check your fuel load, left and right tanks you should see the fuel load is heavier on one side which also has influences.  

 

thanks

And why is it so? I didn't set different fuel load.

 

The picture shows full internal fuel load on mission start (in the Mission Editor the internal fuel is set to 100%). Why I have different fuel load?

And this is not an good explanation why the wheel brakes in one moment are braking left and in the other moment are braking right. The different fuel load surely wil not jump from one tank to another.

It is also not an explanation why the plane brakes out left or right directly before it stops. If the real Viper does it, too, ok, but if not than the DCS Viper shouldn't does it. By the way the braking works wrong. If the left wheel brakes, the plane should go left and if the right wheel brakes it should go right, or I am wrong?

Edited March 19, 2021 by Ithronwise

[SmirkingGerbil]

I have noticed this behavior as well. Mostly in the A-10C/II, but I always assumed it was because it was offset from Center-line.

 

I am now learning the F-16C and have the exact same issue. Running TM Rudder pedals (T Series), and setup as shown in your last pic.

I just assumed it was normal behavior, and I would pump the brakes left/right alternately as needed to keep the aircraft straight.

[Machalot]

2 hours ago, Ithronwise said:

By the way the braking works wrong. If the left wheel brakes, the plane should go left and if the right wheel brakes it should go right, or I am wrong?

I think you're talking about both wheels braking, but one skidding while the other maintains traction. In that case, the skidding wheel has less braking force, so the airplane should turn away from the skidding wheel and toward the wheel with traction. 

[Ithronwise]

49 minutes ago, Machalot said:

I think you're talking about both wheels braking, but one skidding while the other maintains traction. In that case, the skidding wheel has less braking force, so the airplane should turn away from the skidding wheel and toward the wheel with traction. 

Ok, this makes sense, but then there are still two open questions (at least for me):
1. If the reason for the different braking effect of both wheels is the unbalanced fuel load as BIGNEWY said, why switches the braking effect from the left wheel to the right wheel and back when I use both wheel brakes simultaneously (for example by using the key command) like in the first track?

2. Why are the internal fuel tanks of my Viper unbalanced loaded even if I have a fuel state of 100% (that means all internal tanks should be completely full so there shouldn't be a different load between them)?

Edited March 19, 2021 by Ithronwise

[=Panther=]

Fuel weight is balanced forward and aft and would not cause any issue. Since we don't have imbalances in the game naturally, and OP isn't carrying any externals, a normal FWD/AFT fuel split will not cause a drag left or right.

[Machalot]

4 hours ago, Ithronwise said:

Ok, this makes sense, but then there are still two open questions (at least for me):
1. If the reason for the different braking effect of both wheels is the unbalanced fuel load as BIGNEWY said, why switches the braking effect from the left wheel to the right wheel and back when I use both wheel brakes simultaneously (for example by using the key command) like in the first track?

2. Why are the internal fuel tanks of my Viper unbalanced loaded even if I have a fuel state of 100% (that means all internal tanks should be completely full so there shouldn't be a different load between them)?

 

Nothing is perfectly symmetrical, even in a digital simulation (with very, very few exceptions for special cases and highly simplified models under artificially perfect conditions).  If there is any wind at all, any control input, any slight roll angle on touchdown, there will be asymmetry in the weight and traction on the tires.  Also consider the fact that the engine spools in one direction, so any motion of the aircraft in pitch causes a gyroscopic yaw coupling torque (and vice versa), and any change in engine RPM causes a roll torque.  On top of that (and I don't know if this is the case) ED might be modeling slight random variations in each aircraft to add realism, such as in the alignment of wings and control surfaces, the suspension spring force and damping, the fuel flow rate from each tank, etc.

[Hammer1-1]

Shouldnt the anti skid keep the rotation of the wheels synchronized with both brakes depressed? I mean I get it that one wheel will turn faster than the other while it is turning, but that logic can be suspended with the nosewheel steering activated. Of course Im most likely wrong.

Edited March 20, 2021 by Hammer1-1

[Machalot]

13 minutes ago, Hammer1-1 said:

Shouldnt the anti skid keep the rotation of the wheels synchronized with both brakes depressed? I mean I get it that one wheel will turn faster than the other while it is turning, but that logic can be suspended with the nosewheel steering activated. Of course Im most likely wrong.

 

My understanding is that anti-skid is not yet implemented for the Viper.

[Hammer1-1]

Then thats probably 1/2 of the problem. FWIW, antilock brakes is supposed to keep the wheel from locking up and skidding and all it is is just a rotation sensor.  I work on aircraft but thats not my area of expertise.

[Dee-Jay]

Hi!

It can't work properly. Anti-Skid is not implemented yet.

Regards.

[Ithronwise]

3 hours ago, Machalot said:

Nothing is perfectly symmetrical, even in a digital simulation (with very, very few exceptions for special cases and highly simplified models under artificially perfect conditions).  If there is any wind at all, any control input, any slight roll angle on touchdown, there will be asymmetry in the weight and traction on the tires.  Also consider the fact that the engine spools in one direction, so any motion of the aircraft in pitch causes a gyroscopic yaw coupling torque (and vice versa), and any change in engine RPM causes a roll torque.  On top of that (and I don't know if this is the case) ED might be modeling slight random variations in each aircraft to add realism, such as in the alignment of wings and control surfaces, the suspension spring force and damping, the fuel flow rate from each tank, etc.

I know this fact but no other plane in DCS behaves so and in the test mission for the track to demonstrate the issue the Viper was clean, there was no wind set or other circumstances they could explain this behavior. I am an old Falcon 4.0 veteran with almost 600 flight hours on it and I don't know this from the F-16 there. 

It is a fact, the nose wheel steering and the wheel brake behavior of the DCS Viper is strange. My question is, is it realistic? If yes then I have to learn to handle it, if not ED should fixing it. 

[Dee-Jay]

16 hours ago, Ithronwise said:

And why is it so? I didn't set different fuel load.

 

The picture shows full internal fuel load on mission start (in the Mission Editor the internal fuel is set to 100%). Why I have different fuel load?

 

 

Per design. Fuel is not unbalanced here. Forward tank has more capacity than the rear, that is all.

 

note - removed image from manual 1.16 rules apply.