reported CROSS OVER ALPHA (rudder) FM

[janitha2]

30 minutes ago, DummyCatz said:

The directional static stability derivative (Cn-beta) of the F-16 reduces significantly at 25 to 30 deg AOA, from positive static stability to neutral and even negative static stability. Hence rudder inputs are strictly prohibited and restricted by the FLCS at high AOA in order to prevent yaw departure, which the F-16 is very susceptible to.

Please refer to 'Rudder Authority Limiter' in the FLCS section of dash one.

hey i did refer and even the dash one says "NOTE: Zero rudder authority available at 26 AOA" 
I lost rudder at 24 AOA so is this a bug or is it "correct as is"?

I uploaded both tacview and dcs tracks and you can see it in the replays.

[janitha2]

3 hours ago, Tholozor said:

The main point I was trying to convey is that the video doesn't provide enough hard data in regards to the handling performance of a Block 50 to achieve that maneuver without knowing the parameters in which it was executed. Different blocks/variants could have differing FLCS tolerances/limits depending on the computer or software installed.

Same video, different thread, it's a good read: 

 

Rudder limits have also been discussed before, which is also under investigation: 

 

 

hey i went through both and it was good, also the HAF manual although not the one we have in dcs says "NOTE: Zero rudder authority available at 26 AOA" and i had no rudder at 24 AOA and i doubt that there is any difference between the two so why is that i run out of rudder at 24 alpha and not at 26? i mean i have provided the tracks also why did this get moved to wish list?

[janitha2]

NEWS!!! 

DCS F-16 runs of out rudder at 20-19 deg aoa 

cross over aoa2.trkTacview-20230102-144803-DCS.zip.acmi

So what is going on @Tholozor @DummyCatz ? this has to be wrong. 

Edited January 2, 2023 by janitha2

[Tholozor]

From what I can see in the USAF -1 figure for FLCS Limiter Functions, there should be zero rudder authority at 26° AOA in CAT I, and 15° AOA in CAT III.

Maximum pedal commanded deflection is reduced (with zero roll) when AOA is greater than 14° in CAT I, and 3° in CAT III, but it does not specify the amount of reduction.

Edited January 2, 2023 by Tholozor

[janitha2]

38 minutes ago, Tholozor said:

From what I can see in the USAF -1 figure for FLCS Limiter Functions, there should be zero rudder authority at 26° AOA in CAT I, and 15° AOA in CAT III.

Maximum pedal commanded deflection is reduced (with zero roll) when AOA is greater than 14° in CAT I, and 3° in CAT III, but it does not specify the amount of reduction.

 

So what we know is that in the real world, the rudder command in the viper will start reducing starting from 14 aoa and will be zero at 26 aoa 
but in dcs the rudder command stops at 19-20 aoa. 

I hope ED fixes this if it is not "correct as is" because we know the "knife edge" pass is still not possible. 

No hate but I would like to see more than one SME look at this because the current SME couldn't recall whether the F16 had prf tones and people pay 80 dollars!!!! for this?

• Professional Flight Model (PFM) and authentic fly-by-wire Flight Control System (FCS).
• The most realistic model of the F-16C imaginable, down to each bolt and flake of paint, animated controls surfaces, lights, damage model, and landing gear.

Its been over 4 years now and its "close to complete " and we still dont have a proper FM.

Edited January 2, 2023 by janitha2

[janitha2]

On 10/18/2022 at 7:06 PM, Terzi said:

Regarding the rudder limitations of the FLCS, when you bank the jet 90 degrees and apply the full rudder, the nose will always drop. No matter what your speed is, no matter how light your jet is.

But the real F-16 can keep the altitude. Please see this video from 3:55 to 4:05 or 12:15 to 12:30. Before entering 12:15 he says 400kts.

I am not saying something is definitely wrong, but it is worth to check once more.

 

You are correct the viper in dcs has the wrong rudder limits, 

cross over aoa2.trkcross over aoa.trk

In dcs the jet starts limiting the rudder command way earlier than 14° AOA and to make it worse rudder command goes to zero at 19°~20° AOA.

In the real jet rudder command will start limiting at 14° AOA and rudder command will be zero at 26° AOA (viper can only pull 25° AOA) 

You can see rudder limits on page 140 in the dash one.

@BIGNEWY please take a look there is public evidence to support my claim and I can PM you if you need.

 

 

[janitha2]

On 12/6/2022 at 3:32 PM, BIGNEWY said:

We can not use video as evidence in this case, we do not know the config of the aircraft, its weight, the weather conditions. 

We are not seeing a problem here, we would need more evidence to make a change. 

thanks

 

On 12/6/2022 at 10:16 PM, LowGlow said:

That more reads like "we don't want to see a problem here".

Current behaviour with DCS is significantly different than those in the demonstrated videos, which even show a knife edge at high altitude and not even going to maximum rudder.

In DCS you can't even hold a knife edge at low altitude, empty load out, yaw trim at maximum, rudder pedal fully pressed.

Look at the HAF dash one or the F16A dash one both of which are publicly available on page 140 it will clearly say the rudder limits then compare with DCS, i posted twice and what i got in return for helping was a deleted post and 50 penalty points. 

 I am literally posting the tracks and showing you where to look @NineLine

cross over aoa.trkcross over aoa2.trk

Also you cant say that those manuals are not related because the F16A has a different tail compared the the BLK52+ and they STILL have the same limits!

[TEOMOOSE]

for "Need Evidence" I recommend read T.O. GR1F-16CJ-1 FLIGHT MANUAL HAF SERIES AIRCRAFT F-16C/D BLOCKS 50 AND 52+ year 2003

Page 1-125 Figure 1-44 FLCS Limiter Functions

 

[janitha2]

14 hours ago, TEOMOOSE said:

for "Need Evidence" I recommend read T.O. GR1F-16CJ-1 FLIGHT MANUAL HAF SERIES AIRCRAFT F-16C/D BLOCKS 50 AND 52+ year 2003

Page 1-125 Figure 1-44 FLCS Limiter Functions

 

Exactly you can find the "Evidence" there you can also find it in T.O.1F-16A-l same page.

please check@BIGNEWY 

Edited January 5, 2023 by janitha2

[_SteelFalcon_]

how's that a "whishlist" thing now?

[bukizzzz]

Looks pretty straightforward to me

I assume we will see changes in the next patch

[TEOMOOSE]

soo some bug reports become a wishlist item so that it never to be worked on ? - or is it mean its recognized but low priority? - Could of just mark it as reported in the bugs section ?

[_SteelFalcon_]

One could argue that every bug is a wishlist item since we „wish“ for it to be fixed…

[DummyCatz]

I can see two separate bug reports here which may not be linked to each other.

The first one is an aerodynamic issue, about not being able to hold the Knife Edge while maintaining the nose above the horizon, at a relatively low AOA. The problem seems to be related to the lateral forces that are created by the rudder (delta CY-rudder).

The second one is about the FLCS limiting logic, which is related to AOAs above 14 deg where the rudder authority starting to be reduced by the system. And you certainly won't be executing a Knife Edge when flying above 14 deg AOA.

[janitha2]

weird how the rudder limits was also moved to wish lists, i guess FM topics are still giving ED ptsd 

[Moonshine]

indeed two BUGs related to the rudder, not wishlist items. little ridiculous how such things are treated.

[darkman222]

A beer barrel, or a travel pod is a wish list item. A proper flight model is not. As long as youre not playing a "sim" with a snail logo.

Edited January 6, 2023 by darkman222

[LowGlow]

@BIGNEWY Was this flight model misbehaviour accidentally assigned as wish list item? Or does that simply mean it is low priority for ED?

[janitha2]

6 hours ago, LowGlow said:

@BIGNEWY Was this flight model misbehaviour accidentally assigned as wish list item? Or does that simply mean it is low priority for ED?

rudder FM should not be low priority in any case since how off it is compared to the real deal, rudder is very useful at high AOA but in dcs its useless.

[BIGNEWY]

A fix has been made for this issue and will be in a future patch. 

thanks