[NO BUG] Maximum G-limit 9.0 or 9.3?

First I'll state the source I'm using. I'm not using anything from the flight manual because it is NOT a proper engineering source for coding the inner loop logic of FLCS.

F-16 Digital Flight Control System Functional Block Diagrams. Data obtained from Lt. Bruce Peet, F-16 System Program Office, Wright-Patterson OH.

According to the DFLCS block diagram, the upper limit of the stick command limiter block is 8.3 (+1.0) = 9.3G.

While I also have a copy of the block diagram of Analog FLCS, and the figure is 8.0 (+1.0) = 9.0G.

So could the DCS F-16 be actually using the logic from Analog FLCS instead of DFLCS?

Just test in other sim. level turn limit is 9.3

With respect, ED should looking into this.

F16 in DCS coding for FLCS seems to be from out dated source

As far as I understand it ED used NASA public FLCS code to build the FLCS.

And the NASA version was obviously way tamer than what the military used.

https://forums.eagle.ru/showpost.php?p=4433620&postcount=34

Looks like dev build addressed this issue according to NL. Ideally the DFLCS diagram can be coded line by line instead of just using NASA/Analog FLCS as a baseline and changing values based on other sources.

https://forums.eagle.ru/showpost.php?p=4433620&postcount=34

 

Looks like dev build addressed this issue according to NL. Ideally the DFLCS diagram can be coded line by line instead of just using NASA/Analog FLCS as a baseline and changing values based on other sources.

Sadly I don't think it is LJ, according to what NL said it's only G tolerance that's different in the dev build.

Also the graph there is one I made to show what the real progression looks like based on RL footage and the DFLC laws you've posted earlier, NineLine then overlayed his results on top of that.

I mean I hope something has been tuned in the dev build and that the limit is 9.3 instead of 9.0 there, but based on what NL said I don't think that's the case.

F-16 in DCS just feels it's under performing. Especially when comparing to other jets in DCS. They can do some crazy things but F-16 in real life should outperform them. It is designed to do that.

Sadly I don't think it is LJ, according to what NL said it's only G tolerance that's different in the dev build.

 

Also the graph there is one I made to show what the real progression looks like based on RL footage and the DFLC laws you've posted earlier, NineLine then overlayed his results on top of that.

 

I mean I hope something has been tuned in the dev build and that the limit is 9.3 instead of 9.0 there, but based on what NL said I don't think that's the case.

I saw his blue line being topped at 9.3, that's why I guess something is changed. But we won't know util the patch drops.

As far as I understand it ED used NASA public FLCS code to build the FLCS.

 

And the NASA version was obviously way tamer than what the military used.

concur !

I saw his blue line being topped at 9.3, that's why I guess something is changed. But we won't know util the patch drops.

Yeah I noticed that too, but the time to get there is also long according to that plot when compared with the green line.

Hence I fear it's the same as now, that 9.2-9.3 strangely can be reached within a very limited speed range at very high speeds (Mach 1+), but not at the lower speeds where it's possible in real life, i.e. ~ M 0.68 onwards.

To illustrate what I mean:

In summary at 26,000 lbs 9.0 G is possible between 0.78 to 0.97 Mach, and 9.2-9.3 between 0.97 - 1.02 mach, above that 9.0 G is suddenly the hard limit again.

However watch as something very curious happens if you take out a clean Viper @ 22,000 lbs:

Note how I am able to reach 9.2 G's at 0.75 mach (according to HAF charts it should be reachable much sooner at 22,000 lbs [~0.65 M]), but as I reach 0.92 Mach it suddenly dops back down to 9.0 G (stick stays full aft the entire time), and then starting at 0.95 M it starts to gradually drop until finally reaching 8.5 G at 0.99 M. 8.5 G continues to be the hard limit until 1.06 M where you then again return to 9.0 G which is the final hard limit.

This is very inconsistent and strange behavior by the FLCS in DCS.

That sounds weird. The 8.5G hard limit (0.5G steady-state error) seems like the proportional-integrator failed to eliminate the error between the commanded value and feedback value. But it's hard to tell where the problem is. Are you decelerating rapidly?

That sounds weird. The 8.5G hard limit (0.5G steady-state error) seems like the proportional-integrator failed to eliminate the error between the commanded value and feedback value. But it's hard to tell where the problem is. Are you decelerating rapidly?

No it actually happens whilst I am accelerating with full aft stick, so max G command. (clean jet, light at 22,000 lbs, lots of Ps).

Note as I hit 0.92 M (around 0 min 27 sec in vid) the G's start to drop steadily until at 8.5 G at 0.99 Mach, where it stays until 1.02 Mach from where it slowly begins to increases until hitting a hard limit of 9.0 G at 1.06 Mach.

SPO4T30o-Bk?t=27

No it actually happens whilst I am accelerating.

Seems like due to the transonic aerodynamic center shift, pitching moment changes rapidly in this region. I guess you can overshoot 9.0G when rapidly decelerating through transonic speeds.

Yes, that's a likely explanation, question is wether or not the FLCS should compensate for this.

From what I've heard, the absolute hard limit of the F-16 FLCS is 9.8G. Anything above that counts as a FLCS failure whether or not the FLCS is degraded or not. Not sure which block that applies to, but that's what I heard anyways.