New stability patch = UFO

[Shmal]

You should not look to the TacView AOA it is not right AOA i think its just simple geometry angle between touching line to the arc of the turn and vector for aircraft. I guess.

So we found that 1.2 lift coeff is maximal and has to be on 28° AOA on cockpit gauge! My estimating turn AT 0.31M was with normal afterbuner! No emergency aft. and as you see in cockpit i've got 2.8g, what is too much and overestimated

Edited July 16, 2020 by Shmal

[Hiromachi]

Alright Shmal, I looked through your report and to be completely fair the speed at which you try to compare things is way below normal flying curve. At speeds you push that aircraft I land :)

But in all seriousness, I took a look through my documentation and most of graphs for sustained turn, turn radius and turn time end at Ma 0.5. So in order to get something for a speed around 0.31 - 0.32 such data would need to be extrapolated (and even that would not be precise enough, we're basically moving from what is known and described to what is unknown and undescribed in documents). Since that is beyond my skills, Im going to forward your report to Dolphin over the weekend for him to review it.

 

Thank you for the input !

[Shmal]

Yeah, Hiromachi! I would really appreciate it!

 

I guess you understand why this topic is so hot for many of us!

First of all, because we're indeed want MiG-21bis become an enough presice and decent simulated model of this iconic aircraft - we belive it's deserved it!

Second is we are just a humble virpils flying on Cold War and want to see realistic air combats at least against F-5 what is quiet accurate module and we just want to use against it proper and real tactic!

Thank you for your commitment and efforts!

We are keeping our wishes!

[KAKTYC_11]

Yeah, Hiromachi! I would really appreciate it!

 

 

Second is we are just a humble virpils flying on Cold War and want to see realistic air combats at least against F-5 what is quiet accurate module and we just want to use against it proper and real tactic!

What fair tactics at coldwar server are you talking about!!!??? With human-cheater-avacs who talk about all targets on map to his teammates in realtime & point 5 teammates on 1 target??? Who are you- F-5 crying pilot???

[probad]

hahaha okay unfairness and cheating is always a part of winning, but it would be nice if we can only cheat in the same ways people cheat in real life.

[BIGNEWY]

Hi all,

 

please stay on topic and dont turn this into some MP dispute.

 

thanks

[Sideburns]

Alright Shmal, I looked through your report and to be completely fair the speed at which you try to compare things is way below normal flying curve. At speeds you push that aircraft I land :)

But in all seriousness, I took a look through my documentation and most of graphs for sustained turn, turn radius and turn time end at Ma 0.5. So in order to get something for a speed around 0.31 - 0.32 such data would need to be extrapolated (and even that would not be precise enough, we're basically moving from what is known and described to what is unknown and undescribed in documents). Since that is beyond my skills, Im going to forward your report to Dolphin over the weekend for him to review it.

 

Thank you for the input !

 

Any update on this?

[Hiromachi]

Not yet.

[Sideburns]

Not yet.

 

As a paid up customer when can we expect the flight model corrections to arrive?

[Hiromachi]

All customers are paid up customers :) We treat everyone equally.

 

We've had a few months of MiG-21 updates and fixes (including FM ones, read this thread in detail please), but we also have to work on other projects to be delivered (so we have to balance one with the other as a small team) and most importantly there are already verified issues with 21 pending. Namely, the problem that concerns many users which is radar performance decrease. This one was and is priority, especially since new GPU generation from Nvidia is going to arrive in the upcoming months.

 

Second, you're post assumes there is a correction needed. But when you quoted me, its said in the post specifically that we dont know if there is issue or not since there are no data (at least available to me) to verify it prima facie.

[Sideburns]

All customers are paid up customers :) We treat everyone equally.

 

We've had a few months of MiG-21 updates and fixes (including FM ones, read this thread in detail please), but we also have to work on other projects to be delivered (so we have to balance one with the other as a small team) and most importantly there are already verified issues with 21 pending. Namely, the problem that concerns many users which is radar performance decrease. This one was and is priority, especially since new GPU generation from Nvidia is going to arrive in the upcoming months.

 

Second, you're post assumes there is a correction needed. But when you quoted me, its said in the post specifically that we dont know if there is issue or not since there are no data (at least available to me) to verify it prima facie.

 

Not sure if you are a native English speaker but you may wish to be careful with your language as it could be considered patronising. I never expected to be or implied I be treated differently to other paid up customers and I am aware of this thread's contents and recent updates.

 

Good point on the radar bug that has persisted for several updates now, I wouldn't disagree this should be the priority. And you're right, I am assuming it needs correction based on the prevailing and as yet unchallenged evidence that the MiG21 is over performing at low speed, and also in a smaller part based on my own experience in developing flight sims. Is there an ETA on the review by the more experienced team member?

[Shmal]

Hiromachi! I was told to show and translate it to you! 

A page from flight manual concerning automatic of SPS system (BLC - boundary layer control, boundary layer blowing)

So, the point is that it starts to work when flaps are reached 30-45° position and throttle lever is in position between Maximal and SPS marks on the quadrant.

These conditions gives an electric signal to take an air from the engine and blow it to flaps.

Plus it makes an electrically impossible for the afterburner to turn on!

Edited January 1, 2021 by Shmal

[Hiromachi]

If that is a separate bug than please make a new bug report. 

[Shmal]

Roger that!

[Ravenus]

@Hiromachi Has the slow speed overperformance been looked at.? It's clear that the sustained load factor from the mach .3 to mach .5 range is a bit higher than it should be, as articulated by Shmal. You can fight the F5 in a turn fight at these speeds when you aren´t supposed to be able to.

 

You can see the graph stemmed from in game tests at mach 0.4 its at 3.2 G at H=1000(after burner, not emergency AF). 

 

Further note after Shmal's input : You can observe a difference between the graph from the german manual and the Polish and Russian manuals. Nevertheless, whichever one is more accurate between the 2, the loss of load when decreasing speed should have an "exponential" decline or logarithmic shape. Whatever you want to call it. 

This currently translates in the turn rate where the rate is higher at mach 0.4 than at mach 0.6. It doesn´t take a professional extrapolation to see that it is plain wrong. 

 

 

 

Edited May 31, 2021 by Ravenus
Edited " the convex shape of sustained load factor" out, as it´s wrong.

[Shmal]

Yes, Hiromachi MiG-21bis in the DCS is definitely overperformed! It is clear to see to merge the diagram from soviet manual of the MiG-21bis (Izdelie 75A) with an automatic calculation made a very good guy here: 

So, I took the diagram for MiG-21bis with 7496 kg (closest to 7500kg to match with the

 Russian manual) and two R-3S missile for 1 km altitude, then scaled it based on two points (0.329M - closest to 0.33M and 1.005M - closest to 1M) for the speed and two points for G load:

Edited May 31, 2021 by Shmal

[Shmal]

I extrapolated the line for 1 km below 0.5M to see the 0.33M. But even you do not believe to my extrapolation you may easy to check other represented speed ranges.

You can see that for all speed range MiG-21 from DCS is overperformed especially below 0.5M - than lower speed than lesser G load might be but we can see opposite picture! Correspondingly the time of turn and turn rate also overperformed. I already checked it be sure! 

There is very strange looking pick in the range 1.1M Looks like fantastic boost.

 

 

 

Edited May 31, 2021 by Shmal

[Hiromachi]

On 5/30/2021 at 3:25 PM, Ravenus said:

Has the slow speed overperformance been looked at.?

Not yet, but Im forwarding all your and Shmal material to Dolphin  

[Ravenus]

20 minutes ago, Hiromachi said:

Not yet, but Im forwarding all your and Shmal material to Dolphin  

IF you need  more material, such as, manuals, Topolo's(from BMS) computed EM charts, I can PM them to you for use. Just let me know.

Edited May 31, 2021 by Ravenus

[Hiromachi]

We have manuals, but if you feel like it, you can send me material. Or try creating a ticket on Mantis: https://leatherneck-sim.mantishub.io/view_all_bug_page.php 
That way you can attach materials so that Dolphin will see them too. 

[m4ti140]

On 5/30/2021 at 3:25 PM, Ravenus said:

@Hiromachi Has the slow speed overperformance been looked at.? It's clear that the sustained load factor from the mach .3 to mach .5 range is a bit higher than it should be, as articulated by Shmal. You can fight the F5 in a turn fight at these speeds when you aren´t supposed to be able to.

 

You can see the graph stemmed from in game tests at mach 0.4 its at 3.2 G at H=1000(after burner, not emergency AF). 

 

Further note after Shmal's input : You can observe a difference between the graph from the german manual and the Polish and Russian manuals. Nevertheless, whichever one is more accurate between the 2, the loss of load when decreasing speed should have an "exponential" decline or logarithmic shape. Whatever you want to call it. 

This currently translates in the turn rate where the rate is higher at mach 0.4 than at mach 0.6. It doesn´t take a professional extrapolation to see that it is plain wrong.

 

It's not exponential, it's quadratic. nz is Lift/Weight, which for constant (max) C_L is proportional to dynamic pressure, and therefore to square of airspeed.

[Ravenus]

4 hours ago, m4ti140 said:

 

It's not exponential, it's quadratic. nz is Lift/Weight, which for constant (max) C_L is proportional to dynamic pressure, and therefore to square of airspeed.

Thank you! I knew i wasn´t expressing it right.

[Shmal]

Time of sustained turn. It is from soviet manual Izdelie 75A(MiG-21bis). My extrapolation below 0.5M

So, at 0.347M time of the turn has to be 37.5 sec = 9,6°/sec. We have in DCS now 12,9 sec. As I said before - the reason of this fact is over performed G-load!

It is with Max AB for sure, look at noted heights (1,3,5 km - 5 km mean it is not the Special AB it is Max AB)

Radius of sustained turn. It is also from the Soviet manual Izdelie 75A(MiG-21bis). My extrapolation below 0.5M

We may see here that it has to be like 650 meters but in the DCS we have 516 meters.

It is with Max AB for sure, look at noted heights (1,3,5 km - 5 km mean it is not the Special AB it is Max AB) 

Edited July 15, 2021 by Shmal

[Shmal]

So, calculating the error in G-load, radius and the turn rate and comparing as we have in DCS and in my extrapolations:

2.86g/2.2g (as I extrapolated) = 1.3

12.9 sec/ 9.6 sec (as I extrapolated) = 1.34

650 meters (as I extrapolated) / 516 meters = 1.26

 

So, my errors are correlating between each other. Looks like we have 30% overperformed MiG-21 below 0.5M!

 

The true is somewhere close!

 

Here are two charts of MiG-21bis performance! It proves my extrapolation also!

You may look that the turn rate at this speed is significant lower, and the radius of turn is bigger!

Hiromachi I asked a mutual friend of ours to bring you the full manuals of these charts!

Edited July 8, 2021 by Shmal

[Barra1]

This is affecting the AI flight model as well. It can pull more AOA than the Hornet and remain in control.