Thank you for the new FM

[Etirion]

Potipu figures of the cobra Pugachev? Why duck? MiG21 does not fulfill this element. And then, there are air brakes)

 

Aerobraking is used on landing, here is an example of a Eurofighter (1:45min). It helps with slowing down by using your wings as a big airbrake and not using the brakes too much, which makes the ground crew happy.

 

 

Couldnt find one of a mig21 quickly, sorry.

[Dr_Arrow]

Here are plenty of Mig-21 (Lancer and UM) landing rolls with aerobraking (starting around 19:00). IRL a good landing with Mig-21 is landing on main landing gear (MLG) and then aerobrake. Landing on all wheels was considered as a bad one (at least by pilots I've spoken to).

 

 

Another examples of correct landings (MF versions):

 

[Sceptre]

thank you M3 for keeping this beauty alive instead of letting it become abandonware. It was the first ever radar capable DCS fighter and still one of the best IMO

[jojyrocks]

Here are plenty of Mig-21 (Lancer and UM) landing rolls with aerobraking (starting around 19:00). IRL a good landing with Mig-21 is landing on main landing gear (MLG) and then aerobrake. Landing on all wheels was considered as a bad one (at least by pilots I've spoken to.

 

 

 

 

Nice vids man!

 

 

This is what I have been talking about.

 

 

The Mig 21 landing physics need more tuning and as of present its almost impossible to aerobrake unless you have near empty fuel and load. It is the number 1 most difficult plane to aerobrake (barring Hornet on full flaps). I could manage with F-5, though...

 

 

 

There are more vids of Romanian Mig 21 with wing tanks and heatseakers and still be able to land with aerobraking.

 

 

I've also noticed that there are more vids of OLD school pilots landing more with the aerobrake format...like Su-7, Su-17/22, Su-15, F-4 Phantom and Mig 21 etc....but modern vids of F-4 and Mig 21 landing are majority on the without doing the aerobraking...

 

 

 

 

 

 

 

 

Its easier to do on Fly by wire planes ( Barring the Hornet landing on land bases with full flaps).

[Lovcar]

agree for 10,000%) Thank you guys for working on the MiG21! This is a legend of the aircraft not only in the USSR, but throughout the world! I love MiG21! And I'm waiting for MiG23)

[pierrewind]

Guys and girls...

 

How to say it nicely... I didn't want to give out my opinion before I actually went through my testing... :music_whistling:

 

I was biased, I did see the welcome improvements on the departures and so on... Like most I thought this is it, the mig performs as it should. :pilotfly:

 

So I went through the same testing as before, And my disapointement was noticeable when I realised we still are able to pull a lot more than we should without consequences... In fact the CL VS UUA plot is still as wrong as it was before :cry: ... I can consider the charts identical... as you can see attached.

 

So as good as the departure is, we are still able to extract too much performance out of the mig without consequences... (The "safe g" pull should be significantly reduced by more than 40% in most cases...) :music_whistling:

 

I am disapointed by these finidings. I hope it is improved in the future... :book:

 

https://forums.eagle.ru/showpost.php?p=4304015&postcount=61

 

Ps: Max CL is from previous testing

 

Pps: additional testing shows 4.5G at UUA 32 and 515km/h instead of expected 3.2g... With an airshow weight likely below the one I used...

Edited July 28, 2020 by pierrewind
additional testing

[riojax]

So I went through the same testing as before, And my disapointement was noticeable when I realised we still are able to pull a lot more than we should without consequences... In fact the CL VS UUA plot is still as wrong as it was before :cry: ... I can consider the charts identical... as you can see attached.

 

So as good as the departure is, we are still able to extract too much performance out of the mig without consequences... (The "safe g" pull should be significantly reduced by more than 40% in most cases...) :music_whistling:

 

I am disapointed by these finidings. I hope it is improved in the future... :book:

 

The current CLmax is correct, and about the UUA the bug isn't the FM, is only the indicator as I did show on a RL video. Please, review your data with the possibility of a bad UUA indicator and don't spread FUD.

 

About the "we are still able to extract too much performance" statement, this is simply a lie, the stall point is exactly the same on alpha and G values to the real tables, anyway if you want to rely on the UUA indicator, as I said before, the current output is wrong, don't use it.

[Frederf]

If you look at published charts UUA 33° and 28° CL should be about 0.80 and 0.68 respectively for low Mach range ~0.3-0.7. UUA 21° is about 0.52. CLmax in this range is ~1.25 to ~1.10 decreasing occurring significantly at more than UUA 33.

 

Of course in DCS the relationship between UUA and CL is much different. CLmax is occurring at reasonable numbers but UUA gauge is reading 33 at the moment instead of linear extrapolation of ~45-52°.

[pierrewind]

The current CLmax is correct, and about the UUA the bug isn't the FM, is only the indicator as I did show on a RL video. Please, review your data with the possibility of a bad UUA indicator and don't spread FUD.

 

About the "we are still able to extract too much performance" statement, this is simply a lie, the stall point is exactly the same on alpha and G values to the real tables, anyway if you want to rely on the UUA indicator, as I said before, the current output is wrong, don't use it.

 

Riojax, I very much appreciate your constructive statements and your amazing testing skills. However, I disagree with some of your findings. :thumbup:

 

I won't go through everything again as I have done it previously. However, If you look at the Mig-21 airshow demo, you will find the pilot puling 32UUA at 515 km/h giving out 3.2G. If you do the same in DCS you will pull 4.5G. That is just about 40% extra performance. So something is obviously wrong.

We can't seem to agree on the exact error. To me, there is a discrepancy in the tables between UUA and CL. But frankly, I don't care if this issue is from a bad UUA coding or inacruate CL.

 

Though, my testing agrees with NASA papers and the AOA/UUA relation is coherent with mach numbers meaning the UUA is behaving as I expect it to.

 

Whatever the source of the problem is, my issue is that there is a problem with the mig 21 still overperforming.:pilotfly:

[riojax]

Riojax, I very much appreciate your constructive statements and your amazing testing skills. However, I disagree with some of your findings. :thumbup:

Thank you, and sorry if I was too rude, but I did think that on my last video all was crystal clear. My fault.

 

 

I won't go through everything again as I have done it previously. However, If you look at the Mig-21 airshow demo, you will find the pilot puling 32UUA at 515 km/h giving out 3.2G. If you do the same in DCS you will pull 4.5G. That is just about 40% extra performance. So something is obviously wrong.

This is easy explainable by an UUA indicator error, if it's wrong your G will be wrong too.

 

 

About the video, I will expose my findings:

 

I know that it's a 23UB. this means a very different airframe than the 21Bis, but it have the same DUA-3 and UUA-1 sensors and indicators. As you can see on the attached image, this is the exact moment that the nose wheel lose ground contact. On this, the UUA-1 measure only can be pure instrumental AoA and in this exact position the airframe differences are almost unmeasurable, also you can see that the difference is almost the third part, by that we can only conclude that the instrument is returning a bad measure.

 

I hope that this ends the FM vs UUA-1 measuring error dispute, also thank you for your time, dedication and reading.

 

P.S. If anyone finds a 21bis takeoff showing the UUA-1 it will be greatly appreciated.

Edited July 29, 2020 by riojax

[pierrewind]

Thank you, and sorry if I was too rude, but I did think that on my last video all was crystal clear. My fault.

 

 

 

This is easy explainable by an UUA indicator error, if it's wrong your G will be wrong too.

 

 

About the video, I will expose my findings:

 

I know that it's a 23UB. this means a very different airframe than the 21Bis, but it have the same DUA-3 and UUA-1 sensors and indicators. As you can see on the attached image, this is the exact moment that the nose wheel lose ground contact. On this, the UUA-1 measure only can be pure instrumental AoA and in this exact position the airframe differences are almost unmeasurable, also you can see that the difference is almost the third part, by that we can only conclude that the instrument is returning a bad measure.

 

I hope that this ends the FM vs UUA-1 measuring error dispute, also thank you for your time, dedication and reading.

 

P.S. If anyone finds a 21bis takeoff showing the UUA-1 it will be greatly appreciated.

 

 

I am very sorry, I must be too dumb to understand your amazing reasoning.

 

Let's just consider for a second, the UUA was accruate, wouldn't this issue possibly come from a different place? Like airplane overperforming?

 

Or let's just consider the mig 23 and mig 21 are two different airplanes. Oups... there are... :doh:

Two different airframes in two different configurations (in your photo, the mig 23 rotation has started; right before it the instrument shows about 5 units... very close in fact to what the mig 21 shows). Plus both are on the ground and subject to factors such as ground attitude even down to struts that could have different pressures but since it is two different airplanes, I'm going way to deep for something irrelevant...

 

I am very sorry, I am unable to see something that seem so obvious to you. :cry: But I would love to learn more from your great knowledge as to why the UUA is wrong.

Edited July 29, 2020 by pierrewind

[Frederf]

You can figure out what G should occur during a turn with UUA equal to any value, say 21 at M0.6. This is because CL value at M0.6 UUA 21 is known.

 

But if you go into DCS and pull UUA 21 at M0.6 and then calculate G you will get a much higher number. I don't think it's because too much lift is occurring at this UUA but instead UUA is reading too high for that lift.

[pierrewind]

Well, in order to not mix up things, we should go back to the facts.

-Testing showed an error between the actual UUA vs CL charts.

 

This error could be attributed to a few factors.

1) Our testing or the charts provided are false.

2) UUA is wrong and does not correctly represent the correct expected behaviour.

3) Flight model performance is wrong for a given UUA number.

 

These are my hypotesis. I'm sure we could find more.

Now as to were the error lies...

Let's start with point 1. 2 of us have tested the mig 21 model with similar results. We could run into similar errors, but if the data capture and the widely available informations are correct, this option is to be ruled out.

 

Point 2... UUA is wrong. Well, my personal limited testing shows that the AOA and UUA numbers are correlated based on a mach number. The error produced is in accordance with NASA papers.

As these papers do not specificaly apply to the mig-21 it doesn't really prove anything, but to me it makes the behaviour reasonable. Though not proven 100% accruate.

Lastly riojax is of the strong opinion the UUA is wrong. However at this point other than from videos comparing the mig21 to the mig23 UUA behaviour on the ground which is not something comparable. No one has been able to come up with anything but opinions regarding this matter!

 

 

Point 3... flight model performance. As you might understand this is were my heart falls. If we go back to the airshow video and the UUA at 32 UUA we yeld about 40% extra performance. Even if the UUA was wrong, given the charts available this 40% extra performance would put us right at the stall point. This should for obvious reasons not be safely and continuously manageable. Though it is to note the weights are unknown, the airframe could be modified and some avionic logic could be different.

 

At the moment, I can not match the sim performance to the reality. To me it seems this mismatch is produced by slightly wrong performance tables leading to over-inflated simulated performance.

 

I am very much open to receiving actual and proper information/testing to once and for all close this debate. I would love to be proven wrong!

[gavagai]

I am not an expert on the Mig-21, but the new FM makes it unenjoyable to fly and fight. This plane used to be fun.... now there is this wild aileron snatching that prevents maneuvering.

 

I hope the FM is wrong so it might change again, but it could be right. A brick with wings flies better.

[rossmum]

Don't pull the stick so much? The aircraft will develop a wing rocking tendency and tip stall at angles of attack well into the "red-and-black zone" on the UUA. You can edge it if you know what you're doing or have a good feel for stick position, but snatching and pulling the stick like you're in an F-18 will cause a departure, exactly like you would expect from a jet that first flew in 1955 and does not feature any kind of control augmentation beyond a simple G-scheduler and damper system.

 

The only difference is that before the aircraft would stall symmetrically, because the tip stalls weren't working, which was obviously easier to recover from and less detrimental in combat.

[gavagai]

Oh, I recognize that the snatching is caused by too much AoA. It is just sad that the Mig-21 no longer maneuvers as well with moderate AoA, within limits.

 

--------------

 

Just off the cuff...

 

550kph, 4g turn sustained, 0.60km turn radius

700kph, 5g turn sustained, 0.77km turn radius

850kph, 5.5g turn sustained, 1.0km turn radius

 

Impossible to black out at any airspeed because of the inability to pull sustained g. Can briefly reach 9 or 10 g for a split second if you dump airspeed in a hard turn from 900kph downward. Max AoA is about 15deg, at 16deg the ailerons snatch.

 

Compare this to the F-5, which can hold 8g for many seconds after you reach 900-1000kph IAS. The poor Mig21 can't even pull 8g at that speed if you try.

 

Again, it could be correct, I just hope it is not. :(

Edited August 27, 2020 by gavagai

[Cgjunk2]

It seems the latest update changed things a bit. The stall behavior is no longer snatchy all over. Now, with low G stalls, it mushes straight ahead smoothly. Only with highly accelerated stalls do you get the violent snap-stall behavior.

 

Also, Im not sure if it’s just me, but the nose up/down oscillations seem to be more damped now.

[Hiromachi]

Oh, I recognize that the snatching is caused by too much AoA. It is just sad that the Mig-21 no longer maneuvers as well with moderate AoA, within limits.

 

--------------

 

Just off the cuff...

 

550kph, 4g turn sustained, 0.60km turn radius

700kph, 5g turn sustained, 0.77km turn radius

850kph, 5.5g turn sustained, 1.0km turn radius

 

Impossible to black out at any airspeed because of the inability to pull sustained g. Can briefly reach 9 or 10 g for a split second if you dump airspeed in a hard turn from 900kph downward. Max AoA is about 15deg, at 16deg the ailerons snatch.

 

Compare this to the F-5, which can hold 8g for many seconds after you reach 900-1000kph IAS. The poor Mig21 can't even pull 8g at that speed if you try.

 

Again, it could be correct, I just hope it is not. :(

 

What engine setting ? Afterburner or Emergency afterburner ? Altitude ? Temperature and pressure used for test ?

Also, I suggest to use M number since its quicker to compare with the manual.

Edited August 27, 2020 by Hiromachi

[rossmum]

I'm a habitual low-speed turnfighter so I wasn't really familiar with the ARU scheduling at high speeds - but I can absolutely say you can hold well beyond 15/16 indicated AoA per UUA-1 at any speed, at any altitude, comfortably. Stall onset remains around 32-34 as it always was. I'm not sure why you'd be getting any stall behaviour at all at 15 indicated, that's well within the safe envelope and not far off what you should be holding for a landing approach.

 

ARU seems to transition fairly abruptly around the 700km/h mark, which is the only way I could overstress the aircraft consistently. If you're holding the stick to your guts for max turn at higher speed and the ARU suddenly flips, I could see that causing the jet to skate out from under you before you realise to relax the stick, but the jet's always done that for me - it's just more pronounced now.

[AeriaGloria]

I'm a habitual low-speed turnfighter so I wasn't really familiar with the ARU scheduling at high speeds - but I can absolutely say you can hold well beyond 15/16 indicated AoA per UUA-1 at any speed, at any altitude, comfortably. Stall onset remains around 32-34 as it always was. I'm not sure why you'd be getting any stall behaviour at all at 15 indicated, that's well within the safe envelope and not far off what you should be holding for a landing approach.

 

ARU seems to transition fairly abruptly around the 700km/h mark, which is the only way I could overstress the aircraft consistently. If you're holding the stick to your guts for max turn at higher speed and the ARU suddenly flips, I could see that causing the jet to skate out from under you before you realise to relax the stick, but the jet's always done that for me - it's just more pronounced now.

 

With FFB the ARU makes it stiffer the higher the speed setting. I thought it was just normal forces until I put it in manual. So you can literally feel it. And I’ve got to say, no other module has this much force.

 

I always thought it would be opposite, the more deflection per stick travel ratio would need more force, but maybe I misunderstand the system

[Shibbyland]

Speaking of MiG 21, has there been any progress with the massive performance drop when using RADAR?

 

It's fine when using old Nvidia drivers but there comes a time when you really do need to update the drivers for other things.

[gavagai]

I'm a habitual low-speed turnfighter so I wasn't really familiar with the ARU scheduling at high speeds - but I can absolutely say you can hold well beyond 15/16 indicated AoA per UUA-1 at any speed, at any altitude, comfortably. Stall onset remains around 32-34 as it always was. I'm not sure why you'd be getting any stall behaviour at all at 15 indicated, that's well within the safe envelope and not far off what you should be holding for a landing approach.

 

ARU seems to transition fairly abruptly around the 700km/h mark, which is the only way I could overstress the aircraft consistently. If you're holding the stick to your guts for max turn at higher speed and the ARU suddenly flips, I could see that causing the jet to skate out from under you before you realise to relax the stick, but the jet's always done that for me - it's just more pronounced now.

 

So, is something completely borked with my install? I've had this module since the early days... Right now it stalls reliably at 16deg AoA.

[MiG21bisFishbedL]

Speaking of MiG 21, has there been any progress with the massive performance drop when using RADAR?

 

It's fine when using old Nvidia drivers but there comes a time when you really do need to update the drivers for other things.

 

A WIP was included in the latest update. It's a mixed bag, but a start.

[Hummingbird]

Do some sustained turn tests and see if you can match this EM diagram (7500 kg weight 2x P-3C's):

 

 

If you can't, something could be amiss.

[rossmum]

So, is something completely borked with my install? I've had this module since the early days... Right now it stalls reliably at 16deg AoA.

 

Something's definitely not right, assuming you mean 16 indicated on the UUA. If you mean the F2 telemetry bar - I'm not sure, I can't remember what the relation is between UUA units and true AoA. Either way, anything below about 32 indicated should be fine, with a subtle wing rock developing sometimes between 28-32.