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New stability patch = UFO


BadHabit

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Here's one I recorded a few weeks ago. The UUA-1 may as well not exist now as you can comfortably fly at 24-28 deg true AoA, which reads off the scale on the UUA, well past the 33-34 local that it used to depart at and very far beyond the safety limits noted in the POH.

 

While the current flight model may not be 100% realistc and still needs some tuning it is much better than what we used to have. Plane at least feels like a delta now.

 

No, it really isn't. The FM prior to this one felt realistic, the one before that would never drop a wing but could at least still depart to some extent. Now it does neither, and while I can't speak for 1.5 as I've only been playing since late 2018, this is by far the least realistic the FM has ever felt since I started.


Edited by rossmum
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The previous FMs were just as unrealistic. As soon as you hit 33 degrees the aircraft became uncontrollable and went into the ground. From Constant Peg pilots we know that the aircraft has excellent low speed characteristics. In the Red Eagles book one guy even says that only the F-18 had better low speed handling.

I spoke to a guy who flew the early F-13 and the Bis versions as well. He says the wing rocking at low speeds were typical of the F-13 but he has never experienced it in the Bis even though it is in the manual. No wing drop either. On the other hand, he says dogfighting should be flown around 800km/h and above where the extra afterburner is at its max. At those speeds or above with the second AB on every maneuver can be flown without loosing airspeed even at max G (below 4000m AGL with thurst to weight ratio higher than 1). That's why you should be able to beat the F-5 every time in the Bis:smilewink:.


Edited by Argo Navis
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If your goal is to reach a state where "you beat the F5 every time in the Bis", that's certainly not the way to do it. You say it should because it has positive T/W ratio, in which case pulling the stick as hard as I want wouldn't be at all the way I would take advantage of this T/W ratio.

Again, we can currently pull the stick as much as we want, the FM magically stops the Mig at the critical AoA and the plane never departs in any way. This ofc leads to completely unnatural behavior of the plane and the pilot. It's like the plane now has an onboard flight computer and is an actual modern aircraft.

And no, this is not the correct direction to go. Maybe previous iteration was a bit too brutal when going out of AoA enveloppe, but at least this behavior was simulated. We now lost this.

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So to who to believe? There are comments that it is now very close to realistic behavior as pilots, and some pilots in books says. And then there are who say it is unrealistic because it flies better like a 5th gen fighter.

 

These are the challenging things, just like I have never seen any aircraft perform such maneuvers as Su-27 in the 1989 airshow. Neither has I ever seen any other aircraft beat Su-27S at the 360 degree turn in speed or minimum radious, beating everything there is from F-14 to F-22 and F-16.

 

Yet there are even public records of F-22 pilots making such claims that Su-27 can't go past 90 degree in cobra but F-22 can, or when Su-27 performs cobra it will stall and lose all speed and drop down the sky and needs to dive to get speed....

 

Simply put, "you need to see it to believe it", and that there are lots of pilots who simply doesn't know what they are talking about.

 

The other challenge is as well that even the manuals can be seriously wrong. They are rewritten often when the new issues appears etc. They are just a "procedure at the moment" kind, where claims in them can be false or very true. There are checklists how to do things like in case of controlled ejection that what to do for the engine, gear and flaps etc that are simply estimations instead that will work so.

 

The pilot book can say that "you can't do this at this and that altitude" and yet then someone goes and does exactly that.

 

The main challenge in the aviation is that lots of things are unknown and especially in the era before computers to make the number crunching in far more accurate simulations than it was previously possible.

 

I lost my faith to MiG-21Bis long time ago because it received so many controversial flight modeling changes in the past. One update took it to opposite direction and then it got reversed to another direction on next one. You couldn't anymore trust anything that is there. And so on how it could be trusted today?

 

MiG-21Bis is a delta aircraft, yet there are people talking like it is a F-104 etc.

 

If a pilot comes and say they had speed X, altitude Y and performed turn at Z AoA, and manual says it is impossible, who to trust? A guy who made it, or then remembers it wrong, or a engineer writing the manual based calculations but never flu the aircraft?

 

Is seeing believing?

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Whoever is saying that this or that MiG-21bis cannot perform are forgetting one if not the most important thing about this module: Lead developer is actual MiG-21bis pilot in Serbian Airforce. Difficulties behind some decisions on what the DCS should and can have are something that we cannot know and it's not affecting only the latest jets in the DCS. Remember that MiG-21bis is still being flown in the world around today. Disregarding the secrecy behind actual FM, you still have one more difficulty to pass on to the simulation environment: stick movement that are incomparably large when compared to the small sticks that we use at home. Fishbed stick is attached on the floor directly and lateral movements are going alsmot in the line with your shoulders. This is very difficult to transfer and because the roll rate for the Fishbed is extremely high which is reported by many pilots that flown the aircraft. One of the things that real Fishbed pilots were talking about that wasnt possible to do with the previous FM is climbing 180 turn after takeoff (initiated by the end of the runway). This is now possible. Previously you would just drop as a f* brick which Fishbed is not - it is a highly manuevreable rocket.


Edited by Pr0metheus
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I do not have a goal here. My opinion has no impact on DCS Mig-21 development. Of course, I do agree, there should be a stall speed there, and a departure as well. My comment about the thrust to weight ratio is actually ended up in the wrong topic here. It was meant to be a reply to a comment in a different topic about the F-5 being a better dogfighter by default. Apologies for that (the wink at the end was there for a reason). On the other hand, if you are familiar with the book mentioned above, it is stated several times by pilots who flew both types, the F-5 and the Mig-21 at the same time, that they are almost identical when it comes to performance. It must be pointed out that the constant peg program flew the Mig-21F-13 which is way behind the Bis at low altitudes. There are implications that they also flew the MF, but that info is still classified. I got the info from Mig-21 pilots that the Bis was a beast with the 2nd AB when it is compared to the MF or the F-13. It is a totally different ballgame when your thrust to weight ratio changes so much in the Bis. If the F-13's performance is identical to the F-5, the Bis should be a much better performer even if the 2nd AB is only allwed for 3 minutes (no restriction in the sim, and not much performance gain in the sim either). Now, about how you exploit that thrust to weight ratio I have no idea. It is definitely not by pulling as much as you can. The emphasis is on the AOA. The aircraft WILL NOT STALL at 33 degrees on the UUA-1 instrument. There are a bunch of videos on youtube where the aircraft is at 33 degrees and the speed is only around 115 knots. There is no stall, no wing rocking, no wing drop. I have seen 90KTS on HUD footage! (Romanian Lancer which is basically an MF with the R-13 engine). The Bis manual is stating minimum speeds at around right there by the way (190km/h). The most surprising info is an F-13 flying against an F-14 where the 21 pilot slows down the aircraft to 70KTS with flaps! No stall. The F-14 still beats him though. In a different chapter there is a departure described way above the stall speed. You gotta forgive the devs for trying to figure out the whole envelope. Anyway, read the book. I can't wait to see the next update.

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Whoever is saying that this or that MiG-21bis cannot perform are forgetting one if not the most important thing about this module: Lead developer is actual MiG-21bis pilot in Serbian Airforce.

Yeah, that same pilot said the FM was "finished & final" >3y's ago! Is he even still on the team? we know nothing since M3 ain't communicating.

Fishbed stick is attached on the floor directly and lateral movements are going alsmot in the line with your shoulders. This is very difficult to transfer and because the roll rate for the Fishbed is extremely high which is reported by many pilots that flown the aircraft.

Not a problem. Either you use curves, joy-extension or do small movements. All other sim modules manages that just fine.

This is now possible. Previously you would just drop as a f* brick which Fishbed is not - it is a highly manuevreable rocket.

The 21 has a broken (FM & many other bugs) it doesn't stall...look at the AoA if you're in RED you're supposed to be stalled. It's not rocket science!

If you think the current FM is correct then why the does it have the biggest colorful AoA indicator in the cockpit?

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There's actually a margin of safety on the UUA redline. You previously had (and from the reading I've done, should have) a few degrees more you can ask before the aircraft starts misbehaving. The difference is, that used to take very precise stick movements in DCS, and now you can exceed that limit with no consequences - and then you hit a glass ceiling of sorts where the aircraft will not raise its nose any further, so you can maintain it in that state indefinitely. At a low power setting it will maintain that AoA and descend slowly, at higher power settings (1st or 2nd burner) it will maintain it perfectly with no loss in altitude.

 

I don't believe this was a deliberate change, more likely something got pushed to the patch that wasn't ready yet, or DCS' notorious spaghetti code somehow broke something in the FM. The prior patch seems to have been close to what was actually intended and if anything I'd imagine there was some fine-tuning going on to try and adjust the amount of porpoising the aircraft was exhibiting at certain speeds.

 

I am very aware of the findings about the 21's exceptional low speed performance and good nose authority, but that doesn't mean you should be able to pull the stick to your guts and cruise around without a care. If that was the case, there would be no need for the UUA-1 to be redlined (or even installed, considering you can currently maintain an AoA beyond what it is capable of displaying), there would be no need for any restrictions in the POH, and you slash pilot training enormously since you actively have to fly into the ground to crash the plane in its current state.

 

There were memoranda put out by the Soviets to cover low speed/high AoA flight in the 80s. Skyrider has posted an example fairly recently, I forget which thread it's in. They still include a number of restrictions, though they also demonstrate awareness of the aircraft's capabilities and provide figures to help pilots safely exploit them.

 

The 21 does not have FBW. It should not be handling like it does, and I don't believe it's intended to be.


Edited by rossmum
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If you think the current FM is correct then why the does it have the biggest colorful AoA indicator in the cockpit?

I maybe wrong, But I think AoA indicator in Bis model is reused form earlier version of the aircraft. It effectively reduces cost of making another calibrated indicator. Since Bis has significant upgrade over earlier version, making the instrument (not required). See some cockpit videos in youtube.

 

For eg. Su-25T uses same fuel Indicator as most russian planes, Even with full fuel it stays below half of the indicator.

 

It's just my thought

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No, this is not the reason. Instruments which were reused from earlier aircraft had no redlines of their own, these were instead painted around the rim of the instrument or as hash marks on the instrument panel itself (see: Su-25 airspeed indicator marks, MiG-21 RPM/eng temp gauge marks).

 

The AoA vane is positioned where the airflow hitting it is already disturbed, so the AoA reads higher than the true AoA. This was common for aircraft of the era (hence US Cold War fighters measuring AoA in 'units' to note the difference). The red zone starts at 28 degrees, where the operating manual states the pilot is not to increase AoA any further within a particular speed range, and runs to the end of the scale - the aircraft's actual critical AoA is only a few degrees before the gauge runs out. The UUA-1 is marked exactly according to the same restrictions, charts, and cautions laid out in the aircraft's operating manual.

 

The instrument absolutely was required, the 21bis did not magically solve the problems of departure from controlled flight at excessive AoA or low speed. It had more thrust to help avoid that situation but thrust isn't the answer to every problem, and the engine can't be relied on to deliver its full rated thrust at especially high angles of attack/low airspeeds anyway.

 

I'm guessing you're talking about the LanceR HUD footage, but the vane is still in the same place - the AoA is being fed through to the HUD and you can still see the pilot is very careful not to exceed more than 28-29 degrees of 'local' AoA as registered by the DUA sensor.


Edited by rossmum
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I dont know how much accurate this FM is. But the earlier FM was total BS. See the Lancer cockpit video. You shouldn't fall like a brick when you touch 30 in UUA indicator. We need to see what FM, M3 will introduce in May 20 update. But seriously I would be against anything that resembles last FM.

See the position of UUA indiactor and reference it to the 2nd video

 

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You didn't fall like a brick if you hit 30. You could pull up to 33-34 AoA before the aircraft would roll-off or drop out from under you, depending if you were in a turn or level, respectively - which matches descriptions I have both read and heard of the MiG-21's behaviour during a stall, mostly stating it was fairly benign and self-recovering.

 

If you pull the stick to your guts, pass the stall and continue trying to pull the stick into your lap, of course it's going to drop like a brick. Any aircraft will. This is a problem with lack of pilot experience, not flight model. The amount of times I saw people in MP servers stall at 2-3km altitude and simply continue downwards in a stall to the ground made it pretty clear that the FBW jets have spoilt a lot of people.

 

In your second video the pilot is staying well within the core of the yellow/black zone. To force the aircraft to depart with the previous FM you would have to aggressively pull it past the middle of the red/black zone, or hold it around that area and neglect to ease off stick pressure to account for increasing AoA as speed washed off.

 

The aircraft takes stick and rudder skills, so develop them.

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A bit off-topic, but that LanceR video reminded me how great it would be to have a nice, smooth take-off run in the MiG-21. Like you're actually rolling a solid 10-ton chunk of metal down the runway instead of something that feels like a dune buggy that will bounce off into a wheatfield if you hit a pothole the wrong way.

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A bit off-topic, but that LanceR video reminded me how great it would be to have a nice, smooth take-off run in the MiG-21. Like you're actually rolling a solid 10-ton chunk of metal down the runway instead of something that feels like a dune buggy that will bounce off into a wheatfield if you hit a pothole the wrong way.

 

+1 :thumbup:

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A bit off-topic, but that LanceR video reminded me how great it would be to have a nice, smooth take-off run in the MiG-21. Like you're actually rolling a solid 10-ton chunk of metal down the runway instead of something that feels like a dune buggy that will bounce off into a wheatfield if you hit a pothole the wrong way.

 

The bounciness only really became an issue (again) recently - it seems like it's a reversion to the early days, as I didn't play DCS back then but did keenly watch a lot of MiG-21 flights in it. I actually wonder if something was adjusted in the base game, because I've noticed some other A/C feel very bouncy on their takeoff rolls lately as well, especially on Caucasus.

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Apparently the lack of stall is a bug. Shame this information couldn't have got to us sooner as it would have saved many pages of analysis and discussion by the community.

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Next OB update will fix it.

https://leatherneck-sim.mantishub.io/view.php?id=939#c1625

 

patch day... and nothing in the changelog...:huh:

https://www.digitalcombatsimulator.com/en/news/changelog/

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So, i congratuate everybody with new update of the flight-model and it's fixed many problems which we've been watching before:

1. Old stall behaviour when plane was going to fly by it's belly to forward with crazy 40° AOA in level flight.

There was no any other features on critical AOA at all! Done!

2. Now we have pronounced stall behaviour after 32° (35° on cockpit gauge). We have rapid wing rocking, throws from wing to wing in turn and it's going to opposite side of the turn, out of the turn as it has to be because its tipical for delta shaped wing! It is not so simple and not so scripted as we can think, for example if you push a pedal in to the side of turn the wing rocking starts into the turn too! And it's great! Is'nt it?

3. We have central directed stall without wing rocking with spetial conditions!

4. We have inproved behaviour while take off running! No more crazy jumps!

5. We have much more realistic duration of the gear while rude touching! I was trying to brake the gear on 340km/h and -5m/s vertical speed and it's Ok after that! Done!

6. There is no more suspitious wobbling of the nose on pretty good speed 400-700 km/h. Also there was hard to trim. Done!

7. I have noticed there are no more UFO down directed spot lights to the ground when it extended. Done!

8. Bug with critical reducing the heat signature of the jet nozzle with afterburner. Done!

 

Dear developers! I sincerely thank you for the work you've done!


Edited by Shmal

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