Exaggerated oscillation ?

[theGozr]

Since the last update I find the MiG21 with exaggerated pitch oscillation..  Doesn't seems quite right imo ..  very!

[Woc_pilot]

pitch seems ok - the landings seem a lot smoother. Ground effect modeing is different?

 

[theGozr]

Impossible to fly it correctly at slow to mid speed unless you engage after burner .. 2 updates before it was much more stable.  Ground effect and atmospheric physics are not existent in DCS a big disappointement !!

 

Edited March 12, 2021 by theGozr

[Woc_pilot]

I wish they'd say exactly what they tuned/changed in the flight model at the time of release. I agree - overall the aircraft model seems different at low speeds.

[Skysurfer]

On 3/12/2021 at 5:21 AM, theGozr said:

Impossible to fly it correctly at slow to mid speed unless you engage after burner .. 2 updates before it was much more stable.  Ground effect and atmospheric physics are not existent in DCS a big disappointement !!

 

 

 

Don't get too slow obviously or you'll get wingrock. Ground effect is very much a  thing in DCS so I don't know what you are talking about. 

I have been flying the 21 in DCS for many years now and NEVER had any problem with he FM (even the old one) - you fly the speeds, dont bust limitations and most importantly, don't suck.

Edited March 13, 2021 by Skysurfer

[theGozr]

No.. oscillation is too high at lower to med.. So basically we have to fly on after burner all the time which it by far not how it works..  I have an FFB stick to take in consideration but the plane was lesser prone to make me sea sick or rock me to sleep ..  this is not how it should fly simple I know my stuffs.

[Skysurfer]

5 hours ago, theGozr said:

No.. oscillation is too high at lower to med.. So basically we have to fly on after burner all the time which it by far not how it works..  I have an FFB stick to take in consideration but the plane was lesser prone to make me sea sick or rock me to sleep ..  this is not how it should fly simple I know my stuffs.

 

Might be an issue with FFB. Stay above 600kph and you should be fine. If you can please record a video showing exactly what the problem is.

[theGozr]

Skysurfer  yes I'll try

[Fri13]

On 3/14/2021 at 5:06 PM, Skysurfer said:

Stay above 600kph and you should be fine.

 

Well the pilots say that 450-500 km/h should be good stable handling with it, but comparison to F that fly like a dart the Bis flies like a beer bottle. The flight performance is otherwise identical by speed and turn rates etc. 

 

It is crazy at the moment that you need to use afterburner in landing, as maintaining a 320-350 km/h landing slope drops it easily like a rock. And on moment you put afterburner on, the aircraft becomes stiff and easy to control regardless that your AoA doesn't change and speed is same until it gets accelerating (slowly).

 

It is almost constant dancing around mil and AB to keep a 3-5 m/s sink rate as required to pull nose too much slows quickly down so easiest is just go almost full mil and perform the proper speed (280-290 on touch down). 

 

[cro_mig_21]

59 minutes ago, Fri13 said:

 

Well the pilots say that 450-500 km/h should be good stable handling with it, but comparison to F that fly like a dart the Bis flies like a beer bottle. The flight performance is otherwise identical by speed and turn rates etc. 

 

It is crazy at the moment that you need to use afterburner in landing, as maintaining a 320-350 km/h landing slope drops it easily like a rock. And on moment you put afterburner on, the aircraft becomes stiff and easy to control regardless that your AoA doesn't change and speed is same until it gets accelerating (slowly).

 

It is almost constant dancing around mil and AB to keep a 3-5 m/s sink rate as required to pull nose too much slows quickly down so easiest is just go almost full mil and perform the proper speed (280-290 on touch down). 

 

These are exactly the words a real MiG-21BisD pilot used when he explained to me this behavior. As if you place a bootle on the table and wobble it. Also, he said that no matter how good you trim it, you always have to give some pull on the stick

[Skysurfer]

1 hour ago, Fri13 said:

 

Well the pilots say that 450-500 km/h should be good stable handling with it, but comparison to F that fly like a dart the Bis flies like a beer bottle. The flight performance is otherwise identical by speed and turn rates etc. 

 

It is crazy at the moment that you need to use afterburner in landing, as maintaining a 320-350 km/h landing slope drops it easily like a rock. And on moment you put afterburner on, the aircraft becomes stiff and easy to control regardless that your AoA doesn't change and speed is same until it gets accelerating (slowly).

 

It is almost constant dancing around mil and AB to keep a 3-5 m/s sink rate as required to pull nose too much slows quickly down so easiest is just go almost full mil and perform the proper speed (280-290 on touch down). 

 

 

Don't land overweight simply.

[Fri13]

1 hour ago, Skysurfer said:

 

Don't land overweight simply.

 

Empty + under 200 L of fuel... If that is overweight.... 

[Dr_Arrow]

33 minutes ago, Fri13 said:

 

Empty + under 200 L of fuel... If that is overweight.... 

I cannot imagine you need afterburner to arrest the sink rate. I have maybe some 500-600 landings in the BIS, not once I needed afterburner in any of its FM iterations. Afterburner during landing would be a big NO IRL, as the SPS system does not work with afterburner, in fact afterburner is disabled in the real BIS having the SPS system engaged.  You must be doing something wrong with such low landing weight. 

[Skysurfer]

10 minutes ago, Dr_Arrow said:

I cannot imagine you need afterburner to arrest the sink rate. I have maybe some 500-600 landings in the BIS, not once I needed afterburner in any of its FM iterations. Afterburner during landing would be a big NO IRL, as the SPS system does not work with afterburner, in fact afterburner is disabled in the real BIS having the SPS system engaged.  You must be doing something wrong with such low landing weight. 

 

Yep, just did some pattern work in the 21 in 2.7. Flies just fine, powered approach 360 on final 340-330 over the treshhold, lands like butter. When dirtied up the 21 requires lot of power ~ 85-90% N1.

Edited April 15, 2021 by Skysurfer

[rossmum]

On 4/15/2021 at 9:54 PM, Fri13 said:

It is crazy at the moment that you need to use afterburner in landing, as maintaining a 320-350 km/h landing slope drops it easily like a rock. And on moment you put afterburner on, the aircraft becomes stiff and easy to control regardless that your AoA doesn't change and speed is same until it gets accelerating (slowly).

 

It is almost constant dancing around mil and AB to keep a 3-5 m/s sink rate as required to pull nose too much slows quickly down so easiest is just go almost full mil and perform the proper speed (280-290 on touch down).

 

This again? I already told you last time you repeated this "needing AB to land" thing that if you fly it correctly, you should not ever need to touch the AB during landing unless to go around on a missed approach. Don't land overweight (and you say you're not - which makes this even more confusing), don't hold the AoA too high (I can only imagine you must be descending at something absurd like 20-25 indicated AoA to need AB!), and if you're already low when you enter your approach, only use one stage of flap. Full flap + too low of an entry point into the pattern will cause you to 'need' AB because you're configured for a much steeper descent than what you're attempting to execute.

 

I really don't know what on earth you're doing but whatever it is, it definitely isn't what you're supposed to be doing. Work on your airmanship.

Edited April 16, 2021 by rossmum

[toilet2000]

On 4/15/2021 at 10:43 AM, Fri13 said:

 

Empty + under 200 L of fuel... If that is overweight.... 

Just landed yesterday with a 21 loaded with 3 R-60s and 1800L of fuel and it was smooth like butter, no need for AB. And this is a somewhat heavy loadout to land with.

 

I think most of the issues come from flying the -21 like other planes in DCS on landing, ie dropping full flaps and gear and trying to fly in that configuration. Landing flaps should be used a bit like those on warbirds: you put them out when you're about to land and need to drop speed.

[Art-J]

^ True that. I've been always using them as per manual since the module release (ie. going full flaps only above inner NDB/marker) and I never had to go above mil trust event on sloppy approach.

[Frederf]

In real manual it is said to need about 80% RPM on approach. In DCS it is about 90% RPM. But perhaps manual is a constantly decelerating technique and airspeed is never stable (and perhaps power required to maintain speed is more RPM like DCS).

 

Day 600m rectangular circuit flying:

600 km/h reduce throttle abeam

550 km/h gear down

increase throttle to prevent below 500 km/h

500 km/h level quarter turn at 20 deg past radio beacon (outer), bank 35-45 deg

recover and begin 3-5m/s descent, flaps T/O

450 km/h final quarter turn

400-420 km/h and flaps landing

overfly beacon at 200m 360-380 km/h

overfly inner beacon at 60m 330-340 kmh

aim for point 150-200m prior to threshold minimum 330 km/h

at 8-10m pull back stick to level off 1m while reducing throttle to SPS gate

pull stick back forcefully as nose lowers in last 1.5-2s before touching down (260-280 km/h) touchdown

 

I do find I need to use about 90-92% throttle in some part of the circuit otherwise 75-85%.

[Hiromachi]

2 hours ago, Frederf said:

80% RPM

Polish 21bis manual I've seen indicates more like 85-87 % for 1200 l of fuel left. 75-80 % is for 21M with R-11 engine. 

[MiG21bisFishbedL]

On 4/15/2021 at 6:54 AM, Fri13 said:

 

Well the pilots say that 450-500 km/h should be good stable handling with it, but comparison to F that fly like a dart the Bis flies like a beer bottle. The flight performance is otherwise identical by speed and turn rates etc. 

 

It is crazy at the moment that you need to use afterburner in landing, as maintaining a 320-350 km/h landing slope drops it easily like a rock. And on moment you put afterburner on, the aircraft becomes stiff and easy to control regardless that your AoA doesn't change and speed is same until it gets accelerating (slowly).

 

It is almost constant dancing around mil and AB to keep a 3-5 m/s sink rate as required to pull nose too much slows quickly down so easiest is just go almost full mil and perform the proper speed (280-290 on touch down). 

 

You should post a track of this. Give yourself about 900m/3,000ft of altitude AGL so you have plenty of room to set up your approach. Set fuel to like ~30% or so. I've never needed AB to make a landing. 

[Ala13_ManOWar]

On 4/15/2021 at 1:54 PM, Fri13 said:

 

Well the pilots say that 450-500 km/h should be good stable handling with it, but comparison to F that fly like a dart the Bis flies like a beer bottle. The flight performance is otherwise identical by speed and turn rates etc. 

 

It is crazy at the moment that you need to use afterburner in landing, as maintaining a 320-350 km/h landing slope drops it easily like a rock. And on moment you put afterburner on, the aircraft becomes stiff and easy to control regardless that your AoA doesn't change and speed is same until it gets accelerating (slowly).

 

It is almost constant dancing around mil and AB to keep a 3-5 m/s sink rate as required to pull nose too much slows quickly down so easiest is just go almost full mil and perform the proper speed (280-290 on touch down). 

 

Yep, that's called second regime, quickly explained it's the line determining the point where you need more power to fly slower, contrary to "logic", and 21 falls like a stone when in second regime. I personally find that 21 flies a better approach if you never get into second regime, so about 400Km/H glide path is better, lowering full flaps only when really close to threshold (so draggy they are) unless you follow a 4º glide path like PRMG marks in which speed doesn't tend to drop so dramatically since your glide is quite steep. Even though it looks a high speed, everything is fast in the 21 anyway, and just chopping throttle while crossing threshold from those 400-380Km/H you can flare all the way until she falls easily onto the ground. That way landing run isn't the long you might expect at all, sometimes even shorter than a "per manual" landing, and I suspect after watching some RL MiG-21 videos on YT it's not me but many pilots since you see those long flares out there very often. On the other hand performing the manual stated approach you can't barely flare and she plummets into the ground right away. That makes me think mine is not a so crazy procedure as it might sound at first. Give a try and you'll see how she flies way steadier approaches. I really wonder why manual doesn't explain at all anything about first and second flight regimes and the dangers of it in this plane.

 

S!

[Fri13]

3 minutes ago, Ala13_ManOWar said:

Yep, that's called second regime, quickly explained it's the line determining the point where you need more power to fly slower, contrary to "logic", and 21 falls like a stone when in second regime. I personally find that 21 flies a better approach if you never get into second regime, so about 400Km/H glide path is better, lowering full flaps only when really close to threshold (so draggy they are) unless you follow a 4º glide path.....

 

3 minutes ago, Ala13_ManOWar said:

.....I really wonder why manual doesn't explain at all anything about first and second flight regimes and the dangers of it in this plane.

 

 

Sorry to quote you like that.

All was interestingly said.

 

I have known that with MiG-21 the approach should be done faster and time the specific speeds at the outer and inner markers, with oddly rapid deceleration. 

 

What you wrote explains things more. That you come fast in and you do the landing quickly by utilizing it's speed to decelerate fast in controlled manner.

 

 

 

On 4/16/2021 at 7:55 PM, rossmum said:

 

This again? I already told you last time you repeated this "needing AB to land" thing that if you fly it correctly, you should not ever need to touch the AB during landing unless to go around on a missed approach. Don't land overweight (and you say you're not - which makes this even more confusing), don't hold the AoA too high (I can only imagine you must be descending at something absurd like 20-25 indicated AoA to need AB!), and if you're already low when you enter your approach, only use one stage of flap. Full flap + too low of an entry point into the pattern will cause you to 'need' AB because you're configured for a much steeper descent than what you're attempting to execute.

 

I really don't know what on earth you're doing but whatever it is, it definitely isn't what you're supposed to be doing. Work on your airmanship.

 

Yeah, insult and make a guesses (AoA indicated below 10) . That is a way to improve someone's airmanship....

 

Yes, you don't know and as you don't even consider someone needing help, it doesn't help them.

[MiG21bisFishbedL]

1 hour ago, Fri13 said:

Yes, you don't know and as you don't even consider someone needing help, it doesn't help them.

How can we know when we can't even diagnose the issue you're having? Like I said, post a track. We'll be able to figure it out real quick given how simple the -21 is.

[rossmum]

There is no way you'd need afterburner below 10 AoA, especially if you're not overweight. The only other thing I could possibly imagine is airbrakes out and even that shouldn't require you to use the burner.

 

Whatever you're doing is obviously wrong, there is no situation where you should ever be in AB on approach. If you can't provide a trackfile or video, we can only connect the dots, and figure you're doing something wrong. I've never had to use AB to land and from the sounds of things, nor has anyone else here, whether flying by the manual or not.

[Reflected]

I just flew a pattern yesterday, not overweight, flying by the book. The aircraft was stable at low speeds and I did not need AB at all. Felt quite realistic to me.