Odd behaviour at landing

[MiG21bisFishbedL]

19 hours ago, CoBlue said:

 

It was between 4-10% fuel in ME as I tested different fuel-loads, no way 40%!, 3rd landing was deliberate chute-before-touch-down to check suspension. Reread my post again, as this was a quick suspension test, not a check-ride including perfect traffic-patterns etc.

 

It's what happening after a little "hard" landing that is disturbing, the "strange bounce", if you're doing perfect landings all the time you never going to notice it. You've got to be testpilots.

 

Re-watch my video above & this & tell me why you don't see any bounces???

 

Former FM during touch-down was spot on IMO, the 21 has beefy landing-gear, it was build for landings on unprepared strips & "hard" landings. Currently it behaves like a 737.

 

 

 

 

First, I was looking at your fuel indicator in the track. You're at 1,000l of fuel, indicated. EDIT: Art-J pointed out I should convert the track into a miz, so yes, you did have 10% fuel internal, my bad. I dun goofed and forgot you had the external. Disregard this then.



This is from your track. At 2,900l internal, you're going to be at 34.5% of fuel with the 1,000l indicated. Again, this is the track you provided. If you're down at 10%, you'd be at 290l and 4% you'd be engine out since that's probably out of usable fuel that the fuel pumps can move. This matters as the airspeed at touchdown changes based on the weight of the aircraft and it becomes very apparent in something like a MiG-21. Unless you mean the percentage of weight that fuel accounts for, that is. At anyrate, this is all minutia when you consider you're dropping onto the tarmac at 4-5m/s. That is simply too steep and always has been. I've flown the -21 since release in 2014 and that's stayed fair constant in my experience. Aim for 2-3m/s. You sheered the center-line tank off on touchdown. That's a hint you landed way, way, way too hard. 

 

Secondly, You say you don't need pointers there, but the MiG does benefit from a nice lazy pattern that gives you ample time to set up for landing. Just offering advice.

 

And finally, yes, we've all seen the video of chute deployment prior to touchdown, but let's compare that video to what you did:

 

This guy's chute fills when he's close to the ground, probably about the height of the landing gear strut and wheel combo with some space to spare.

 

You could easily fit another MiG-21 in the space between your wheels and the tarmac when your chute deployed in the track provided. You could chalk that up to engine limitation, though. Pop the chute lower to the deck, either way.

Yes, we can lavish Artem with praise for days about how rugged the MiG's gear is, but it still has its limitations. Even then, the gear still held up. And, for the record:

 

I did it myself. It just takes practice. You and your buds have some incorrect procedure and assumptions about the MiG and now you're just starting to notice them. You could correct them, or just blame Mag3 for changing the FM when all they did was address the lack of tension in the suspension.

Edited June 2, 2021 by MiG21bisFishbedL

[Maxthrust]

9 hours ago, rossmum said:

 

Pros: you have more finesse in your controls,  as the real aircraft also uses a substantial stick extension and is very sensitive in both pitch and roll

 

Cons: uh, you need some more room for your setup, I guess.

 

Curves should only really be needed without an extension (or with a very short one), IMO. Flying with an extension-less TM Warthog I have like 2 degrees of stick throw between documented AoA limit and THE WOBBLE ZONE and it makes it quite hard to ride the edge when I need to.

 

I have the same setup with you and I settled on 10 curve for the pitch axis. The long throw on the short pivot length does not help with comfort or ease of use..  An extension without FFB does not make sense to me as the amount of physical stick travel remains the same after trimming out regardless of how fast or slow you are. I like this hack job, the -21 with its notchy trim seems like a perfect candidate;

 

 

Edited June 2, 2021 by Maxthrust

[EnvyC]

Quite simply you're forcing the plane to the ground, you're coming in far too steep and absolutely slamming it into the ground, not only that your stick control is all over the place. The plane when trimmed correctly and setup correctly (in advance rather than immediately in the mission 1min to touchdown) floats to the ground with minimal input. For reference I'm flying on a TMWH with no extension.

 

This is pilot error, not FM error. As an example I've attached a screenshot of my own landing using your own track. I'm also attaching two examples that show a vastly superior method of getting the plane to the ground that while not necessarily by the book, definitely doesn't end up breaking the plane like you did. While using an older version of DCS, as tested its still relevant to your requirements.

 

And this one I did without a wing

 

tl;dr: you're doing it wrong.

 

edit: On a side note, thankyou thankyou THANKYOU for fixing the landing gear clipping issue. Just fantastic that its finally fixed

Edited June 2, 2021 by EnvyC
Grammar

[rossmum]

2 hours ago, MiG21bisFishbedL said:

If you're down at 10%, you'd be at 290l and 4% you'd be engine out since that's probably out of usable fuel that the fuel pumps can move.

 

I am not sure exactly where the engine starves, but I do know it's less than 4%. For reasons.

[Ala13_ManOWar]

Well mates, do you all realize this is not what I was talking about, right? 

 

I'm not complaining the MiG-21 is hard to land, I know it is since 2014 and I like it that way, I know how to land, I know how to flare just inches above the ground, I know what a dynamic brake is, I know how to stop it in half the runway or less, etc, etc. All of that is not the problem or what I meant… But I guess it's harder to explain than it looks like.

 

I still think it might be either from the module, or the map perhaps. I was just sharing something really weird that happened once (TBH I've had no time to fly much more since that happened last week), and not only me but my squadmates either, had it been only once and only me, "bug" or not, I would have thought it was just a bad landing from me, period. I explained my experience wondering if anybody experienced the same and so I might know in the end what that behaviour could be, perhaps a punctual bug, or a map/airport bug. I didn't mean to start some kind of bashing on a module I really like, I from whom I already know quirks and problems, or a fight on how you're supposed to land the beast. I know that, I don't care that much right now about funny landing techniques we all have seen on YT, or whatever.

It's just, has somebody experienced that behaviour (not bad landings, I know when it's a bad landing of my own), but maybe at some concrete airport/map and not others or is it a change in the module (which apparently isn't)? Only that. Thanks.

 

S!

[randomTOTEN]

38 minutes ago, Ala13_ManOWar said:

Well mates, do you all realize this is not what I was talking about, right? 

We don't know what you're talking about because you didn't upload a track.

 

CoBlue might not like our analysis of his tracks, but at least he uploaded them. We can carefully examine each one, and take control of it and test it for ourselves. These tracks are worth about 5 million words each. People can hate them when they try to use it as a replay system, but for "seeing what you saw" they are fantastic. Much better than, "well it happened to me and all my buddies, why aren't you guys seeing it?"

 

Recreate it and upload it here. If you can't... well then that's valuable information too.

[Art-J]

I'd also like to remind, that after renaming track extensions from trk to miz they can be opened in the editor as mission files, so that one can check once and for all how much fuel CoBlue had on board during his tests.

[MiG21bisFishbedL]

36 minutes ago, Art-J said:

I'd also like to remind, that after renaming track extensions from trk to miz they can be opened in the editor as mission files, so that one can check once and for all how much fuel CoBlue had on board during his tests.

Thanks for that tip. Once again, replay tracks reveal a failing as he did have it at 10%.

[Ala13_ManOWar]

4 hours ago, randomTOTEN said:

We don't know what you're talking about because you didn't upload a track

 

As I told I don't know how to cut it, but please be my guest for a whole flight hour to the landing. I'm eagerly awaiting that flight analysis for any flight tips, not just landing ,

 

https://we.tl/t-MZNPKeZUBt

 

Now I think I hope it works, we use some minor mods sometimes in missions, but I didn't created this one and I don't know if there's any.

 

S!

[randomTOTEN]

43 minutes ago, Ala13_ManOWar said:

Now I think I hope it works, we use some minor mods sometimes in missions,

It fails to load because I miss the following mods: VPC Object by voc & Virpil.com Ala13 Pack

I do have VPC airfield equipment mod if that's what "VPC Object by voc" is, but I don't know if we have the same version. I don't know what "Virpil.com Ala13 Pack" is.

It's also possible that these mods are what was causing the problem for you and your squad mates (especially considering they were using the same mods). So that's another avenue of investigation.

 

Can you create a simple (and short) mission (with the mods disabled) and try to recreate it? That's really what I was asking for, and what CoBlue provided. That also gives you the chance to try and reproduce it on your end, before suspecting there's a bug with either the aircraft or map. Just some basic troubleshooting, you understand.

 

EDIT: I just realized, the two mods are probably correctly titled "VPC Object by voc & Virpil.com," and "Ala13 Pack." Considering your name is Ala13_ManOWar, this 2nd one is probably unique to your squadron.

Edited June 2, 2021 by randomTOTEN

[Ala13_ManOWar]

No, mods didn't cause the problem, those are just a few ground stuff but modules are unaltered.

 

Will try that, it's been a week and I couldn't even fly again .

 

BTW I'm trying to play the track and it's not very helpful, it's desynchronized from quite early and before I tried to fast forward. I was flying close formation with more people but we appear far away from each one. In the end (fast forward quite quick) i was going to land at sea instead of the airbase.

 

S!

Edited June 2, 2021 by Ala13_ManOWar

[randomTOTEN]

 

yeah that happens with long tracks,

meanwhile every other track posted in this thread (that I downloaded) works beautifully

 

6 minutes ago, Ala13_ManOWar said:

those are just a few ground stuff but modules are unaltered.

You don't know that. It's entirely possible that what sent you back bouncing into the air was a collision with some mod object on the airfield, that's probably nowhere close to your landing point.

Things like this are why tracks are useful.

Edited June 2, 2021 by randomTOTEN

[CoBlue]

16 hours ago, EnvyC said:

Quite simply you're forcing the plane to the ground, you're coming in far too steep and absolutely slamming it into the ground, not only that your stick control is all over the place. The plane when trimmed correctly and setup correctly (in advance rather than immediately in the mission 1min to touchdown) floats to the ground with minimal input. For reference I'm flying on a TMWH with no extension.

 

This is pilot error, not FM error.

tl;dr: you're doing it wrong.

No S##t Sherlock! maybe you don't know what deliberate means? Maybe you can show me how to land in a 50kt cross-wind?

 

Why y'all over-analyzing what was done before "over the threshold"? It's a fighter-jet not a 747 with "stable approach criteria". It's a fighter-jet, you get it down how the hell you feel like for test-purposes.

....it's what happens after touch-down when landing "hard", the bounce, that is unrealistic! Either the whole landing-gear should collapse & you could bounce a little, but not like a freaking football 10m up in the air!

 

Thanks for all the "landing" advice's but I had the 21 since release, & it's the module I have most hours in.....

 

1:st track, 21 landing in 50kt cross-wind with max turbulence. 2:nd short-field landing at heliport. Analyze this! or better, put up a track.

mig21 land 50kt 3 .trk mig21 land heliport .trk

Edited June 3, 2021 by CoBlue

[MiG21bisFishbedL]

33 minutes ago, CoBlue said:

No S##t Sherlock! maybe you don't know what deliberate means? Maybe you can show me how to land in a 50kt cross-wind?

 

Why y'all over-analyzing what was done before "over the threshold"? It's a fighter-jet not a 747 with "stable approach criteria". It's a fighter-jet, you get it down how the hell you feel like for test-purposes.

....it's what happens after touch-down when landing "hard", the bounce, that is unrealistic! Either the whole landing-gear should collapse & you could bounce a little, but not like a freaking football 10m up in the air!

 

Thanks for all the "landing" advice's but I had the 21 since release, & it's the module I have most hours in.....

 

1:st track, 21 landing in 50kt cross-wind with max turbulence. 2:nd short-field landing at heliport. Analyze this! or better, put up a track.

mig21 land 50kt 3 .trk 818.52 kB · 1 download mig21 land heliport .trk 618.45 kB · 1 download

 

There's no need to get hostile, I'm sure you're very cool in your squad that air-starts.

[rossmum]

11 hours ago, MiG21bisFishbedL said:

Thanks for that tip. Once again, replay tracks reveal a failing as he did have it at 10%.

 

Fuel gauge may not have been calibrated as he said it hasn't been doing that automatically for him on mission start/rearm (I haven't checked if this is an intentional change since the patch or not - some people have been complaining of this issue for months or years but I've never seen it - I've spent the past month testing the MiG-19 and then getting to grips with it in combat so haven't really done any 21 turnarounds to check for myself). I seem to recall in at least one of his tracks, the gauge was indicating >1000L but the empty lights were all on except service and possibly #3.

 

5 hours ago, CoBlue said:

No S##t Sherlock! maybe you don't know what deliberate means? Maybe you can show me how to land in a 50kt cross-wind?

 

Why y'all over-analyzing what was done before "over the threshold"? It's a fighter-jet not a 747 with "stable approach criteria". It's a fighter-jet, you get it down how the hell you feel like for test-purposes.

....it's what happens after touch-down when landing "hard", the bounce, that is unrealistic! Either the whole landing-gear should collapse & you could bounce a little, but not like a freaking football 10m up in the air!

 

Thanks for all the "landing" advice's but I had the 21 since release, & it's the module I have most hours in.....

 

1:st track, 21 landing in 50kt cross-wind with max turbulence. 2:nd short-field landing at heliport. Analyze this! or better, put up a track.

mig21 land 50kt 3 .trk 818.52 kB · 2 downloads mig21 land heliport .trk 618.45 kB · 2 downloads

 

 

Really good way to get people to stop bothering to read your posts, for what it's worth.

 

I wouldn't complain if the aircraft smashed the gear/blew its tyres/bent the wing spars/whatever off a hard landing versus bouncing like that, but the end result is more or less the same and I suspect the end result on the forums would be about the same, too, especially given the course of this thread. That or there'd be something else to lambast M3 about, I'm sure.

 

e/ Alright, I'm going to waste more of my time by attempting to be diplomatic here:

 

All you had to do was come into the thread, say something like "the suspension stiffness seems like it's producing an exaggerated bouncing behaviour, possibly unrealistically so, especially from heavy landings". That's it. Admittedly it looks like most of us missed the "deliberately hard" part of your post, but in any case, if you were the dev... which are you going to read, a post that is short and to the point, or a screed about how things are worse than ever, the MiG-21 is the only module that does this (it absolutely isn't, the MiG-29 has always done it, and far worse at that), coupled with a video claimed to show the plane doesn't bounce from a hard landing... which shows a very obvious, though less severe, bounce?

 

As for your latest tracks, we get it, you can land. If you really want to see me land on a <1km "airstrip" I can provide clips, or on roads, or on a bridge (until DCS despawned it underneath me on rollout), whatever. It's not going to further this thread and it isn't going to change anyone's mind about the suspension behaviour.

 

The biggest problem seems to be that the gear is perhaps more rigid than one would expect, so it doesn't collapse under crash force, or that the nose strut suspension is too springy, or both. The simple solution for those encountering this issue in the wild is just to work on landing technique, since not everyone can grease every landing like those of us with north of 1k hours on the module. If you come down hard enough to bounce fully back into the air you likely would've bent the airframe anyway, so take that as a "crash" until M3 can revise it (or indeed demonstrate it's intended behaviour, if it is.)

Edited June 3, 2021 by rossmum

[randomTOTEN]

10 hours ago, rossmum said:

The biggest problem seems to be that the gear is perhaps more rigid than one would expect, so it doesn't collapse under crash force,

I also agree this is likely the problem. For the MiG-29 too. These landings should probably overload the NLG to the point of failure, but as the gear doesn't fail, the physics simulation tries to process the overwhelming forces anyways, which results in the excessive spring back into the air.

[Maxthrust]

21 minutes ago, randomTOTEN said:

I also agree this is likely the problem. For the MiG-29 too. These landings should probably overload the NLG to the point of failure, but as the gear doesn't fail, the physics simulation tries to process the overwhelming forces anyways, which results in the excessive spring back into the air.

I bounced pretty bad on landing last night (pilot error) but the gear did not fall off. Not even a tire burst.. obviously the devs are sick of people complaining about blown tires and solved the issue for good.

[MiG21bisFishbedL]

21 minutes ago, Maxthrust said:

I bounced pretty bad on landing last night (pilot error) but the gear did not fall off. Not even a tire burst.. obviously the devs are sick of people complaining about blown tires and solved the issue for good.

It's the developer equivalent of carrying a tired child back to the car after a day at the amusement park. But, we actually did get Dairy Queen!

Also, I'm not sure how one'd measure the strength of NLG strut as I'd imagine most POH's would just give you a vague warning.

[Skysurfer]

There are limitations as to what DCS can and also should do. I'd rather have realistic taxi physics and the plane not sinking into the ground during turns instead of a tire burst model or gear strut collapse if I absolutely plant it. 

[EnvyC]

On 6/3/2021 at 3:12 PM, rossmum said:

 

That's it. Admittedly it looks like most of us missed the "deliberately hard" part of your post

 

>"I have to explain first I use a particular procedure I kind of invented for myself after watching some real MiG-21 videos, I come @400Km/H to the end and just chop the throttle at threshold and make a not so long and nice flare to let the aircraft set by itself on the ground"

 

He might have done it "deliberately" for the "test" purposes he posted with tracks buts its clearly a normal thing for him to do when flying the plane (hence the content of my response). Intentionally flying the plane wrong and then being surprised when the plane is fixed and it now has consequences for doing so is simply an irrelevant complaint.

Now if it was bouncing when one landed correctly then yeah it'd be suspect, but it turns out planes do bounce when you land hard, even WW2 birds and they definitely don't have as strong landing gear. Not to mention its an observable phenomenon in other flight sims. People generally wildly underestimate the resilience of landing gear, or take DCS at face value of what should be correct when it turns out it ain't.

 

 

This video clearly shows the front will bounce if you land too hard. By his own admission and description (unlike the video where the pilot is just slow) hes going fast enough to pitch the plane high enough on the front end bounce to get enough air over the wings again to get the plane back in the air.

 

The criticism is valid, fly the plane right the right things happen.