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reverse ground effect


bbrz

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Anyone else noted that the MiG-29 suffers from the same 'reverse' ground effect like the F/A-18?

It's not as noticable as in the F/A-18 because the MiG-29 is rather pitch sensitive.

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I did notice it, was really annoying, but seems like it is gone in the latest open beta! :)

 

 

Edit: Seems like it is gone from the Hornet as well, so that might be connected.


Edited by HWasp
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  • 1 month later...
Anyone else noted that the MiG-29 suffers from the same 'reverse' ground effect like the F/A-18?

It's not as noticable as in the F/A-18 because the MiG-29 is rather pitch sensitive.

 

Erm ... what exactly do you mean with 'reverse' ground effect?

 

I have experienced the following yesterday:

A sudden drop to the runway from a few meters above at (+/-) constant airspeed, but I expected a smoothing of the flare due to the ground effect.

 

Is it that what you are meaning?

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Reversed ground effect as in it will suck you down instead of "push" you up.

 

 

ok, then I got BBRZ it right, thanks!


Edited by TOViper
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There was a thread a little while ago where it was shown that certain planes with low tail planes pitch down in ground effect. This happens with the Hornet also

Mentioned here https://forums.eagle.ru/showthread.php?t=243913


Edited by AeriaGloria

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  • 3 months later...
So has anyone found a logical explanation to the seemingly reverse ground effect for the Mig-29, or is it a bug?

No explanation but the manual, concerning what is done just prior to touching down following normal proceedures, does say that: "The movement of the control stick in the process of leveling is significant: from neutral to almost completely 'into yourself'." So it sounds like you are definitely counteracting something at that point. You certainly don't need to be that aggressive in the Su-27, for instance.

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  • 9 months later...

 

Here is opinion of real pilot of Mig-29. Short resume - "nose lowering effect exists in theory, but on practice pilots don't feel it. And he says than real Mig-29 very easy to landing. Even easer than L-39"

 

Еще раз про пикирующий момент . Никакого пикирующего момента на посадке из-за дополнительного приращения подъемной силы на реальном самолете МиГ-29 не ощущается. Нет никакой ступени, где он бы вдруг бы появлялся. Он есть в теории, а в практике он теряется в обычном взятии ручки по мере приближения к земле. Прямое копирование аэродинамики в модель не дает реальной картины . Мне кажется что тут надо что то интерполировать в сторону уменьшения влияния этого эффекта. Но это дела программистов.

И про « жопамер « . Это конечно очень полезный и нужный датчик на мягком месте пилота, но не нужно преувеличивать его роль на некоторых этапах полета. В частности на посадке. Если на пилотаже или воздушном бою мы без него вообще обойтись не можем, то при полетах по приборам в облаках этот орган-датчик только мешает. А на посадке полезные функции «жопомера» проявляются только с опытом , когда ты реально начинаешь чувствовать буквально сантиметровые изменения положения самолета в пространстве и ускорения жопой . Но и то не у всех. Все молодые пилоты , а некоторые уже и не молодые пилоты всю жизнь сажают самолет , так сказать глазами и руками , как в симуляторе , исключив этот орган :) и ничего, живы и здоровы . Так что перенос летных навыков на посадке с самолета на симулятор происходит абсолютно без потери их качества .

 

Да я уже писал , что в процессе посадки нет никакого ступенчатого провала РУС . Расход рус равномерный в процессе всей посадки и зависит только от темпа приближения к земле и падения скорости . Экран никакого эффекта не оказывает и никакого экстрорасхода по взятию рус не возникает . Вернее экранный эффект может проявиться как частный случай при соблюдении некоторых условий , но проявляется это совсем не так как некоторые его представляют , а как раз наоборот . Происходит так называемое «вспухание « самолета , без взмывания на высоте 10-15 см , ощущается это по кажущемуся поднятию задницы самолета , то есть действительно появляется небольшой пикирующий момент , но при этом уменьшения подъемной силы не происходит ( что не противоречит и ПА 8.3) а как раз наоборот, самолет не хочет садится и приходится ослабевать тянущие усилия на рус или даже немного отдавать ее от себя , с последующим взятием по мере приближения к земле . Но это , еще раз повторюсь , частный случай и возникает он далеко не всегда , поэтому его можно просто disregard.

МиГ-29 ооооочень просто себя ведет и при снижении по глиссаде и при выполнении посадки , очень устойчив и не имеет никаких тенденций к раскачке и резких изменений продольных моментов . При определенных навыках можно идти по глиссаде используя один триммер по тангажу . После опускания передней стойки , оторвать ее от впп будет уже практически не возможно если двигатели на МГ . На посадке самолет проще чем учебный Л-39.

 

Опять все заново который раз))))) . Если честно то я использую только одну функцию модуля любимого самолета - красивые обои МиГ-29((((. И каждый раз пытаясь на нем полетать ощущаю разочарование и опять откладываю в долгий ящик. Потому что не может быть так , что на самолёте на котором ты отлетал кучу лет было летать тяжелее чем на куче других самолетов на которых ты не летал и даже не знал заданных параметров захода на посадку. Тем не менее есть элементарные методики их определения и после пары минут любой самолет элементарно сажается . Тут же зная все до мелочей происходит постоянная борьба с самолетом особенно на этапах захода и посадки . Конечно , его можно посадить и нормально и почти отлично и это иногда получается, но это не тот самолет и он заставляет напрячься чтобы более менее хорошо это сделать. Если бы так было в жизни , я думаю , не досчитался бы многих своих товарищей и не уверен что выжил бы сам :) Еще раз поторюсь, реальный МиГ можно сажать ковыряясь одним пальцем в носу . Вся молодежь после училища вылетала на нем самостоятельно без всяких проблем. На моей памяти только у одного летехи были серьезные трудности из за которых его и списали. Даже Airbus , на котором я летаю сейчас с его fly by wire несколько сложнее на заходе и посадке МиГа .

В общем то модуль для упрощенного варианта не плохой, но посадочные режимы конечно не соответствуют прототипу. Видать поведение математической модели отличается от физической при точном копировании графиков из учебников . Что конкретно отличается тут уже много раз обсудили .

Что касается видео , то тут ничего удивительного , за мгновение до касания , когда самолет уже почти не летит , иногда хочется его еще мягче досадить поддернув РУС, но тут скорость уже настолько мала, что как правило это уже ни к чему не приводит, кроме морального удовлетворения, а самолет сам тем временем плавно касается обжимая амортизаторы . А чтобы РУС не упирался в живот надо от него избавляться :) ( от живота) .

По сравнению с Л-39 наш 29-й не имеет тенденцию к взмыванию , в то же время приличный запас тяги и бешенная приёмистость сильно облегчают заход и посадку .

 

 

Other real pilot of Mig-29 says opinion than FM of Mig-29 don't match of real Mig...

 

Насколько я успел полетать на нем, модель еще очень сырая.

По физике, это "чужой" самолет.

 

Если сравнить знакомые мне модели в DCS, то ближе всего к реальности 9-13 да и 9-12, будет располагаться физика F/A-18, кроме взлета и посадки.

 

Из советов.

Я считаю, надо просто каким-то образом реализовать работу АРУ. И многие вопросы снимутся.

  • Like 1

"Своя FM не пахнет" (С) me
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Thanks for collecting and sharing!!

 

Even if Google Translate did a job on the text, and my weakness not speaking Russian language, I still have the impression that some movement in the last few meters above the runway (talking about the DCS model) seems (feels) exaggerated, despite I have no problems at all to land this thing smoothly (event with the A-10 Warthog stick, which is NOT the best choice for the MiG-29).

 

 

Edit: I will try to produce one track this evening ...


Edited by TOViper

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  • ED Team

If you think there is a problem add a short track replay showing the problem and we will take a look.

 

thanks

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If you think there is a problem add a short track replay showing the problem and we will take a look.

 

thanks

Hello BIGNEWY! I'am posting video with this effect many times

 

1) Like amazing magnet effect of deck

 

2) Balanced Stick and Stab position depend if speed and altitude

 

and many other records, but ED FM enginer (unlike of real pilots) don't see problem in this

"Своя FM не пахнет" (С) me
https://dcs.silver.ru/ DCS World Sustained Turn Test Data

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  • ED Team

Video is nice,

 

what we really need is a track replay,

 

I am not a flight model dev so I wont know the answers, for a report to be made I need to see a track replay. I know Yo-Yo is posting in another thread, he is the best dev to know about this subject.

 

thanks


Edited by BIGNEWY

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Hello BIGNEWY! I'am posting video with this effect many times

1) Like amazing magnet effect of deck

2) Balanced Stick and Stab position depend if speed and altitude

and many other records, but ED FM enginer (unlike of real pilots) don't see problem in this

Correct due to reduced taileron effectivness near ground - already answered in another thread:

https://forums.eagle.ru/showthread.php?t=285324

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1) Like amazing magnet effect of deck

 

2) Balanced Stick and Stab position depend if speed and altitude

1) The pitch down (I don't see any magnet effect) is consistent with the stabilator entering the ground effect of the carrier deck.

 

2) Don't see any problem here either. Just watch this RW video and how much back stick the pilot is adding during the final stage of the flare, without a significant pitch change .

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I did a quick test.

From what I can see the aircraft is still "far" away from ground, and the descent rate starts to increase without changes on elevator or airspeed.

You may all have your ideas for this issue, but I still think that the aircraft is somehow sucked to ground, but in a exaggerated manner. Maybe, it is just because the effect (the maths for ground effect) start just a little too high above ground ... I don't know.

What can be seen is that the pitch angle decreases short before reaching the threshold, and airspeed remains more or less constant. So the programmers made a good job.

 

I think I will "close" my thinking about this story, and the MiG-29 completely, because there is one much more apparent issue that makes my life hard with the module, and that is PITCH TRIM. The trim rate per click is far to high for me. I would fly the module more when ED eventually creates a special option for PITCH TRIM to set the rate by hand. This is to help people like me who use out-of-the-box sticks. Yeah yeah, I know, now the MiG-29 "understanders" will for sure come over me saying:

"You cannot fly a MiG-29 without stick extension!" :tomato:

Yeah, I understand. Thank you. I can live with a short one, because I have the F-16 :D

 

Ah, here is the TRK:

2020-09-11_MiG-29_sucked_into_ground.trk


Edited by TOViper
  • Like 1

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I did a quick test.

From what I can see the aircraft is still "far" away from ground, and the descent rate starts to increase without changes on elevator or airspeed.

You may all have your ideas for this issue, but I still think that the aircraft is somehow sucked to ground, but in a exaggerated manner. Maybe, it is just because the effect (the maths for ground effect) start just a little too high above ground ... I don't know.

What can be seen is that the pitch angle decreases short before reaching the threshold, and airspeed remains more or less constant. So the programmers made a good job.

 

I think I will "close" my thinking about this story, and the MiG-29 completely, because there is one much more apparent issue that makes my life hard with the module, and that is PITCH TRIM. The trim rate per click is far to high for me. I would fly the module more when ED eventually creates a special option for PITCH TRIM to set the rate by hand. This is to help people like me who use out-of-the-box sticks. Yeah yeah, I know, now the MiG-29 "understanders" will for sure come over me saying:

"You cannot fly a MiG-29 without stick extension!" :tomato:

Yeah, I understand. Thank you. I can live with a short one, because I have the F-16 :D

 

Ah, here is the TRK:

[ATTACH]247232[/ATTACH]

 

Yeah, it's futile to convince the devs and some of their followers, no matter what RL pilot inputs you come up with. To some extent it's understandable that devs defend their creation, their "baby". It was the same with another MiG and a chopper named after an animal living the steppes of Africa. With the older MiG model it was funny to see how many significant flight model changes it saw when everytime the devs said it was realistic before :smilewink:

 

Let's just hope that when ED does the full-scale MiG-29A module, other devs work on the project and get it right this time.

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2) Don't see any problem here either. Just watch this RW video and how much back stick the pilot is adding during the final stage of the flare, without a significant pitch change .

 

Also see how large the stick inputs are without any resulting oscillations and how smoothly the pilot can put the aircraft on the ground, how tamely it follows his inputs. Just like any aircraft should do (with or without dampers, FCS or whatever).

 

And again: If elevator effectiveness was reduced during lfare, we might see a nose-down movement that the pilot would counter with more aft stick. Our DCS MiG-29 however doesn't pitch down, it loses lift. And that's even at light weights at around 300 km/h, which is around 160kts, which sounds very high for an aircraft like a MiG-29 with supreme lift-creating wings and fuselage.

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Our DCS MiG-29 however doesn't pitch down, it loses lift.

Looks like we have to agree that we disagree. I definitely see a pitch down and no loss of lift.

Just watch the carrier groundeffect video. At 0:43 you can see the pitch attitude decreasing as the tailerons enter the ground effect.

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  • ED Team
Also see how large the stick inputs are without any resulting oscillations and how smoothly the pilot can put the aircraft on the ground, how tamely it follows his inputs. Just like any aircraft should do (with or without dampers, FCS or whatever).

 

And again: If elevator effectiveness was reduced during lfare, we might see a nose-down movement that the pilot would counter with more aft stick. Our DCS MiG-29 however doesn't pitch down, it loses lift. And that's even at light weights at around 300 km/h, which is around 160kts, which sounds very high for an aircraft like a MiG-29 with supreme lift-creating wings and fuselage.

 

In your track is clearly seen that you lost several degrees of AoA. If you counteract this tendency and hold the AoA pulling the stick there will be no lift lost.

By the way, we conducted a full CFD study to be sure that the effect presents in RL and we got the same results as the manual states. This CFD report is available in Russian.

MiG-29 pilots are tought to pull the stick at flaring, and they just counteract the tendency of reducing G due to reducing AoA IGE. So, it's absolutely intuitive for them. And, finally, several RL MiG-29 pilots have no trouble to land MiG-29 in DCS.


Edited by Yo-Yo

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

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Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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In your track is clearly seen that you lost several degrees of AoA. If you counteract this tendency and hold the AoA pulling the stick there will be no lift lost.

By the way, we conducted a full CFD study to be sure that the effect presents in RL and we got the same results as the manual states. This CFD report is available in Russian.

MiG-29 pilots are tought to pull the stick at flaring, and they just counteract the tendency of reducing G due to reducing AoA IGE. So, it's absolutely intuitive for them. And, finally, several RL MiG-29 pilots have no trouble to land MiG-20 in DCS.

 

It's not my track, sb else provided it, so I'm not sure what you are referring to.

 

I can land the MiG-29 without "problems" too, but it doesn't feel right here and there, and every now and then something breaks where I think it shouldn't. I'll try to provide some tracks too to prove my case, knowing it won't change anything. It's ok, it's your baby, I get it.

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