SU-27 and J-11 slower to regain airspeed after maneuvering..

[dundun92]

4 hours ago, bies said:

 

This are FC3 planes, there is lot of simplifications. Still i think they did some great job given they are low fidelity planes for extremally affordable price.

 

Consider just this one thing:

F-15 had been intentionally designed with requirement to have four semi-recess low-drag fuselage pylons, non-universal (they could carry AIM-7 missile only, and later AMRAAM) but they offered far lower drag increase when carrying a missile - semi-recessed inside the fuselage and within uniform fuselage aerodynamic boundary layer, this missiles had far smaller drag index, especially backward missile being additionally completely shielded by the forward missile.

 

 

(Other F-X competitors - North American and Fairchild shown below - also had to include similar solution)

 

 

In DCS if you put the missile i.e AIM-120 on semi-recess low drag fulelage pylon - it doesn't matter.

On forward (YELLOW) or even backward station (GREEN) AIM-120 still has full drag index exactly identical as AIM-120 on normal full drag under wing pylon (RED).

You can test by yourself.

 

What does it mean? If ED wanted to make F-15C close to real life chart with weapon they had to decrease clean aircraft drag to compensate for excesive weapon drag in semi-recess stations (4 big missiles) which are adding far more drag in DCS than they do IRL.

 

 

In full fidelity i.e. F/A-18C they are adressing such things and drag of the missile on semi-recess fuselage pylon is considerably smaller than under wing pylon. Similar situation with wing-end pylons.

Thay are still tuning this things, there are still some stations to include in different modules as i've noticed testing it from patch to patch but there is definitely work being done.

 

 

Im not nessecarilly doubting this, but have you tested vs the actual acceleration charts to see if the clean drag is actually too low, or it it just speculation (no offense intended here)?

[bies]

1 hour ago, dundun92 said:

Im not nessecarilly doubting this, but have you tested vs the actual acceleration charts to see if the clean drag is actually too low, or it it just speculation (no offense intended here)?

 

For full fidelity planes? Yes.

For F-15 or other FC3? No, not even once. I somehow gave up on FC3 when more full fidelity planes started to show.

(Despite personally I think FC3 reserved the sexiest planes and the best timeframe.)

 

When it comes to F-15 i just checked semi recess low drag fuselage pylons, they don't do anything, they are simply not modelled, (or were not modelled since I did this test in some of the previous patches, but i doubt ED would improve that) which discouraged me even more to continue any further measurements with F-15.

 

What i show can be treated just as a suggestion of starting point if someone would like to test the performance.

 

Full fidelity F-15A or C some day?

 

Cheers

Edited January 26, 2021 by bies

[Spurts]

19 hours ago, bies said:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I swear I've seen this before years ago

[stefasaki]

I ran a first acceleration test with the su-27 in DCS just to give some numbers on the current situation.

 

This test was run in standard DCS conditions (surely this is a higher temperature than the one in the video, but the purpose of this test was to show the order of magnitude of the discrepancy we currently have) with a lightly fueled Su-27  (which would obviously be lighter than the su-30mk2 in the video).

 

The altitude was 3200 m and all the speeds are indicated airspeeds in km/h, times are in seconds:

 

                                            600-1100                          1100-1300

 

Su-30mk2 (IRL)                   21~22                                  18~19 

 

Su-27 (DCS)                          32                                         70

 

 

The results show clearly that this difference in acceleration cannot be attributed to differences in ambient conditions/airframe but that a modeling error is evidently present.

 

The current difference in acceleration that we have between real life and DCS in the 1100-1300 km/h range is comparable to difference that lies between a Formula 1 car and a sedan car (in the 0-100). That's why I think that a rework would be nice, this is not some minor modeling error.

Edited January 27, 2021 by stefasaki
Typo

[bies]

• On this video from 600km/h to 1100km/h pilot is unloading the plane losing ~400 meters of altitude from ~3300m to ~2900m. He is not flying straight.
• What is more he started acceleration at 430km/h at 3400m, already losing 100m, not from 600km/h - having already significant inertia and spooled up engines way below 600km/h.
• So to compare anything we would have to measure acceleration from 430km/h at ~3400m to 1100km/h at ~2900m.

 

---------------------------------------------EDIT ------------------------------------------------------

 

I have read the whole topic and not taking any position one thing immediately catches the eye:

 

If the acceleration of the Su-27 in the sim is going to depends on our, simple users "opinions" based on "looking at some YT videos" with different planes, in unknown conditions...

What amount of fuel the plane from the video has? What is the temperature and pressure? What are his engine power settings? Is his plane clean?

 

It shows how guestimated the whole flight model of this plane is. It means one: data for even for 1980s Su-27S publically available are close to non existent unfortunatelly.

Because ED for sure did everything they could to obtain the data they could get.

 

Seting aircraft parameters in simulation with professional flight model by us, random guys looking on some random YT videos ... It's cheap.

Where are EM charts for Su-27? Where are acceleration tables? Where are engine power curves? Unfortunately classified apparently.

 

Anyway i hope for full fidelity Su-27S from 1980s after MiG-29 9.12.

Edited January 28, 2021 by bies

[Ironhand]

Umm...this just occurred to me. Isn’t the engine mode switch in the sim’s cockpit set to “Combat Training” (up position) rather than “Combat” (down position)? Is the reduced power setting what is being modeled? Unfortunately I’m not in a position to check the switch position myself right now. Don’t remember how much the difference between the two settings is.

Edited January 28, 2021 by Ironhand

[stefasaki]

31 minutes ago, bies said:

• On this video from 600km/h to 1100km/h pilot is unloading the plane losing ~400 meters of altitude from ~3300m to ~2900m. He is not flying straight.
• What is more he started acceleration at 430km/h at 3400m, already losing 100m, not from 600km/h - having already significant inertia and spooled up engines way below 600km/h.
• So to compare anything we would have to measure acceleration from 430km/h at ~3400m to 1100km/h at ~2900m.

 

---------------------------------------------EDIT ------------------------------------------------------

 

I have read the whole topic and not taking any position one thing immediately catches the eye:

 

If the acceleration of the Su-27 in the sim is going to depends on our, simple users "opinions" based on "looking at some YT videos" with different planes, in unknown conditions...

What amount of fuel the plane from the video has? What is the temperature and pressure? What are his engine power settings? Is his plane clean?

 

It shows how guestimated the whole flight model of this plane is. It means one: data for even for 1980s Su-27S publically available are close to non existent unfortunatelly.

Because ED for sure did everything they could to obtain the data they could get.

 

Seting aircraft parameters in simulation with professional flight model by us, random guys looking on some random YT videos ... It's cheap.

Where are EM charts for Su-27? Where are acceleration tables? Where are engine power curves? Unfortunately classified apparently.

 

Anyway i hope for full fidelity Su-27S from 1980s after MiG-29 9.12.

 

The aircraft in the video is pointing down slightly in the first part, but it points upwards in the 1100-1300 range, and that's where we have the biggest difference. It never actually goes to 2900m, what you see there is a typical dip in the altimeter reading across Mach 1, it's a known thing. You should just check the vertical speed indicator. Of course that video cannot be taken as reference for further modeling, it is merely there to show that the current su-27 in DCS is, in fact, wrong.

 

Also I don't get your statement about the 430 km/h thing.... I just chose to measure the 600-1100 and 1100-1300 segments.... it's just a choice, we are also sure that the engines are fully spooled up at 600 km/h in this case

Edited January 28, 2021 by stefasaki

[GGTharos]

50 minutes ago, bies said:

If the acceleration of the Su-27 in the sim is going to depends on our, simple users "opinions" based on "looking at some YT videos" with different planes, in unknown conditions...

What amount of fuel the plane from the video has? What is the temperature and pressure? What are his engine power settings? Is his plane clean?

 

So you did take a position.  The acceleration does not and will not depend on looking at some YT videos.  The acceleration discrepancy is so insanely huge that the video points to something that should be investigated.  None of your questions matter at all.  This Su-30 is heavier and draggier than the Su-27, and uses the same engines.  It accelerates in 1/3rd of the time that our DCS Su-27 does in the transsonic area, at the lightest, least possible draggy configuration in DCS.

 

50 minutes ago, bies said:

It shows how guestimated the whole flight model of this plane is. It means one: data for even for 1980s Su-27S publically available are close to non existent unfortunatelly.

Because ED for sure did everything they could to obtain the data they could get.

 

FM errors simply happen, even if you have the best data.  The data problem is  data problem, the FM error is an FM error.  You're taking a position and judging  'people watching YT videos', and preaching from ignorance.

[Ironhand]

44 minutes ago, Ironhand said:

Umm...this just occurred to me. Isn’t the engine mode switch in the sim’s cockpit set to “Combat Training” (up position) rather than “Combat” (down position)? Is the reduced power setting what is being modeled? Unfortunately I’m not in a position to check the switch position myself right now. Don’t remember how much the difference between the two settings is.

 

Nevermind. My memory sucks. It's in the "Combat" position:

 

[bies]

IF what you said is true, especially

4 minutes ago, GGTharos said:

The acceleration discrepancy is so insanely huge

it means that the whole flight model is "so insanely" far from truth since everything is interconnected in FM.

 

And if it is, it means there is no data. Since i trust ED would do everything they can to obtain the data If they would be available.

 

 

 

IDK if you're right or wrong, but if you are right it means ED doesn't have access even to the absolutely most basic documentation like acceleration table making Su-27 FM. And this tells something about the whole Su-27 FM. It looks like even 1980s Su-27 is still classified.

[GGTharos]

3 minutes ago, bies said:

IF what you said is true, especially

it means that the whole flight model is "so insanely" far from truth since everything is interconnected in FM.

 

No, it does not.  It's not the first time that a specific region of an FM has a problem and the rest is fine.   It can be as simple as the drag coefficients being too high in the transsonic region.

 

3 minutes ago, bies said:

IDK if you're right or wrong, but if you are right it means ED doesn't have access even to the absolutely most basic documentation like acceleration table making Su-27 FM. And this tells something about the whole Su-27 FM. It looks like even 1980s Su-27 is still classified.

 

ED has access to information that we'll not be getting our hands on.  Whether this part of the FM slipped through testing or someone accidentally changed it later, this stuff happens and your assumptions as to the rest are not based on anything solid.

[bies]

Su-27S from 1980s would be my single No.1 the most wanted module possible, but as long as ED will not announce full fidelity one i assume the data are impossible to obtain or use in a publicly available software.

 

As long as it's just FC3 i withdraw from this discussion.

Have a nice day.

[dundun92]

Just now, bies said:

Su-27S from 1980s would be my single No.1 the most wanted module possible, but as long as ED will not announce full fidelity one i assume the data are impossible to obtain or use in a publicly available software.

 

As long as it's just FC3 i withdraw from this discussion.

Have a nice day.

They stated a few years back (like 2012 or smth?) that they had the docs for a FF Flanker, its not the issue here. Its legal issues, as have been the problem for ED from the start

[GGTharos]

5 minutes ago, bies said:

Su-27S from 1980s would be my single No.1 the most wanted module possible, but as long as ED will not announce full fidelity one i assume the data are impossible to obtain or use in a publicly available software.

 

You assume wrong.

[BBCRF]

)

Edited January 29, 2021 by BBCRF

[TaxDollarsAtWork]

Interesting how ED has yet to acknowledge this

Maybe @Yo-Yo can enlighten us on why the Su-27 is behaving like this in game.

1 hour ago, BBCRF said:

Я же написал с 1100 до 1300 км/ч разгон должен быть 11.8 с

A while ago if I'm not mistaken you mentioned the Su-27 was heavier than it should be in game, by how much exactly?

[GGTharos]

They have, BIGNEWY said they'll investigate.

Edited January 28, 2021 by GGTharos

[BBCRF]

17 hours ago, TaxDollarsAtWork said:

Интересно, как ЭД еще не признал этого

Может быть @Йоу йоу может объяснить нам, почему Су-27 ведет себя так в игре.

Некоторое время назад, если я не ошибаюсь, вы упомянули, что Су-27 тяжелее, чем должен быть в игре, на сколько именно?

350-450кг

[stefasaki]

@BBCRF

I just checked the 1100-1300 (true airspeed, km/h) acceleration at 2000 m of altitude and the su-27 in DCS needs about 12 seconds with a total weight of 20000 kg. However, the su-30mk2 in the video needs about 9~10 seconds to do the same (940 to 1110 indicated airspeed, assuming standard day) at over 3000 m of altitude. Are you sure that your value was for true airspeed and not for indicated airspeed?

 

Anyway, a 20% improvement in acceleration is typical for low temperatures, that could explain the discrepancy between the video and your data, what isn't explained is the enormous difference in the 1100-1300 range (indicated airspeed), suggesting that the biggest modeling error is in the drag coefficient at Mach 1.1-1.3

Edited January 29, 2021 by stefasaki

[Exorcet]

On 1/26/2021 at 5:40 PM, bies said:

 

For F-15 or other FC3? No, not even once. I somehow gave up on FC3 when more full fidelity planes started to show.

 

Full fidelity F-15A or C some day?

 

Cheers

 

Just to add to this, I haven't compared the F-15 to charts, but I have compared it to other DCS aircraft. It's actually the slowest in transonic acceleration of all the teen series besides the F-18 (though I think the F-14 has been adjusted since my tests, and I don't know if it went up or down). If the drag is undervalued, it's curious that it would be at the slow end.

 

I tend to think the FC3 aircraft suffer from being earlier products in a product line that was intentionally not at full DCS module level. I'd definitely love to see them all brought to full fidelity and have their flight models reviewed and revised in the process.

[Seaeagle]

28 minutes ago, Exorcet said:

I tend to think the FC3 aircraft suffer from being earlier products in a product line that was intentionally not at full DCS module level. I'd definitely love to see them all brought to full fidelity and have their flight models reviewed and revised in the process.

How so? - the FC3 aircraft only got their PFM within the last couple of years, which completely replaced the old SFMs.

[bies]

35 minutes ago, Exorcet said:

I'd definitely love to see them all brought to full fidelity

I hope MiG-29 9.12 will pave the way since FC3 has all the greatest fighters.

 

My heart, like John Boyd's, bleed seeing "ultimate dogfighter" F-16 in late, overweight ground attack variant, or F-15 once "not a single pound for air to ground" being modeled as full fidelity only in ground attack variant.

[Exorcet]

14 minutes ago, Seaeagle said:

How so? - the FC3 aircraft only got their PFM within the last couple of years, which completely replaced the old SFMs.

The FC3 PFM's (specifically the F-15 (2014?) and then Su-27 (2016?)) were the first supersonic PFM's. ED have probably improved their modeling process since then, and I think it's reasonable to think that FC3 FM's were not researched as much as full DCS module FM's (but someone from ED correct me if I'm wrong).

 

If that's true, it might explain why the F-15/Su-27 are at a disadvantage compared to the F-14/F-16 (the F-18 being such a slow outlier, as long as any wing pylons are loaded).

 

  

6 minutes ago, bies said:

I hope MiG-29 9.12 will pave the way since FC3 has all the greatest fighters.

 

My heart, like John Boyd's, bleed seeing "ultimate dogfighter" F-16 in late, overweight ground attack variant, or F-15 once "not a single pound for air to ground" being modeled as full fidelity only in ground attack variant.

Definitely. There are so many great aircraft and then so many great variants to model, it's a shame it takes so long to craft them into modules, so we can't just get them all.

Edited January 29, 2021 by Exorcet

[BBCRF]

1 hour ago, stefasaki said:

@BBCRF

Я только что проверил ускорение 1100-1300 (истинная скорость, км / ч) на высоте 2000 м, а Су-27 в DCS требуется около 12 секунд при общей массе 20000 кг. Однако Су-30МК2 на видео требуется около 9–10 секунд, чтобы сделать то же самое (указанная скорость полета от 940 до 1110, исходя из стандартных суток) на высоте более 3000 м. Вы уверены, что вы указали истинную воздушную скорость, а не указанную?

 

В любом случае, улучшение ускорения на 20% типично для низких температур, что может объяснить несоответствие между видео и вашими данными, но не объясняется огромная разница в диапазоне 1100-1300 (указанная воздушная скорость), предполагая, что наибольшая погрешность моделирования заключается в коэффициенте лобового сопротивления на уровне 1,1-1,3 Маха.

 

в эти 20тонн еще входят 2 Р-27 под фюзеляжем и 2 Р-73 на законцовках

[stefasaki]

11 minutes ago, BBCRF said:

в эти 20тонн еще входят 2 Р-27 под фюзеляжем и 2 Р-73 на законцовках

I did that test with a clean aircraft, meaning that a slighly better result was expected. 

 

What we really would need is an official acceleration chart...

Edited January 29, 2021 by stefasaki