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Degraded Su-27 aerodynamic lift


Maverick Su-35S

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cft.jpg

 

CL should increase up to 40deg AoA.

 

Sorry I continue to talk about the Eagle, but I can't help it!

 

The fact that even this function of CL to AoA isn't copied as it is for our DCS F-15 is a problem. Even though I disagree that these are the real F-15's performances (too good to be true), they are still lower than what we see in game. During testing, the F-15 flies at 16000kgf at 27 AoA at 205km/h IAS, therefore the lift coefficient is 1.4. In that graph it should reach 1.4 at 33 degrees. So our plane turns even better than in that graph.

 

Regards!

When you can't prove something with words, let the maths do the talking.

I have an insatiable passion for helping simulated aircraft fly realistically!

Sincerely, your correct flight model simulation advisor!

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HWasp, I was able to match everything you said. At least in terms of Load-factor.

 

Check out the attachments below.

 

Conditions:

 

Standard day; 21,400 kg total, 3900 kg of fuel (41%). Average height 130 meters above the ground.

 

One thing; at 600km/h IAS I was able to reach 7G instead of 6G. I should have used Ground speed as reference :doh: :doh: I also forgot the fact that I can use infobar in the cockpit :D

FWIW, the V speeds given in the real world manual, unless otherwise specified, are IAS. They are referencing the УСМ-2 (airspeed/mach indicator on the front left panel). Like most people, I jump straight to the good parts. I just got around to looking at the Introduction a few minutes ago and noticed that was how they were defining it.

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FWIW, the V speeds given in the real world manual, unless otherwise specified, are IAS. They are referencing the УСМ-2 (airspeed/mach indicator on the front left panel). Like most people, I jump straight to the good parts. I just got around to looking at the Introduction a few minutes ago and noticed that was how they were defining it.

 

So that was actually correct? Using IAS?

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Yes, unless something is mentioned, all values are IAS from the УСМ-2.

 

And yes the MAX ALLOWED AoA is 24º.

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jackmckay said:
If its allready well known to ED then why it is so drasticly and obviously changed with each new update? How come module flight performance margin is not sealed from beginning?

 

 

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Exactly, because from what I feel, there is someone (higher rank) who wants to add a little extra to the Eagle without telling anything in the update info (it's a secret, right?), but I don't really get the reason..., that won't make the real Eagle's performance also rise, but it's just making DCS's reputation decay and it really hurts! The Eagle, without droops (which do increase the critical AoA, not as bbrz who thinks they don't) and without useful vortexes (which are created just by special surfaces) seems to roll so easily from one wing to the other (with rudder deflections held neutral by forced inputs) at AoAs above 25 (35 on indexer) like it's some supernatural creation that defies all aerodynamics laws, called DCS creations!

 

If you have the patience, do a test in DCS with the F-15, find the lift coefficient at each AoA from zero to 38, plot a curve of lift to AoA and guess what you find! That's right..., the most rudimentary lift to AoA function which is nothing but a curve (something that you get using 3D panels methods on CFD). That's how sophisticated the aerodynamic functions are actually in DCS. The simplest functions ever in a simulator we all believed in. No linear lift slope portions (although for a lower AoA range, but real), no stall onset curve. I don't even wanna know how the drag to AoA function looks like (which is far more complex than for lift)..., I don't want to hurt my eyes with that!

 

Regards!


Edited by Maverick Su-35S
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When you can't prove something with words, let the maths do the talking.

I have an insatiable passion for helping simulated aircraft fly realistically!

Sincerely, your correct flight model simulation advisor!

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Macerick gave good CL lift progression vs AoA. Im sorry I cant test anything now becouse DCS 2.5 eats my gtx760. Obviously not best time to buy gcard but have to. Regardless of CL, the drag is very important in linear acceleration and in turn as it bleeds speed directly. I did linear acceleration subsonic test from 650 to 1100kmh all modules AI simultaniously, all AB engined fleet, made power to weight progression charts, setup things and run.. A got a complete mess, planes with lower T/W ratio accelerated better than other with higher.. Egg. Viggen had linear acceleration up to vmax without ease out on peak as fastest plane there.. Mig21 was behind many even it has better T/W ratio than mirage that was second befind viggen... The problem is unreal drag calculation in basic linear acc test. Also IAS is onl relevant speed wind tunnel testing. Cd vs AaA is a must chart for flight model correction.

 

 

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For F-15 it is known that it gets heyvy buffeting at peak turn rate high AoA and pilots must ease out becouse of heavy vibrations also becouse it has no LE stats to keep laminar airflow on wing. That was MD's trade for speed to reach Foxbat, rember mach 2.5? So eagle shouldnt perform STR better than LE slatted planes.

 

 

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Maverick, with all due respect, I appreciate your knowledge about aerodynamics, and being technical is a good thing, but you were wrong about the Su-27 FM in DCS, it perfectly matches the real life charts. Are you sure about what you're saying regarding the Eagle performance in DCS? Saying Belsimtek (which developed the FM) added an extra performance for the Eagle on purpose is a bit too much. Just be careful with this kind of affirmation.

 

So eagle shouldnt perform STR better than LE slatted planes.

 

What's your source for this? Are you just guessing? Otherwise, that's not a valid argument; Saying the X shouldn't perform STR better than Y isn't helping. See, someone pulled up some charts from the manual and we checked it, they match each other.

 

Let's do that with the Eagle too. I'm aware that we don't have ITR charts though.


Edited by Vitormouraa
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Exactly, because from what I feel,

 

No one cares what you feel.

 

there is someone (higher rank) who wants to add a little extra to the Eagle without telling anything in the update info (it's a secret, right?),

 

Nope. And now you're on the verge of being ignored thanks to making up baseless conspiracy theories.

 

You then continue to fail by putting up airshow routines - guess what, airshow routines are quite strict regarding what you can and cannot do, and they don't demonstrate anywhere near all of the aircraft's capabilities.

No one cares about your personal determination of the eagle's CL given that real numbers are available from NASA, gathered by flying the aircraft. And now your credibility goes further down the drain by claiming that those numbers are somehow false. Even if you were to finally find an actual flaw in the FM, you now look like you're just on a witch hunt. :)


Edited by GGTharos

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Slight aside obviously but I have a gtx760ftw (4GB RAM) + 24GB RAM + SSD ... works ok aside from the occasional stutter. Just as a point of comparison.

 

Macerick gave good CL lift progression vs AoA. Im sorry I cant test anything now becouse DCS 2.5 eats my gtx760.

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Reminder: SAM = Speed Bump :D

I used to play flight sims like you, but then I took a slammer to the knee - Yoda

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No one cares what you feel.

 

 

 

Nope. And now you're on the verge of being ignored thanks to making up baseless conspiracy theories.

 

You then continue to fail by putting up airshow routines - guess what, airshow routines are quite strict regarding what you can and cannot do, and they don't demonstrate anywhere near all of the aircraft's capabilities.

No one cares about your personal determination of the eagle's CL given that real numbers are available from NASA, gathered by flying the aircraft. And now your credibility goes further down the drain by claiming that those numbers are somehow false. Even if you were to finally find an actual flaw in the FM, you now look like you're just on a witch hunt. :)

 

Amen!

 

From promising flight sim enthusiast to tinfoil hat wearer in one month, what a career...

 

I enjoyed the early Tests but now it's nothing more than pointless "who has the biggest... Russia vs US" Like all these stupid clickbait YouTube Videos.


Edited by FSKRipper
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Well, I may be too harsh. He knows his aero.

 

But the point is that all of this word salad is not worth much - 'but the f-16 ... ' no one cares.

'But the NASA data is fake' ... no it isn't.

 

NASA conducted their tests on a couple of F-15 test-beds. It is possible that these airframes are less representative of an F-15C as configured in-game, but that's something that we'd have to dig into. The fact is that a lot of this research was in fact used to improve the eagle's handling characteristics.

 

What needs to be done is simple: The chart's available, show it, plot the problem on it. Like the signature says, 'let the math speak for you', not the rest of this blah-blah.

 

After this, we can dig in and see if the data is simply not representative enough (what if you have a 30000lbs F-15A in this test? Highly unlikely, but you never know - the papers usually describe any such parameters and modification where necessary).

 

But NASA's eagle's, while modified, were no prototypes - aside from very obvious changes like the STOL demonstrator together with TVC nozzles, they were pretty much F-15's. Not-so-obvious changes relate to increasing engine thrust and changing the flight control programming/mechanization for their experiments. But those aside, it's still an F-15 with an F-15 fuselage, wings, and control surfaces.

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This is science guys. Maverick talks with better flight dynamics understanding than most guys here. But talking who's daddy is stronger(f15&su27) is way below descent conversation. Anyway its constructors achievement and not the one who are flying it. Airshow performance is competition, tough one, bigger balls kind alike so that means pushing performance margins. If plane sucks there, it will suck anywhere. DCS problem is still in equlity of laws of physics not applied to all becouse of different FMs and there story ends. Why modules dont have tryouts in a first place? @tharos my double chipped 2xgtx760 SLI 4GB is not fully supported aside from 6cored i7, 32GB, SSD and I get 20fps, only all low gets 40fps.. Ugly game then. Off topic.

 

 

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  • 4 months later...
... got a complete mess, planes with lower T/W ratio accelerated better than other with higher.. Egg. Viggen had linear acceleration up to vmax without ease out on peak as fastest plane there.. Mig21 was behind many even it has better T/W ratio than mirage that was second befind viggen... The problem is unreal drag calculation in basic linear acc test. Also IAS is only relevant speed wind tunnel testing. Cd vs AaA is a must chart for flight model correction.

 

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Spot on Jackmay, it seems that there are very few people around here to really and seriously understand flight dynamics and aerodynamics correctly and what is wrong with these simulations in DCS because very many misinterpreted this science and no one can easily better teach them now. They rather ban you and me and anyone else who contradicts them (ED devs) because you become a threat by trying to bring up what's true, but sooner or later people will realize the absurdities that develop right in the heart of a correct simulation.

 

Because they (ED first of all, being the masters) don't understand what's wrong and believe that what they did is correctly simulated, won't listen to someone like you or me or anyone else who comes with detailed and correct analysis due to many subconscious reasons such as ruining their image...!

 

But ED, may I ask you... who's fault is it because the simulation is wrong? Your customer's fault for finding and pointing out the mistakes in the simulation? You should be grateful that at least you can make it better, but no, you don't wanna listen because you think you already done it correctly, you put the hand before your eyes and no longer want to look into problems and just focus on new projects and leave the unfixed problems behind, some problems even staying in for good because for years they have been addressed and no one even budged to fix anything (ex: the A-10C's CCRP and LASTE problems that I addressed many years ago).

 

If I were to develop my own simulator and someone would point out at something he considers wrong, I would assess the problem and re-evaluate my knowledge, because who knows, maybe I need to learn some more, maybe there's something that I missed or didn't completely understand throughout my years of knowledge (we're all humans) and If I conclude that there might be some truth in what my customer says, although I may indeed feel a bit embarrassed, I WILL DO AGREE with him and try to solve the problem together, because in the essence what matters most to me is the accuracy of the simulation because this will affect my reputation on the long term, not by trying to protect my image and by denying the truth which only may help me on a short term! But from what I experienced so far regarding the F-15's aerodynamic performance (which is definitely way off track simulated in comparison to the real jet's aero performances), I no longer believe that this will be corrected, because I can see the replies I get towards my efforts to prove what's true from what's false. I have my answers and I feel very hopeless to think that ED will ever get accurate aerodynamic models and data estimations (because they use equations from what I heard and not necessarily real charts) which will correctly simulate the CP (center of pressure) travel with AoA and CL/CD polars (CL&CD vs AoA vs Mach).

 

 

Cheers!


Edited by Maverick Su-35S
missed prepositions

When you can't prove something with words, let the maths do the talking.

I have an insatiable passion for helping simulated aircraft fly realistically!

Sincerely, your correct flight model simulation advisor!

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But ED, may I ask you... who's fault is it because the simulation is wrong? Your customer's fault for finding and pointing out the mistakes in the simulation? You should be grateful that at least you can make it better, but no, you don't wanna listen because you think you already done it correctly, you put the hand before your eyes and no longer want to look into problems and just focus on new projects and leave the unfixed problems behind, some problems even staying in for good because for years they have been addressed and no one even budged to fix anything (ex: the A-10C's CCRP and LASTE problems that I addressed many years ago).

 

If I were to develop my own simulator and someone would point out at something he considers wrong, I would assess the problem and re-evaluate my knowledge, because who knows, maybe I need to learn some more, maybe there's something that I missed or didn't completely understand throughout my years of knowledge (we're all humans) and If I conclude that there might be some truth in what my customer says, although I may indeed feel a bit embarrassed, I WILL DO AGREE with him and try to solve the problem together, because in the essence what matters most to me is the accuracy of the simulation because this will affect my reputation on the long term, not by trying to protect my image and by denying the truth which only may help me on a short term! But from what I experienced so far regarding the F-15's aerodynamic performance (which is definitely way off track simulated in comparison to the real jet's aero performances), I no longer believe that this will be corrected, because I can see the replies I get towards my efforts to prove what's true from what's false. I have my answers and I feel very hopeless to think that ED will ever get accurate aerodynamic models and data estimations (because they use equations from what I heard and not necessarily real charts) which will correctly simulate the CP (center of pressure) travel with AoA and CL/CD polars (CL&CD vs AoA vs Mach).

 

 

Cheers!

 

Yo-Yo himself already said he is not going to change anything until you prove it's wrong, not based on common knowledge, youtube videos or friends (may or may not be the case here), but based on actual documentation, especially about the aircraft in the discussion.

 

From my understanding, you are trying to teach Eagle Dynamics on how to receive feedback from their customers and possibly fix what (supposedly) is wrong. But see, you are talking to a company that is developing flight simulators for almost 30 years, you are NOT talking to amateur people here on this forum.

 

The developers do know what they are doing, especially the FM engineers. They have a TON of experience. It wouldn't be fair for them to change their code or whatever they programmed because of a random person (not in the offensive way - just a random person on a forum) considers a specific item to be wrong.

 

So please stop using common knowledge and try to use real documentation and if possible make comparisons between X and X and not X and XZY. They don't want to know if slats give you X% of lift or drag so therefore this Y aircraft is supposed to turn better than X. That's not going to help anything since they are interested in seeing a solid proof of what's wrong with the FM (if there is something wrong - which is not the case here since what you were trying to say before was not correct).

 

Conclusion, ED devs do know what they are doing, and most of the time they are open to discussion about their work as long as you can provide enough documentation and/or images to prove your point. Seriously ED has been doing this for longer than you may imagine.

 

Also, let's try to not say things like "They rather ban you and me and anyone else who contradicts them (ED devs)" because that's far from being true. And THAT can get you banned.

 

Just my 2 cents.


Edited by Vitormouraa
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There are exactly two sources that are acceptable:

 

#1 Official documentation and performance charts

#2 Verifiable experience with the aircraft in question

 

 

 

Non-comprehensive list of unacceptable sourcea

 

#1 Feelings

#2 Napkin math

#3 Wikipedia or other random websites

#4 TV / YouTube documentaries

#5 Your friend

#6 Your buddy

#7 Your uncle

#8 Your friend's cousin's uncle

#9 ''Everybody knows''

#10 Other games

#11 The online degree you have in ''engineering''

#11 Etc

Де вороги, знайдуться козаки їх перемогти.

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Eh, you could lump that one into 'feelings' really. ''I feel this or that'' and ''I think this or that'' are pretty much the same thing, but yeah, I could have phrased it differently =)

Де вороги, знайдуться козаки їх перемогти.

5800x3d * 3090 * 64gb * Reverb G2

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