Maverick Su-35S

It's good being back to useful conversations. Thank you Darkfire! So, if that plane's version should have similar performances to the Su-27's version in DCS, that acceleration would relate to almost 1G, better said 0.9432Gs along the X axis as an average acceleration between those 2 speed ranges at that altitude. By simple math: 18,920kg * 9.25 / 9.80665 = 17846 kgf or 39350 lbf is the resultant total propulsive force (Thrust - Drag), which turns out that the plane you've talked about accelerates relative to a total propulsive force of about 71.4% of 27560lbf (which is the manufacturer's max thrust rating). But that also includes the drag. If the drag would be eliminated, it's logic that the resultant thrust per engine would be greater than 71.4%. How much? Depends on drag! Eliminating the drag (which is relatively high at those speeds) in the given example, the Thrust / Weight ratio will certainly go above 1, resulting in higher engine thrust than we can see with DCS Su-27. So how bad can the AL-31 actually be then? Let's leave it to the devs for an answer.

Maybe it's already lost, who knows..., it's not up to me to be understood anymore and I don't even care anymore! I feel like I've done my duty to point out what's wrong here and there inside out and yes..., I will have my rights revoked again for telling the truth in a mix of "losing the filter" and through arguments which seem to attack those who have the power to rule this forum (moderators, devs, etc.) regardless of what's actually true. How would you personally feel about having a fist put to your mouth and being made look like s$it after all that you worked on to point out (with good intentions, in this case for DCS) which eventually is not just disrespected, but also modified to turn you into a foul, by lying about the facts or hiding the truth about those facts. Changing a thread's name to: "NO BUG", just by brute force, by someone who has it, without any real proof and/or agreement with the one who initially created that thread, again with the purpose of discussion and truth emerge, but only with a few people who anyway are on the same side with those who control it all, is what creates the big and not funny picture (yes, not funny at all) about DCS...! I've got what's it all about and why I'm seeing the replies that I usually see (very rarely I see someone who shares my opinion and looks for hard evidence) and why threads names that regard simulation are modified into the well known and wonderful "NO BUG". It's all about money! Some may laugh, yet some may not...! I am pro DCS, but I am against this mockery here and the great disrespect which is oriented to otherwise loyal clients...! I know, the perspectives of what I say are shared, some are with me some are very infuriated, but I'm not the problem..., the problem actually is the problem and it's getting bigger by ignoring it.

Well, I felt I had to "considering the company here, eh?" -from Top Gun- Joking! Smartness and foolishness are relative to some reference! If you move the reference, you can have both ends of the domain lie in the same bucket, but the difference remains unchanged. I may have a great personal habit of making my statements look or become complicated that the message addressed is blurred or creates confusion (at least this is what I believe it happens to those not understanding what I say, but I sometimes truly start to believe that no matter how much I try to simplify, it's still too much to be comprehended, so instead of losing it I'd rather try joking, nothing more.

Look...! I feel sorry now for that arrogant reply there, but I just don't know to stimulate the thinking of some people here and that one wasn't addressed to you, it was my way of discharging my anger to see how badly understood a relatively (as I see it) easy test is. I wonder...! If I would've used my second method (but I forgot to try it and it's a much easier method for me) to determine the maximum engine output thrust which uses F=m*a (Newton's second law) form the start, perhaps everything would've been clearly understood, but now I wonder if anything out of it would've been understood at all if even the simplest test was interpreted in the way the earlier replies prove! You seem to be among the few around here to try and test what every "stupid" like myself talks about. Really..., I respect you and don't consider you a farmer, yet even if you might be, you're a lot better than most "wanna know aviation", to say so! Cheers!

You prove for the second time you do not understand...! Man..., from where do you get the idea that I'm "estimating thrust via climb rate"? From climb rate? Sorry man, but you seem to lack general knowledge of physics and I have to waste my time here with you to answer. If you can prove how you estimate a force through speed, you're even smarter than those who invented quantum mechanics! I hope everyone else can see what you wrote before commenting on this subject. I didn't use elaborate charts with graphs (I don't want to buy Tacview yet) and no longer have the patience for DCS (maybe just for other sims that worth it, but not for DCS anymore), yet why do you find my methodology to not be useful, neglecting the possible errors which I personally consider very small or which rather affect the output result by a small enough amount for the result to be accurate. Yes, in this example of trying to estimate the engine's maximum output thrust as a ratio to that given by wikipedia (or other source) by knowing the weight force which affects the plane's X axis acceleration, I have 2 rapid options: 1. Try to find at what weight (which is a force) the plane's engines maximum thrust would deliver a 1G longitudinal acceleration, thus trying to find at what weight the plane will eventually stand on it's tail in Full AB is an option, or... 2. Simply use the Newton's second law and find out the delivered engine thrust force by knowing the plane's mass (which can be any) and the dV/dT derivative (acceleration). I used the first method (although I passionately had to do more tests to find the 1G weight) as it can be a "harder proof" and quicker to understand by most and uses almost no math (just a thrust ratio). I would've personally used the 2nd method (more engineering oriented), but as I see that the message I tried to address is so difficult, I don't know what did I do wrong with to come here and even post these problems...! I appreciate you for being honest, yet I no longer believe I can change my reputation anymore and become more patient in the future because through all the talks I have here on this forum I feel like "fighting with a wind" which only "likes" to blow a wrong direction, to say it as a metaphor. Btw, I'm not looking towards being appreciated, but only f#@&ing taken into consideration by testing what I say as I'm not trying to steer anyone in a wrong direction or "my direction", but just to have a look at what I found...! But seeing that even what I found isn't understood, then..., what a heck am I doing here? I don't know how..., seems like a miracle to me, although it shouldn't normally be so if everyone wouldn't be so ignorant and born for denial without any tests to prove otherwise..., only Ironhand actually took the time, and I can only start appreciating him for this as he can "think out of the box" and has proved that I was right when I was freaking trying to point out in a dozen replies that the Su-27's CG shifts back and forth, back and forth as the fuel gradually depletes, instead of constantly shifting towards 1 direction. He was the only one in there to notice that I was right. I'm not looking for any kind of reward, not even a "thank you", but to see all of those who only start by not accepting that DCS is wrongly simulated here and there, without even testing what me and others are saying..., ohhh..., that makes me just sick and makes me hate DCS more and more everyday! Regards!

Where did you see fuel starvation? Didn't you see that I was throttling back on purpose just to not let the speed build up (which creates drag) and climb (which reduces the air density and available thrust) and then slam at full AB and see how the speed varies while the plane is still at 90 deg. of elevation? I'm out of words...!

You guys truly are amazing! How come you guys don't understand anything? Really? Did you correctly watch the track and correctly interpret what you saw there? 1. I didn't check to "see" at what throttle the plane stands on it's tail. This proves you understood nothing! I start losing my patience again! Man, this test is to see at what plane's weight force and at full AB throttle, thus maximum engine output thrust, the plane has 1G along it's X axis (constant speed) and I tried to reduce the speed after climbing from sea level (where the thrust is maximum) in order to not let the drag interfere, because I only wanted to determine the engine's maximum thrust force through the plane's weight. At what weight force the plane's speed won't vary at full AB, that's the thrust force produced by the engine! If this is so hard to understand..., then everything else makes a lot of sense! 2. I never had flaws in my approaches to testing techniques. Never! This gives the feeling that I'm probably much too smart for you guys to understand either what I'm doing or trying to suggest and in your conclusions you self-lead yourselves into a confusion which you eventually also believe to be correct. Fascinating! I feel like losing my time here and also with those who believe DCS's simulation but are blind to see what's wrong and also don't even want to listen to those who found what's wrong, simply because they accept things as they are and don't give a s@$t if it's wrong because they only want to fly! Honestly, this joke is not for me!

Hi Ironhand, Perhaps you don't imagine, but although I didn't use any software for charts drawings which might've made things clear much quicker than I try to explain, I've done simple investigations (exactly as I detailed them) using simple math to determine the ratio between the simulated AB output thrust of each plane's engine and the AB output thrust told by wikipedia (I believe it's enough accurate from there). I've simply used the plane's weight force and true airspeed variation to determine when the thrust force equaled the weight one. The ratio is remarkably similar to all the mentioned fighters, around 0.85, except for the Mirage which has it 1 (so it's a bit abnormal) or possibly higher and for the Su-27/33 which has it at only 0.71. Test it for yourself, cause no one has to take my word for granted, but test please. And if you have the time and patience (I've lost it and Ill leave it like that), please draw the results. Kind regards!

Is the AL-31F such an alien engine to have so drastically different thrust characteristics from other engines? If you completely read it all, every other aircraft has it's engines maximum thrust output in AB at around 85% of the value found on the internet (ex: wipiedia). How come only the Su-27 has 71%? Indeed temperatures affect density, thus thrust, but common, this is common sense! You might be right and indeed the temperature data might be overrated in the simulation, thus we get this inexplicable thrust decrease, but this can only be corrected by the "experts" who made the Su-27's FM. Kind regards!

If the plane's weight matches that of a 50% fuel, clean config, it could be 9325kgf (from DCS, if it's correct) and if the zero AoA lift coefficient would be 0.04 (although it may be a bit lower), the resultant lift slope may become 1.068 in radians or 0.019 in degrees. So it's lifting performance could drop to about half (as it usually happens to every fighter aircraft) of what it used to be at lower subsonic Mach. I can't tell much about it's engine, but giving the fact that it's a combination of very low bypass single shaft turbofan engine, in theory, it's thrust performance should still be able to increase with Mach number, yet only a testbed chart could provide true data. If I correctly recall, theoretically, for a given inlet geometry the higher the fan's diameter and/or bypass and the higher the number of compressor stages, the worse the thrust increase slopes with Mach, while opposite to that (for the same inlet) gives a more rapid thrust increase with Mach. On the other hand, it's engine should be a rather reliable one for having just a single spool (easier/cheaper to maintain). Regards!

Oh, right! I didn't look at every detail on the HUD although it was right underneath the speed indication.

Did someone test the Su-27's acceleration in horizontal and/or vertical plane? Probably not too many bothered with it! The Su-27's engines AL-31 are rated at 27560lbf in full AB on test beds. I had an interesting discussion with GGTharos (a guy with a relatively respectful knowledge) about the F-15's ability to accelerate into the vertical. And yes, by the maths, in DCS and certainly in reality it is possible, but at a considerably low fuel % status at no loadouts and only at low altitudes <3000m. "Tharos" gave a rather useful ratio between the maximum available jet engine thrust (full AB) on the aircraft and the maximum achieved engine thrust on bench tests. This ratio, as he said, would be found about 0.8-0.85. So around 80 to 85% of the maximum jet engine thrust that we may find on the internet regarding a jet engine may probably be the maximum available on the aircraft. The engines tested on test beds are fed with air through a bellmouth intake (https://i.ytimg.com/vi/SIjBU9tI-Go/hqdefault.jpg) which makes sure that the tested engine provides the best performance possible, no matter how will it degrade on the mounted aircraft. On the aircraft however, the airflow qualities decay more or less due to the intakes designs and flight regimes (ones are better for low speed & altitude, some for higher speed & altitude. That 80-85% maximum jet thrust of the one found on fighter jet engine data documentations is confirmed in DCS with the F-15, F-18 and other aircraft (except the Mirage 2000 which has 100% or probably more the value found on wikipedia). Simply take the F-15, put some 18400kg of fuel, no loadout and see how the plane can stand on it's tail at very low airspeed (to eliminate drag from the equation as much as possible) into the vertical near sea level. This results that the F-15's engines in DCS develop about 84.6% of the maximum engine thrust of 24000lbf which is told by the manufacturer. The DCS F-18, at 38% fuel with no loadout proves a T/W = 1 at sea level, thus it's engines also provide exactly 85% of the maximum available thrust found on wikipedia for example. Also the Viggen proves 84.7% engine thrust of that found in online documentations. If DCS is correct for the engine thrust tables of F-15, F-18, Viggen, Harrier, F-5 and other (except for DCS Mirage 2000 which has it's engine's thrust overrated) then what "Tharos" said is relatively accurate. Here's a track: F-15 at 18400kgf for a unitary T to W.trk Now watch out what happened to the Flanker (of course, after many FM modifications throughout FC1, FC2 and also FC3). At only 2% fuel with no loadout, weighing 17800kgf, the Su-27 is barely holding a 1G (barely stands on it's tail) along the longitudinal axis at sea level in full AB. This results that the simulated maximum jet engine thrust for the AL-31 of the Su-27 only develop some 71% of the known 27560lbf. I'm not pro one aircraft and against other aircraft and stuff like that! My only goal is to see them respect real data. From my point of view, the thrust ratings on the Su-27 and 33 are kind of much lower than expected. Just 71% of the maximum achieved on test beds is just way lower than expected and may even be unacceptable on a real Su-27. I believe that the drag tables should be slightly increase for higher speed regimes only (the deceleration at high and low AoAs looks natural for lower speeds) on the Su-27 besides increasing the thrust data values in order to maintain the aircraft's maximum speed where it has to be, because as it is, the full AB engine thrust seems too low to be true. Here's the one for Su-27: Su-27 at 17800kgf for a unitary T to W.trk Regards!

Hello "Ironhand", At least they believe you for the exact things I also pointed out in repetitive ways! Who knows, maybe they have a difficulty understanding what I write (although if I read my own posts everything should be well understood). I've only said (from what I was able to observe without any special software and just by eyes) that as the fuel depletes (besides the case of unlimited fuel), at full aft stick direct pitch control and constant elevator position, the AoA jumps some 10 degrees higher at an instant when the fuel status becomes X, then at some lower fuel status Y the AoA reverts, then again at some other fuel status it jumps back to 10 degrees higher. I don't get it why it was so hard to understand this, but maybe the word "AoA spike" finally convinced them. Thanks "Ironhand"! Seriously..., I truly appreciate that you made an abstraction from how the conversations evolved (because I have my limits of patience and I sometimes feel that I'm talking to who I should) and separately done a verification and finally "smashed" all the ignorance and false claims that everything is "OK" when they're not OK in plain sight! I kind of like the hypocrisy that goes around by trying to deny what's true and I became so used to it that I no longer feel like needing to put it to the heart. In general, I'm kind of done with DCS! I've made my impression about DCS's level, talking about flight models only (what I only care about) and I really wouldn't want to share my words for it, especially for how it's creators and/or defenders treated me here here! I've made my points clear and fair almost every time and never sought to get into conflict with anyone, insult or misbehave, but the responses I get, especially by re-naming the thread's title as a "NO BUG" when I know for sure and can clearly see what's wrong, is too much for me giving what I know. I moved to simulators which I personally find on the right track and on which the flight model problems can be more quickly spotted and resolved. Regards!

Copy! People don't get frustrated! I just asked and now I have my answer! If I was going to get something like: "yes, of course it's done, it's all good", then I would've started shooting, but as long as we're true with each other, there's no worry. This is what I've found so far. The following might be helpful for the FM developers who are still working on it. No criticism yet, only spotted problems by some random guy for who the aerodynamics simulation is like a drug. I've done 4 tracks, each one regarding a different subject. The difference is that the 4th track is a congratulations and not an issue. 1. Between some AoA and Beta (sideslip angle) ranges, the aerodynamic forces generated are a bit strange (at least that's how I find them) and also the expected rolling moments and rolling oscillations are non existent: Between some AoA and Beta angles, the rolling moment becomes null.trk 2. When rapidly changing the AoA from a low to high value, the initial roll rates rapidly go to zero. Either the rolling inertia suddenly becomes as low as null as the AoA goes past some threshold or the lift differences due to the AoA difference between the wings become so predominant over the remnant roll rate that the roll rate becomes zero in no time. Don't want to make it sound strange but the way I feel it is like the FM is partially SFM, partially AFM. It's like no matter the speed or the weight (thus the moments of inertia) of the aircraft, the roll rates are "forced" to have X value at Y AoA and airspeed. Also from my opinion (hope this will be more appropriate when the FM is finished for the F-18 at least), the rolling moment coefficients are being simulated with the highest errors among all the aero coefficients that take place. I consider that the motions of the airplane should be more dynamic (forces and moments calculated on their own based only on accurate initial values) and not give the feeling that they are scripted or simulated only through big matrices of fixed values and tables. I don't know what the FM's core is based on in DCS but in other simulators there are data tables which contain only some necessary variables and from there on, the aerodynamics equations combined with the flight dynamic equations automatically calculate how should a force develop on a particular part of the aircraft and the resulting moment/moments. I'm not saying anything to criticize, but I'm partly sharing what I found and how the plane feels for me and it's not due to how the surfaces deflect due to flight controls logic, no..., it's about how the plane responds to each surface deflection and momentum (angular rates). Roll rate becomes 0 rapidly with AoA onset. Feels like the rolling inertia becomes 0.trk 3. The flaps vary the pitching moment by a rather tremendous amount. Simply fly at maximum constant AoA, some 50 AoA and lower the flaps to full. Indeed the rudders will deflect towards generating a slight pitch down moment (maybe they are programmed so to act as airbrakes or to assist in pitching moments) and the elevators also initially deflect towards positive to reduce the AoA but after the AoA starts to drop, the elevators come back to full negative deflection. Somehow our plane now sits at around 15..16 AoA with full negative elevators and just some half rudder deflection towards pitching the nose down. I hope people won't consider the rudders deflection as the reason for the low AoA trim/settle, as their effect on pitching moment is far reduced from that of the elevators considering the fins dihedral from the vertical axis and low rudders surfaces and about half deflection. The clue that the flaps increase the Cm towards negative (which is normal along with the droops as well) in a very exaggerated manner can be seen after pushing the stick full forward and watching how the AoA starts to accelerate violently towards higher negative values after passing through some -20..-25AoA. The plane will settle in a negative deep stall at around -50AoA and the AoA won't vary at all no matter how the controls are deflected: Negative Cm vs flap is incredibly high.trk 4. The inertia coupling for which the F-18, especially the CF-18 (Canadian version) that develops within some circumstances of roll rates and alpha-beta combinations are on the other hand remarkably well simulated. This kind of eliminates (at least in this area) my above thought that the FM is scripted, yet anyway I believe it is partially in some places giving how the plane reacts sometimes. Spot on inertia coupling + high AoA and beta through cross controls.trk Congratulations on the inertial coupling phenomena which throws/departs the plane into a negative spin if the stick is pulled with cross controls (stick to one side, rudder in the other). Try not to affect this side of simulation which is otherwise authentic. Here's a life test (I've provided it for different subjects before): Anyway, in the first video the guy just held cross controls throughout both spin departs, yet in our sim the F-18 holds a rather constant rate negative spin. This might happen because probably the F-18 in the video had full authority over the rudders and ailerons deflections (no FBW filtering). Those who deny videos as proof for one plane's behavior in the subject of comparing a simulation with it, when everything is plain sight clear, are just those who either don't understand or are blind (apparently) or don't want to recognize the true facts. Regards & good day!

Now, the thing with the lift is settled and realistic (but only above very low speeds though), but what about the thrust tables? After retesting the lift capabilities, the tests on the outstanding climbing performance of the Mirage's FM in DCS show no corrections and the Mirage 2000 still has a tremendous thrust/weight versus altitudes. At much higher altitudes, the Mirage still outaccelerates the F-15. Regards!

Well, sorry I tried approaching the stall speed in the conventional manner without knowing what weirdness I'd get by doing so and holding the critical AoA while gliding (engine idle) and waiting until the speed settles, then from that data determine the lift coefficient. If I could've known what would happen and get that false result of 1.96 I would've determined the maximum lift coefficient another way at any higher speeds than that of stall. It still kind of puzzles me why at very low speeds and critical AoA (28-29 limited by the FBW), the lift coefficient goes towards 2, but I don't have to worry about it anymore as long as it's correct in dogfights. After re-doing the tests (as I check after sim updates) I no longer tried using the stall speed as a reference to calculate the CL max, but the aircraft's performance at some constant or instantaneous turn rates actually proves that the maximum lift coefficient becomes ~1.3. I don't brag about it, but from the start (even before looking into that AI M-2000 lua file) I have personally determined on my analysis that the lift coefficient should be around this value for this wing with it's airflow enhancing devices for that alpha. So...good job RAZBAM! You grown back into my eyes and I feel a bit relieved with the results of the later tests that I've done again, but your general aerodynamics knowledge should've been proven right away from the start through pinpoint replies and not letting me search for the truth on my own for so long! The only answers I've got were that the Mirage 2000's wing has 70% greater max CL than the Mirage III. On another thread or here (don't remember) I have also determined by analysis that the Mirage III's maximum CL at M=0.2 should be about 0.78..0.8, so all I could do was to determine some accurate numbers by analysis while others were telling me only what they know. It was a sort of discussion between people speaking only in their own language but in the end they were telling the same! I'm still kind of puzzled why couldn't someone rapidly correct me and say that the simulated maximum CL for the player M-2000 is also around 1.3, so I wouldn't need to worry in the way that I did and tell all I've said...! Cheers/regards!

Hello man, It is a useful picture from which someone can rapidly determine the lift slope by having the actual alpha, knowing the zero AoA lift coefficient (using 0 for fighters won't result in a too great error) and determining the actual lift coefficient by knowing the G-load, airspeed (it's very important which airspeed indication, IAS, EAS, TAS) and actual weight. So if one can find out the current weight of the plane and what type of speed is indicated on the left top corner, this is the formula (using metric system) on which anyone can determine the lift slope (lift versus AoA function) which is very important to be similar in the DCS M-2000 simulation as well. As for the zero AoA lift coefficient variable, I'll arbitrarily use 0.04 (instead of 0, to increase the accuracy of the result) by my quick estimation for supersonic. Lift slope in degrees = (ZG load*Weight / (0.5*1.225*(KIAS/1.944)^2*Area)-0.08 ) / AoA Lift slope in radians = (ZG load*Weight / (0.5*1.225*(KIAS/1.944)^2*Area)-0.08 ) / AoA*pi/180 Area stands for wing are and for Mirage is 41 m^2. 1.944 is the ratio between knots and meter/second. If someone knows the actual plane's weight and determine the IAS, the rest comes easy! Cheers/regards!

Hi, I'd just want to ask if this awesome bird's FM is finished? Nothing else! Regards!

Ok, now coming back to the subject. What "proof" do we need more than actual tracks to see the wrong that goes here in there in the simulation? Take this example only for now. The outside AoA indication. If you don't believe that track I've shared then do it yourself and test to see how the AoA rapidly varies only with elevator displacements. Be careful to not misinterpret what you see (it's easy to get into confusion), try to do it with a heavy enough plane (take the su-27 or 33 or F-18 ), jerk the stick back and forth and you'll notice that the AoA indication actually varies much quicker than the pitch attitude angle for example. My personal explanation would be that the AoA is somewhat affected by the elevator's deflection also (not completely, but rather an average between wing and elevator). Waiting for your reply on the "proof". Regards!

Lol! I didn't say it's a conspiracy. You said that! I've only said that I interpret the replies as coming from ignorant people or people with not enough knowledge (as it appears from their replies) when discussing various stuff. I personally don't find very wrong what I've said in what you quoted. Yes I may sound like talking from somewhere upstairs (yet I'm not), but I've gotten sick of seeing replies from people who prove to have little knowledge, but dare to ask questions in which they only show how little they know/understood about the subject. Sort to say, they're wasting my time and theirs by forcing me to reply to a nonsense. I believe I have my reason to be angered a bit, yet maybe I'm just too harsh in the way I write back, yet I don't feel like being wrong with my statements. Good day!

Yes, and that makes a lot of sense now! This is sad, but not for me, I've made my point and I'm greatly disappointed!

Yes? Did you convince them to correct aerodynamic issues? Certainly not! I could also point out the problems using far less sentences, but I'm afraid that I might leave a gap of misunderstanding therefore the conversations would go on and on, so by trying to detail the problem more and give a more accurate understanding of it I may inadvertently complicate my phrases and sentences. I'm not a good narrator, but I want to prove my points with what I know and interpret! Back to the subject, as you've seen in those tracks, there's not a smooth transition of CG, thus maximum constant achievable AoA, when the fuel constantly drops from a quantity to another and it's logically at doubt that the real system has the capability to "instantly" transfer fuel from one side of the plane to another to make the CG (thus AoA) shift as quick as seen in the tracks, besides that this shift doesn't even have a logic, because now it's fore, now it's aft. I don't get it why you people try to find alternate explanations to something that won't make any sense.

Hello Yo-Yo, I'd be pleased to talk about it. Can you share us more light into that through a better detailed analysis? For example, how long (altitude loss or time spent) did the plane remain in that condition? How were the pilots inputs and elevators responses, thus the plane's response to those inputs? How was the alpha varying according to pilot inputs in that condition? Many of these types of questions for a better look into it and therefore a conclusion of error between the DCS simulation and reality. Let the numbers step in and tell the truth. From my point of view (although I may miss something from the details, reason why I may be wrong), the vortex generated by the LERX would happen for the negative AoAs as much as for the positive ones, except that at negative AoAs it's strength may be a little weaker (not stronger because the LERX is asymmetrical towards increasing the vortex strength at positive alpha), but still, the vortex should flow over the underside of the wing and past the elevators (on the elevators doing it even better than at positive AoAs) and still maintain a good quality airflow up to a vortex breakdown AoA (which shouldn't happen at -20 AoA only, but much higher by common sense, I'd say -40..-45AoA). Yes, this is my perception, that this plane have a slight increase of static stability margin (although it may still be negative, it's towards more stable) throughout the whole Cm versus negative AoAs function in comparison to the Cm versus positive AoAs function. For short, from my opinion, the plane should find an overall slightly increased pitch stability (or a slightly reduced instability, depends from which way one may want to see it) at negative AoAs than it would find at positive AoAs. Somehow though in the sim, we have just the opposite. We have a very highly stable aircraft at all positive AoAs (there is no positive AoA below/above which the plane's static stability margin is negative), but at negative AoAs beyond -20, the static longitudinal stability margin becomes negative (the plane goes away from the AoA where it should trim according to, for example, the elevators), thus the plane is unstable and now tends to pitch accelerate towards higher negative alpha. Again, from how I consider, the plane should find a reduced static stability margin (but positive), with elevators at zero degrees deflection (the elevators being at 0 degrees is a fundamental condition when analyzing a plane's pitch stability) up to some 20..25 AoA. The F-16C for example, with elevators at 0, meets exactly zero static stability (statically relaxed) at 15 positive AoA. Below 15 AoA, with elevators at 0 deflection, the F-16's static margin is positive (pitch stable plane), above 15 AoA, with elevators 0, the static margin becomes negative (pitch unstable plane). Our aircraft, the Su-27, from my opinion, should pass through the relaxed static stability margin at around 20..25 AoA (I don't have access to it's real Cm2AoA, maybe you do, yet I'm confident the Su-27 is only slightly more stable (and/or less unstable) than the F-16 at any AoA between 0 and positive 90) and above 20..25 AoA, with elevators at 0 deflection (luckily on Su-27 we have an arc with degrees painted ahead of the elevator's leading edge) the plane should now become statically unstable unless the elevators are deflected trailing edge down (pitch down) before the wing's AoA reached a value from where the Cm of the wings and fuselage combined is positive enough to overcome the down pitching moment (negative Cm) available from the full down elevators deflection or unless the elevators have somehow stalled (elevators which stall too quickly in DCS and the lift after stall becomes way too low. I don't need to have any diagram against plain sight bugs in the end...! Why are you trying to be ridiculous? I thought that you are the most knowledge based around! I provided a few tracks here that show what happens wrong in plain sight, why do you have to try arguing with me instead of watching the tracks? Can't you see that with fuel status decreasing from 100% to when the fuel weight is just below 8000kgf the AoA jumps some 8 degrees instantly? Then after the fuel reaches somewhere below 7000kgf, the AoA drops some 8 degrees (comes back to where it was between 100% and 8000kgf). At below 6000kgf, the AoA again instantly increases some 8..9 degrees AoA. Then again, below some 1500kgf, the plane becomes more stable, AoA capping out around 40..41 as average. Do you we all (who find these things during actual play) look like idiots and accept this to be normal just because you, ED or anyone else forces us to believe? How could you say what you say? How long should people working for ED keep on not recognizing the truth just to make it look like their simulator is realistic? Please, don't pretend you don't see what's wrong in there! Wow! Just wow! Control algorythms? Man, do you even know what you're talking about? You blow my mind with your incoherent answers! This is kind of tragic, seriously! How could you even question the controls surfaces (the elevators are not affected anyway by gear during direct pitch control ASC, but only with FBW ON) if the plane starts to pitch up only due to landing gear extension and/or finds a reduced pitch stability at positive AoAs when the weapons are loaded? Do the Su-27's controls affect the f#$@ing center of gravity man? I'm kind of speechless now! Are you helping ED develop their FMs? That might make sense then! Again..., do the controls make any sense to you regarding this subject and to what you find in those tracks? As long as you have the recording and also as long as maybe you don't even know how the plane should behave with gear down or external loadout (ie: CG repositioning, global drag vector (drag center) and global lift vector shifting (both lift and drag vectors being affected by pressure distributions)), then what are we talking here...? As long as the FMs in DCS are built only through some equations (who knows how validated they are) which sometimes develop abnormal aerodynamic functions and I will name the most important ones that are having huge problems in DCS: lift coefficients at null AoA, lift slopes (lift coefs. vs AoA), stall onset AoAs, stalled lift (lift available beyond stall AoA), lift functions between stall AoAs (positive and negative) and +/-90AoA. As I repeat myself: The lowered gear and also the weapons loaded on wings should only increase the negative Cm in the aerodynamic center, NOT increase it as DCS simulates. With many occasions, things that are normal in the real world..., are turned upside down in DCS World. Well, giving the above facts, do you still wanna talk about criticism? I'm not even here for criticism after all! If it were to have these discussions criticism oriented, you could make sure that only little has been done so far. Instead of complaining about the clients criticism (nothing wrong from my opinion after spending more than 1000$ myself on modules, from which only a few deserve some respect) for pointing out unresolved and still questionable things you or ED should start giving credible answers about the FM, but all you guys say is: "AAHMM! We did it good, we don't need to give you answers"! Is that the kind of politics go on at ED? Look at other flight simulators which do actually cover a lot more in aerodynamics (all aero coefficients versus Mach and Beta) than DCS and it's a fact! Just watch their discussions and see how every question is being respectfully replied by professional aeronautical engineers, not some wannabes, with detailed explanations on how things work and how the FMs are being done. I personally won't take for granted the way that planes behave (in terms of flight dynamics and aerodynamics) in this World of DCS (as most random people that are trying DCS actually more or less do).

Hi, After some playing with airplanes from outside view I found that when the plane's AoA remains almost constant (or doesn't have enough time to vary), the indicated AoA does vary instantaneously with pitch controls deflection. The AoA indication isn't necessarily that of the elevators for example, but is definitely some sort of average between the actual wing's AoA and the actual elevator's AoA. There is no other explanation why the outside view AoA indication varies a lot more than the actual plane's pitch elevation angle may vary for a given constant airspeed and initial constant flight path. Proof wanted? From in game, here it is: AoA indication as average between wing and pitch control.trk When the plane is flying slowly enough and it's heavy enough (so it has a relatively high pitching moment inertia), if you jerk the stick quickly fore and aft you'll notice that the AoA indication is actually not a wing AoA indication, but rather an average between elevator AoA and wing AoA, otherwise what's the explanation for the high AoA variation which happens instantaneously with elevator deflections? For instance, when the plane is at a constant AoA indication, if the elevators are rapidly deflected trailing edge down, the AoA indication rapidly starts increasing (a couple of degrees) during the elevator transition from the initial position to full deflection. So, although the plane starts pitching down as the elevator travels, the AoA first increases during the elevator movement, before it starts decreasing and following the whole aircraft. Normally/conventionally in aviation, the aircraft's AoA reference is between the undisturbed air and the wing's MAC. Of course, this problem is not a big deal now in DCS, as we have far better ones to deal with including all kind of ignorant around who'd rather do anything to deny the truth instead of trying to fix something, but this one also adds a bit to the whole thing.

I've got to ask. Are you an aerodynamicist or just someone who's looking for learning through an initial denial? Now seriously, almost everyone who replies to problems found by other people in DCS put the responsibilities upside down. Are you from ED? Are you a flight model engineer? Sorry, but by how you replied you only look like some random guy who knows very little about the subject and dares asking for a proof on normally well known things! The fact that a leading edge device modifies the local AoA and critical AoA are common sense and it would be a painful shame for someone who makes a flight simulator to even question this! ED and their third parties should've "eaten" these principles well in advance before attempting to make a flight simulator. As long as the truth is out there for you and all other ignorant who blindly pretend that DCS is a realistic simulator and before asking someone who spots a problem to provide a link on something that you should've known about (which is definitely not the case through your reply), please do a simple google search on the subject and find out that even the first links that you'll get are the "proof" you're looking for. To re-clarify: The leading edge devices aerodynamic effects are incompletely simulated in DCS. Reason: having them retracted or deployed, there is no effect on the actual AoA, critical AoA and lift. Even the drag doesn't seem to vary during actual simulation (but anyway, before the LE devices drag simulation, the most fundamental are not yet even present). The context and title are plain clear for those who understand what they mean.