Maverick Su-35S

You know 100% inside and out of subsonic + compressible aerodynamics? Now don't get me wrong, but I'm an aerodynamicist and I don't make such claims although I know and have learned a lot having a decade of experience in this domain including supersonic airflow and even so..., I know that I'll never know it all even after I die, but hearing you saying that no wing should ever produce lift if it doesn't have positive AoA..., just leaves me speechless! What about cambered airfoils, I guess you heard about them, right? Even car aerodynamics take the lateral shape of the car as an airfoil and it NEVER had been symmetrical...! I honestly bet you meant something else by what you told!

Are you sure?... If the real MIG-21 would fly straight and level at the so high negative angle of attack in our sim, please show me a real life footage of that or some relevant real life data which to make me believe that, otherwise this is only what ED's CFD or their third party members CFD or a form of aerodynamic analysis that would suggest such a thing and it's not the first and will not be the last time when those kind of analysis, not supported by real data, could be wrong. Now, this happens to be my domain and I'm curious about the results that can come up...! Let's presume that the MIG-21's lift produces a maximum lift coefficient of 0.9 (from some real aerodynamic tests with no flaps it almost reached 0.9 at very low subsonic Mach numbers for 1:1 scale model) at a critical or stall AoA of about 20 and a 0.016 lift coefficient at 0 AoA. Later I should turn the AoA from degrees to radians in order to use it in calculations to determine the lift slope of the MIG-21's wing for low subsonic speed. I've talked early in this year to a RL and active MIG-21 pilot in order to have the maximum (critical) AoA and 0G AoA which I desperately wanted to know because I debated the real AoA vs indicated AoA of the MIG-21 on a thread that I've started on the subject much earlier before. Now let's calculate the lift to AoA derivative or slope (which is otherwise important to predict the lift coef. at any given AoA) by dividing the lift difference to AoA difference on the linear lift/AoA margin only (at least 2 degrees AoA before stall): 0.9 - 0.06 / (18*pi/180) = 0.9 / 0.3142 => lift slope of MIG-21's wings alone = 2.6738 We must know that the CL of an aerodynamic component like wing, fuselage, fin, etc., for some AoA (already knowing the slope and the CL at 0 AoA) is: CL = CL at 0 AoA + lift slope * AoA in radians By knowing from experimental results that the mig-21's wings produce about 0.06 lift coef. at 0 AoA, then for -2.5 deg. AoA which is now equivalent to the -2.5 pitch down attitude that the fuselage's axis has in straight horizontal flight, we should get a positive wings lift coefficient at which the plane should be flying with, but sadly this is what we get: 0.06 + 2.6738 * (-2.5*pi/180) = -0.0567 So, there you go, -0.0567 lift coef. at -2.5 deg. The plane should in NO WAY keep flying straight and leveled as it seems to do in the sim, but rather plunge at some negative G-load instead. The wings should produce such negative lift coefficient alone at that negative AoA. In order to produce no lift, the wings should be flying at this AoA: -0.06 * 180 / (pi * 2.6738) = -1.2857 That's the 0 lift angle of attack -1.2857 Now let's calculate the lift slope for fuselage also (for the sake of discussion) where the fuselage would have a CL (lift coefficient) of 0.024 at 10 deg. AoA (obtained this one using a CFD). As you can see, the fuselage would produce mostly 0.048 lift coefficient at 20 deg. AoA, so it's very small in comparison to the wings..., and if you want a relation between them: 0.048/0.9 = 0.0533 (so 5.3% of the total lift is produced by the fuselage itself), but let's see the fuselage's lift slope now...: 0.024 / (10 * pi/180) = 0.138. THAT'S your lift slope for fuselage only! As a contradiction to some who believe that the fuselage produces upward lift by being pointed downwards like that, guess what..., the fuselage's lift coef. at 0 AoA is about 0.0005 and at -2.5 deg. AoA where the game tells that the plane still has 1G, the lift coef. for fuselage only is: 0.0005 + 0.138 * (-2.5 * pi/180) = -0.0055 Now as a final conclusion, let's calculate the total LIFT (careful, not lift coefficient or CL) for the MIG-21 at near sea level altitude using the following well known formula: Lift = q * A * CL MIG-21's wing planform area (A) = 23 m^2 MIG-21's fuselage planform area (Af) = 7.25 m^2 q, which stands for dynamic pressure, where "rho" is the local air density and near sea level it can be taken as 1.2: q = 0.5 * 1.2 * (1300/3.6)^2 * 23 * -0.0567 = -102033.75 Newtons of lift force produced by the wings alone. Now let's calculate the lift force from the fuselage (which is ALSO NEGATIVE and not positive as everyone started thinking) q = 0.5 * 1.2 * (1300/3.6)^2 * 7.25 * -0.0055 = -3119.85 The TOTAL lift would now be: -102033.75 + (-3119.85) = -105153.6 Newtons..., which is as negative as nothing can stop it. The weight of a MIG-21bis (took from mission editor) with 50% fuel, having it's mass multiplied by the gravity acceleration: (7480kg + pilot) * 9.81 = (7480 + 90) * 9.81 = 74236.34 Newtons of weight force. Now if we divide the lift force to weight force we'll get the G-load: -105153.6 / 74236.34 = -1.4165. There you go now..., the G-load should be -1.4165. Even with some error from my part let's say..., the G load still can't be even 0, with no room for saying it's above 0 or equal to +1. Let's stop calculating for the alt of 10000 meters and presume that for the same "q" (dynamic pressure) that occurs at much higher true airspeed and Mach number but the density drops much also (the dynamic pressure is what matters), the negative lift would provide almost the same negative G-load as for near sea level, which is about the same -1.2 Gs! Keep in mind that these calculations took the presumption of having the CL constant with Mach number. This CL only varied with AoA here and was taken for a very low Mach number, but in reality, shock stall phenomena would make things even worse and would require the aircraft to stand at an even higher AoA in order to maintain a straight and level flight..., and there's nothing like that seen yet in DCS, but I can only wish for better days when ED will actually take into account that variation too. It would definitely make a much greater difference and realistic challenging experience. Some can also check this for MIG-21's lift variation with Mach at constant AoA: http://forum.keypublishing.com/attachment.php?attachmentid=180128&stc=1&d=1262166833 Indeed this is the variation of lift coefficient (NOT DIRECT LIFT, learn what a lift coef. is) with Mach number when a critical angle of attack is held constant, but the general shape of the curve will remain almost the same (slightly flattened so the variation would be a bit lower) even at lower AoA where the wing still produces a non-zero lift coefficient. That drop of lift coefficient and then rises again (somewhere at the middle) is the so called "shock stall" which no aircraft escapes from, sooner or later as Mach increases. And as a matter of fact, I didn't even need to tell any of this..., it could've been obvious and simple enough for anyone to just try and compare how the MIG-21 with it's very poor lift slope wings and almost symmetrical airfoil which produces very little lift near 0 AoA flies at such negative AoA in relation to the F-15 and Su-27 under same conditions, cause they all have PFM. Someone should try and fly the F-15 and Su-27 in level flight at supersonic and find out that they always have positive AoA at any height and even with empty weight (almost no fuel left) when flying supersonic. If there was an aircraft to have a nose down attitude at supersonic (even regardless of shock stall that I discussed about and doesn't exist yet...) that should've been the F-15 which has a drastically cambered airfoil which produces a lot of lift at null AoA, and even so it keeps a positive alpha or near 0 in such circumstances...! Try it: F-15 & Su-27 supersonic AoA in level flight.trk

Ok, that's right! My brain hurts...! What would the icing, or not, of the pitot tubes ever have to do with what you clearly see? The icing affects pressure sensors such as altimeter, variometer (vertical airspeed) and forward indicated airspeed and AoA vanes which you clearly know, but NOT EVER IN THIS WORLD it can affect gyroscopes (artificial horizon indicator) and what you can see! Why are you lying to yourself that way? There is no descent even in the video! Can't you see that even in the next video at high altitude where the density is almost a quarter than it is at sea level and so would the dynamic pressure and IAS, the nose is still pointing downwards? Well, if you mentioned this..., tell us about this magic zone where the lift goes against the laws of physics! When any aircraft reaches a critical Mach number know as "Mach Drag Rise", where the drag starts rising rapidly (as Mach continues to increase towards 1) on par due to shock resistance (which besides the modification of important thermodynamic parameters, is nothing more than an abrupt deceleration of the upcoming air making that air almost move with the aircraft) and to "shock stall" (here's a link:http://scilib.narod.ru/Avia/DAC/dac.htm#1_1_3) where the LIFT suffers a massive degrade as Mach continues to increase up to a given number, from where the lift starts rising again with Mach number until the wing alone becomes supersonic (Mach 1-1,1...) and then will starts degrading again as the Mach number continues to increase towards hypersonic. The "shock stall" which is inevitably going to happen to any man made aircraft once the wing of that aircraft has 3 zones of airflow on it (2 subsonic and one supersonic) has never been seen in DCS neither in SFM, nor in AFM/PFM up till this day, at least not by me. This wasn't such a great concern for me cause I haven't seen it here..., but seeing such aberrant values and seeing people trying to give all sorts of explanations to themselves of what is happening, explanations which ultimately tend to mislead from the initial facts and which will NEVER help us evolve and find the truth..., is a bit disappointing!;(

1. Tsagi S-12 is not symmetrical, it still produced minor CL (lift coeffiecient) at exactly 0 AoA. 2. The MIG-21's fuselage shape, especially due to it's very low planform projected area in relation to that of the wings, shouldn't produce even 20% of the wing's lift. The MIG-21's wings have zero degrees of incidence (angle between wing's root chord and fuselage's axis), so if the fuselage is at exactly 0 degrees on the artificial horizon so should the wing be at 0 deg AoA in also. That's the answer, not that the fuselage creates opposite lift to the wing, cause that won't happen, except when the wing's incidence would be drastically high positive or high negative...!

YES! It is safe to assume it is not more correct than it was before and even if generally seems more correct than it was before in some places, it is less correct at other important places. I'm not looking to say this, but maybe I should mention that I'm an aerodynamicist, flight dynamics specialist and pilot and I know exactly what I'm saying! The MIG-21, had very realistic pitch-yaw-roll couplings and oscillations at high AoA spins and lovely wing rocking at high AoA when almost no yaw rates were developed, among it's first patches (early when it came in DCS). These might've been modified a bit and have different values but are still present in some form and they might still be realistic. The ONLY problems with it's FM at that time were the "stalled lift" which came to zero, the rolling moments that were too high due to aileron deflection at some AoA and the high reduction in pitch stability (tended to pitch up) immediately after the wings stalled. When the wings stalled they produced 0 lift (you could tell that by the G load indicator returning to 0 when stalling) which is wrong. In real life, when a wing or even airfoil (infinite wing span wing) stalls beyond a certain AoA, it still provides lift, but only between 50..66% (depends on 2D/3D shape) of what it should've had if there was no stall and as the AoA continues to increase after stall, so should the G-load or lift should also increase with further AoA even through stall..., cause that's reality...! Here's a picture for closer understanding of how lift develops with AoA between null lift AoA and 90 deg. AoA: http://www.aerospaceweb.org/question/aerodynamics/q0194.shtml It never hurts to learn aerodynamics now and then and you'll always learn that you could've known more...! Another problem that I told above was the fact that with the wings stalled, the center of lift moved too much forward (relative to the CG position), making the plane almost become unstable and tended to pitch up a lot, but this was partially fixed, because when passing through about 10 more deg. of AoA beyond that of stall with the remnant pitch up momentum that was accumulated, the aircraft suddenly develops a high pitch down moment although your stick is still full aft...! No matter if you try to pitch rock up and down and then back up to pass beyond that "magic" AoA which tends to snap your nose down, you still can't pass it. It's like a wall that the AoA slams into. Indeed as the AoA continues to increase, so should the pitch down moment continue to increase as well, but that should be a smooth and nice transition to higher pitch down moment up to about 90 deg.AoA, yet it seems that somewhere around 30-35 deg. of AoA (real AoA better seen from outside the aircraft using smoke and not the AoA indicator which indicates much higher values than real) the pitch down moment is even higher than it should be at 90 deg. of AoA with full forward stick, for this kind of aircraft in particular. These were 3 things that seems like were tried to be fixed, but it seems that one of them (the pitch moment due to AoA) turned even worse than it was and the lift due to AoA beyond stall isn't high enough because for example even if the airspeed is almost constant (doesn't drop much) and you pull the stick until you reach your maximum G-load/lift and continue to pull and increase AoA beyond stall, the G-load drops to about a quarter (25%) of the lift it had at critical AoA (keeping in mind that the airspeed didn't drop more than 8-10%), so it's still not enough. The lift or G-load should still be somewhere between 50-66% left after the stall developed. P.S.: Stall has nothing to do with airspeed as most people tend to think it has or learned so and makes them not understand aerodynamics anymore..., in reality ONLY the AoA governs stalling up to supersonic speeds and only from there the stall occurs according to both AoA and airspeed.

You need stall and spin? First off, make sure your pitch trim and indicated airspeed (IAS) combination allows your AoA to go beyond the red mark on the AoA indicator when you pull full aft stick, cause no matter how slow you fly, if the trim is pretty much pitched down, you can barely reach the yellow mark on the AoA with full aft stick, so you must trim to pitch up as much as needed in order to go beyond stall AoA with full aft stick. It was the trim that didn't allow most of you guys to have full pitch up elevator travel in order to overshoot the critical/stall AoA. To induce a spin, you must simply use cross-controls (aileron and rudder inputs opposite to each-other) and a yaw rate will develop opposite to your aileron and towards your rudder. In order to get out of spin, use cross-controls in the opposite direction now, having the stick (aileron) towards the spin and the rudder opposite to spin and you'll stop the spin.

Hi man! Sorry to intervene, but "Otto" most probably have referred to the engine seizure phenomena before the patch which seems to have disappeared after the patch, so he probably didn't change his flying techniques and engine management at all. I don't know, it's up to him to answer this, not me..., I'm only curious if he really referred to the manual pitch engine seizure before and after that patch without treating the engine differently in between. That's when tracks are of 100% value of truth, but maybe now he can't revert to the earlier version in order to make the comparison by tracks.

Hi Flieger, I've also started applying sharp full inputs of rudder, by instinct, rather than constant (cause I saw I couldn't hold) inputs due to the yaw instability and I have an answer for why the RL pilots of WW2 were able to takeoff more easily from 2 points (but landing remained a 3 point touchdown or else they could easily roll over) is because they mainly did it from grass terrains, not from tarmac/asphalt, where the grass had lower friction coefficient and so the main gear tires could slip sideways more and more as the speed build up providing lift and thus reduce the effect of instability, but if we try doing so in DCS at this point it would be perfect suicide due to actual grass grip. About the tail heavy characteristics as compared to the E model in that vid (I firstly didn't know about this difference) I also thought but I didn't know for sure, so this applies to be authentic for the K model at least. About the aerodynamics of the aircraft I can say that the slats pop out about 1..2 degrees of AoA before the buffet onset (which triggers airframe shake) which is fairly good, otherwise if they deflect when the buffet already occurs it would be too late to develop a smoother airflow once the transition to turbulent already started, so from an aerodynamicist point of view this is correct as it is!

Thank you all..., happy skies!

Hi Sporg, I also lifted the tail 1 to 2 seconds prior to takeoff many times with flaps settings varying from null to full in the BF-109 K4, but couldn't maintain a perfect straight line whatever I tried on two points due to the very limited yaw stability (using only the rudder without diff brakes, of course...), at least at lower IAS where the dynamic pressure is quite low for control. With P-51 and FW-190 Dora I otherwise can hold a straight line for long distances because the yaw response and it's stability are much greater for those 2 aircraft in comparison to the 109. I'll check out that forum link you gave me about this subject. Thanks!:smilewink:

Thanks Yo-yo..., I believe you took the effort to mark the important info in red, so I thank you once again for that. This is probably for the G2 (as the bottom suggests) and if you know that it has the same stability characteristics compared to our aircraft (K4), then I'm happy to know the truth now and no longer believe that something could've been wrong with the CG's position. Now I've got a better picture of how the longitudinal static stability margin and maximum aft CG positions evolve with indicated airspeed at a given engine torque, RPM and trim setting. The stability margin increase with airspeed can also be confirmed by the fact that when the airspeed is higher (mostly above 350-400km/h), the virtual stick travel (NOT the personal joystick as some might confuse with) is actually greater when pulling until the stall starts to buildup, as the stability curves/slopes within the diagram prove. Even if the stick travel between the aerodynamic limits seems small, I can't be more happier to know this is true with our airplane!:thumbup:

Honestly I don't have any access to such data, that's why I was wondering if the CG might not be a little too far aft. I now understood from Jcomm and might definitely correlate with what you're telling about balance curves (probably stability derivatives) which vary with engine power setting, so I'm all hats down if that's the case for the pitch stability behavior..., but I'm still curious if this plane couldn't have been ridden only on the 2 main gear with the tail lifted to have the plane almost horizontal without loosing directional control that easy, so now I'm pointing my view towards the yaw stability problems when rolling at high speed on 2 wheels on the ground. Thank you!

Did you even watch the track to understand what I meant? It's all about the REAL stick travel of the BF-109 between having it at almost null lift and then at maximum lift (critical AoA), which of course it's the virtual one in the cockpit for this subject, not mine at home! Doesn't matter how much I move mine, I can move it even 1 millimeter if that makes you happy, it's all about the virtual stick's travel between null lift and stall! I'm using a Hotas Warthog and it doesn't make any sense!

Hi, Did anyone else notice the little quantity of stick pull needed in order to have the BF-109 pitch up until it stalls? Now I don't need to be an aviation expert or engineer to find out that with this airplane you are able to vary the angle of attack from null lift towards maximum lift (near stall) with just 5 cm (about 2 inches) of stick travel. The way the BF-109 K-4 feels when handled in pitch gives you an immediate feeling of a plane with very little longitudinal static stability margin left (that's when the CG (center of mass or gravity) is almost near the CP (center of lift/pressure)). Now I don't know why..., but the BF-109 handles almost as difficult in pitch control as the Su-27 (which I had a lot of fun with in the meantime) with ASC direct control ON. It's not that hard but tends to be like it. I know that the P-51D has a reduced pitch stability margin, but that's only when the central fuel tank is full and it's particularly available for it because of the laminar flow wings (it was among the first and few WW2 aircraft to use laminar airfoils) which had this habit of "throwing" the CP rapidly forward as the pilot starts pulling on the stick (gaining AoA), thus making the aircraft reach a stall AoA very easily and quick, but the BF-109's flight behavior should most probably be nowhere near such characteristics. I'm not a noob flyer nor trying to say anything against the BF-109's FM, but I doubt that in the 1940's when they built this plane, they did so wanting the pilot to control the AoA range from very little or no lift angle of attack to almost stall angle of attack by just moving the stick that little (which is about 10% of the maximum stick travel). What would they do such a thing for, cause it doesn't make any difference at high speed, and less to say at low speed, because normally you'll reach about the same angle of attack for the same stick travel at any airspeed, so this wouldn't make any sense to have so much stick travel if it wouldn't be useful, right? Had any RL BF-109 pilot (or someone who knows and can tell) tried this particular aircraft in DCS and felt like the stick travel according to AoA gain is correct? If so, I'm very happy to understand that, cause otherwise I think something's not right! Here's a closer look using a track and at some point you'll see the stick's position at stall and how much more stick travel wasn't even used: BF-109 FM's pitch static stability.trk From my perspective, either the general center of lift (neutral point) is a bit too forward or the CG is a bit too aft close to the lift center, giving a very little gap between them, thus leaving the aircraft with the feeling of very little pitch or longitudinal static stability when flown. One more aspect makes it possible for the CG to be too far aft, because when on the ground and rolling at considerable speed (about 150km/h and higher/lower), the plane brakes with quite a remarkable force (similar to the P-51) but doesn't have any tendency towards flipping over it's nose and as far as I know in fact, the BF-109 had a very likely desire to flip forward when the brakes were applied over a certain amount, so it's very likely that the CG is quite aft compared to the real plane. Another proof that the CG might be too far back is this video: Try this with our BF-109 K4 and you'll loose directional control (yaw) very quickly because it's very unstable in yaw while rolling on the ground. You can only takeoff and land from and on 3 points (main gear and tail wheel), otherwise it's very easy (and almost impossible to stop) to get a side slip and ultimately flip on a wing and this has nothing to do with the infinite grip of the grass, cause even on tarmac/runway you can't hold a straight line before you actually lift off completely or when you touch down with the main gear unless you also put the tail wheel down and hold it, you won't hold a straight line no matter how good you are...!

It's weird how nobody talked about this before, cause it's well into one year since it came in and it's obvious this is abnormal...! Let's hope for the best!

Thanks Kane, Let's see what Yo-Yo has to say! Also, don't forget that sometimes the flywheel is spinning at highest rpm after the crew cranked it up and when you press the starter nothing happens but you can still hear the flywheel spinning..., so this also happens from time to time! Let's hope for the best!

Hi Yo-Yo, I know what you're saying, and that's the P-factor effect and if I remember correctly, a similar discussion had place for the P-51's behavior regarding the same aspect. I'm not telling that I don't believe you, but all I'm saying is that the P-factor, especially when the blades are in low pitch (or lowest anyway), the difference in AoA felt by each blade (as the plane's AoA and beta angles (side slip) vary) has VERY little affect (almost insignificant) on the CL and CD (or lift and drag) of each blade as they are all stalled anyway, and I believe you know it too...! For me it's impossible to accept that the variation of lift and drag on each blade, which indeed vary with AoA and beta, can have such a huge amount of effect when the blades are stalled. Even if the blades would be in high pitch (or highest possible) and not stalled yet, the yawing and pitching moments created on the tons of metal (aircraft) can't be as high as when the prop is spinning and in fact they are even greater than if it was spinning and you can also check that out. Check the gyro and P-factor when the prop is spinning at high RPM and when it's stuck and you'll see the same thing that I'm talking about! Just please..., show us a real life footage or some wind tunnel test data or any kind of real life proof that an aircraft with stopped props would behave like this and swirl so much in pitch and yaw and I'll believe you! Please don't get me wrong, I have at least 10 years of experience in aviation and I'm a pilot, I have seen many and learned many things, yet if there's something that might seem impossible from my perspective and in fact it's true, please be the one to show it and I'll happily respect it. Thank you Yo-Yo!

Hi, As I've been playing with the K4, I've started testing the gyro effects driven by the spinning propeller on the BF-109K4 and found out that when it's completely stopped or stuck, the gyro effect becomes tremendous, where in fact it should be null. Now as most of the prop plane pilots might know, when you have a yaw or pitch rate and especially when you reverse it you should notice that a commanded pitching effect will unavoidably induce a yawing effect and vice-versa. This effect, combined with the P-factor effect (which is purely aerodynamic) will tend to counter each-other (i'm not going through these details..., who has the knowledge or likes to understand it, can tell) when pulling-pushing the stick or snapping the rudder, but the gyro effect is mostly dominant above the P-factor in all cases. So, in reality, if there would be no P-factor, then the gyro effect would have an increased amount, but only when the propeller spins...! There should be no gyro effect at all (cause there's nothing to create it) and even more no word of P-factor effect (this one tends to become infinitely low when the prop's pitch is low and should be non-noticeable even with the prop in high pitch). With the prop fully stopped, the whole plane starts swirling in pitch and yaw just the way both the P-51 and FW-190 do as well when the prop doesn't spin. Please verify this cause this has nothing to do with reality. Here's a track regarding all that I'm saying: [ATTACH]120616[/ATTACH]

As long as you unlock the tail wheel and use diff braking, just a little bit of power is needed to turn as you desire, with stick in any position. And yes, the airflow from the propeller can be felt quite well if you apply power at the right moment while the tail wheel is unlocked. For example, the plane is rolling slowly at about 10-15km/h and with the tail wheel unlocked you press right brake pedal and induce a yaw (towards the right it would be better, because when you apply throttle it will naturally tend to yaw left, thus making it harder to see it otherwise)..., now as the yaw rate increases (because the CG of the plane is behind the main gear's touching point on the ground) you should apply full opposite rudder and power, with NO brakes, and you'll see how it responds to your input. The 109 is pretty heavy compared to other smaller prop planes that react almost instantly in yaw due to prop effects on their deflected rudder and this also matters even more for a tail wheel plane as compared to a free castoring with 3 main gear plane, so the differences can be quite big. The only problem that disturbs me and makes me pull my hear off is the grass that has infinite grip and smashes your face into the ground in no time if there is a tiny amount of beta/sideslip when the wheels touch the grass or when having a remnant yaw rate.

Hi Kane, Thanks for the reply! As I mentioned, the engine/propeller spins very slowly after pressing and holding the starter although the flywheel is spinning at it's peak RPM just before pressing the starter and this should have nothing common with having fuel or not, because with or without fuel the prop should be spinning at the same rate every time I restart the engine, but for some reason the prop starts to spin very slow after a given number of restarts. Otherwise, in some occasions it doesn't even spin at all when pressing the starter button while you can still hear the flywheel spinning, just as if something mechanical would be broken and the flywheel no longer connects to the engine and although this happens much rarely, it does happen. Here's the track with the slow spinning prop/engine: BF-109 engine restart.trk

Hi, I've been trying to fly the BF-109 lately and as I've selected one that starts at the rampstart with the engine running (so the engine wasn't too hot and stood at idle for more than 2 minutes minimum, as the manual requests) I started "playing with the engine" a bit there by shutting it down then restarting it up then shutting it down again from the magnetos or from the fuel pumps by putting them to off or normally from the shuttoff yellow lever, and then at one time I suddenly found myself unable to restart it anymore!O.o The behavior is that after asking the crew to run the inertial starter and they manage to spin the flywheel to the highest RPM, I press the starter switch which normally acts as a clutch actuator which engages the engine to the high RPM spinning flywheel, the engine is barely moving just like if it would be seized or it would have a very high friction in it, or else to say, the flywheel can't seem to have enough angular momentum to start spinning the engine anymore. So this would happen if you'd stop then restart the engine a couple of times and eventually you'll find yourself unable to spin it up anymore because it acts like it has no more lubricant or something like that...! If this is a realistic feature and not a bug, I'd like someone to explain me why would this happen! Many thanks!:thumbup:

Hello everyone, I'm "Maverick", I joined your server by chance 2 days ago and I played as red in the MIG-21. I have to say that I really like this kind of scenario which only allows you to play once per mission..., if you're dead, you stay dead until it all finishes! It doesn't seem to have very difficult tasks but indeed it requires a lot more patience, awareness and focus in order to accomplish your goal before the enemy does it first. I'd like to thank you all for allowing me to stay (even after the server went locked) and I hope everyone else had a good time at least as much as I had! Should I select an aircraft that I'd remain with during every mission from now on or does the selection occur just prior to each mission? Starting from the most important I'd prefer the MIG-21, SU-25T, KA-50, A-10C, and lastly the Huey on either side, if I need to choose an aircraft before the event. Again, it's been a great time with an interesting event/mission type which shows our orientation towards realistic missions! I like that...!;) Have a great day out there, Cheers!

Hi "Fishbreath"! Sorry I didn't RTFM first, so now I feel a bit of shame! It only seemed too obvious that something is wrong when I've made the high difference comparison, but I take your word now and understand that maybe they were such sensitive indeed and blow up that easily. It's a bit of a challenge to be a 21 driver when you don't watch the true airspeed (because if you have a good tailwind, you can blow them up looking only at the indicated airspeed) while rolling on the tarmac. Thanks bud!

Here are some examples for what I said and after you'll see them you should understand how it works. Look at this HARV F-18C: The inputs for putting it into spin are just what you said that the manual is opposed to what I told, so therefore the manual would put you into a spin or make it much harder or impossible to recover from if you should use ailerons in the opposite direction of the spin or yaw, so when you want to enter a spin you rise the alpha (AoA) to critical or beyond and apply cross-controls (in this case he put full left rudder and full right stick). At 0:30 seconds you can see the ailerons being deflected so that the stick is towards the spin and slightly pulled and although the aircraft (typically for the F-18C's aerodynamic configuration) rolled and entered a negative spin, the yaw rate had already been reduced by then. If anyone wonders why would cross controls (for positive AoA only) put you into a spin is because the ailerons increase the yaw in the direction given by the rudder and vice-versa for negative AoA where the ailerons would increase the yaw if they are in the same direction as the rudder. The cross-controls (stick opposite to rudder) can get you much quicker into a spin (at low airspeed only) as well as out from it, rather than the case when they are coupled to the same side which would get you slightly later into a spin (only for low airspeed) and would be much harder to get out. As I said, the ailerons control the yaw rate and yaw acceleration/deceleration when the AoA is far beyond the stall point, so they become more like a rudder effect at those alpha (AoA) and coupled with the elevator input they can help you increase the yaw rate of the spin or decrease it as you wish. Anyone can test it and see! The way he gets it out is exactly as I've already told you: full opposite rudder and stick towards the spin, with the elevator full up or slightly up, but NEVER down before the yaw rate is low enough or you'll start dancing in pitch! Another example is this F-15: See? Same inputs to get into stall! This should tell all the logic behind. Although the F-15 didn't want to apply stick towards the spin is because the purpose of the test was to see if they can make the aircraft recover only from rudder inputs with stick neutral. The F-15 is a statically stable aircraft and it comes out much easier without stick inputs as compared to the F-18 which is statically relaxed and slightly unstable. Here's another example: Although it's harder to see the inputs (but not impossible), this F-18 did the same to get in and out of the spin. Test it on the MIG-21, you'll see the same results. The MIG-21's aerodynamics and flight dynamics are the best simulated in DCS, even better than for the F-15C (tested by myself). The reason why it starts becoming almost unstable (tends to recover harder from high high positive AoA or high negative AoA) is because the leading edge root vortex that is known for all high sweep wings and delta wings, and even more for wings with LERX (like the F-16, F-18, SU-27, MIG-29), tends to move the center of lift/pressure (or CP as it's known) very much forward making the plane very less stable than it was at lower AoA. So this is not a bug as someone said, and it's tremendously realistically replicated here. If you guys don't know why it behaves like it does, simply ask and don't throw the bug issue before you are certain. Have a good day guys! Learning is an everyday routine! Cheers to everyone!