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Everything posted by Fox One
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^^^ I don't know best. I know when something is wrong by so much, that is obviously wrong ;)
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Hi =DECOY=, I am not a Mirage pilot. But I am convinced that by carefully studying what is out there and using a little "engineering common sense" the flight model can be improved A LOT. I know jojo is one of the knowledgeable guys on this forum and usually I read his posts. But I am quite disappointed that he is not exactly objective on anything regarding the M2000 simulator.
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silly... Because somebody shot down somebody else this somehow makes what I said wrong? On what logic? I also did the turning test described in my previous post in the F-15, that is classified as an aircraft with a "cropped delta wing". It turned 200 deg. But unlike the Mirage 2000, the F-15 is not a relaxed static stability aircraft. It is a conventional aircraft, and in flight its horizontal tail is producing a downward lift force, and this downward (adverse to the wing lift) lift force also generates drag. On Mirage the entire wing is producing an upward lifting force. The Mirage is also a delta wing aircraft, but conceptually superior to the F-15. It also has leading edge slats so the wing has "variable polar" characteristics, it continuously moves the slats and adapts to the existing AOA to optimize its characteristics, something the F-15 doesn't do at all. So the Mirage compared with the F-15 has A LOT OF STUFF in its favor. Its only minus is a smaller thrust/weight ratio. So the results of the turning test are for F-15, F-16 and F-18 are 200, 200 and 210 deg. Do you think it is a coincidence they are practically similar? It's not. This is what a high performance aircraft of 4th generation would behave like, of course the numbers are similar. On the other hand the result of the turning test for the Mirage 2000 is 95 deg. Perhaps you think it differs so much from the F-15, F-16 and F-18 because the Mirage 2000 is not a " high performance aircraft of 4th generation ". No. I'll explain to you where the very big difference comes from. The difference is explained by the fact that the F-15, F-16 and F-18 flight models were made by competent aviation engineers. The Mirage 2000 flight model was made by... a guy with different qualities ;) As I already said, the Mirage 2000 flight model is not a little off. A little off would be fine and I would have no criticism, as you said no simulator is perfect. But it is completely off, as this simple test proves. You just need a little common sense to see it, but you know what they say, common sense is not that common... I would like to hear from you a comment about the fact that on landing during aerobraking an increase in AOA of only 1.5-2 deg would instantly DOUBLE the longitudinal G. In you opinion this makes sense and is plausible, correct? This has nothing to do with what I am explaining here. I haven't said anything about the Mirage not producing sufficient lift, have I? What I am criticizing here is the drag that is excessive. The Mirage simulator "lift-producing abilities" I think are actually pretty close to the real aircraft and I actually have no criticism in this regard. In simulator the aircraft can generate very high pitch rates that look to me very similar with what can be seen from the well known Mirage aerobatics HUD video. Because it can produce plenty of lift, of course it can perform maneuvers with a small radius, like the split-s you described. I haven't said the Mirage flight model is crap. Or the Mirage module in its entirety is crap. There is plenty of good stuff in it, like what I said just above. Do you think I am criticizing it because I don't have anything more interesting to do? I would like very much to have an accurate flight model on this interesting aircraft. I paid 60 bucks for it, just like you. Personally, I think you are blinded by your love for this aircraft. It is well known that when you are blinded by love, you are completely unable to view the object of your love in a critical way...
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You don't say... Attached is a track with a test I performed with the Mirage. With 50% fuel I accelerate to 360Kts, then I reduce throttle to idle. When speed drops to 300 I start a horizontal turn keeping the AOA between 10 and 12 deg, and I turn until the speed decreases to 150kts. The aircraft will turn approximately 95 deg. I performed similar tests with F-18 and F-16. Until the speed decreases to 150kts the F-16 will turn about 200 deg, the F-18 about 210 deg. If the Mirage 2000 would really behave like that IRL it would be a very poor aircraft. 10 to 12 deg is not a large AOA, in fact most supersonic aircraft have the optimum maneuvering AOA in this range, perhaps even slightly higher. The difference in this test between M2000 and the F-16 and F-18 is obviously brutally large. You don't have to be a scientist to figure in the M2000 the lift/drag ratio is really off as soon as you start to increase a bit the AOA. I mean really really off, not 10%. Next in the test I perform a landing and I aerobrake the aircraft with the inverted T on horizon line. In the real aircraft, from a HUD video during aerobraking the longitudinal G is -0.15...-0.13 In simulator it is almost double that value. A video with a Mirage aerobraking for 14 seconds (and still going when filming stops): Can you do that in DCS? Then in the test I take off again and made another landing. During aerobraking I perform some small stick pulls, increasing the AOA with 1.5 to 2 deg. Look at the longitudinal G - with an AOA increase of just 1.5 to 2 deg in a fraction of a second the longitudinal G practically doubles!!! There is no need to perform any other test to realize the M2000 flight model is not bad. It is amusingly bad. In the first turning test I wouldn't be surprised if an F-104 would perform better that the M2000. In fact, I also performed the turning test in the F-5, but with 100% fuel and the LE/TE flaps "UP" to make its small wing even less efficient at 10-12 deg AOA. The F-5 turned about 140 deg in the test. Gee, I never knew the Mirage 2000 is so aerodynamically inefficient at an AOA of just 10-12deg! The French aerodynamicists are the worst in the world! Who would have thought!!! It blows my mind how the author of the Mirage flight model, who if I'm not mistaken is an aeronautical engineer, doesn't see all of this! This is elementary stuff and elementary observations, it's not rocket science. "This is a French Air Force-approved simulator" is a nice trick that probably works on naive and uninformed people. Then convince a French Air Force pilot to register on the forum and say the real aircraft behaves just like the simulator in the tests described above and he really sees no problem at all. Go ahead. I'm serious. Get a real pilot here to tell everybody how the real aircraft would behave in the tests described here. I know a major revision of the avionics is in the works. Even if they get that as good a a real military simulator, with the current flight model it would have no value. Any moment jojo will appear to "get things straight" and "defend the module" :D Cause we all know its flight model was made by NASA scientists and is close to perfection... z.trk
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For me landing with full flaps after main wheels touchdown even with full aft stick the nose wheel touches the runway in 2-3 sec (even at minimum vertical speed at touchdown). Can you keep the nose wheel up longer? In the first video in this thread it's 6 seconds. The airbrake I don't think it has any nose-up pitch effect in sim.
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The flight manual says aerodynamic braking is not recommended. It doesn't say aerodynamic braking is not possible, even pulling the stick fully aft. The first video link in this thread clearly shows IRL aerodynamic braking can be done nicely. However in DCS when landing with full flaps aerodynamic braking is not possible, even if you quickly pull the stick fully aft. Just not possible, even if you land with close to zero fuel and remove gun ammo. Obviously, in DCS F/A-18 there is still some stuff that is not accurate in the flight model. However in the sim aerodynamic braking is possible if you land with HALF flaps. So the error in the flight model might be flaps related. With full flaps some data in the flight model is probably incorrect.
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I'm sure most people here remember exactly the same discussion taking place when DCS Fw 190 D-9 appeared. One of the developers posted a factory drawing of the windshield saying they used that for the model, and model is 100% accurate and everybody is wrong to criticize the now famous "cockpit bar". What I find amazing is that developers really don't seem to understand that the forward-downward visibility angle through the gunsight reflector is INCREDIBLY IMPORTANT. This angle is already pretty small for most WWII fighter aircraft. And the developers appear to think reducing the angle by 50% is really no big deal!!! I have the Fw 190 D-9 module but I don't have (yet) the A-8. In the day it was released I was curious how the cockpit looks like and I searched youtube for videos. When I saw the "cockpit bar" blocking half of gunsight's reflector glass area below the central cross I was really shaking my head in disbelief! They did it again! And it appears that is actually worse than in D-9. During the internal testing of the module nobody was bothered by this? Nobody noticed that you can't hope to shoot down anything except an aircraft in linear flight? Of course the real aircraft was designed so that the ENTIRE gunsight reflector glass is unobstructed. It's common sense. I see there is even video proof of this, posted somewhere else on the forum. I hear that simulating refraction in the simulator is not an option because it would hurt performance. The developer's solution? They decided there is no solution! The solution was really obvious but nobody bothered. When designing the cockpit model they should have DEVIATED from factory drawings of the real aircraft. Make the cockpit bar lower/thinner, or move the instrument panel sun shield together with the gunsight higher, or a combination of both. I don't know exactly how it should have been done, I am no 3D modeller and I don't know in detail the geometry of the problem. But definitely the geometry could have been modified in a graceful way so it appears like a close replica of the real one and the gunsight is unobstructed.
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I haven't flown the Spitfire for more than a year. Tried it today and honestly I am shocked this problem is still not solved. This is not something of little importance. Really nobody is bothered by this? Developers included?
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MiG-29 engine RD-33
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Fulcrum is a handfull in landing pattern.
Fox One replied to DmitriKozlowsky's topic in MiG-29 for DCS World
Yes, I have also tested Su-27, Su-33 and F-15. Ground effect is not simulated. -
Fulcrum is a handfull in landing pattern.
Fox One replied to DmitriKozlowsky's topic in MiG-29 for DCS World
Yes, I tested it using the method described here https://forums.eagle.ru/showpost.php?p=2901404&postcount=2 If I remember correctely, I maintained 280 Km/h during the test with minimum fuel remaining. I switched on the flight information bar in the cockpit to be able to maintain the speed precisely. -
Fulcrum is a handfull in landing pattern.
Fox One replied to DmitriKozlowsky's topic in MiG-29 for DCS World
That is most likely because, unfortunately none of the FC3 aircraft has ground effect implemented (demonstrable fact). If ground effect was implemented, in MiG-29 for a given AOA at touchdown the speed would easily be like 15 Km/h lower. -
Bug: MiG-29A/G/S Not working 1 flap position.
Fox One replied to Quetzalkoatl's topic in MiG-29 for DCS World
As has already been said here, the MiG-29 flaps is a "floating" type - the extension angle depends on airloads. Nothing really new - MiG-21 and -23 have floating flaps too. The diagram for MiG-29 flaps below shows that above 460 Km/h flaps will start to gradually retract. Below 460 Km/h its deflection angle is maximum, 25 deg. They also show typical lowering and retraction speeds for the flaps, suggesting that during normal, routine operation of the aircraft at takeoff and landing the flaps usually doesn't have the "chance" to float. -
Right cockpit panel with dimensions:
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Bug: MiG-29A/G/S Not working 1 flap position.
Fox One replied to Quetzalkoatl's topic in MiG-29 for DCS World
Yes. MiG-29 has only up and full down (25 deg) trailing edge flaps positions and this is clearly described in RL manuals. The reason in cockpit there is a flaps control panel with 3 buttons - this is an old control panel type that is also used on MiG-21 and -23. On most MiG-29 built they simply didn't bother to change it. http://hunavia.freeweb.hu/TYPE/MiG-29%20base/MiG29UBCOCKPITIDNo27/photos/photo4.html In this picture is front cockpit of MiG-29UB two-seater. This is most likely a later-built aircraft and the flaps control panel was changed with two buttons, but the flaps system of MiG-29 and MiG-29UB is of course identical and always was with only up or down positions. -
In the attached track, I take off with 100% fuel in full AB. At the beginning of the takeoff run I pull the stick completely. Watch the aircraft from outside at 1/4 speed. The nose gear lifts off the runway at 75 Km/h. The aircraft has so much desire to rotate even at such ridiculously slow speed, I actually have to push the stick to stop the nose up motion. By the time the speed reaches 130 Km/h, I'm already at the required 10 deg standard takeoff pitch attitude, with the stick pushed completely! I'm not saying the real flight manual says to pull the stick completely on takeoff. It doesn't. But the behavior I described above is laughable. There is no supersonic aircraft of any era that can be rotated on takeoff at 75 Km/h. Not even close. I know when the axial air intakes open at 200 Km/h there is a nose down moment and an additional stick pull is necessary to maintain the pitch, this is described in the real flight manual. In simulator the additional stick pull is moderate and I see no problem here. But in the attached track I tried to maintain precisely 10 deg pitch during takeoff run and immediately after getting airborne. The feel of the aircraft in pitch is incredibly wobbly. As if it has almost no angular inertia. Several very fast control inputs are necessary but precise pitch control is close to impossible IMO. And no, it's not a matter that I don't use enough curvature on pitch axis. I use much much more curvature than I usually do on fast jets, but it's still kinda in vain. 29TO.trk
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When we will be able to aerobrake like that? Right now after touchdown with minimum descent rate, even if stick is pulled fully aft as fast as possible, the nose gear still goes down quickly. Something is really off in the flight model.
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The test (track attached): With 30% fuel and no external stores, I fly horizontally at 240kts. The required engines rpm is 74%. Then I lower landing gear and increase the rpm to 94% to keep the speed constant at 240kts. So in order to compensate for landing gear drag the engines rpm must be increased by a shocking 20%. For 2 engines in this class, an increase in rpm of 20% means an increase in thrust for both engines of SEVERAL TONS. You need something like a Concorde landing gear to have a drag of several tons. MiG-21 in reality typically extends landing gear and fly the circuit at 500Km/h. If the F-18 with gear down needs 94% rpm to fly horizontally at 450Km/h, the MiG-21 should need afterburner to fly horizontally at 500Km/h with gear down. The good thing is that for F-18 in simulator at typical approach speeds landing gear drag seems resonably low. Out of curiosity I performed tests with Su-33 and F-15, I extended landing gear in horizontal flight at 500Km/h and increased rpm to keep the speed constant. For both aircraft the required rpm increase was about 5%. gear drag.trk
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@Vatikus Can you please provide a link for that document? Thanks
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The last MiG radar that used conical scan for locking was MiG-21's RP-21. RP-22 from MiG-21bis is monopulse. MiG-23M, MF radars naturally are also monopulse. Even R-23R missile seeker is monopulse. MiG-23M, MF radars - monopulse, inverse cassegrain antenna MiG-23ML, MLD, P radars - monopulse, twist cassegrain antenna
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From Su-27 flight manual:
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I just checked the flight manuals I have (MiG-21, -23, -29) and for all they say the pilot before landing flare should look left and down to visually estimate the height. The MiG-21 and -29 also have landing lights pointing slightly to the left (demonstrable fact). On MiG-31 landing lights are also pointing to the left, see picture. The purpose of this is not for the pilot to admire the landscape left of the aircraft during landing approach when he is at 100m altitude. The purpose is to aid the pilot in visually judging height immediately before and during landing flare. And it's not like the left side is bright from the lights and in front of the aircraft you have a big and fat darkness. The lights are pointed to the left just a few degrees, IRL they are illuminating left AND forward. So MiG has built for decades aircraft with landing lights pointing slightly to the left but, BREAKING NEWS, Sideslip finds it a very strange design choice.
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On real aircraft, the radar altimeter value is displayed on HUD with 10m increment. The 1m increment is a gameplay compromise. So IRL you don't have the luxury of knowing radar altitude down to the last meter. When you land, after you see 10m on HUD, the next value displayed will be 0. Sure, you could try to look at cockpit instrument for a more accurate reading when below 10m, but I very much doubt IRL anybody is looking low on the instrument panel during landing flare at night.