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ahinterl

Airliners more stable in the air in real world?

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I've started to watch JustPlane's MD-11 video, and every time I see videos like this, from the cockpit perspective, I have the impression that in real life, airliners are much more stable in the air and perform more fluid movements than what I experience in FSX with any of my many payware airliners.I like to hand fly my planes, but when I do so, I need to constantly fight against e.g. nose dropping by heavily using trim, course changes and ILS approaches are quite difficult because of lateral corrections and over-corrections, and all in all I don't "feel" a similar degree of fluidity of movements and stability like I do when watching those videos even in big jets like the PMDG MD-11.Approaches there have a different taste, everything looks like it was much easier to perform than in FSX, and big plane don't "dance and rock'n'roll" in the air. The same when I attend a flight as a passenger, rolls are smooth always, from start to finish of the roll.Is it really so that in FSX, airplanes behave significantly different to their real world counterparts, no matter how "good" their FDEs are, and that hand flying in FSX is more "demanding" than in reality?Andreas

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I dont know what you use to fly, but if you use a joystick then compared the travel of the joystick to the travel of a real life yoke. The real life yoke has a much bigger working range compared to a joystick, effectively making steering less sensitive. Add in the 1000s of hours of experience the real life pilots have when it comes to hand flying, not to mention the old "seat-of-the-pants" effect. You'd feel motion changes in the plane alot easier through your ear than you would by looking at a monitor and they are therefore able to make adjustments way earlier than us sim pilots

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When I first flew a small GA plane after years of sim experience, I was surprised at how much easier the real thing was to control. It's not just airliners - the sim just has a hard time simulating the "feel" of flying with a high degree of accuracy. That seat-of-the-pants sensation of flying in the real thing helps tremendously, and it's completely missing in computer-based sims.

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When I first flew a small GA plane after years of sim experience, I was surprised at how much easier the real thing was to control. It's not just airliners - the sim just has a hard time simulating the "feel" of flying with a high degree of accuracy. That seat-of-the-pants sensation of flying in the real thing helps tremendously, and it's completely missing in computer-based sims.
I agree with Bill, at least for GA aircraft. Even the Frasca sim that I have used for IFR currency is harder than the real thing, we used to say that if you could fly the sim then you could ace the real plane. The largest issue for both FSX and the Frasc sim, for me at least, is the pitch attitude stability. I don't know why sims are so hard to get pitch stability like the real airplane, and this could also be a yoke issue, although I find it interesting that two totally different sims with totally different hardware produce the same distortion.If I get the real airplane properly trimmed with the correct power set, I can "ride the glide slope" to near minimums with hands off ( but not the localizer, obviously)Bruce.

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I agree with Bill, at least for GA aircraft. Even the Frasca sim that I have used for IFR currency is harder than the real thing, we used to say that if you could fly the sim then you could ace the real plane. The largest issue for both FSX and the Frasc sim, for me at least, is the pitch attitude stability. I don't know why sims are so hard to get pitch stability like the real airplane, and this could also be a yoke issue, although I find it interesting that two totally different sims with totally different hardware produce the same distortion.If I get the real airplane properly trimmed with the correct power set, I can "ride the glide slope" to near minimums with hands off ( but not the localizer, obviously)Bruce.
I think you are spot on with your observations. I drove a 777 sim at the UAL training center when AVSIM had its conference in that city. The plane was very easy to fly - and tended to be very stable. It went where you pointed it. I was able to land three times, once in a 20 knot cross wind, without breaking the bird. The plane descended on rails. Small trim adjustments were all that were necessary to keep it dead on the glide slope. Colin

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Hi Andreas,My future son in-law flies for a major carrier(First Officer) He flys the CRJ 200. Last time he was in my studio to visit, I let him have a whirl at my setup. He wanted to use a island hopper. At the time I was just using FS9. I let him use the Aerosim DHC6 Twin Otter. Very dated as of today. I just never liked the FDE on this bird and found it to be somewhat of a pain trimming and on takeoff it was just a real pain as sometimes, as I pull the yoke back at VR, all of a sudden the aircraft would rocket up way beyond what would be acceptable in real life. Every barf bag would be gone in seconds! I told him to use some of my higher end add ons with good FDE's, graphics and such, but he said that would be fine for S & G's. So, he takes off from TNCM and didn't take his eyes off the instruments and was steady as a rock, and I mean nothing like I was able to get from this bird. So I really believe that the hours under the belt of a real world pilot does make the difference along with the distance of yoke control in certain aircraft as well. I realize you were comparing the MD11, but I thought this made sense. Hope I helped in some way to answer your question. Sorry for such a long response, I'm way overtired and need some sleep. Have a good night.Warm regards, Jeff Moss

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Hi Andreas,My future son in-law flys for a major carrier(First Officer) in the CRJ 200. Last time he was in my studio to visit, I let him have a whirl at my setup. He wanted to use a island hopper. At the time I was just using FS9. I let him use the Aerosim DHC6 Twin Otter. Very dated as of today. I just never liked the FDE on this bird and found it to be somewhat of a pain trimming and on takeoff it was just a real pain as sometimes, as I pull the yoke back at VR, all of a sudden the aircraft would rocket up way beyond what would be acceptable in real life. Every barf bag would be gone in seconds! I told him to use some of my higher end add ons with good FDE's, graphics and such, but he said that would be fine for S & G's. So, he takes off from TNCM and didn't take his eyes off the instruments and was steady as a rock, and I mean nothing like I was able to get from this bird. So I really believe that the hours under the belt of a real world pilot does make the difference along with the distance of yoke control in certain aircraft as well. I realize you were comparing the MD11, but I thought this made sense. Hope I helped in some way to answer your question. Sorry for such a long response, I'm way overtired and need some sleep. Have a good night.Warm regards, Jeff Moss

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So, what would be the most realistic settings in FSX under "Realism".. I heard that all sliders to the right are not the most realistic?

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I think you are spot on with your observations. I drove a 777 sim at the UAL training center when AVSIM had its conference in that city. The plane was very easy to fly - and tended to be very stable. It went where you pointed it. I was able to land three times, once in a 20 knot cross wind, without breaking the bird. The plane descended on rails. Small trim adjustments were all that were necessary to keep it dead on the glide slope. Colin
I was there too Colin and used the 737 and A320 sims. Both of these were actually very easy to fly - yes, even the A320 without using the AP! Regardless of how easy the real sims are, evey pilot I've ever discussed this with claims that the real sims are actually harder to fly than the real plane!That said, there are a few add-ons that have managed to capture the "feel" of real aircraft. IMHO, the flight model should always be setup to assume FS realism settings are all to the right (because that's where most users will have them) and should also be dampened down enough to give the typical joystick user the "feel" of the real thing (again because most users will be using a joystick and that tends to be be far more sensitive than a yoke). Ideally, products should actually include 2 flight models; one for joystick and one for yoke. This has become a bit obvious with the recent Aerosoft AirbusX with some users claiming it's really sluggish to control. With default settings for the controller and using a joystick I'd say it's very close to what I remember the sim felt like in roll and for me at least, it's still too sensitive in pitch. I wonder how many that think it's sluggish are using a yoke though?My pet hate with almost all flight models is the poor pitch stability and the even poorer constant need to trim. People who use FS actually think that when you change pitch (especially in an airliner) you need to repeatedly re-trim, even though the A/THR is keeping the speed constant. If you're flying without AP and say just using A/THR to hold the speed, you should firstly be able to trim for level flight and walk away for at least a few minutes without any drama...........how many add-ons can you do that with? Once in trimmed level flight, if you pitch up 10 degrees and hold it while the A/THR catches up, you should be able to release the controls and maintain the pitch without the need to re-trim.............how many add-ons can you do that with?So yes (to the OP) airliners are, in at least 95% of add-ons, more stable in the real world than the sim.

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Thank you for the answers.I guess that if it were possible to replicate the stability of real airliners in FSX, developers like PMDG would have created flight dynamics different to what they have delivered with their products.On the other hand, it could be possible that the specialists who are in charge of developing the flight dynamics for FSX add-ons aren't aware that real life planes are so much more stable in the air - like "on rails" as someone said - and because of that don't see a requirement to change their development goals.Is it possible to alter the FDE somehow to make a plane more stable without breaking the entire flight dynamics? I know of some parameters in the aircraft.cfg file which have to do with moment of inertia and axis stability. But I wonder whether I can kind of adjust them without destroying the flight dynamics completely because they are related to many other parameters which would then yield a different outcome and the flight experience would change drastically and be worse than before.At least I'd wish a higher pitch stability for my airliners...

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AndreasIt's not an airliner I know, but have a go with the Lotus Sim L-39.Of all the planes I've ever flown in FS that's the one I find is the best for pitch stability.I've only flown Warriors in real life, and had a go in a couple of airline simulators, but for me, the L-39 gets closest to that feel.The CLS 767 is also pretty good in that regard. It's got a heavy, 'solid' feel which I like, and feels more like the professional sim. Ian

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My pet hate with almost all flight models is the poor pitch stability and the even poorer constant need to trim. People who use FS actually think that when you change pitch (especially in an airliner) you need to repeatedly re-trim, even though the A/THR is keeping the speed constant. If you're flying without AP and say just using A/THR to hold the speed, you should firstly be able to trim for level flight and walk away for at least a few minutes without any drama...........how many add-ons can you do that with? Once in trimmed level flight, if you pitch up 10 degrees and hold it while the A/THR catches up, you should be able to release the controls and maintain the pitch without the need to re-trim.............how many add-ons can you do that with?So yes (to the OP) airliners are, in at least 95% of add-ons, more stable in the real world than the sim.
Second that, the weak pitch stability of airliners is the main weakness I struggle with for years now.Leaves the question: Are the FDEs of current FSX add-on airliners (sorry, I fly that type of planes almost all of my time) the best that's possible to replicate the real world counterparts or are they mainly the result of a best-guess of a developer who has no experience with full motion professional simulators and/or real airliners?

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I find this an odd or more disturbing discovery. Aren't most add on's always advertise about being "approved" by a "real" pilot? if so, then should we be having these pitch stability issues?

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I find this an odd or more disturbing discovery. Aren't most add on's always advertise about being "approved" by a "real" pilot? if so, then should we be having these pitch stability issues?
Of course they are, but what does it actually mean?It's a bit like the other bit you often see added "within the limitations of FS" :( Fact is, some flight models are more realistic than others and generally, the forums are the best place to find the truth. As a "commercial member" it would be wrong of me to comment on other products specifically, but you can sometimes use commonsense i.e. the PMDG J41, I mean Robert Randazzo flew the bloody things for a living so one would imagine it must be pretty similar. But, your experience will only be like his if you have the same settings for the same controller.I also know of a 727 that was modelled by a former 727 FO and included 2 current 727 pilots in it's beta team as well as a number of former 727 pilots including the late Clay (B52drvr) and many seem to think that it flies correctly; probably because of the countless hours spent on the phone flying simultaneous flights with real pilots and listening to what they were being critical of!

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That's funny. Since years everyone is complaining that MSFS planes feel 'like on rails' are too stable and x-plane is much better etc...And now just the opposite happens, why? I have no idea.Just tried the default 737 and I didn't find her to be too unstable in pitch at all(turning behaviour is unrealistic but easy to correct).Pitch feels quite realistic to me.The 777 and the A320 aren't valid examples as the FBW system makes flying much easier.On a 737 or 767 you are trimming a lot if you change the thrust setting etc.. as the thrust line is very low with the low mounted engines.E.g. when you pull the thrustlevers back during the flare in the 767 you need to pull back considerable, just to keep the nose from dropping.If you fly level with the default 737, trimmed out, hands off and you add thrust, she starts to climb as she's supposed to do.@ AndreasWhere in VIE are you living? Maybe we could meet if you wantBest regardsBernt

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As a real pilot I can confirm that maintaining stability in the sim is much more difficult than in real life.For example the VC10 in real life has a fly by wire (long before Airbus) and hydraulic combination with an integrated "feel" computer to make it a little heavier, being as it is a high performance a/c. Coupled with the high momentum of a jet a/c (which is not modelled in the sim)jets generally are very easy to fly. And, I can tell you from personal experience that landing at VHHX was a quite normal event even with cross winds. Because in the a/c you could feel the aeroplane and compensate. Whereas in the sim there is no feel. No feed back from the control surfaces at all. All you have are the visual cues which in themselves are like flying an aeroplane by looking through a keyhole in comparison to reality.vololiberista

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The question was if FSX airliners are too unstable or not.I agree that without the feedback and only tiny visual cues it's more difficult, but I don't think that the planes are too unstable.I'm surprised to learn that the VC-10 was a FBW plane! Didn't know that. Always thought the Concorde was the first FBW airliner.If you mean the hydraulic packs located in the vicinity of the flight controls....that was even earlier in the Vickers Valliant

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Just tried the default 737 and I didn't find her to be too unstable in pitch at all(turning behaviour is unrealistic but easy to correct).Pitch feels quite realistic to me.Best regardsBernt
Hi Bernt.Funnily enough, I've always thought the default 737 was OK though I couldn't say the same for the Lear or CRJ.What are you up to these days?

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Hi Bernt.Funnily enough, I've always thought the default 737 was OK though I couldn't say the same for the Lear or CRJ.What are you up to these days?
Hi Paul, Exactly. If you want I can e-mail you the changes for the FDEs concerning the turning behaviour. It's a real nice plane to fly and you are correct the Lear, CRJ and the especially the A320 aren't too realistic. The only other shortcoming with the 737 is the engine spool up rate, but as I've just finished the new FDEs for the Flight Replicas Me262 I've found a nice solution.The last patch for the Milviz Cessna 310 should be out soon and I've started already working on the FDEs for the next Milviz project. With the little remaining time I'm working on my first own FSX freeware plane, a PZL-104 Wilga35. Any news concerning a FSX 727? Are you still involved in FS projects?Best regardsBernt

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As a real pilot I can confirm that maintaining stability in the sim is much more difficult than in real life.For example the VC10 in real life has a fly by wire (long before Airbus) and hydraulic combination with an integrated "feel" computer to make it a little heavier, being as it is a high performance a/c. Coupled with the high momentum of a jet a/c (which is not modelled in the sim)jets generally are very easy to fly. And, I can tell you from personal experience that landing at VHHX was a quite normal event even with cross winds. Because in the a/c you could feel the aeroplane and compensate. Whereas in the sim there is no feel. No feed back from the control surfaces at all. All you have are the visual cues which in themselves are like flying an aeroplane by looking through a keyhole in comparison to reality.vololiberista
Also, to add to my earlier comments- in FSX when you do have the aircraft trimmed for level flight (and this takes using ALT-HOLD with the AP in some if not most instances, as discussed above), then you bank the aircraft, there is an instantaneous pitch down effect. When I trained for my instrument rating I had picked up real flying after a long hiatus of nearly 10 years since I had flown before, and my CFII continually balked at my climb from level flight when turning, until I identified this as a bad habit from FSX- as you need to apply nose-up input to the yoke on the sim to avoid descending. We discussed this at length after several flights. This is all connected to the lack of pitch attitude stability- if you don't pull back in the sim when turning you descend, AND your speed increases. Now, an aircraft is trimmed for speed, that's why you trim- and while eventually the nose of a real aircraft will start to fall in a turn with no correction (not talking steep turns here), if speed increases then the nose will tend to rise relative to the wing (as long as the angle of bank is not in excess of 40 degrees for a C172 where the over-banking tendency starts to become a factor).I'm not criticizing FSX, I'm just wondering why it has always been this way in a sim- and not just a desktop sim either, as I mentioned before, a multi-thousand $$ Frasca sim does the same. I don;t know enough about how sims work to know why such a critical relationship cannot be better simulated, after all- this attitude stability stuff goes right back to basic stick and rudder theory that pilots get rammed down their throats by frustrated instructors in the first hours of flight.Interesting topic! Bruce.

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I think there are a multitude of different mathematical models to simulate air dynamics. None of them could simulate reality 100% correctly. They all are an approach to what exists in the real world, they model highly complex procedures. They are what they are, models and approximations. Maybe one day when computers are powerful enough there will be an increase in the level of fidelity. I don't expect that FSX simulates a real plane 100%, I just want to dampen some nasty things that annoy me for a long time. The pitch stability problem is high up in my list, guess I'll start to play with config file editing and see where I end up...

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The problem is not really down to mathematical models although they have to be close. The real problem is complete lack of feel. As a pilot you feel the aeroplane. It is telling you what it wants to do and the pilot's control inputs aim to prevent the aeroplane from diverging from the intended trajectory.Go up with a real pilot on a gusty day and you will see him or her constantly adjusting the control surfaces and if he/she is good the wings will stay level. That is just one example. The feedback that an aircraft gives you as a pilot and how you respond is what makes you a pilot and not a simmer. This will never be modelled in the sim so from that aspect it most definately NOT as real as it gets!!!!!!vololiberista

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@bruce>This is all connected to the lack of pitch attitude stability- if you don't pull back in the sim when turning you descend, AND your speed increases. >Now, an aircraft is trimmed for speed, that's why you trim- and while eventually the nose of a real aircraft will start to fall in a turn with no correction, if speed increases then the nose will tend to rise relative to the wing If you trim for straight and level flight is not possible to maintain the altitude and/or speed without compensating for the turn. The lift vector is pointed straight up during level flight, but banked during a turn.Hence the vertical component is shorter as the banked part is needed for pulling the plane through the turn. You need to compensate for that.@ahinterl>I don't expect that FSX simulates a real plane 100%, I just want to dampen some nasty things that annoy me for a long time. >The pitch stability problem is high up in my list, guess I'll start to play with config file editing and see where I end up...As vololiberista pointed out, it's more difficult (even a 'real' sim is more diffcult to fly because it can't replicate the 'feel' and motion exactly), but this is NOT a pitch stability problem!You can make it easier but less realistic by simply pumping up the pitch stability in the cfg file.@vololiberistaThere's simply (luckily!) no substitute for flying a real plane and even the best multi million dollar sims are more 'procedure trainers' than 'flight sims'

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Thank you all for your input. Guess I do the ATPL and buy me a customized airliner once I crack the lottery... :(

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@bruce>This is all connected to the lack of pitch attitude stability- if you don't pull back in the sim when turning you descend, AND your speed increases. >Now, an aircraft is trimmed for speed, that's why you trim- and while eventually the nose of a real aircraft will start to fall in a turn with no correction, if speed increases then the nose will tend to rise relative to the wing If you trim for straight and level flight is not possible to maintain the altitude and/or speed without compensating for the turn. The lift vector is pointed straight up during level flight, but banked during a turn.Hence the vertical component is shorter as the banked part is needed for pulling the plane through the turn. You need to compensate for that.
Yes- I know, it's the distortion of over-emphasising this in the sim that is the issue.But- as you say:"There's simply (luckily!) no substitute for flying a real plane and even the best multi million dollar sims are more 'procedure trainers' than 'flight sims'". I agree, but in this age of virtual worlds, it's a shame that something that seems to transgress at least several sim platforms can't be at least made to be behave more realistically. Also agree with you- FSX is great for procedural stuff, sure beats chair flying :)Thanks, Bruce.

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