Stiff flight model problem

[teopereira 25]

I've just downloaded the Windows v9.45 Demo. But I'm noticing that the flight model for all aircrafts are unusually stiff. I mean, there is no smoothness in the flight models, if you for example let the joystick free during a turn, the aircraft will remain in the exact position without swinging a bit. Is that normal or just a configuration adjustment?Thanks!

[Simmo W 24]

I've just downloaded the Windows v9.45 Demo. But I'm noticing that the flight model for all aircrafts are unusually stiff. I mean, there is no smoothness in the flight models, if you for example let the joystick free during a turn, the aircraft will remain in the exact position without swinging a bit. Is that normal or just a configuration adjustment?Thanks!

Sounds very strange, normally it's the opposite - Hands off stick without ap = gone! Is it a slow pc? Very hard to diagnose without more info. MAybe somehaw ap accidentally on, or else how can u take off

[teopereira 25]

Sounds very strange, normally it's the opposite - Hands off stick without ap = gone! Is it a slow pc? Very hard to diagnose without more info. MAybe somehaw ap accidentally on, or else how can u take off

It's a "AMD Quad" and joystick "Leadership gamer". What I notice is that there isn't that smooth rolling real flight models have. For exemple, if you center the joystick during a roll, the aircraft immediatly stops its roll and stays banked.

[Guest Setanta]

It's a "AMD Quad" and joystick "Leadership gamer". What I notice is that there isn't that smooth rolling real flight models have. For exemple, if you center the joystick during a roll, the aircraft immediatly stops its roll and stays banked.

This is one of my pet hates within X-plane (and MSFS btw) - though normally it's only noticeable if you deliberately provoke it. It does depend on the aircraft and possibly on your settings. Since it seems to be happening with all aircraft my first guess would be that you have the stability augmentation turned up too far. Go to Settings > Joystick Keys & Equipment and click on the 'Center' tab. On the right hand side there are three sliders. Turn these down to minimum and try again. Most native X-Planers tend to fly with them off while most people converting from MSFS tend to keep them on to some extent until they get used to the different handling within X-Plane. It's mostly a matter of personal preference.If this doesn't help - I'd recommend trying Morten's excellent Piper Archer - It's still in beta and has no 3-D cockpit as yet, but the feeling of the flight model is the best I've come across in any sim. Oh, and it's free :) Actually come to think of it I recommend this aircraft to anyone who will listen :) It flies fluidly and to me is the first aircraft I've flown that actually gives me moments where I forget I'm using a simulator.If this also feels 'stiff' then I'd advise deleting your X-Plane preferences (in 'X-Plane Folder'/Output/Preferences) and reconfiguring because there's something wrong somewhere.Setanta

[teopereira 25]

This is one of my pet hates within X-plane (and MSFS btw) - though normally it's only noticeable if you deliberately provoke it. It does depend on the aircraft and possibly on your settings. Since it seems to be happening with all aircraft my first guess would be that you have the stability augmentation turned up too far. Go to Settings > Joystick Keys & Equipment and click on the 'Center' tab. On the right hand side there are three sliders. Turn these down to minimum and try again. Most native X-Planers tend to fly with them off while most people converting from MSFS tend to keep them on to some extent until they get used to the different handling within X-Plane. It's mostly a matter of personal preference.If this doesn't help - I'd recommend trying Morten's excellent Piper Archer - It's still in beta and has no 3-D cockpit as yet, but the feeling of the flight model is the best I've come across in any sim. Oh, and it's free :) Actually come to think of it I recommend this aircraft to anyone who will listen :) It flies fluidly and to me is the first aircraft I've flown that actually gives me moments where I forget I'm using a simulator.If this also feels 'stiff' then I'd advise deleting your X-Plane preferences (in 'X-Plane Folder'/Output/Preferences) and reconfiguring because there's something wrong somewhere.Setanta

This is an amazing aircraft! I'm getting to the conclusion that this kind of aerodynamics is normal in X-Plane, although I don't know whether it's normal in real flight. I was controlling the aircraft through the mouse and it seems that this sudden stop on the rolling when you center the ailerons is normal, at least for the smaller aircrafts.Thank you!

[LAdamson 240]

This is an amazing aircraft! I'm getting to the conclusion that this kind of aerodynamics is normal in X-Plane, although I don't know whether it's normal in real flight. I was controlling the aircraft through the mouse and it seems that this sudden stop on the rolling when you center the ailerons is normal, at least for the smaller aircrafts.Thank you!

If I quickly turn the yoke (aileron) in a real Cessna 172 to the left and let go, the plane will swing back to neutral. Even might roll to the right just a bit before going back to level.If I do the same in my Van's RV (but with a stick), the wing will just stay at that angle for a bit.Keep in mind, that airloads move the stick/yoke back in the real planes, while sim stick/yokes have a centering spring...........and I have no idea of what a mouse is doing as far as centering.L.Adamson

[teopereira 25]

If I quickly turn the yoke (aileron) in a real Cessna 172 to the left and let go, the plane will swing back to neutral. Even might roll to the right just a bit before going back to level.If I do the same in my Van's RV (but with a stick), the wing will just stay at that angle for a bit.Keep in mind, that airloads move the stick/yoke back in the real planes, while sim stick/yokes have a centering spring...........and I have no idea of what a mouse is doing as far as centering.L.Adamson

When I said "centering with the mouse" I meant neutralizing the ailerons. So, that means X-Plane's Cessna stays banked when you neutralize the aileron during a roll, while a real Cessna swings back to level. That's something I didn't know about real aerodynamics and that shows X-Plane aerodynamics has this yet to solve fault.Thank you!

[LAdamson 240]

When I said "centering with the mouse" I meant neutralizing the ailerons. So, that means X-Plane's Cessna stays banked when you neutralize the aileron during a roll, while a real Cessna swings back to level. That's something I didn't know about real aerodynamics and that shows X-Plane aerodynamics has this yet to solve fault.Thank you!

That's why flight models need to be "tweaked" to perform like the real airplane, if the programmer wants to take it that far.Another example is flaps. When flaps are deployed in a high wing Cessna 172, the plane balloons (pitches up). You're normally prepared for it, and just push forward on the yoke a bit, as the flaps go down.On my low wing RV, the nose will pitch down when I extend flaps. If I let go of the stick, the airplane would actually descend, but the stick forces to keep it level are light. The RV's that come as default for X-Plane 9 ..........pitch up just like the Cessna does. This is another case where tweaking has to be done to reverse the situation. I'll just assume that plane maker isn't powerful enough to do it on it's own. For all I know, maybe flap pitch is something that has to be set manually anyway.And you can't assume that high wings will pitch up & low wings will pitch down. Just depends on the airplane.L.Adamson

[Guest Setanta]

If I quickly turn the yoke (aileron) in a real Cessna 172 to the left and let go, the plane will swing back to neutral. Even might roll to the right just a bit before going back to level.If I do the same in my Van's RV (but with a stick), the wing will just stay at that angle for a bit.Keep in mind, that airloads move the stick/yoke back in the real planes, while sim stick/yokes have a centering spring...........and I have no idea of what a mouse is doing as far as centering.L.Adamson

When I said "centering with the mouse" I meant neutralizing the ailerons. So, that means X-Plane's Cessna stays banked when you neutralize the aileron during a roll, while a real Cessna swings back to level. That's something I didn't know about real aerodynamics and that shows X-Plane aerodynamics has this yet to solve fault.Thank you!

Just wondering if we're all talking about the same thing here (or maybe it's just me that's misunderstood). Before I start I need to point out that I don't fly RL and what I'm basing my comments on is a knowledge of basic physics. If I have anything totally wrong let me know - I'm always willing to learn :) And yes, I'm generalising a lot - assuming that aircraft are designed to be stable etc.What I was talking about was the situation where you're trimmed for level flight and, for instance, you initiate a maximum rate roll to the left. The aircraft won't instantly start to move at the maximum roll rate because it has to overcome inertia so it will build up to it. This seems fairly well modelled in X-plane (at least in well modelled aircraft :). However, if you then neutralise the ailerons, the momentum should keep the aircraft rolling increasingly slowly to the left until it stops. This doesn't seem to be modelled at all in either X-Plane or FSX from what I can see as the aircraft just seem to stop rolling instantly.LAdamson's example above seems more to refer to the so called 'pendulum effect'. The C172 is a high wing/low CoG aircraft and basically acts like a pendulum. Nudge it to one side and the weight of the aircraft will tend to swing it back to level once more. The RV being a low wing/high CoG aircraft depends (as far as I understand) on the dihedral effect to stabilise it under the same circumstances which would explain the different behaviours of the two (and why low wing aircraft tend to have much higher dihedral angle than high wing aircraft). I'm not sure how well this is modelled if at all in either X-Plane or FSX but given the scenario I was talking about originally I wouldn't tend to hold out much hope.Of course we could both be talking about something wrong altogether when I look back at the original post. Spiral Mode stability. Most aircraft are designed to have a stable spiral mode which mean that given time with no control input they will return to a wings-level bank angle. From what I recall both X-Plane and FSX model this effect.

That's why flight models need to be "tweaked" to perform like the real airplane, if the programmer wants to take it that far.

Yep - an awful lot depends on the particular aircraft - why I love that Archer :)

Another example is flaps. When flaps are deployed in a high wing Cessna 172, the plane balloons (pitches up). You're normally prepared for it, and just push forward on the yoke a bit, as the flaps go down.On my low wing RV, the nose will pitch down when I extend flaps. If I let go of the stick, the airplane would actually descend, but the stick forces to keep it level are light. The RV's that come as default for X-Plane 9 ..........pitch up just like the Cessna does. This is another case where tweaking has to be done to reverse the situation. I'll just assume that plane maker isn't powerful enough to do it on it's own. For all I know, maybe flap pitch is something that has to be set manually anyway.

Oh no not this again :) Yes the default RVs in X-plane do not behave very realistically - but there's a reason for this (given in Austin's own inimitable style):

...Now, of course, I have one WARNING!These planes are very GENERIC instances of each RV!I DON'T KNOW what the V-speeds will be, exactly, for your particular RV.I DON'T KNOW what the engine will be, exactly, for your particular RV.I DON'T KNOW what the prop will be, exactly, for your particular RV.I DON'T KNOW what the weights will be, exactly, for your particular RV.I DON'T KNOW what the paint will be, exactly, for your particular RV......You, as an RV builder or flyer, must now MODIFY any of these craft in Plane-Maker to be the same as YOUR ACTUAL RV! That way, you can use these 'default starting-point' craft to get to your particular RV in no time flat...

The above quote is extracted from a file supplied with every copy of X-plane in the 'Van's RVs' folder.They're not meant to be finished aircraft but a starting point for people to build their own. Incidentally, the amount the aircraft pitches up/down on deployment of flaps can be set in PlaneMaker by modifying a single value (well, two if you have two separate sets of flaps ;).

And you can't assume that high wings will pitch up & low wings will pitch down. Just depends on the airplane.L.Adamson

What, you mean like two different RV's perhaps? :(Setanta

[LAdamson 240]

What I was talking about was the situation where you're trimmed for level flight and, for instance, you initiate a maximum rate roll to the left. The aircraft won't instantly start to move at the maximum roll rate because it has to overcome inertia so it will build up to it. This seems fairly well modelled in X-plane (at least in well modelled aircraft :). However, if you then neutralise the ailerons, the momentum should keep the aircraft rolling increasingly slowly to the left until it stops. This doesn't seem to be modelled at all in either X-Plane or FSX from what I can see as the aircraft just seem to stop rolling instantly.

It was probably five years ago, when I tested the Cessna 172. It was in response to flight sim questions such as this. I quickly rolled the yoke to the left & let go. Probably was full deflection, but I no longer remember. The response was neutral stability, and it rolled right back to neutral, and actually past neutral for a portion of a second. If you slowly roll a Cessna into bank, it will get to the point to where the bank increases if you let go. At least as I remember.I already knew from a Pitt's aerobatic plane, that that aircraft would remain in a bank when letting go. Same with my RV, that's semi aerobatic. I've never kept a Cessna in a spiral & let go to check stability, and have not done it with the RV either. If I ever fly a Cessna again, I'll check it out. Flew one home a year ago, that had to have the windscreen replaced in another state. But other than that, I don't fly them anymore.

Yep - an awful lot depends on the particular aircraft - why I love that Archer :)

I mostly flew the Archer for the PPL

The above quote is extracted from a file supplied with every copy of X-plane in the 'Van's RVs' folder.They're not meant to be finished aircraft but a starting point for people to build their own. Incidentally, the amount the aircraft pitches up/down on deployment of flaps can be set in PlaneMaker by modifying a single value (well, two if you have two separate sets of flaps ;).

Yes, but you have to figure that they made the initial run through plane maker...

What, you mean like two different RV's perhaps? :(

All RV's pitch down. However, I don't know about the four place RV10 for sure. BTW, the Piper Warrior & Archer are more neutral in pitch when applying flaps. They might pitch down just a hair, but nothing like the RV. L.Adamson

[60North 120]

BTW, the Piper Warrior & Archer are more neutral in pitch when applying flaps. They might pitch down just a hair, but nothing like the RV.

Not sure if you are talking about the "old" straight wing or the "new" tapered one.I have done several tests taking notes of AoA and fpm with the "new" Archer and it definitely pitches up.Flap 10, 10-12 Deg pitch up, 2-400 fpm. Flap 25, 10-15 Deg up og 3-400 fpm. Flap 40, 5-10 Deg up, 100 fpm.Speed is offcourse a factor as well..M

[LAdamson 240]

Not sure if you are talking about the "old" straight wing or the "new" tapered one.I have done several tests taking notes of AoA and fpm with the "new" Archer and it definitely pitches up.Flap 10, 10-12 Deg pitch up, 2-400 fpm. Flap 25, 10-15 Deg up og 3-400 fpm. Flap 40, 5-10 Deg up, 100 fpm.Speed is offcourse a factor as well..M

Are these test's from a simulated aircraft or the real one?If it's simulated, then somebody is going to have to take a tapered wing Archer up & see. It's been 15 years since I've flown the PA 28's, but most of the time it was in the tapered wing Warrior and Archer. I soloed in the Warrier & finished the PPL in the Archer. Also flew the straight wing Arrow. From what I remember, the pitch with flap extension was nothing like the upward ballooning of a Cessna. I just seems to me, that the downward view in the Archer increased as flaps were set. But I could be wrong.L.Adamson

[60North 120]

Tests are from the real one that I fly.I agree that the sense of "ground view getting bigger" is there after a a couple seconds because one pushes extra forward compensatefor ballooning. and one ends up at a more down attitude than before.The C17x is a different story since much of the pitch up effect comes from changein downwash angle over the tail (pushing it down) which is not the case on the PA. Havn't flown the C but probably feels very different...M

[Guest Setanta]

Tests are from the real one that I fly.I agree that the sense of "ground view getting bigger" is there after a a couple seconds because one pushes extra forward compensatefor ballooning. and one ends up at a more down attitude than before.The C17x is a different story since much of the pitch up effect comes from changein downwash angle over the tail (pushing it down) which is not the case on the PA. Havn't flown the C but probably feels very different...M

You beat me to it Morten :) (I'm assuming that's the same Morten whose X-plane Piper Archer I've been waxing lyrical about).Not being a RL pilot I went and did a little research about which way an Archer pitches on flap deployment since I knew your model pitched up and LAdamson was saying otherwise, and man did I find a can of worms. On another board, in this case one for flight instructors and examiners, they were arguing about it quite vigorously a couple of years back!The upshot of my research is (as best I can put it together):1: PA28 aircraft may pitch up or down depending on the particular model (and the age of the model)2: The PA28-181 Archer (as modelled by Morten) pitches up (as does his excellent model).3: The PA28-180 Cherokee (aka Cherokee Archer) pitches down - I'm guessing that this is the source of the confusion.I'm guessing that it's the same with the PA28-160/PA28-161 Warrior. It seems that Piper made a conscious decision to make their aircraft pitch up on flap deployment as this was considered 'more desirable' (better stall speed and less effort required during landing flare).Setanta

[LAdamson 240]

You beat me to it Morten :) (I'm assuming that's the same Morten whose X-plane Piper Archer I've been waxing lyrical about).Not being a RL pilot I went and did a little research about which way an Archer pitches on flap deployment since I knew your model pitched up and LAdamson was saying otherwise, and man did I find a can of worms. On another board, in this case one for flight instructors and examiners, they were arguing about it quite vigorously a couple of years back!The upshot of my research is (as best I can put it together):1: PA28 aircraft may pitch up or down depending on the particular model (and the age of the model)2: The PA28-181 Archer (as modelled by Morten) pitches up (as does his excellent model).3: The PA28-180 Cherokee (aka Cherokee Archer) pitches down - I'm guessing that this is the source of the confusion.I'm guessing that it's the same with the PA28-160/PA28-161 Warrior. It seems that Piper made a conscious decision to make their aircraft pitch up on flap deployment as this was considered 'more desirable' (better stall speed and less effort required during landing flare).Setanta

I spent some time looking at various websites yesterday also. I found one that mentioned that the Warrior (could have been Archer) didn't require much trim attention as a Cessna would when deploying flaps. That's pretty much how I've remembered it, but it has been 15 years. But all in all, the info just wasn't as good as I hoped, and a can of worms as you say. It really gets into the tapered wing versus the hershey bar too...As to my own aircraft, I'll have to take it up and see what happens when I deploy the flaps with a power setting above that of an approach and landing...................and not touching the stick to automatically adjust the situation. I'll do this, because I know that the plane pitches down with flaps as I've pulled the power for the approach descent. But I also know that partial flaps & even full flaps have been used to get the RV's into the air very quickly. The fastest/shortest RV demonstration for takeoff used the full 40 degrees of flaps. In the case, of an RV, there is enough excess engine power to easily climb atfull flap. Of course, the more we find out, the more that supposeably has to be modeled.L.Adamson