Auto-rudder?

[Geofa 108]

I'll state again-almost all xp aircaft I have tried exhibit negative stability-both dynamic and static.It is quite simple to perform the stability tests-they would never pass FAA muster.The Carenado aircraft may "cheat" but they pass the tests much better-along with ability to trim the aircraft easily-do reasonable maneuvers without losing total control of the aircraft, and a more realistic roll, pitch rate.I'm no engineer, but really could care less if the fm is based on pi meson quantum particle physic phaser sensors, or lookup tables from the farmers almanac.I just want the aircraft to bear resemblence to the rw aircraft in its imaginary handling on a one dimensional computer screen with a spring loaded joystick. I use sims for valuable home training-if they don't react somewhat like the real thing in all areas (including looks, real working instrumentation, sounds) it isn't very useful for me.So far imho the Carenado have nailed it-at least to the abilities of xplane. I hope more do too-and if "cheating" is what it takes-or a look at the farmers almanac-go for it!

[Alec 370]

Hi Geofa, I like your approach to this issue. If that's what it takes to get it close to RW, then that's what has got to be done.Can I ask you where do I find these stability tests you tried? I'm interest in checking the addons I have to see if they would react stable or unstable, i bet many wouldn't be so stable.As much as I like the thought of real physics instead of just tables, I have to agree that I can't imagine a PC being anywhere close to calculating fluid going through aerofoil in real time. That's like expecting a PC to render the entire New York City in real time with all the details down to the street signs.I believe I read Morten saying that his 733 addon is going to use a lot of plugin, due to the inability of modeling a correct 737 behavior purely under X-Plane physics. And that's not like saying X-plane FM doesn't work, that's being smart and joining the best of what X-Plane can do to the benefits that only Real World data can offer. That's what I hope is the future of X-Plane Addons, best of both worlds, you can't beat that

[60North 120]

Right, what counts is offcourse the end result one experiences in the sim. Doesn't matter if it looks good in a lookup tableor in PlaneMaker if it doesn't meet expectations in sim. The best designers for each sim will never be confined to the limit's of their respective simulator.X-Plane is offcourse a simplification of real physics - FS even more so - and I have over the years documented loads of issues on both sims.The trend in XP is now use of plugins for flightmodel.- Bend the core flightmodel where it's off- Add functionality where planemaker is limited and simplifiedThe end result is incredible - trust me! We'll see a lot more of this when the big designers come over from FS.As we have concluded before for both sims, it pretty much boils down to the skills and the amount of information each designer hasto work around the issues present in both sims.M

[Geofa 108]

Hi Geofa, I like your approach to this issue. If that's what it takes to get it close to RW, then that's what has got to be done.Can I ask you where do I find these stability tests you tried? I'm interest in checking the addons I have to see if they would react stable or unstable, i bet many wouldn't be so stable.As much as I like the thought of real physics instead of just tables, I have to agree that I can't imagine a PC being anywhere close to calculating fluid going through aerofoil in real time. That's like expecting a PC to render the entire New York City in real time with all the details down to the street signs.I believe I read Morten saying that his 733 addon is going to use a lot of plugin, due to the inability of modeling a correct 737 behavior purely under X-Plane physics. And that's not like saying X-plane FM doesn't work, that's being smart and joining the best of what X-Plane can do to the benefits that only Real World data can offer. That's what I hope is the future of X-Plane Addons, best of both worlds, you can't beat that

Sure.First let's take the definitions from the faa handbook:Static StabilityStatic stability refers to the initial tendency, or direction of movement, back to equilibrium. In aviation, it refers to the aircraft’s initial response when disturbed from a given AOA, slip, or bank.• Positive static stability—the initial tendency of the aircraft to return to the original state of equilibrium after being disturbed [Figure 4-18]• Neutral static stability—the initial tendency of the aircraft to remain in a new condition after its equilibrium has been disturbed [Figure 4-18]• Negative static stability—the initial tendency of the aircraft to continue away from the original state of equilibrium after being disturbed [Figure 4-18]Dynamic StabilityStatic stability has been defined as the initial tendency to return to equilibrium that the aircraft displays after being disturbed from its trimmed condition. Occasionally, the initial tendency is different or opposite from the overall tendency, so a distinction must be made between the two. Dynamic stability refers to the aircraft response over time when disturbed from a given AOA, slip, or bank. This type of stability also has three subtypes: [Figure 4-19]• Positive dynamic stability—over time, the motion of the displaced object decreases in amplitude and, because it is positive, the object displaced returns toward the equilibrium state.• Neutral dynamic stability—once displaced, the displaced object neither decreases nor increases in amplitude. A worn automobile shock absorber exhibits this tendency.• Negative dynamic stability—over time, the motion of the displaced object increases and becomes more divergent.Stability in an aircraft affects two areas significantly:• Maneuverability—the quality of an aircraft that permits it to be maneuvered easily and to withstand the stresses imposed by maneuvers. It is governed by the aircraft’s weight, inertia, size and location of flight controls, structural strength, and powerplant. It too is an aircraft design characteristic.• Controllability—the capability of an aircraft to respond to the pilot’s control, especially with regard to flightpath and attitude. It is the quality of the aircraft’s response to the pilot’s control application when maneuvering the aircraft, regardless of its stability characteristics.Now here are some simple tests and see what kind of the above results you get:1) Trim the plane in level flight and let go of the controls. (In mild disturbances does it gradually get back to the trimmed position or does it show neutral or even negative tendancies.)2) Put the plane into a shallow bank and let go. Does the plane gradually right itself back or does it show neutral stability or most likely negative stability?3) Trim the plane for level flight, then pull slightly up on the yoke and let go. Does the plane gradually go back to its' initial trimmed position with a few ever decreasing occilations or does it show negative tendancies, and increasing gyrations?4) Try a maneuver such as the steep turn requirement on the commercial checkride: "Rolls into a coordinated 360° steep turn with at least a 50° bank, followed by a 360° steep turn in the opposite direction."How is the controllability and the maneuverability?Ok -my answers. 1) Most xplane aircraft I can't get trimmed ever for hands of flight as they exhibit a squirrly pitch axis. Doing the test most show negative stability2) Most xplane aircraft will continue to steepen bank and thus show negative stability3) Haven't done this one for a long time so I don't remember!4) Most xplane aircraft will go bezerk during this maneuver causing loss of control of the aircraft due to too fast a roll rate.Just some examples to get started with...

[60North 120]

Don't have the Bonanza, but just got from a reliable source it has a yaw damper, so thats probably what theyuse their AS for..M

[Geofa 108]

Don't have the Bonanza, but just got from a reliable source it has a yaw damper, so thats probably what theyuse their AS for..M

Actually many don't. Mine didn't. Some put them in. You will find yaw dampers more often in Vtails which have the reputation of being uncomfortable in the back seat due to dutch roll.

[800xp 0]

The closest to the RV for X-Plane is the 3rd party Falco. I just leave the settings at full realism for that one.

.I will look into that Falco, thanks for the recommendation. I am glad to see so many users agreeing with the philosophy of tweaking the model until it matches real life. I look forward to the new generation of highly tweaked payware flight models. This is a useful article that contains an interview with one of the best flight modellers from 2001: http://www.avsim.com/pages/0201/young_v88/young88.htmlFlying these v88 aircraft back then was the first and only time i have been truly wowed by a computer flight sim. I really felt that the computer flight sim had reached a new level. X-Plane's flight model is still a bit of a disappointment right now, but the right foundation is there for it to be a great computer flight sim.

[LAdamson 240]

Flying these v88 aircraft back then was the first and only time i have been truly wowed by a computer flight sim. I really felt that the computer flight sim had reached a new level. X-Plane's flight model is still a bit of a disappointment right now, but the right foundation is there for it to be a great computer flight sim.

I don't know if you've mentioned it previously, But Rob Young does the flight dynamics for RealAir, which is his addon company. The RealAir Marchetti SF260 is still my favorite. I may be a bit biased, because I've flown the real Marchetti, and it's much like my RV. However, its still very comfortable to go from a real flight, to the sim. Much seems the same. Since I like this aircraft so much (FS9/FSX)...............it's the one, that I compare any X-Plane to.

[Alec 370]

Thank you Geofa for the nice explanation.I will try that with every addon on my list, and any future one as well. That really is the basic for any aircraft to be considered good for hand flying

[Bartbear 10]

(Microsoft) FS has reminded me very much of flying through real air. You don't need to be constantly yawing or rolling........to simulate flight.I've experienced flight, in many real life airplanes, ranging from aerobatic, to WWII fighters. Gliders, hot air ballooons, and a Ford Tri-motor too. Sometimes, this yawing/rolling action in X-Plane, would irratate me enough, that I'd usually quit after five minutes. It's as if I'm doing constant corrections with the stick or yoke, to maintain smoothness. In effect, I'm just "chasing it" with the stick. Real life flight, isn't like that. Not even with an aerobatic plane, that just requires thinking of moving the stick, to get it done. If it's adding a bit more "artificial", to what's artificial anyway, then I have no problem with it. Any way you look at it, X-Plane is NOT a real airplane. I believe that some, seem to confuse that issue..........to the point of believing it is.L.Adamson

That's exactly how i experienced X-Plane until now.I must confess that after reading all the comments in this topic i feel rather shocked and a bit disappointed.I always thought X-Plane was a pure and total different approach from other flight simulators.Although, i always found it strange that after all the versions, updates, upgrades and other betas that claimed to be "much more realistic than it's rival(s)" for the last 6 years, they never had the flight dynamics really 'right'.OK if it's really necessary to 'add tricks' to the practice of the 'Blade Element Theory' on current (limited) software and hardware, or in other words: to take the approach off other flight simulators like FSX, Flightgear, level D simulators, ... so be it.At the end if they finally get flight dynamics more realistic in general, it's fine for me.Nevertheless i think i shall always look at X-Plane through different eyes now. :( Edited February 27, 2012 by Bartbear

[GoranM 3,764]

That's exactly how i experienced X-Plane until now.I must confess that after reading all the comments in this topic i feel rather shocked and a bit disappointed.I always thought X-Plane was a pure and total different approach from other flight simulators.Although, i always found it strange that after all the versions, updates, upgrades and other betas that claimed to be "much more realistic than it's rival(s)" for the last 6 years, they never had the flight dynamics really 'right'.OK if it's really necessary to 'add tricks' to the practice of the 'Blade Element Theory' on current software, or in other words to take the approach off other simulators like FSX, Flightgear, level D simulators, ... so be it.At the end if they finally get flight dynamics more realistic in general, it's fine for me.Nevertheless i think i shall always look at X-Plane through different eyes now. :(

It is not necessary to add tricks. Both Morten and I have said that.

[Janov 2,383]

...and I really don´t know which version of X-Plane everyone else is playing, but even in the DEFAULT Cessna the plane is totally stable around the pitch axis for me and will readily return to a steady state at the trimmed speed. Banking is at least not unstable - but to tell you the truth most planes I flew DO require pilot input to return to level wings. I know, certification demands otherwise, I have always wondered about that, too.The yaw axis - which would be affected by yaw damper artificial stability - is not prone to oscillations, at least not in non-gusty wind conditions.So in conclusion: the Cessna in XP10 - as mediocre as the flight-model might be - flies very smooth and absolutely controllable for me. All sliders to "full realism"...Jan

[strider1 575]

I've never been impressed with the carenados flight models, especially when it comes to sideslips to landing in crosswinds conditions.You can't keep the nose pointed down the runway when slipping to compensate for a side wind in a Carenado plane.

[Geofa 108]

I've never been impressed with the carenados flight models, especially when it comes to sideslips to landing in crosswinds conditions.You can't keep the nose pointed down the runway when slipping to compensate for a side wind in a Carenado plane.

I posted a video showing you could in a thread way back...but whatever.http://forum.avsim.n...__fromsearch__1

...and I really don´t know which version of X-Plane everyone else is playing, but even in the DEFAULT Cessna the plane is totally stable around the pitch axis for me and will readily return to a steady state at the trimmed speed. Banking is at least not unstable - but to tell you the truth most planes I flew DO require pilot input to return to level wings. I know, certification demands otherwise, I have always wondered about that, too.The yaw axis - which would be affected by yaw damper artificial stability - is not prone to oscillations, at least not in non-gusty wind conditions.So in conclusion: the Cessna in XP10 - as mediocre as the flight-model might be - flies very smooth and absolutely controllable for me. All sliders to "full realism"...Jan

Don't you find the roll axis way too fast in the default 172?As far as banking -I get negative stability.Pitch is not too bad though.As far as rw experiencing it I have one word-Piper (anything and all axis's)... :)I'll be glad to post some videos to show-including freeware/ payware planes (that don't cheat thank god) that exhibit the negative tendancies.

[Janov 2,383]

Don't you find the roll axis way too fast in the default 172?As far as banking -I get negative stability.Pitch is not too bad though.As far as rw experiencing it I have one word-Piper (anything and all axis's)... :)I'll be glad to post some videos to show-including freeware/ payware planes (that don't cheat thank god) that exhibit the negative tendancies.

I agree with you, the roll axis is very sensitive - not beyond controllable, though. A lot depends on the controls, and the old discussion about PC-input devices versus "real" aircraft controls comes to mind.I only have a little over one hour in a Cessna (152) and it´s been 20 years ago, so I can´t really say I remember. My 200+ hours in the F33 are equally long ago - but I do remember that I always wondered why the aircraft wouldn´t return to level wings fairly rapidly if I let go of the controls...Banking in the default Cessna in XP10 gives me neutral stability at best. If the trim is just a tad off, it will increase the bank, that is true.Same is true for the 737s I fly - you often need a bit of "level wings" input to keep the bank angle constant - letting go of the controls would increase the bank. At least past the "target" of 25deg - not sure if the tendency might stop at 60 bank (and won´t try it with passengers on board, either).I did fly the Archer II for a few hours (usually Phoenix - Sedona for the great applepie they have at the airport restaurant) and agree, a very docile and convenient aircraft to fly. Since I flew it mostly during the hot hours of the day over Arizona I can´t say much about it´s stability - that get´s relative fairly quick in those kind of thermals...Jan