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tf51d

X-Plane Flight Model really that good?

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I was all set to take the plunge and buy the new X-Plane 9 (Even though still in Beta!) mainly due to their much tauted claim for accurate flight models. Then I saw a series of videos on youtube showing Belly Up takeoffs? So I downloaded the Demo, and sure enough, belly up takeoffs are possible. How could this be in a sim, that claims to have accurate flight models to the point they get FAA certification for training. So my real question, is are the flight models in X-Plane really as good as they claim to be? So far the demo hasn't really impressed me, but I'm just a simmer, although I have flown a Mustang and an AT-6 (With a CFI for their type) they just doesn't seem right to me!!

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Well. Compared to what?I don't think that one not-so-well modeled aspect of a sim means the whole sim is rubbish, we would never play any of them. However, given enough thrust I don't see why a sim plane couldn't take off with a retracted undercarriage. There is a lot more drag but if the aircraft has the power it should move forward and if it can move forward it can generate lift. Consider the Cirrus jet, light weight, lots of thrust and sims don't model ground handling anywhere near as well as flight, for obvious reasons.The one aspect of x-plane 9 that definitely is unrealistic is that I can have a 10knot wind blowing and my aircraft sometimes spins around and pickups 80 knots being blown around with it's engine off. Well, it is a beta...Now that I have balanced my controls with the sim the flight model seems pretty good, before I balanced the controls the pitch and roll were waaay too sensitive. I don't think it is light years beyond FSX though, certainly way better than FS9 though. In other words, I think FS is catching up, slowly.Next time your with the CFI ask him to drop the undercarriage and see if he can still get it into the air, that way we can see if Austin has even modeled that! Steven.

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Next time your with the CFI ask him to drop the undercarriage and see if he can still get it into the air, that way we can see if Austin has even modeled that!I don't think he's going to do that in a Mustang. :-lol

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After further experiments it seems it only happens on runways, on other surfaces, friction prevents such free movement as it should, so maybe it's just a bug! I have decided though to pass on X-Plane, not because of that, but the lack of a decent ATC system. I didn't expect default to be that great, but I was hoping there would be 3rd party alternatives, like there is in FS to fill the gap. So far I haven't found any!

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>So my real question, is are the flight models in X-Plane>really as good as they claim to be?Well, from a strictly technical point of view, ground physics are not part of the flight model :(Actually both flight sims have a raw modeling of ground/water physics and damages, hence the several inconsistent behaviours you can experience in both when the a/c is on ground.The FAA certification has actually very little to do with accuracy of flight models.Basically the current X-Plane flight model has 2 issues:.a definite issues in the stall/post-stall region (as most, but not all, MSFS aircrafts). Only the author can completely correct this, since X-Plane FM is harder and more limited to tweak compared to MSFS;.a suspect general over-sensitiveness of the flight model, the real extent of which is currently unclear. On-going research on the subject from expert users is going on;So the final answer is "not quite". Most certainly, as of now, the overall best flight models can be seen in some 3rd party MSFS add-ons.From my point of view, X-Plane has some advantages and basically a lot more potential than MSFS on most areas, but this potential still remains often un-expressed.Let me show you some examples of expressed and un-expressed potential:.Extensiveness of the flight model: MSFS is limited to a few types of vehicles, while X-Plane can natively model just about everything, e.g.: airships, VTOLs and thrust vectoring, unstable aerodynamic configurations, rockets/spaceships (_AND_ orbital mechanics), prop+jets aircrafts, etc.While _some_ of these can be modeled in MSFS with heavy FM tweaks, it often involves limitations in the final result;.Damage modeling: X-Plane has far more and also more realistic damage options. Just an example: the airspeed indicator failure is completely unrealistic in MSFS, while in X-Plane there are various failures modes, including the failure of static port, pitot port, or both, each of which producing a different final behaviour of the indicator: did you know a clogged static port can produce an hazardous condition in which the lower you fly, the greater the indicated airspeed?.Ground physics: while X-Plane has definitely more complex ground physics, tire modeling, runway friction, aquaplaning, prop slipstream on aerodynamic surfaces (important for taildraggers), it seems to be definitely out of tune and hence producing unrealistic behaviour in several circumstances (try to maneuver an aircraft on an icy runway with a little wind to see what I mean!).The same holds true for water physics (seaplanes);.Helicopter modeling: though not perfect, X-Plane has a far more complex helicopter FM: "low skid" at hover, retreating blade stall, rotor loading and its influence on RPM/torque/maneuverability, autorotations, are all modeled much better in X-Plane (or not modeled at all in MSFS);This is mainly due to the more complex modeling of prop physics on X-Plane, for example:fly a turboprop and see how in MSFS you have costant torque, while in X-Plane the instrument reacts in real-time to the airflow through the prop. I think you can even over-torque the engine in flight, though no engine damage is modeled.Generally speaking, there are a lot of tiny little details not evident at first or even second glance, that show the complexity of X-Plane.For these reasons I say great potential, but a lot of it unexpressed, and for these reasons I support it.But if you ask me only about the "bare" flight model, then no definite advantage. :)Marco

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>Now that I have balanced my controls with the sim the flight>model seems pretty good, before I balanced the controls the>pitch and roll were waaay too sensitive. I don't think it is>light years beyond FSX though, certainly way better than FS9>though. In other words, I think FS is catching up, slowly.>Personally, I still prefer some 3rd party addon's that were created for FS9 over anything found for X-Plane. Take the FS9 RealAir Spitfire for example. A very good sense of power to weight, excellent rudder response on the takeoff roll and climb for slip stream/P-factor, torque, and great maneuvering while in flight. It's also a blast to land. Seems very real, and is a true joy to sim fly with rudder pedals! A new version is near release for FSX; and if it's lile the RealAir SF260 Marchetti, then it will have even farther improvements.I do have a problem with X-Planes sense of inertia, mass, and dampening; which also includes helicopters. I feel like it's more of a "magic carpet ride" in a vacuum, rather than the force of air reacting on a flight surface. Just quickly throw an aileron or rudder to one side, let go, then see. X-Plane oscillates like a pendulum, and will swing (rudder) or roll (aileron) side to side in progressivly smaller steps until it stops. It only takes a few seconds; but it's not like wind quickly returning a Cessna 172 to neutral stability in roll, as with the real one. Or a low wing aerobatic aircraft remaining at an angle in roll. This is just something I do in real life airplanes to make sim comparisons. However, I see at X-Plane org. this evening, that this is being worked on in version "9". So bacially speaking, I've never been that impressed with X-Planes "superior" flight model. I like it's smoothness and topography with global scenery disks more than anything.L.Adamson -- FS9,FSX, X-Plane 8 w/global scenery

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