800xp

Well i perform finite element analyses on a daily basis and I am aware of the limitations of finite element theory. I know that 10 elements per wind and flying surface is extremely low, we call that a "coarse mesh" and we use it for nothing more than rough approximations before we get on with the real analysis. Even a model with 100,000 elements has an error and if there is a dynamic/nonlinear event or complex 3d geometry, the error can be quite significant even with "fine mesh". Fine mesh models of a few seconds of a dynamic event take me days to solve on a super computer. I am sure you are aware of the limitations of finite element analysis so i won't continue any further. I see Austin makes claims that such a coarse mesh FEA (less than 100 elements) with interpolation in between elements is just as accurate as a 100,000 element mesh. Well that is hard to believe but it is not impossible. What he fails to mention is how close the 100,000 element model is to flight in real life. We all know airplanes have complex 3d surfaces and experience turbulent and non linear events in flight. Now tell me do you think that even 100,000 finite elements can provide an accurate solution? I think i know enough about the core (coarse mesh FEA) to present my opinion. My opinion is that it will take some time before we can simulate real-time flight on a personal computer based on input based parameters (like aircraft geometry, airfoils, etc..) to any degree of simulation accuracy. I believe the accuracy of this "core" is enough to provide conceptual level, back of napkin approximations. If we could predict aircraft flight based on just input parameters and no real life flight test data, there would be no need for wind tunnels and structural rigs.. I red the section on the IXEG 737 flight model from the IXEG website and I believe we are on the same page. This is exactly what i was trying to communicate: to create a good flight model you have to be aware of X-Plane's limitations, test and tweak with real world test data and write plugins to adjust/calibrate where BET falls short. Exactly what i think should be done. And it's great that you sold 50,000 copies, i bought one of them, but how about 4 times that amount? I think you have an opportunity to convert every former FSX user if you clean up the flight model. FSX sold 200,000 in 2007 alone.

I think that at the end of the day improving the flight model will be a good business decision for Laminar. There is a market opportunity in the flight sim world, many users including myself are looking for something better and X-Plane delivers on many levels like lack of stutter, smooth gauges, night textures, rural autogen scenery, replay and analysis, avionics, lighting etc... There are however issues with static and dynamic pitch stability, flight control authority and response, weight and balance (cannot seat passengers in the CRJ, the CofG never moves because of uniform passenger load), real weather turbulence and windshear (a 22 knot gust still makes the x737 nearly uncontrollable on approach) and ground handling. If Laminar does not fix these issues X-Plane will remain a niche product, with a group of users who accept its limitations. Laminar has an opportunity to blow everyone else out of the water if they fix their flight model. I see that the next version of X-Plane will feature an improved user interface and improved scenery. To me these are secondary elements that should be improved only after the core of this sim (the flight model and weather) is fixed. I understand that working on a Ipad app is probably more lucrative from a business point of view, but i think that at the end of the day the core of this simulator has to be fixed or it will be just a matter of time before a new sim takes over and becomes the leader in computer flight simulation. Austin also has to be more aware of the competition out there before he makes claims against the highly efficient and customizable table based flight model which is the basis of Level D sims. To say that BET is superior for flight simulation is just plain wrong. BET is superior for rough conceptual aircraft design, not for a high fidelity simulation. A highly calibrated table based model is extremely accurate. To achieve a high fidelity simulation including accurate static and dynamic stability, the BET model must be tweaked and calibrated just like the table based model.

I took a long break from this hobby and i only recently got back to it. i don't own FSX or earlier versions of X-Plane. I have a Mac and wanted to buy the latest flight simulator. I bought X-Plane without enough research. I have to admit the FAA certification was what swayed the bar. The only other sim i can speak about is the now outdated Fly 2K! and the v88 aircraft versions made by Rob Young. I believe these models were even more refined in Fly! II, but i never bought Fly! II so again i have no opinion about it. I would not hesitate to recommend the Fly 2k! (v88 freeware patch) aircraft if you are looking for the sensation of good positive static stability. I believe Rob now works for a company called Real Air and I am pretty sure his flight modelling work there is just as outstanding as in Fly!, probably even more accurate. I have also heard that ELITE has a good, stable flight model. I have to remind you again that i am not a real pilot (not for at least a year) and i believe that the best way to evaluate a flight simulator is to get feedback from an unbiased real world pilot of that same aircraft, not an engineer. Although we understand the math and all those things I am sure that there are intricacies that i don't have a feel for yet. I am not one of those engineers that think they know everything.

So what is X-Plane's intended purpose? Provide 2 standard deviations of error? I think you need to examine your competition and at least provide something that is in the same ball park in terms of stability and control feel. Getting the steady state portion of a flight model is not good enough. It's 2012 and i think the user expects more, especially since great flight models have been available ever since Fly! and maybe even before that. There are other products out there that are available to the flightsim consumer base that simulate static and dynamic stability to much higher degree of accuracy. I am not much different than the rest of of X-Plane's user base. I'm just like any other user looking for a realistic experience. I really like X-Plane's lack of stutter, smooth gauges, lighting, replay, night textures, failure and analysis options. I also like the user interface, but i think the core of this simulator (flight model) needs some work.

Thanks for your offer, i am glad that i'm not the only one seeing this large discrepancy with stability. I would first like to eliminate all hardware/install issues by seeing if others are experiencing this kind of stability error. I understand X-Plane has a large base of very intelligent users including pilots and engineers and even some who are both. Surely they would have noticed that something is wrong if the error is this large. (Something that should take 4 seconds happens in over 12 minutes.. >18000% error.. little bit more than two standard deviations) I am not a pilot in real life and ideally this case is best presented by someone who is both a pilot and an engineer. I am also a junior engineer, again it would be great if a senior pilot/engineer can present something to Austin. My obesrvations with the CRJ: static stability is very low, bordering on neutral, control response/authority is very high, probably 300% more than what is should be. Short-period dynamic stability is not modelled (understandable, related to flutter), long period (phugoid) is inacurate and easily excited due to a lack of static stability and overly high control authority. I first have to confirm that nothing is wrong with my system/hardware/install.

I am a new user of X-Plane and an aerospace engineer in real life. I was initially disappointed in X-Plane but was convinced that payware aircraft fly much better than the horrible default models. I recently bought the CRJ-200 and although the plane flies much better than the default aircraft, it's pitch stability is very wrong/unrealistic on my computer. I was hoping some of you can perform this flight test just so that i can eliminate hardware issues, or issues with my operating system/install. The CRJ flight model on my system shows very low positive/neutral static stability and a highly underdamped phugoid mode which gets easily excited and and is very difficult to arrest. All of these features are highly unrealistic and not what i was expecting in a payware aircraft. Flight test I deleted/reset my preferences, set number of flight models to 4 and adjusted weather (low visibility) so that i can get about 40 FPS. Set data input and output to output of flight control deflections to make sure there are no ghost control inputs. Get a stopwatch. Do not use the autopilot at any point in the flight. Get the plane up to about 12,000 feet and a speed of 240kts. Trim for straight and level flight. It took me about 4 minutes just to trim the plane as it was in a constant phugoid that would not stop oscillating. This shows very poor static stability bordering on neutral (low positive). Assuming you can get it staight and level (vsi=0) perform a small quick elevator control pertrubation: simply pull back on the elevator until data I/O reads 0.500 (50% elevator up) and release the controls within one second. Make sure the elevator centers back to neutral (0.000 control deflection). After this action start the timer and record the following: Time until straight and level flight (VSI=0) Maximum and minimum altitude Maximum and minimum vertical speed Number of oscillations until straight and level flight What should happen in real life? Jets are subject to strict FAA requirements regarding stability (FAA part 25.181). A pitch up like this should excite the short term period oscillation (not the phugoid) and should dissipate within 2 cycles and 4 seconds. In regulatory practice, “heavily damped” means in no more than two cycles. Test pilots for the Raytheon Premier I took the aircraft to 35,000 feet to evaluate short period behavior in gusts. After pitching up and releasing the controls (stick-free), they found that the aircraft took approximately 2.5 cycles and 5 seconds to return to level flight. The FAA agreed that this presented no safety issues, but refused to wave their criteria (2 cycles and 4 seconds). The designers fixed things by adding wedges to the trailing edge of the elevator to change the hinge moments, making the elevator’s response to vertical gusts more neutral and bringing the aircraft into line with FAA requirements. (from Flight Emergency & Advanced Maneuvers Training, Inc. dba Flightlab, 2009. All rights reserved. For Training Purposes Only) In real life the phugoid takes some effort to get excited, usually a long duration elevator deflection from trimmed flight that allows the speed to drop 20 kts and then a release of the elevator. In X-Plane it gets excited instantly, even with minor elevator deflections. What happened to the CRj on my system? After i pitched up (50% elevator) and released the elevator quickly the plane entered a large amplitude phugoid with a VSI of +1.9K FPS. The plane climed to 12,200 ft after the peak of the phugoid the VSI read -2.2K FPM and it started a descent. It settled down at 11,550 ft after which it started to climb again at about 2.0K FPM the first cycle took about 37 seconds. The plane was still oscillating after 6.00 minutes!!! with about half amplitude and half the vertical speed (1.1K) not even close to being damped out. I shut down X-Plane before it could ever return to straight and level flight - waste of time to wait more... I really want to know if this is an issue with my system. I can't comprehend that a model this wrong would be sold as a payware aircraft. It is impossible to fly accurate IFR with such poor stability. This really makes me question if this model was flight tested by real CRJ 200 pilots and how involved real world pilots were in the making of this aircraft. There are plenty of things i like about X-Plane, but the flight model is a major deal breaker for me. As soon as i feel the phugoid and see the VSI start to dance out of control i lose all sense of realism. I currently fly Rob Young's models for Fly 2K! and they show accurate static and dynamic stability. (I assume users are familiar with the concepts of static and dynamic aircraft stability. They are a little tricky to understand especially the difference between static stability and the two dynamic modes: short period and long period)

I just purchased my first payware aircraft for X-Plane (the CRJ) and it is very impressive. The flight model feels very good, it appears to have that realistic feel i was looking for and never experienced with the default aircraft. Hand flying landings are rather effortless and the aircraft needs minimal flare and floats if flared too much. It behaved very well in gusty conditions, alot more inertia and stability. It is a bit more sensitive in pitch but i can blame that on my hardware. It is however a rather large drain on my system and i can rarely get over 20 fps on my i7 macbook pro. About 10 fps in rain and clouds so it is currently not flyable in bad weather on my system. I get about 30 to 40 fps with the x737's 2d panel with 6 displays. I think the plane desperately needs a nice, crisp set of 2D panels, i am not proficient to 3D cockpits and although they look nice, i find them frustrating to use. I can't seem to find one view that gives me a clear look at all important displays so that i can do a regular instrument scan. I tried pilotview and still can't seem to find a view that works for me. The center pillar in the cockpit blocks alot of the the outside view and i find visibility form the cockpit to be very poor. I find that alot of valuable panel real estate is wasted on empty space and a very large autopilot column, while the important stuff (like displays and fms) appears to be very small and unreadable. On the other hand the pop up displays are too large and again take up alot of panel real estate. I think that a set of 2d panels with larger displays (the displays are a work of art by the way, very well done) and a smaller autopilot column and a smaller or non existent center pillar will really help those of us who like to hand fly IFR accurately and do a proper instrument scan. Overall i think it is a great product for the current reduced price and everyone who hasn't bought it already should look into it.

I am also a new user and have put X-Plane on hold. I am looking forward to the IXEG 737 and other highly tweaked, plugin augmented flight models. I think XPX is a great foundation for a great flight simulation experience but the poor flight model is killing the flying experience for me. I like to fly precise and stable IFR with accurate wind and gust modelling. For me flying X-Plane involves fighting never ending oscillations in inertialess aircraft with exagerrated turbulence and gust wind effects. I find it impossible to fly within ATP tolerances and my instrument scan is also getting worse due to too much instability in the pitch axis. I was wondering if there are any demo payware aircraft i can test out before buying. I can usually tell right away if the aircraft feels right or not.

I feel the same way. I have yet to find an X-Plane aircraft that is smooth and stable enough for precise IFR flight. Back to Fly! 2K v88 for a smooth and stable IFR experience for me...

I am not trying to become a leading authority on X-Plane, just stating my opinion as an aerospace engineer working in the industry, that's it. Take it or leave it, this is just my constructive opinion. Austin in a brilliant engineer but also a great marketer/salesman. If i ever speak with Austin i will not be discussing BET, but asking for advice about how he developed his strong marketing skills. This is the combination of skills that makes engineers millionaires. Most engineers like to criticize and focus on the weaknesses of an analysis, but there is nothing wrong with hyping up the positives. X-Plane and Fly!2K are the only sims i own, and the latter will probably be retired very soon. There are many things that i like about X-Plane and I am sure that when the program becomes bug free and stable; and when i find a great payware flight model, it will officially become the best flight sim i have owned. I think every aviation enthusiast must have a copy of X-Plane, it is worth the money for the conceptual design capability alone. X-Plane is a product which has literally made Austin a millionaire and i doubt he will discuss the limitation of BET with me. Putting myself in his shoes i would probably be hyping it up even more if i had such a major commercial stake. I would love to discuss the new 850hp turbine in his Lancair though that would be great. Austin is an inspiration to all aerospace engineers. I have nothing but respect for him and his product.

Well NASA could be using X-Plane to make a nice quick 3d movie about space shuttle re-entry on the kids' section of their website. So the fact that they are using it is not pretty big. I see a use for X-Plane in the marketing department of an aircraft company for quick 3d movies of a new concept that can catch someone's eye in a trade show. Although you may know more about the user interface and inputs of Planemaker I am certain i know more about the calculations, the element mesh (not much of a mesh) and the interpolation that takes place and how that compares to professional aircraft design software. X-Plane is a very quick conceptual design program, one can examine many "quick and dirty" designs and configurations, certainly much more quickly than a pen and paper, but i am having trouble believing it can be used for any serious engineering or design past the conceptual design stage.Also as a new user I expected this program to live up to the advertisement: "ultra realistic flight simulator". The default aircraft display nothing close to "ultra realism" so there is a bit of false advertisement there. Right now i think only a few offerings for FSX (e.g. PMDG) can live up to the title of ultra realism.

I don't even have time to open up plane maker and have not created any X-Plane models. I recently started testing the sim and am not impressed with the flight model including inertia control response and authority, dynamic and static stability etc.. I also understand the limitations of finite element analysis and understand what happens under the hood of this magical black box that is BET. I use professional finite element analysis and CFD software at work and know what it takes to design a real world aircraft so i am just stating my opinion. i still think X-Plane has potential as a home computer simulator and it is great as a game, but am having trouble seeing any serious real world application.I red the "ultra realistic flight simulation" on the box and am holding this software to a higher standard than a typical home computer sim.

Where can we find more information about the exact use of X-Plane as a real world aircraft design tool? I want to learn more about what exactly it is being used for, Austin is very vague in the manual. I work in the aerospace industry and would not recommend this software for any form of real aircraft design. I can see it being used at the conceptual or pre-conceptual design stages of aircraft design by companies that are extremely strapped for cash, but not for anything more. Definitely not at the preliminary or detailed design stage, where the real design actually takes place.Conceptual design is something that can be done on the back of napkin and has very loose tolerances for accuracy, basically ballpark calculations. Of course companies can use it to map out flight recorder data in 3d, or other applications like this that don't involve the flight model, but absolutely not for advanced design.

.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.

The point I am trying to get across is that X-Plane it is not real physics, but a rough approximation of real physics. It solves for a gross approximation of what the real aircraft is actually doing. And I am not familiar with the table based model but suspect that these tables are not as simple and linear as one might expect. Austin certainly describes the table based model as a simple linear table, but I can bet putting real life test data into a Level D sim is more involved than a simple liner table. What I am trying to say is that solving for the "physics" is not necessary, unless you are making a simulator for an aircraft that has never flown before. As for real aircraft manufacturers I can see them using this at the earliest, conceptual stages of aircraft design. It is a great conceptual design tool and solves for aircraft flight within the loose conceptual design tolerances. X-Plane is worth the 80 bucks just for that capability.But it may not be the most efficient solution when it comes to simulating flight on aircraft that already have real life counterparts that are flying. We will be able to solve for physics that resemble "real physics" when CFD becomes sophisticated enough to render wind tunnels obsolete and computing power increases to the point where we can run CFD in real time on the full aircraft. I estimate it will take about 100 years until that can happen given the current state of CFD and computing power. I see, how about the stability settings for the X-Plane model that you fly in real life in the current build of X-Plane?