I'll repeat... and clarify: What he's showing in that video is not the default Extra 300. Despite repeated attempts to duplicate what is in that video... the Extra 300 in the default FSX does not exhibit any of that behavior. In fact, once I start doing rolls, the aircraft tends to lose altitude, not maintain... even moreso with faster rolls. At no point have I ever been able to get it to climb at idle, no matter what. Of course, I fly with the flight model in FSX at 100% realistic...

 

So... I'll call shenanegans...

 

It is the default FSX Extra 300. Or at least it's a very good rip off.

Can we please stop now?

On my PC..

 

And the video...

 

For the record, I was able to reproduce the exact same behaviour with the default C172 some time ago (don't have FSX now, so it's only my word for it). The reason, I strongly suspect, is integration instability due to low frequency of MSFS flight model, 16/32 Hz IIRC (basically very similar to what happens in X-Plane when frame rate is too low). It cannot always be reproduced, sometimes can be made to happen other times not.

 

However my main point was that both platforms have default aircrafts with relatively poor flight models, although I agree X-Plane aircrafts are way too twitchy, especially with default control settings (and I agree they should be improved).

Actually you can climb with the default extra 300 in a fully developed spin in FSX. I have done it myself. I have also done it in Flight using the Stearman under the same circumstances.

 

I would qualify spins as well outside the scope of the sim flight model envelope for most desktop sims.

 

I would not expect one to take crosswind landings and takeoffs out of scope.

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.

Wait and see, thats all I can say..

 

M

So the whole drama queen reply was because I didn't qualify my statement with 'some'? True, some are rubbish or at least elicit a feeling of ##### was that. Others have a reasonably nice virtual cockpit and are OK but the impression is severy let down by the rest.

 

I think there is a glaring difference between lathing something to within 0.05mm and calling that same piece rubbish.

Personally, if I had a hand in making any of the default aircraft, and you called it/them rubbish, I would not appreciate it.

And in the same way you think I'm jumping in defending the default aircraft, you seem to want to jump in and overly criticize them.

I never said I didn't know why Laminar didn't/doesn't improve them. I've rarely ever flown a default aircraft in any sim.

Do the default aircraft in X Plane need adjustments? In some areas, yes. But calling them "rubbish" is a bit too much.

For the record, I was able to reproduce the exact same behaviour with the default C172 some time ago (don't have FSX now, so it's only my word for it). The reason, I strongly suspect, is integration instability due to low frequency of MSFS flight model, 16/32 Hz IIRC (basically very similar to what happens in X-Plane when frame rate is too low). It cannot always be reproduced, sometimes can be made to happen other times not.

 

However my main point was that both platforms have default aircrafts with relatively poor flight models, although I agree X-Plane aircrafts are way too twitchy, especially with default control settings (and I agree they should be improved).

 

Flight dynamics are processed a bit better than the rate of variable updates. Variable updates are at ~18 Hz. Also... scenery load, processor speed and a few other items affect how efficiently the sim can do it's FDE processing. I believe X-Plane also suffers from the same issue?

I have never been able to get the Extra 300 to climb at idle throttle, no matter what I do. As I've stated... I run with 100% realism in the FDE area.

 

My point is that tossing out a video that shows where someone was able to get a computer simulation of flight to do the impossible only proves they were using a computer. Even level-D simulators have limitations in the flight dynamics area. That same person even has a video of X-Plane and a glider where the glider does something absolutely insane. Notice I didn't post that in a rebutal. ;)

NOTE: These statements are personal and in no way reflect the position of Laminar or any other of it's employees. I make them as in individual and long time x-plane user, long time XP developer, senior engineer and pilot. I'm not sure what else he wants....Austin is a 20 year engineer with 3000+ hours.

 

I think that at the end of the day improving the flight model will be a good business decision for Laminar.

 

I should point out to others here that 800xp knows nothing of the x-plane flight model core. He has none of x-plane's code, no 'white papers' about how Austin's coded it. He's a self-admitted junor aero engineer....self-admitted new to x-plane with no significant XP experience...and self-admitted no significant flight experience.... He also admits to not knowing everything but consistently insinuates he knows X-Plane's core. I'm here like a lawyer, to remind the jury that he is an unreliable source.

 

Until you have tried to model 1 aircraft completely and thoroughly in x-plane ...from scratch...and allow it to be reviewed by a senior engineer with XP developer experience (there's not many of us), I will be here to counter you any time you purport or claim to know x-plane's flight model core without information worthy of engineering evaluation because you are misrepresenting X-Plane with your opinions. Its like writing a technical report with summary only and no supporting documentation.

 

I will give you just one thing P. X-Plane has simplified algorithms for some inputs, but the core algorithms of the flight sim that processes these inputs are as stable and robust as ever. At IXEG for example, we do have to customize the input frequenly....but when we do, the core flight model does a killer job with that input. If you want to talk about deficiencies in the simplified input....or the aircraft models (not flight model...there's a difference), then that is a whole other topic I will engage you on intelligibly and be happy to listen to your experience and education....but as long as you use the generic terms, "X-Plane" and "core", I will be all over it.

 

And just so you know that I am consistent on this and heard it all before....check this old post. I've been dealing with the same old song and dance a long time.

 

http://forum.avsim.n...79#entry2357979

 

 

Tom Kyler

Laminar / IXEG

www.ixeg.net

It is a dead horse topic, mostly because everyone at some point including yourself has said you don't know why LR doesn't improve them.

 

Fair question. We do plan to improve them, but probably not to the point of making every forum users here happy. There will always be something to complain about and as you said, the cost/benefit may not be worth it. Now before that gets debated, keep in mind that the specification for 'benefit' is "we don't get significant complaints from the population", which is a valid statistical eval method. In engineering, they teach us to do the minimal required to achieve the specification.....above and beyond is wastage. So if I have one C90B pilot here for example, maybe 2 or 3 others that complains about flight accuracy and say if we could fix it we'd sell more (while having no access to sales data?.....pfff), yet Laminar sold 50,000 copies with only the 2 or 3 complainers....tough luck for the few folks complaining, welcome to supply and demand! Also, usable feedback is generally in the form of "the roll rate is too fast" or "the fuel consumption is 12% too high" or "the stall is too abrupt".....non-usable feedback are phrases like, "rubbish" or "horrible" So if that's all we get from folks, well then we really don't care to address those. I am perfectly content to live with sour grapes, they're as much a part of life as supply and demand.

 

Tom Kyler

Laminar / IXEG

www.ixeg.net

(personal opinions only expressed, not those of Laminar)

He also admits to not knowing everything but consistently insinuates he knows X-Plane's core.

 

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 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 have to agree with this. I've been around aircraft design long enough to know that small changes, and addtions such as wedges, cuffs, plates, etc......have have a large effect on the flight surface & flight characteristics of the airplane. It would be hard to convince me, that X-Plane could tell a

designer of the shape & proper placement for these devices. Or that X-Plane could tell Cessna or Boeing, that a re-design of the vertical stab & rudder is in order. I still believe that X-Plane requires third party intervention, and that the program isn't fully capable of producing precise results on it's own........even if the programmer is highly familiar with it. Is that bad? Not really.

Hey 800xp, now that is a good post. I'm an FEA guy also. Regarding the number of elements, of course we are concerned with a reasonable convergence limit and balancing all factors relating to computational performance, Austin obviously feels that a certain number of elements can suffice..and given my experience and "old timer" methods of hand calculating and assembling basic stiffness matricies before going to the computer, I have to agree with him. Now whether or not a author leverages x-plane tesselation density options is up to the author. You can make a wing out of 4 subwings, 10 elements each giving 40 elements per wing. This is bordering on a well refined mesh for the purpose....we are not dealing with high density gradient values or singularity situations such as might be seen in stress anaysis. Sure Larry is correct for the level of analyses he's discussing, but that's 100,000.00 or in-house software probabaly. We have to draw the line somewhere. With 40 elements per wing, perhaps we'll see convergence around 95 - 98% (guess). Go to 1000 elements, you may get 99%....go to 100,000, maybe 99.5. You get diminishing returns after some point. Without conducting a thorough validation test ourselves...which is VERY standard practice in good FEA, we are speculating and this is where respecting Austin's experience is the best we have. If you don't trust him, then you must test the software results yourself in an organized manner. You make an argument with 10 elements, yet I can put in 40....so how do you feel about 40 elements? Does it change your perspective etc? Now....the FEA component is only a force calculation mechanism and regarding your original post as to the stability of x-plane, I only want to get you to focus on the nature of oscillations, step impules etc., given dynamic inertia and response and investigate x-plane's handling of those parameters as opposed to blanketly criticizing the flight model from an FEA only perspective, which is insufficient to make a determination. FEA is only a small component into the behavior. If we can make our plane stable at IXEG (and we did test it against the phugoid), then x-plane's core...which has not changed for us, is not the issue and it should not be said so in that manner. Now of course there are errors in numerical analysis but that does not stop us from designing aircraft. At some point we say, "that is sufficient" and we take it. I think X-Plane is sufficient for an 80.00 software package. What Larry describes is not X-Plane's market. If you want to hold Austin's feet to the fire as to "stretching some marketing rhetoric"...you'll hear no objections from me...clearly I'm a stickler on choosing words but given the "as real as it gets" tagline....there's just some aspects to the real world you have to deal with.

 

Tom Kyler

Laminar / IXEG

www.ixeg.net

Even level-D simulators have limitations in the flight dynamics area.

 

Which apparently appears quite acceptable to some unless it happens to be Xplane.

Which apparently appears quite acceptable to some unless it happens to be Xplane.

 

Actually I think what is the 'issue' is the claim that X-Plane is better... yet when people purchase it and try it out... it's not better at all. It's actually just different.

 

To get 'better', you have to shell out money for the 'better'... because your $70 just wasn't enough to actually purchase the 'better'. $70 plus $50 gets you closer to 'better'.

 

And that can go on ad nausem.

 

From where I sit I see pluses and minuses for both FSX as well as X-Plane. But I really don't see where one can be completely honest and state that in a side-by-side comparison of 'out of the box' that either is 'better'.

Well "limitations" are relative. I do prefer xplane overall to fsx now-but they both have broken areas.

 

The problem I see is that xplane's broken areas are often in the areas that most pilots would be familiar with. I am really tired in xplane of gamelike brake sounds screaming on takeoff/landing, not being able to not only track the centerline but barely being able to keep the airplane on the runway in any xwind, and the twitchy instability and increasing phugiods as mentioned in this thread-pitch especially and inability to hands off trim, and the being blown backwards or in a slow 360 while holding the brakes on the runway in a wind is really a drag. Flying a real plane not this difficult, and if it was there sure would be a lot more fatalities. Seems some of the "cheating" planes don't exhibit this-still really confused about "cheating" in xplane.

 

Spins-did them once in 1990,did them again for my cfi training 8 years ago , and that extra stuff in the videos above-never really want to do it myself nor would really know if it is accurately modelled or really care. Sure I've done the commercial maneuvers for my license and recognize those are not modelled right either in xplane or fsx-but in normal flight realms which most pilot's experience in aircraft that most experience I would hope a sim would be close enough to put a smile on the face.

 

When simple parameters of flight that most anyone with any flying experience would recognize are not right vs. some only a few would experience are broken-seems to me a high priority should be made to make the ones the majority would see and recognize work right. Seems also to me that is what is being commented on in this thread.

 

I have always respected Marco's attitude-xplane has some really great stuff-but let's hope the not so great get fixed too. Sounds like the mantra of a flight sim enthusiast to me! Isn't everyone's goal really a really great sim? I really don't care who makes it-I just hope for the best sim available at any given time.

 

.

Not acknowledging or dismissing areas that many critics-especially from many who have backgrounds of rw pilots, engineers, programmers,simmers of many years, flight sim beta testers of many titles--varied backgrounds yet all are saying the same thing and making the same critics....well I won't state the obvious but it doesn't bode well in my opinion on many levels to simply dismiss such opinion as ill informed.

 

As far as the numbers, I am shocked by the 50,000 number quoted above. That is "nitch"-it is time for xplane to move past that because it should, the golden time is here right now, and I am shocked the sales numbers are that low -(I bet the iphone/ipad apps are logarithmically larger)! Simmers are looking for something better to move onto-and they are right now largly directionless from what I can see. Direction could easily be given-maybe even by listening to the user base.

 

The demographic survey here at avsim is also shocking-and I am one of the 13 total members as of today (2% of the total) that voted xplane as my primary sim. I think we can say for sure more than 13 on avsim have bought the sim...wonder why it hasn't become their sim of choice? I have a theory...

 

..and before that is tossed to the usual mantra of fs zombies...don't think so. I think everyone especially at this juncture is ready to embrace something different if it has what is needed to fully compete and reward. Period...Please let it compete and move forward, and take constructive critisism to heart as a way to move forward in this goal which could bring great reward to all involved-pi mesons and all are great-but let's help move towards a great recognizable sim which if recognizable will be recognized!, mesons and all.