Why do some simulation aircraft behave so weirdly?

I have been simming for some ten years and have tried all kinds of aircraft both freeware and payware. I have about 500 hundred hours of sim flying experience.

I probably have upwards of 200 hours of GA flight in the real world, flying as a passenger (mostly upfront with the pilot) in Cessna's, Beechcraft Bonanza's, Beavers and King Air's. I flew a couple of hundred miles in a Harvard and did short test flights in a Shackleton and DC3.

In real life I have never experienced a situation where the plane "just decided to drop out of the air like a brick" or "soar uncontrollably to the heavens". Why do some flight simulation aircraft behave so badly? There are some that seem very realistic in their behavior and others that just act like demons.

I have recently decided on a path forward for my simulation hobby.

I like to fly low and slow and pick out places that I know or can recognize. I fly mostly in the PNW using the ORBX PNW scenery with some additional airports and a set of simple aircraft all from a somewhat bygone era. I have just purchased REX Essentials Plus to add to the realism. I plan to purchase the ORBX Northern California scenery along with some additional airports as I know the westcoast of the USA pretty well and like to fly "the places I know".

I would like to build a simulation cockpit but looking at the cost of instruments have decided that it needs to be simple so I have chosen a set of single engine aircraft with fixed propellers and simple controls. My aircraft are:

Cessna 172

Piper PA-18 Super Cub

Stinson SM-8 Junior

Fieseler Storch - I would like to see some more civilian repaints

De Havilland Puss Moth

Fairchild 24W

Boeing Stearman

I really like the Dave Garwood Auster Autocrat but it behaves poorly as does the Miles Hawk Speed Six which I have just bought. Any thoughts on how to "tune" these two planes would be useful as to thoughts on other simple singles that would be good experiences would be useful

I generally put most of my purchases of payware done to "the cost of learning" but am disappointed by some.

Thoughts on how to keep simming interesting would be useful.

In MSFS (FS9, FSX, and P3D) there are two files that control how an aircraft flies, the aircraft.cfg and a file that ends in .air.

The reality is these two files need to work together in order to provide the FDE for the simulator to use. A single wrong parameter in either of these files can create havoc.

You can try to fix simple things but often the gross hacking to fix something such as fuel flow has other unexpected results.

The aircraft.cfg can be edited in Notepad and is generally in plain language. This is where most people start when trying to fix issues. The .air file will need software to read the file and the parameters are often tables or 3D tables that require some aerodynamic knowledge to manipulate correctly.

Often when an aircraft has aerodynamic issues the best way to fix it is through the tables in the .air file.

X-plane uses a different technique called Blade Element Theory in which parts are described as having aerodynamic properties. Much more information then that and you need to ask the Xplane forums. I have used Xplane a number of times, but did not get into the guts of the software or design aircraft.

Bottom line, is if the products are payware then I would contact the authors and describe the problems you are having and see if they will be willing to issue a fix. if they are unwilling or unable to fix the FDE then I would request my money back. Unfortunately only a few developers offer money back guarantees. I would also recommend writing a customer comment if purchased through a major retailer.

How well any particular sim aircraft flies is dependent on how much time its creator puts into the physics. Many people are excellent at 3D modeling but not so expert with physics and just tack on tweaked files from a similar aircraft, so you get a beautiful aircraft with a questionable flight model (one well known freeware developer uses a turboprop model for every prop driven plane he creates).

But even with a well designed aircraft the sim occasionally just "hiccups" and something weird happens. I was on a leisurely flight 5000ft over Tokyo in a payware P-39 when suddenly there was a "flash" (screen went white for perhaps a couple of frames) and I was at 99000ft! ...with the engine stalled. I glided/plummeted for 50000ft before the engine would restart.

In real life I have never experienced a situation where the plane "just decided to drop out of the air like a brick"

I have. A few years ago in a Ford Trimotor, on a very windy,gusty day. Cruising along, it would just drop a few feet in a second and catch the air again with a very abrupt stop. Hell of a rough ride that day.

Perhaps have a look at A2A's aircraft.

Remember FS98? Well the FDEs are still being used by modelers so they are still around. Not all, but some. The usual is to use the Cessna FDE for single prop (as it was back in FS98 so there has been NO CHANGES). 'Blind As A Bat' comes to mind. 'Follow the Leader' also comes to mind. And even payware is 'take it or leave it'.

The modelers of today put out a PICTURE of an aircraft for you to LOOK at. That's as far as their 'responsibility' goes. The FDE is NOT their problem - it is YOURS.

Nels should of put in a 'Flight Dynamics Review' forum years ago. Perhaps they (the modelers) would of been shamed into getting some help (there is plenty out there) with the FDE BEFORE they put out the model. But noooo... that would be politically incorrect. So there is no way to fix 'it'. It's too late. The Sim world is coming to IT'S end. Repent? Too late for that - won't do any good NOW. (Oh, I became aware of this 'attitude' back when (FS98) so I don't have NOT ONE payware (ever-never-period) in my Sims (FS98, FS2k, FS2k2, FS9 and now FSX Accel). Oh...the humanity!!

Chuck B

Napamule

My thoughts.

Aircraft are all too light in fsx. They have to be, to stay responsive and flyable for beginners. After all it should be a fun game and most don't fly in real life. I knew little about planes, bought the game and flaw the ultralight the same day and the cessna 3 days later. (then kept practicing with the ultralight.). Can't do that in real life.

Cycling is easy. Accel From stopped to 15 mph is quick. And easy to make a turn and come to a stop.

Getting from 0 to 90 mph in a big rig and keeping it on the road is difficult. And getting that heavy thing up to speed takes a lot of time (and miles). Stopping in time is an art.

Sitting next to a big rig driver you would think it's all smooth.

To drive a big rig you are constantly shifting gear and thinking ahead. Just imagine a turn with a 15 ton vehicle. It's a very demanding and specialised job.

Very different from cycling.

Aircraft are just like that. To climb you need to get the engines ready, adjust thrust, wait for vga heavy plane to get to best climb speed, have clearance, and start a slow climb focussing on not too high pitch, no stall, vs within limits etc. A lot to know and have under controll.

For a game like this noone wants to have to read hundreds of pages and do an exam before getting to fly. Jump in and go!

So the planes in fs are like big rigs that drive like bicycles. Sharp turns, fast acceleration, no helmet or training needed.

Some things to consider, not specific to the original post, nor intended to disparage anyone in any way:

I won't pretend that anything that I put out was perfect - there's a reason I left the FDE work to people who specialized in it, often with mixed results - but there are factors to consider that most simmers do not. For example - I am willing to bet that the average simmer lines up with the runway, hits F4, and leaves it there until cruise. This is, of course, how engines are overboosted and ultimately destroyed, but the casual simmer has no idea how to find the correct EPR values for takeoff, nor what phrases such as "maximum continuous thrust" mean. You get the idea. I used to say that there is a world of difference between "realistic" and "accurate." Most flightsimmers want "realistic;" that is, they want their airplanes to behave based on what airplanes do in films, or how they imagine they'd behave based on having flown something else, or from what might appear to be "common sense." Of course, "realistic" and "accurate" often conflict with one another. I once took flak because a JT8D powered aircraft had "too much reverse thrust available - 70% is more realistic." The truth is that, in the pre-FADEC days of yore, it was perfectly possible to overboost an engine with reverse thrust selected in many applications (this was most definitely true of the early 737). In the real world, pilots do not hit F2 and hold it until the lever stops, they pull the levers to the idle detent, and, when the interlocks allow, they then select more as required by the conditions and their judgment. Idle reverse is fairly common today, and adding more reverse thrust will often result in negligible benefit, as the autobrakes will compensate. This is lost on most simmers. This isn't to say that some pilots haven't tried to do it the MSFS way, which is a good way to kill people (in the real world, the application of engine power is never symmetrical).

Let's have another example. Folks often take typical roll rates in a commercial aircraft for maximum roll rates. The rule of thumb in the 737 is to fly it like you're "milking a mouse." This is because the roll control surfaces are perfectly capable of doing all kinds of things to make the passengers sick (see: PIO) - especially if a pilot tries to roll with the speedbrakes in any setting other than "flight detent!" A cursory search over at PPRuNe (the place where the commercial pilots all hang out - be prepared for lots of tech talk) will make it quite clear that your average airliner can roll much, much faster than most people think it can (there is a reason DC-9 pilots described it as having "fighter-like" flying characteristics). In the modern world, of course, many commercial airplanes are fly-by-wire, and such systems often place definite limits on what the pilots can command... your average Boeing control wheel is capable of over 90 degrees of movement (I think it's 110 on the 737). Your average Boeing pilot rarely uses more than 20. Think about that.

I have come to the point where I am bothered little by such things, and regard them with some degree of cultural relativism - I understand that not everyone among us has the same number of hours in commercial airplanes as, say, Jim Campisi, and that their impressions might be coloured by their expectations. But, by the same token, if Captain Jim says it's good, I'm not exactly going to take the criticisms of someone whose sole experiences comes from a consumer PC simulation product quite so seriously. I am not trying to excuse anyone for gross inaccuracies (after all, I'm pretty guilty of a few myself), but one must consider that, for example, a "stock" airliner addon might come unloaded (with the expectation that one might load it up as they so please). Such an aircraft would seem to be impossibly overpowered and light to anyone whose overall impressions of commercial airplanes come from seat 25A. I think the original FFX 737s had this problem. Mea culpa - although, again, someone else did the physics. A little leeway for minor things is a good idea. Of course, that does not apply to a 172 that needs 10,000 feet of runway and is uncontrollable in the air.

Remember FS98? Well the FDEs are still being used by modelers so they are still around. Not all, but some. The usual is to use the Cessna FDE for single prop (as it was back in FS98 so there has been NO CHANGES). 'Blind As A Bat' comes to mind. 'Follow the Leader' also comes to mind. And even payware is 'take it or leave it'.

 

The modelers of today put out a PICTURE of an aircraft for you to LOOK at. That's as far as their 'responsibility' goes. The FDE is NOT their problem - it is YOURS.

 

Nels should of put in a 'Flight Dynamics Review' forum years ago. Perhaps they (the modelers) would of been shamed into getting some help (there is plenty out there) with the FDE BEFORE they put out the model. But noooo... that would be politically incorrect. So there is no way to fix 'it'. It's too late. The Sim world is coming to IT'S end. Repent? Too late for that - won't do any good NOW. (Oh, I became aware of this 'attitude' back when (FS98) so I don't have NOT ONE payware (ever-never-period) in my Sims (FS98, FS2k, FS2k2, FS9 and now FSX Accel). Oh...the humanity!!

Chuck B

Napamule

While I do agree that many FDE designers are somewhat stuck in FS98 (particularly with respect to the internal workings of the jet engine tables), people like you are why I quit. Here's an idea: why don't you download the relevant SDKs, get a copy of AirEd, and learn to do it yourself? Instead of disparaging the people who choose to share the fruits of their labour with you - often with no expectation of compensation - why don't you do something constructive, so that we all might benefit? The tools are, after all, free. I am certain that many model builders would be quite pleased to have someone doing for the MSFS world what Bob Boudin has done for rail simulators. I am also most certain that this would accomplish a fair bit more than gracing us with your joystick button assignments.

Sitting next to a big rig driver you would think it's all smooth.

Unless they came from the CDL mills! You oughta see some of the idiots I put up with every day on MN 55 - "smooth" ain't in their lexicon, and neither is "control!" :D

Glad to see you are still around, Erick! I still enjoy flying many of your aircraft.

Darrell

Erik Cantu: I think I speak for all of the flight simming community - your name brings back lots of good memories flying around the world in many of your creations...

+ This 1!!

Mr Cantu,

I left out 'And Tested' after the word 'complete'. Of course that would be too much to ask. Who am I kidding.

And I DO have the SDKs and AirEd (have had since FS98) and I edit FDEs everyday for last 10 years. But since (like you say) a lot of simmers don't appreciate 'accurate' FDEs why bother. You found that out - you get no respect. It's 'gimme gimmie gimmie'. And if you are online you will get buzzed by the same idiots.

I have used your F-104 jet engine sound since FS2002. All the mil jets (and some 'Concept' and UFOs) have them. I thank you for the sound (ahead of it's time) as they work perfect even in FSX Accel.

//Aircraft Sound Manager ASM V1.0 pl1

///Lockheed F-104 'Starfighter'

///Copyright 2002 Erick Cantu, original sound clips copyright Danielle & Bart

I also have stuff from Lampart, and Bill Lyons, that I use even today. It works or it's junked (file 13). If I like I port over, if possible. I don't 'do' tubes anymore. Too much to do with GA and Bush. And vehicles, tanks, boats, etc. If I did put out FDEs and someone had something bad to say it would NOT interfere with my hobby one bit. I do what I do (fly/drive) because I like it. I share my FDEs (if asked). Ask around. There is no pride involved. But I don't like to be 'fooled' into buying junk that don't work. That is what riles me.

Chuck B

Napamule

I really like the Dave Garwood Auster Autocrat but it behaves poorly as does the Miles Hawk Speed Six which I have just bought. Any thoughts on how to "tune" these two planes would be useful as to thoughts on other simple singles that would be good experiences would be useful

 

An idea for you , try Dave Molyneaux's Auster Autocrat, & my Hawk Speed Six & see if their performance meets your criteria. These are for FS9, but will port over to FSX. Both of these models are in the library here.

Keith

I think we are forgetting MS itself on this equation. Since FS2002, the one that got me back into MS-FS’s again after being fed up with previous versions for twelve years, I noticed slight but annoying changes on the FDE with all the following reincarnations of the simulator all the way to FSX Gold.

They removed parameters, recombined them with other ones and twisted and tweaked this and that in the FDE for no reasons other than “users will never notice them anyway”. But many of us did notice.

No way will someone be willing to open again an old FDE file and re-tweak it for a new version, especially when all the previous labor of love laid wasted now in the new version for now real reason. Matter as well start a new project for the new version. Also it is well known that many developers just take/use the FDE from MSFS default stock and do minor changes and then let them loose. It is just that simple. Thank goodness for the real ones that did the walk and continues to this day doing their best for the love of this simulator of us.

Cheers,