Some people don't like change and hold on to dead things. IE FSX. They are convinced FSX is superior to XP yet have never really given XP a fair go and will try and discredit anything to do with XP no matter how great it is.

 

Not sure I follow. People are trying to discredit our X-Plane offering by claiming it's using an FSX external flight model (by using our PFPX profile as evidence). This sentiment isn't coming from users of FSX...

 

No need to lay down fuel for the platform flame war, either.

Simple question:

 

X-Plane uses blade element theory for physics calculations.

 

What does FSX use, precisely?

 

The sim1.dll dates back to FS3.0 (and perhaps as far back as FS1.0). It is what drives the flight models right up to FSX today.

 

All this ignores something extremely important:

 

FSX flight model runs at a paltry 18 Hz! It is also incredibly low resolution on its data.

 

A good flight model needs to run in excess of 120 Hz to have any chance of behaving realistically.

 

Rob Smith.

Oh come on, neither sim is entirely realistic when pushed outside the limits.  Even superb P3D aircraft like the Majestic Q400 can keep climbing to altitudes seen only to the SR-71, on X-Plane the default 747 is capable of barrel rolls, and immelman loops like an Extra 300L. 

 

So i don't think you can say one engine is better than another, it's the skill of the people developing for it.

Oh come on, neither sim is entirely realistic when pushed outside the limits.  Even superb P3D aircraft like the Majestic Q400 can keep climbing to altitudes seen only to the SR-71, on X-Plane the default 747 is capable of barrel rolls, and immelman loops like an Extra 300L. 

 

So i don't think you can say one engine is better than another, it's the skill of the people developing for it.

 

Come now, comparing the Majestic Q400 to the default 747? Play fair haha.

Come now, comparing the Majestic Q400 to the default 747? Play fair haha.

 

Without dwelling on this, i have no horse in this race, i prefer DCS to either P3D or X-Plane.  I think you missed my point, i was stating that the underlying engine is not indicative of the quality of the add on aircraft; it is entirely down to the skill of the person developing for them.  

Without dwelling on this, i have no horse in this race, i prefer DCS to either P3D or X-Plane.  I think you missed my point, i was stating that the underlying engine is not indicative of the quality of the add on aircraft; it is entirely down to the skill of the person developing for them.  

 

I understood it. So you're calling Majestic unskilled?

 

 

I understood it. So you're calling Majestic unskilled?

 

Sigh...not at all, quite the opposite actually.  For the 3rd time, I was (apparently failing) to make two points:

 

1. When pushed into extremes neither engine behaves particularly well.

2. The underlying engine does not determine the quality of the flight model of all aircraft running on it.  Compare the defaults to amazing aircraft like the IXEG 737 and (i dare say) the DC6 on X-Plane, or the 737NGX, A2A C182 on FSX/P3D.

 

The person above me in the forum, Rob, indicated that X-Plane uses Blade Element theory, like it was some kind of magic engine that turns all aircraft into amazing representations of the real world ones, i was attempting to point out that isn't the case.  Both engines can produce excellent results, depending on the people developing for them.

Sigh...not at all, quite the opposite actually.  For the 3rd time, I was (apparently failing) to make two points:

 

1. When pushed into extremes neither engine behaves particularly well.

2. The underlying engine does not determine the quality of the flight model of all aircraft running on it.  Compare the defaults to amazing aircraft like the IXEG 737 and (i dare say) the DC6 on X-Plane, or the 737NGX, A2A C182 on FSX/P3D.

 

The person above me in the forum, Rob, indicated that X-Plane uses Blade Element theory, like it was some kind of magic engine that turns all aircraft into amazing representations of the real world ones, i was attempting to point out that isn't the case.  Both engines can produce excellent results, depending on the people developing for them.

 

Looks like you missed the haha.

The major advantage is that it can correctly model individual airfoils (FSX can't - its internal representation is a rhombus!), and all the subtle details that make the difference between a Beech 36 and an Extra.

 

FSX uses simple effects like control authority to simulate that difference, but if you ever edited the Cessna to make the engine rediculously powerful, it is no different to the Extra.

 

Note that I'm talking normal handling here, not extreme maneuvers.

 

Rob Smith.

IMHO ( really humble these days... ) I feel that the potential in X-Plane's FDM is bigger than in MSFS core FDM, still used in DTG Flight School, Prepar3d and partially in MS FLIGHT, although MS FLIGHT goes a bit further in some aspects...

 

There isn't for instance any fair comparison between rotary wing flight dynamics in MSFS vs X-plane 10, and DODOSIM doesn't count because it uses, just like the Q-400, and external fdm!

 

This being said, it doesn't certainly put X-plane 10 in the winners podium because a developer wanting to get out of it the performance required to build an aircraft model as close as possible to real figures will have to strive to get there, and be very "creative" in order to find viable ways to bypass the simpistic "plausibility" assumptions made by X-planes flight dynamics in some areas.

 

Systems wise it's pretty much the same I guess. Although X-plane offers some more elaborate control, thrust, and a few more systems by simply using it's standard Plane-Maker tool, I am sure just like in the most sophisticated add-ons for FSX a lot of code must be written to be able to model details.

Simple question:

 

X-Plane uses blade element theory for physics calculations.

 

What does FSX use, precisely?

 

The sim1.dll dates back to FS3.0 (and perhaps as far back as FS1.0). It is what drives the flight models right up to FSX today.

 

All this ignores something extremely important:

 

FSX flight model runs at a paltry 18 Hz! It is also incredibly low resolution on its data.

 

A good flight model needs to run in excess of 120 Hz to have any chance of behaving realistically.

 

Rob Smith.

Rob,

 

Some older full flight simulators successfully run at 20 Hz. Many more run at 30 Hz, most Level D standard. Approved by the FAA an others to train airline pilots. Are they not good flight models? None use blade element physics by the way.

The major advantage is that it can correctly model individual airfoils (FSX can't - its internal representation is a rhombus!), and all the subtle details that make the difference between a Beech 36 and an Extra.

 

This is correct.  X-Plane has a much more advanced wing than FSX/P3D.  In X-Plane we can have dozens of wing stations with individual airfoils, incidence, dihedral washout, sweep, reynolds# etc.  FS has a much simpler approach mainly dealing with "total" forces.

 

Also there is the stability, I think the expression "flying on rails" best can be related to this. Phugoid Oscillations (long term), Short period oscillations (short term), Roll subsidence, Dutch roll, spiraling etc. XP handles most of these very well out of the box (if the aircraft is well designed).

 

But, offcourse - like all sims - it doesn't help you if you do not have the skills or information needed to take advantage of this.  X-Plane also has a few "issues", which you need to know about if you aim for the highest level of flightmodell realism, 

 

So ultimately it boils down the the skill of the designer/team, but personally I'm convinced that PMDG (being very skilled) will be able to create better performing aircraft in XP than in FS.

The major advantage is that it can correctly model individual airfoils (FSX can't - its internal representation is a rhombus!), and all the subtle details that make the difference between a Beech 36 and an Extra.

 

FSX uses simple effects like control authority to simulate that difference, but if you ever edited the Cessna to make the engine rediculously powerful, it is no different to the Extra.

 

Note that I'm talking normal handling here, not extreme maneuvers.

 

Rob Smith.

FSX certainly can represent different aerofoils, albeit in a more simplified form. Only one CL v alpha profile for example. If you just look at default Cessna and Extra models you are missing a lot of possibilities. It isn't just control effectiveness that makes the difference. Mass, moments of inertia, stability derivatives, etc can all be changed. Sure you can make a Cessna shaped model fly like an Extra but so what?

Also there is the stability, I think the expression "flying on rails" best can be related to this. Phugoid Oscillations (long term), Short period oscillations (short term), Roll subsidence, Dutch roll, spiraling etc. XP handles most of these very well out of the box (if the aircraft is well designed).

You can get these behaviours in FSX too, out of the box. As for stability, a recent FSX addon was found to be longitudinally unstable because of a mistake by the developers. Easily fixed by editing the air file though. Whole aircraft aerodynamics is perfectly respectable and does not lead to inherently stable models. Every full flight simulator I've worked on uses it, including military fast jets.

 

I suspect the people who say FSX flies on rails aren't flying payware addons in a decent weather engine like ASN. They may also have swallowed rather too much of Austin Meyer's promotional comparisons which not surprisingly heavily favour X-Plane. FSX's flight model is simplified, but it is more than good enough for a desktop sim. Some find X-Plane excessively lively with large aircraft. No doubt this is the fault of the modeller, but it is possible to get it wrong.

 

Where X-Plane scores overwhelmingly is its ability to explore the world of the aircraft designer and examine the effects tinkering with incidence, twist, washin/out, etc. But to simulate the flight performance of a real aircraft the whole aircraft approach is much more direct and accurate. That is why Boeing and Airbus, among others, use it when supplying flight simulator data.

So as I understand it, the basis of the theory is that PMDG used a workaround for xplane whereby they found out how to make xplane's flight model behave like FSX's.  Then they could just do what they'd do for FSX.

 

That would be a bit rubbish, but as I understand it PMDG have said that this isn't the case.  Great.