Flight Model Question

[SectorNine50]

Hey guys, I know this has been covered before, and I did a search but I didn't find the answer to my particular question in the few threads I looked at.

I know that FSX's flight model uses a set flight model and each plane that is modeled in game has a file with all the pertinent flight information in it.  For example, wing span, wing chord length, fuselage length, weight, width, etc. etc.  This information is then plugged into the flight model and the flight dynamics are produced.

Now the other way I've heard of the flight model being done is the way X-Plane does it.  The flight model goes quite literally off of how the plane 3D model is shaped.  That means that aircraft with more polygons and more accurate 3D modeling have a more accurate flight model (In theory).

I'm curious as to which way this game chose to execute it's flight modeling.  It would be interesting if those people that think their beloved aircraft (who's 3D models are re-done) flies differently after the patch are actually noticing a more accurate flight model due to more polygons on the wing for the flight model to calculate on (as significant or insignificant as this may be).

I know I've seen a picture portraying the flow over a few points on the wing of an aircraft (F4U maybe?) somewhere on this forum, but for the life of me couldn't find it again.

Thanks for the help!

[SectorNine50]

Does no one know or is this kind of information classified?

[Strip]

There are people who know the answer to this question, relax tho, they dont get on the boards daily sometimes.

Widewing comes to mind, he isn't on here a lot but I would bet money he knows the answer.

Strip

[ImADot]

My guess is proprietary algorithms that are corporate secrets and probably patented.

[TequilaChaser]

I'm curious as to which way this game chose to execute it's flight modeling.  It would be interesting if those people that think their beloved aircraft (who's 3D models are re-done) flies differently after the patch are actually noticing a more accurate flight model due to more polygons on the wing for the flight model to calculate on (as significant or insignificant as this may be).

I know I've seen a picture portraying the flow over a few points on the wing of an aircraft (F4U maybe?) somewhere on this forum, but for the life of me couldn't find it again.
Thanks for the help!

Does no one know or is this kind of information classified?

Heya SectorNine50,
not sure if any of these following links help, but maybe they will.......

from Brooke's website:
Techniques for Finding Stall Speed in Simulated Aircraft
by Brooke P. Anderson (Brooke in Aces High), January 28, 2007
http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/stallSpeedMath.html


The Math Behind Turning, v1.2
by Brooke P. Anderson ("Brooke" in Aces High)
http://www.electraforge.com/brooke/flightsims/aces_high/stallSpeedMath/turningMath-v2.html


? Stall Speed Bug Thread on AH BBS
http://bbs.hitechcreations.com/smf/index.php/topic,197316.msg2304898.html#msg2304898

EDIT: click this quote of Pyro's for those wing cord pics and how many points they gather data from

hitech gives example of compression model used
http://bbs.hitechcreations.com/smf/index.php/topic,28640.msg302361.html#msg302361


hope some of these help

[SectorNine50]

Ah-ha!  Thank you so much for searching for that stuff, I found those F4U pictures I was looking for!

However, I'm still unsure.  I see the results of the calculation for each part of the wing on the F4U, but I don't know how it's being reached.  The 3D model technically could still be used to find the information needed for the lift equations.  I'm worried that this information may not be readily available due to how close it is to the core of the game's engine for flight dynamics.



Although, on the same hand, each point on the wing could have a set of constants for the lift equations (if that makes sense).  In other words, the 3D model may not effect how the plane flies at all.

I just had somewhat of an epiphany; if it were based upon the 3D model, how on earth would Santa's Sleigh or the Sharks w/ Freakin' Lazer Beams Attached To Their Head work?  The epiphany was quickly busted when I realized that there are such things as transparent pixels.

 

[EskimoJoe]

I highly doubt 3D modeling affects flight performance in AH. Croda (I believe) once turned a C-47 into a Cessna 172 for H2H, IIRC.

[Stoney]

Basically, the two different approaches would be "vector-based" and one resembling a CFD (computational fluid dynamics) model.  Vector based approaches are pretty much used exclusively by flight simulators or games whereas CFD programs are used for design work and detailed analysis.  CFD models are either very clunky or require huge amounts of computing power to achieve any sort of fidelity with real life, because they basically break the plane into very small pieces and simulate the airflow of that piece, then add all the pieces together to create the total affect of airflow around the model.  The 3D model of the aircraft has a very large part to play in the results of the CFD programs, and as a result, are typically very difficult for games to render without chewing up a ton of resources.  Vector based programs allow the 3D model to merely be an "object" that behaves a certain way.  This way the model itself doesn't have to be very detailed and can be rendered more easily.

AH2 is a vector-based model, as you can see in the picture above.  MSFSX, IL2, and even X-Plane are vector based models as well.  If you want to see a CFD program, do a search for VSAERO.

[SectorNine50]

Thanks for the information Stoney, that's exactly what I was looking for.

However, I was under the impression that X-Plane was CFD and that was the biggest difference between MSX and X-Plane.  I'll have to find out where I read this and see if I can confirm it.

[Stoney]

Perhaps I'm wrong about X-Plane then, but I can't imagine that it could crunch all the numbers needed and render everything without crashing average desktop computers.

[Ack-Ack]

Thanks for the information Stoney, that's exactly what I was looking for.

However, I was under the impression that X-Plane was CFD and that was the biggest difference between MSX and X-Plane.  I'll have to find out where I read this and see if I can confirm it.

According to X-Plane's website, they use CFD based on the Blade element theory.


ack-ack

[SectorNine50]

Ah-ha!  Yeah here's the website:

http://www.x-plane.com/pg_Inside_X-Plane.html

[SectorNine50]

Here is the article that mentioned geometric modeling, just for reference:

http://www.simpilotnet.com/index.php?option=com_content&task=view&id=20&Itemid=9

[Stoney]

According to X-Plane's website, they use CFD based on the Blade element theory.


ack-ack

CFD and blade element theory are two different things.  It certainly appears that X-Plane has a unique approach compared to other sims, but I still doubt it approaches some level of fidelity closer than a good vector-based system.  HTC would probably be best to make the comparison.