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Old 10-22-2012, 11:45 AM   #1
CptSmiley
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Default High Fidelity Flight Dynamics and Tech/Academic Initial Demonstration

F-16 High Fidelity Flight Dynamics and Tech/Academic Initial Demonstration...

**** SEE NEW VERSION WITH CONTRIBUTIONS FROM RAGNARDA AND SKATEZILLA BELOW *****

Hi All, not sure where to put this but here since this is not necessarily going to be a released project but will be used for technology and academic purposes to assist my learning process towards other TeamVRC projects and to help the "How To" community in getting on their feet as we are all learning together...

Please note that this is NOT one of the intended products to be released by TeamVRC, just a stepping stone in that process.

The goal of the F-16 high fidelity model, as it matures, is to make it a "tutorial" of sorts to help others where I have stumbled in utilizing the external flight model. There is currently minimal documentation and most of my efforts were trial and error and it appears that we are going into very unknown territory. So far, this is purely a demonstration of the current progress as many flight dynamic features are missing in this video (leading edge flap aerodynamics, control mixing, higher order control logic, etc..)

In any case, this F-16 high fidelity flight model data is sourced from wind tunnel data that NASA collected for use in their motion simulator. This data is very expansive as it covers Alpha from -20 to 90 and beta from -30 to 30 as well as incorporating all combinations of control surface deflections. Most of my time was spent actually putting the wind tunnel data into a useable look-up table format within the external flight model.

Some statistics:
- Lines of code: >5000
- Aerodynamic look-up tables: >24
- Breakpoints (data resolution): tables range from 5 breakpoints up to 1900 for most of them
- Data source - NASA technical papers

Finally, here is a video demonstration of the fight model in action. Keep in mind I have yet to do actuator modeling or flight control computer logic, so the airframe will let you pull 20g’s if you want to. There is also no mixing logic yet. Another disclaimer, I am not a modeler and am very new to DCS modding, other members of my team are much more experienced in that and will learn from them...

As I hope you can see the "feel" of the aircraft is like one that is actually moving through a fluid, not just on rails.

Further plan of action...
-Clean and comment code so that others can actually see what I'm doing
-Leading edge slat and flap aerodynamic coded but control logic not in yet
-Model engine lag/delays
-Model control actuators
-Model higher-order flight control and stability augmentation logic
-We have other team members helping out with this to put additional goodies on this aircraft, not sure if I want to go there yet as this is currently just my pet project to help the team and the community

Again, this is a flight dynamics model demonstration and would like to keep the subject on utilizing the external flight model for that purpose. It appears that when you decide to use the external flight model, you have to also control all 3D animations as well as ground reaction modeling within the external flight model code as well. The only thing that it appears DCS still handles internally is the weight force of the aircraft...Enjoy!

Also, some stuff I want to tackle in this project to help others where I was scratching my head for days:
- How forces are applied and the code logic to process it correctly
- The units and directions for values within DCS
- Ways to organize the code project

Again, I'm still just learning but wanted to share as soon as I could as we all have questions and can learn from each other. I was having issues after issue and wanted to share as soon as I had something flying...

EDIT: Why did I choose the F-16? It had readily available wind tunnel data and a ton of available flight control information on it...that's the only reason

------------------------------------------------------------------------------------
EDIT: Initial Closed Source Release!

Hi all, so here is the download link for the closed source version (only dlls, no flight model source). The source code will be coming shortly when I finish getting it documented.

Some things to keep in mind (more info, such as data source, including in the readmehttps://forums.eagle.ru/images/editor/color.gif):

How accurate is the flight model (aerodynamics)?
- As accurate as possible with all flight data available (mostly from wind tunnels)

How accurate is the control system?
- As accurate as the NASA manned sim, using the same math model and block diagrams
- Modeling of the mechanical servo-dynamics are in there as well

How accurate is the engine model?
- Extrapolated equations from the NASA manned sim

Is there ground reaction?
- No ground reaction due to public limitation of EFM API
- The FCS controls get jittery when on the ground, this is because the raw sensor values coming from DCS are wack when on the ground. Typical FCS systems use weight on wheels to use a different controller logic, but I can't accurately determine weight on wheels due to limitations of the public EFM API. I tried to filter the sensor values as much as possible without negative affect on the FCS system.

Is there aircraft system?
- No, not even fuel burn
- No weapons
- Only aircraft system modeled is the FCS that is always active in the flight model code

Can I operate the gear?
- No manual gear operation, again due to limitations, I've got a cockpit system that automatically deploys the gear below 200ft, but you can edit that out in the lua code if you want

Is there a cockpit?
- Nope, sorry!

Is there a new 3D model?
- Not in this release, but will be soon!

The aircraft is really meant to fly around in the air...you can do touch and goes but there is NO ground reaction, no braking, no frictions, no steering.

To be clear once again, this project is meant to be sort of an extension to the "Wunderluft" project...it pretty much explores everything that is possible with the public EFM API and, more importantly, shows the limitations. Again, I hope to have the source code out to you guys soon!

Enjoy

Download Link:
* New Link:
RagnarDa Updated and Expanded Version (March 10, 2014) GitHub

PS...If you are on an x86 system make sure you swap the dll in the bin directory with the on in the bin/x86 directory
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Last edited by CptSmiley; 02-12-2017 at 10:13 PM.
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Old 10-22-2012, 12:01 PM   #2
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Excellant ..... Best of luck with this .
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Old 10-22-2012, 12:13 PM   #3
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This actually looks pretty good.

Good luck to you.
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Old 10-22-2012, 02:38 PM   #4
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is VTAI still working on their F-16 Model? Could propose a Co-Project with them.
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Old 10-22-2012, 03:20 PM   #5
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Or your team could consider selling FMs to other 3rd parties. Building a FM is a work of art. Looking forward to seeing your future projects. Whatever they may be.
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Old 10-22-2012, 03:49 PM   #6
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Good show, looking forward to your future projects, and I fully support what your team is trying to do.
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Old 10-22-2012, 04:06 PM   #7
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Nice work & very good of you to open source and share.
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Old 10-22-2012, 04:22 PM   #8
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Very nice looking flight model
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Old 10-22-2012, 04:35 PM   #9
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Quote:
Originally Posted by Druid_ View Post
Nice work & very good of you to open source and share.
Yep, the provided sticky message is great for getting started to setting up your mod, but so far I have not found much, if any, documentation to help those get started with the external flight model. What better than an actual example, right?
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Old 10-22-2012, 04:49 PM   #10
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Looks pretty nice!

All I miss is compare diagram for real and in-game parameters, and correlation coefficient between them
Like here, Yo-Yo show real and ingame Mustang compare
http://forums.eagle.ru/showthread.php?t=87966

Keep info coming!
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