Working on getting our L-39 into DCS using the mod structure given to us by Alex, with good results so far! Thought you would like to see our progress. At this point it has its own slot, FM, cockpit (still early WIP), collision model, normal maps (early WIP) and all animations and lights are working properly.

Originally Posted by Krebs20

Too early to say. We would like to model all aircraft systems when the resources are available to do so. The ZA (combat trainer) and C (trainer) versions, that is.

Figured I'd start a new thread for this little nugget of information.

After a whole 3 days of head-scratching and bug-fixing on both sides of the ED dev fence, I'm proud to announce work has begun on the L-39 ADVANCED FLIGHT MODEL.

As I type, the sim is flying straight and level, and we now have the unenviable task of breaking the aircraft into multiple parts, performing aerodynamic analysis of each part, and computing the actual performance of each component, in order to create a very high-accuracy, high-fidelity aerodynamic model of the aircraft.

Development time of this is unknown, but as soon as we have something worth sharing, you'll know as soon as we calm down enough to write.

Best regards,
Tango.

The AFM is in large part our own. We feed back the results of our computations to the sim, the sim does a small amount of additional processing to complete the model, then it is applied to the sim.

All that is being added by ED is the gravitational model, collision detection, and some physics related to the weapons.

Best regards,
Tango.

I must give credit where credit is due. A big thanks to Alex and anyone else on the ED team that is facilitating AFM integration and 3rd party development in general.

In addition to what Tango described, we are feeding vector summed moments and forces which we must developed from scratch and the sim will run these through the 6-DOF equations of motion. It goes without saying that this will be a long and arduous process of development for not only our AFM module, but also for the development of the AFM API for 3rd party Devs.

If anyone out there is experienced in flight dynamics simulation or flight model creation and would like to volunteer their knowledge or resources to help develop this process, just shoot us a PM. C++ knowledge is not needed, but helpful.

Well the process for doing it isn't a secret, but our own individual code may or may not be shared. Currently we are working with an ED dev to get us the correct coordinate system transformation data we need to make local body frame force and moment calculations.

The API is still WIP, so we haven't really started to make a ton of progress until we have nailed the first step.

We have 12 L-39 rated pilots on the Patriots Jet Team who we will be looking to when it comes time to test flight model fidelity, as well as access to around 8-10 of the actual jets. Rest assured we will be making it as near-perfect as we humanly can.

Short of ED owning/testing/flying the real aircraft - the only way is to see if the FM matches available real world data.

Nate
_____

This. I would add that you should probably understand time/frequency domain dynamic analysis for accurate phugoid characteristics and controls for accurate autopilots and flight control systems (should your aircraft have them). While we all wish we were all experts in these areas, we are doing just fine learning as we go. We currently have 2 engineers and 1 software professional writing and optimizing the code, but it takes a lot of work just to set the FM up.

Over 1500 C++ lines of code are written and the aircraft only has 3 source of lift added and flies nothing like an aircraft, yet. It takes a really fine touch to balance all 6 of the forces and moments to create something that resembles and FEELS like a real aircraft. It's one thing to match numbers and a completely different thing to model proper dynamics as ED and Yo-Yo have done in their products.

**UPDATE**

The following lift and drag forces have been added to the AFM. These are by no means tweaked to their final values, but their effects can be seen in game.

LIFT

Lift due to left wing
Lift due to right wing
Lift due to left wing flap
Lift due to right wing flap
Lift due to alpha rate
Lift due to elevator deflection

DRAG

Drag (zero lift) due to fuselage
Drag (zero lift) due to left wing
Drag (zero lift) due to right wing
Drag (zero lift) due to vertical tail
Drag (zero lift) due to horizontal tail

Drag (profile) due to beta
Drag (profile) due to alpha
Drag (profile) due to elevator deflection
Drag (profile) due to gear
Drag (profile) due to left flap
Drag (profile) due to right flap
Drag (profile) due to speed brake

Drag (induced) due to left wing lift
Drag (induced) due to right wing lift
Drag (induced) due to left wing flap lift
Drag (induced) due to right wing flap lift

And here is what you've all been waiting for. Here's a first look at our WIP AFM!

http://youtu.be/9qxMycachdQ

Suggestions and constructive criticisms are welcome, as this is a very early build of the AFM and has only been in development for three weeks. This video demonstrates wing stalls, spins, tail slides, rolls, loops, rudder kicks, dutch rolls, attempts at landing with no gear (not implemented by ED, yet) and even displays the precision of the flight model with some formation flying.

Current known issues:

Wrong wing rises during spin
All moments and forces need to be adjusted to reduce alpha and beta rates
Ground handling not added to the 3rd party API, yet
Fuel weight not a factor, yet (this aircraft is LIGHT and FAST!)

**UPDATE**

Thermodynamic Gas Turbine Model Implemented

Inputs:

Atmospheric Conditions
Static Temperature
Static Pressure
Local Speed of Sound
Velocity/Mach of Inlet Air

Geometric
Core Area
Nozzle Area
Bypass Ratio
RPM

Properties
Burner Pressure Ratio
Nozzle Pressure Ratio
Max Combustion Temperature
Nozzle Temperature Ratio
Inlet Efficiency
Fan Efficiency
Compressor Efficiency
Burner Efficiency
Turbine Efficiency
Nozzle Efficiency

Thermodynamic Outputs:

Solved Properties
Inlet Pressure Ratio
Fan Pressure Ratio
Compressor Pressure Ratio
Turbine Pressure Ratio
Inlet Temperature Ratio
Fan Temperature Ratio
Compressor Temperature Ratio
Burner Temperature Ratio
Turbine Temperature Ratio

Solved Conditions
Inlet Total Temperature
Compressor Total Temperature
Burner Total Temperature
Turbine Total Temperature
Fan Total Temperature
Exhaust Gas Temperature (EGT)
Inlet Total Pressure
Fan Total Pressure
Compressor Total Pressure
Burner Total Pressure
Turbine Total Pressure
Nozzle Total Pressure

Performance Outputs:
Net Thrust (Gross Thrust - Ram Drag)
Mass Flow Ratio
Fuel Air Ratio
Specific Fuel Consumption (SFC)
Fuel Flow
Overall Engine Efficiency

Example Performance Curves
This example features the peformance of the GE CF6 Turbofan engine

Landing dynamics added to the flight model, along with new custom mechanical animations for gear, flaps, and airbrake.

AIR DATA

* Determination of static and dynamic pressure from first principles
* Air density calculation
* Mach calculation
* Airspeed derived from static and dynamic pressures
* Airspeed error due to density (altitude and/or temperature)
* Compressibility effects and "ram rise" by modelling adiabatic compression using the first law of thermodynamics
* Airspeed error due to AoA and slip angle
* IAS position error precisely matches the L-39 profile
* Complete modelling of static and pitot system with all consumers connected to the relevant system(s)

Best regards,
Tango.

ALTIMETER

* Connected to static system
* Correct failure behavior


VSI

* Connected to static system
* Correct failure behavior


ASI

* Connected to static system
* Correct failure behavior

Best regards,
Tango.

New external mesh for the C model, thanks to DGambo.

More testing of the new external model. Pilot is currently a place-holder, and even more detail is being added to the airframe almost every day. Bare-metal textures for testing purposes only.