DCS: A7 Corsair II · development update 

FlyingIron Simulations has released a new status report highlighting the development of the upcoming A7 Corsair II for DCS World.

Side view of the FlyingIron A7 Corsair II
Side view of the FlyingIron A7 Corsair II. FlyingIron Simulations

Artwork

Lead programmer at FlyingIron Simulations, Daniel Kassabian, explained the 3D modelling was completed last year with both the external and internal models remade from scratch. The process started in 2021 and was completed in the third quarter of 2022. The remake adds significantly more detail than the original model, with almost all aircraft elements accurately modelled, including maintenance areas.

A lot of work has gone into optimising the model for maximum performance without compromising much detail. This is still an ongoing process, but the exterior has been optimised along with large chunks of the cockpit.

Work has also begun on UV mapping (projecting a 3D model to a 2D image for texture mapping) the exterior model using a dedicated paint kit team to ensure the paint kit is as easy to use as possible for livery artists. Work is also well underway in animating the cockpit and exterior and setting up clickable areas, which has been very helpful in testing systems in-flight using proper procedures.

Many parts of the exterior model are animated.
Many parts of the exterior model are animated. FlyingIron Simulations

Flight model

Daniel explained: "The A7 Flight Model has undergone extensive work this year, especially in the first half of the year, with much of that work being 'behind the scenes' so to speak. This year we've been working closely with Research in Flight, an aerospace & hydrodynamics analysis company that creates tools for aerospace engineering applications. They are the developers of Flightstream, a sophisticated numerical flow solver and one of our primary tools that we use for CFD (Computational Fluid Dynamics) analysis and data collection for the A7."

"We have been working to enhance and improve our A7 Corsair model to the point where we have been able to supply validation studies and test cases against the real wind-tunnel data we have gathered. The A7 model has also been used to test and assist in the development of new control surface analysis techniques being integrated into Flightstream, which in turn enhanced our data collection capabilities for various control surfaces and damage configurations."

CFD Collaboration and NASA presentation

Daniel continued: "This allows us to gather CFD data in a fraction of the time required using traditional modelling techniques. Our work was demonstrated at the 2022 NASA OpenVSP workshop, and we have since made the tool publicly available. It is now used around the world for both academic and commercial design purposes. We have even been informed the utility is being used over at Boeing. It is our hope that this simple tool will make CFD modelling more accessible to all sim developers."

"Of course, all this only matters if it helps us to develop the A7. Although it's taken some time, these developments have been worthwhile investments. By forging a new workflow, we can tweak and experiment with our models in a fraction of the time to get the best results possible when testing unusual aircraft configurations. CFD is an enormously time-intensive process using conventional techniques and almost always requires constant model tuning and tweaking to collect valid results. As we are now developing the advanced aspects of the A7 flight model, this has been essential when testing non-standard configurations."

"For example, using our workflow, we've been able to run tests and collect data on virtually every control surface interaction possible, assess the significance of unusual interactions and determine how best to model them in-sim. Some examples include interactions between the flaps and elevator at various high angle-of-attack configs, forces in a spin and leading to a spin, spin recovery analysis and post-stall analysis. Furthermore, this new modelling workflow has provided us with a very efficient means to study the effects of airframe damage on flight dynamics, an aspect that is often modelled with only very simple approximations due to data limitations."

Work has begun on UV mapping the exterior model using a dedicated paint kit.
Work has begun on UV mapping the exterior model using a dedicated paint kit. FlyingIron Simulations

In terms of flight modelling, the latter half of 2022 has been heavily focused on designing and developing the CAS (Control Augmentation System) for the A7 Corsair. This has been a huge undertaking and has required a large amount of time devoted to studying advanced engineering control system design principles.

Daniel explained: "Although we don't have the exact equations used in the real aircraft CAS, we have enough information on the inputs and outputs of the system to be able to reverse engineer it. This has required us to approach the situation in much the same way as the original aircraft designers, attempting to carefully craft a control system to meet the requirements of the airframe and pilots."

The new 3D model adds significantly more detail.
The new 3D model adds significantly more detail. FlyingIron Simulations

"Although work is still ongoing, we are quite pleased with how things are shaping up and are confident that we will be able to fine-tune the CAS to operate almost exactly as the real system would. Flying with the CAS switched on is a completely different experience than flying with it off; the airframe is incredibly difficult to control without it. Therefore, it is critical that we get this right and we are dedicating an appropriate amount of time and resources to try and achieve this."

The CAS is only one part of the A7's AFCS (Automatic Flight Control Systems), which is used not only to enhance flight stability but also for autopilot control of the aircraft. The AFCS is being developed in tandem with the CAS and has made significant progress in 2022. The primary autopilot modes (HDG, ALT, ATT, airspeed) have all been implemented and FlyingIron is currently refining the yaw stab system, which stabilises and corrects for aircraft slip and assists in turn coordination.

CAS and AFCS naturally have a strong interconnection with the control surfaces and have required a complete rewrite of all the control surface models. This was completed last year and the controls are now working in harmony with the AFCS, respecting defined authority limits and behaviours.

Components such as the undercarriage is modelled to a high standard.
Components such as the undercarriage are modelled to a high standard. FlyingIron Simulations

Other flight model developments

FlyingIron has also been refining the mathematical classes and methods in the codebase. Focusing on optimisation, they have implemented new data processing methods that require less computational resources to achieve the same result. An example of this is interpolation and look-up table modelling, which is the foundation of data processing in a simulator and one of the primary methods used to implement CFD and aerodynamics data. These calculations happen thousands of times every second and have been a big priority in terms of code optimisation.

Sound Design

Although in the very early stages of development, work has begun on sound design for Corsair. "Thanks to the collaboration from some amazing people in the community, we were able to record a real A7 during an engine maintenance run. This is an extremely rare opportunity, and we are so grateful to the good people at Tulsa Tech University for making this possible."

"Thanks to some collaborative efforts from 'Armorine' in the Discord community, we organised a professional field recording of the A7. The recording was carried out by Tulsa Tech's sound engineers and students, with the entire engine run captured from various positions by professional-grade equipment. In total, we were given an amazing 29 high-quality aircraft samples from various mic positions and four completed mixdown tracks."

System will interact with each other as organically and realistically as possible.
Systems will interact with each other as organically and realistically as possible. FlyingIron Simulations

System and weapons development

Work has continued throughout the year to develop and flesh out the cockpit systems. One of the biggest priorities has been developing the codebase and logic underlying the A7's targeting and weapon delivery systems. To this end, lots of time has been spent refining and further developing the armament control systems, developing correct pylon release cues and logic, release inhibition conditions, developing calculations for interval drops and developing the core logic that underpins the sophisticated weapons systems of the A7. The culmination of this has been the development and integration of CCIP and CCRP weapon release modes, both of which draw heavily from various sensors and targeting systems in the aircraft before making real-time calculations to determine an impact point.

The A7 radar systems are well into the  development cycle.
The A7 radar systems are well into the development cycle. FlyingIron Simulations

Daniel continued: "We are pleased to say our A7 can now accurately release unguided weapons on target, using both CCIP and CCRP methods unique to different weapon types. Work is ongoing to further develop both weapon release modes to include inhibition cues as well as to develop the navigational modes of weapon release, such as Bomb on Coordinates (BOC) and offset bombing modes."

Navigation systems also received some development time in 2022: the INS and tactical computer systems and the aircraft waypoint system, including storage, recall and editing of flight plan waypoints. Progress has been made in integrating information from the navigation systems into the aircraft's avionics, most importantly the HUD (Head-up Display) and PMDS. This year will see further detailing of the INS, expanding on the modelling of the Inertial Measurement Unit (IMS) and the development of the Doppler Radar, both of which feed information to the INS.

Work continues on integrating information from the navigation systems into the aircraft's avionics and HUD.
Work continues on integrating information from the navigation systems into the aircraft's avionics and HUD. FlyingIron Simulations

Work will continue on implementing mark points, target points and other in-flight navigational systems. Flying the A7 requires careful monitoring and management via positional updates and pilot corrections. The A7 also requires navigational updates to correct for INS drift.

Development of most of the A7's key avionic systems is in various stages of completion. The Projected Map Display (PMDS) is integrated and functioning, with current work focused on integrating navigational data from the Tactical Computer and some lesser-used functionalities. The RWR (Radar Warning Receiver) has been on the back burner for some time due to limitations in the documentation. However, the necessary documents have now been obtained and work is now ongoing in developing the RWR fully. The aircraft's radio systems functionality is almost complete and work continues implementing the cockpit controls, presets and other functions. The A7 radar systems are also well in development, with current work focused on radar targeting functionalities and navigational cues.

Work is also well underway in animating the cockpit and setting up clickable areas.
Work is also well underway in animating the cockpit and setting up clickable areas. FlyingIron Simulations

The current codebase is being refined with a more realistic flow of information. The aim is to mimic data flow as it occurs in the actual A7, with avionics being dependent on other systems and prone to certain failures and accuracy limitations. For example, the tactical computer relies on information from the Air Data Computer (ADC) and the IMS systems to complete navigational and targeting calculations; any inaccuracies in data supplied from either the ADC or IMS will result in flow on errors and inaccuracies further down the avionics chain. In practical terms, this means that simple things like damage or icing to your pitot tubes can result in inaccurate data being supplied to the ADC and the tactical computer, creating targeting and instrumentation inaccuracies. Daniel concluded: "We want each system to be interacting with each other as organically and realistically as possible, allowing for the accurate simulation of failures, errors and inaccuracies as they can occur throughout the aircraft."

The radio functionality is almost complete.
The radio functionality is almost complete. FlyingIron Simulations

"To summarise the state of the A7, most if not all systems have been developed and integrated to at least a basic extent. Work is now focused on expanding the advanced functions and the interconnections between each system. This will happen in tandem with the artwork; as more cockpit controls and displays become available and ready to be tied to the code work. We anticipate this will be ongoing for much of 2023."

Moving forward, FlyingIron Simulations previously discussed a four-phase development roadmap for the A7, which roughly translates to the following phases:

  • SFM Based model
  • Basic EFM & flight systems
  • Advanced EFM and advanced flight/weapon/avionic systems
  • SME testing & tuning and damage modelling

They are currently approaching the tail-end of phase three, and the goal is to move into phase four of development at some point in 2023.

More information is available on the FlyingIron website.