The j2 Builder Plug-In is our graphical user interface for aircraft model building.
Model data can come from any source such as CFD, Wind Tunnel, DatCom and including a direct import from DARcorp’s AAA. J2 Builder allows for “delta” models to be created that can be used to explore multiple variants without corrupting the baseline model. In early stage design evaluations, this powerful sandbox environment provides the end user with greater flexibility when evaluating multiple design alternatives. There is no limit to the number of deltas that a user can create when looking at the impact of design variation or when looking into various trade or sensitivity studies.
j2 Builder can be used to develop a digital twin of any type or class of aircraft:
j2 Builder’s graphical and hierarchical structure approach to model building enables designers and engineers to develop aircraft models in a fraction of the time it takes to write scripts and code. Freed from the requirement to devise code and build formulas, users are able to concentrate on the value in the aircraft data.
j2 Builder automatically combines all relevant factors and their impact on the whole aircraft, evaluating different configurations, equipment locations and more, without the need to continually update the formulas associated with their interaction. Following a well-documented process, this can produce a major improvement in project performance and has been shown to cut model build times down to weeks instead of many months.
In j2 Builder, the model is a self-contained object containing all available information about the aircraft. Any relative connections or interactions are held within the model and all links and connections are tracked.
Items can also be moved and re-scaled at any time – a unique feature that allows the model to be decoupled from the analysis. J2 Builder also enables the same analysis to be performed with multiple aircraft models, or multiple analyses to be performed on a single model, without any need for the continual development of code. Variations can be created using Delta Models to maintain consistency between the baseline and the variation.
Aircraft models are split into 4 sections.
The hierarchical structure layout enables the component parts to be laid out to replicate the aircraft’s configuration.
These are used to connect up the model inputs into the control surfaces and other moving parts through gearing, actuators and other controller components.
- Developer Items
Developer items provide an API that enables external components to be added to the model – this requires the j2 Developer Plug-In.
By rapidly building models from a selection of Structural Items instead of writing code, engineers can distribute aerodynamics, include any control surfaces that are required, add multiple engines located at the appropriate location and orientation, and add internal equipment for mass and inertia calculations and external ground reaction forces.
This is achieved by building the model from a list of available Structural Items:
- Structural Item - used for internal equipment mass and inertia distribution
- Aerodynamic Item- used for adding in aerodynamic contributions
- Horizontal Stripped Item - Integrated Aerodynamic Strip Theory - this requires the j2 Elements Plug-In
- Vertical Stripped Item - Integrated Aerodynamic Strip Theory - this requires the j2 Elements Plug-In
- Dynamic Items - control surfaces, airbrakes, undercarriage etc.
- Propulsion Item - add in engines of any type
- Rotary Assembly Item - main rotor-tail rotor and gearbox for helicopter models - this requires the j2 Rotary Plug-In
- Force Item - include ground reaction or external loads
Data for these items can come from any source, so the model can be built from conceptual design right through to supporting flight test. This flexibility enables designs to be evaluated early in the lifecycle to identify challenges sooner and also allows them to be continually refined through to a high-fidelity model, supporting flight test and simulation.
The user can create any inputs needed to drive the aircraft and these can be linked, crossed and blended to drive any control surface configuration.
Additional links may connected together from any combination of the Link Items:
- Gearing - Create linkage ratios between inputs and outputs.
- Actuators - Dynamic response to an input
- Proportional + Integral + Differential - Integrate a PID controller
- Washout Filter - Output response is dependent upon the movement of the input.
- Rate Limiters - Limit how quickly a signal can change