Technical overview of StallBox
Limitations of Current Level C/D FFS Stall Modeling
Since the regulatory requirements for Level D simulators have not mandated or formally recommended that the aerodynamics model provide representative data outside of the normal flight envelope of the aircraft, the typical coverage of the aerodynamics model has been limited. As shown in the illustration, typical aerodynamics models will have very good coverage for the normal flight envelope, but will have limited data at extreme conditions. As a result, these models are inadequate for comprehensive upset prevention and recovery training.
The StallBox Solution Fills the Gap
StallBox provides the ability to upgrade existing flight simulators with enhanced, aircraft type-representative stall models without the need for aircraft OEM data sets or modifications to the existing baseline flight model code. This is accomplished by hosting the enhanced stall model in an external host computer (i.e., the “StallBox”) which requires only a lightweight code component to establish the communication link between the simulator host and the StallBox. The following diagram depicts how the StallBox solution integrates with the existing flight simulator and the primary functions performed by the StallBox are detailed in the following subsections.
In order to establish the communication between the simulator host and the StallBox, a lightweight interface code component is provided for insertion in real-time executive loop of existing simulator host. The typical communication protocol is Ethernet, but other protocols such as serial, MIL1553, SCRAMNet or shared memory can be readily accommodated. In the event that the established communication is disrupted or even completely disconnected, the operation of the simulator is not impacted and execution seamlessly and automatically returns to the baseline flight model. The StallBox Interface Control Document (ICD) that defines the data needed by the StallBox for monitoring and model update operation will be provided and BAR engineers will work with the customer to coordinate the StallBox implementation.
The representative stall model for the selected aircraft is hosted in the isolated and independent environment of the StallBox computer. The basis of the model is a predictive- and empirically-derived model developed by BAR using methods developed in collaboration with the FAA and which is independent of aircraft OEM data. The model is delivered with the required Statement of Compliance (SOC) for both model as well as SME review (as required by the FAA NPRM) provided with FAA compliance.
In order to provide a smooth transition between the baseline aerodynamics database and the updated model behaviors, the StallBox provides application-specific, multi-variate data blending algorithms. The blending method is integrated in such a way that the existing stall warning is not affected and no existing QTGs are influenced.
The model update is introduced into the simulation host using the established communication connection between the StallBox and the host. The force and moment data in the host is updated and the model response is revised to reflect the representative stall behavior.
This capability provides for the incorporation of the FAA-recommended instructor displays and can be accomplished by modifying an existing IOS, integrating a wired desktop display, or incorporating a wireless tablet computer that communicates with the StallBox. For the tablet computer option, the instructor displays are reconfigurable to show a variety of Vn, α-β, PFD repeater, and pilot input display combinations. Color-coded tell tales provide instructors with quick interpretation of pilot response in stall. The tablet computer can also store, replay and optionally download stall data.