AERODYNAMIC AND FLIGHT DYNAMIC REAL-TIME ANALYSIS DURING SPIN AND CAREFREE MANEUVERING TESTS OF THE SAAB JAS39 GRIPEN

摘要

The Flight Control System (FCS) in JAS39rnGripen has a function called the ManeuverrnLoad Limiter (MLL). Its purpose is to give thernpilot maximum performance in every situation,rnwithout ending up in an out-of control situationrnor overloading the structure. Even if the MLLrnfunction prevents departures in the normal envelope,rnit is possible to enter an extreme lowspeedrnsituation if the low-speed warning is ignored.rnTo evaluate the MLL function and thernspin characteristics, flight test have been performedrnat Saab since 1995.rnOne new tool developed to increase efficiencyrnand reduce costs during these tests isrncalled ROMAC (Real time On-line Model andrnAerodata Control). ROMAC includes a completernsimulation model of the Gripen aircraft,rnrunning in real time using telemetry input datarnfrom a flying test aircraft. With a delay of onlyrnone second it is now possible to perform a realtimernparallel simulation, comparing the resultsrnfrom the complete simulation model with flightrntest data.rnTo avoid that the simulation will divergernfrom the flight path of the test aircraft, a "wingrnman" pilot model has been developed. The pilotrnmodel acts as a wingman flying in formationrnwith the test aircraft. ROMAC also includes arnseparate implementation of the JAS 39 Gripenrnaerodynamic model and real-time aerodynamicrnanalysis of flight test data. In the last five yearsrnthe time to get an aerodynamic comparison plotrnhas decreased from half a day to a second.rnThe use of real-time analysis during carefreernmaneuvering and spin tests has significantlyrnimproved the efficiency of each test flight. It hasrnalso significantly improved the decision supportrnduring flight tests.