Modified p-factor to be different for each engine.  This change is based on the assumption that we're currently using the p-factor parameter mostly to represent the effect of helical propwash (since the p-factor proper is much smaller).  I'm assuming that the propwash from the left engine strikes the vertical stabilizer directly, while the propwash for the right engine spirals away from the plane and has a negligible effect.  This wouldn't be right for a slip, of course, since it could bring the vertical tail more into the right engine's stream, but that will have to wait until we model propwash correctly.
Modified p-factor to be different for each engine.  This change is
based on the assumption that we're currently using the p-factor
parameter mostly to represent the effect of helical propwash (since
the p-factor proper is much smaller).  I'm assuming that the propwash
from the left engine strikes the vertical stabilizer directly, while
the propwash for the right engine spirals away from the plane and has
a negligible effect.  This wouldn't be right for a slip, of course,
since it could bring the vertical tail more into the right engine's
stream, but that will have to wait until we model propwash correctly.

Real data are very welcome.

hrabcak/jsbsim,pmatigakis/jsbsim,cs8425/jsbsim,adrcad/jsbsim,Stonelinks/jsbsim,adrcad/jsbsim,tridge/jsbsim,adrcad/jsbsim,pmatigakis/jsbsim,DolanP/jsbsim-dll,esden/jsbsim,tridge/jsbsim,AEgisTG/jsbsim,airware/jsbsim,cs8425/jsbsim,airware/jsbsim,airware/jsbsim,pmatigakis/jsbsim,hrabcak/jsbsim,tridge/jsbsim,cs8425/jsbsim,hrabcak/jsbsim,DolanP/jsbsim-dll,hrabcak/jsbsim,DolanP/jsbsim-dll,tridge/jsbsim,AEgisTG/jsbsim,airware/jsbsim,pmatigakis/jsbsim,cs8425/jsbsim,AEgisTG/jsbsim,hrabcak/jsbsim,DolanP/jsbsim-dll,esden/jsbsim,Stonelinks/jsbsim,pmatigakis/jsbsim,AEgisTG/jsbsim,airware/jsbsim,AEgisTG/jsbsim,Stonelinks/jsbsim,AEgisTG/jsbsim,pmatigakis/jsbsim,pmatigakis/jsbsim,DolanP/jsbsim-dll,Stonelinks/jsbsim,Stonelinks/jsbsim,airware/jsbsim,Stonelinks/jsbsim,tridge/jsbsim,hrabcak/jsbsim,esden/jsbsim,AEgisTG/jsbsim,esden/jsbsim,adrcad/jsbsim,Stonelinks/jsbsim,airware/jsbsim,esden/jsbsim,hrabcak/jsbsim,cs8425/jsbsim,tridge/jsbsim,adrcad/jsbsim,cs8425/jsbsim,adrcad/jsbsim,tridge/jsbsim