> I'm a bit hazy on the reference frames, and I don't have a book handy, but it > looks to me as if JSBSim doesn't calculate accelerations in the local frame > (north, east, down). Maybe Jon or Mathias can weigh in on this, but looking > at Propagate.h I see local-frame velocities available through GetVel(), > body-frame accelerations available through GetUVWdot(), but I don't see a way > to get local-frame accelerations. > > Dave
We do have vUVWdot, which is body frame. We also have Tb2l, which is a transformation matrix that goes from body to local. This is where it gets hazy for me, too, and I have to sit and think about it, but since the body frame is rotating wrt to the local frame, I think there is an acceleration due to the rotation, as well, so one cannot simply transform from body axes to local frame. We can do this, it will just take some thinking. And, yes, Mathias is the expert, here. This is where it gets a little hazy for me, too, but IIRC, vVeldot = vUVWdot*Tb2l + vPQR*vUVW If that's not right, it's something like that, and I know we can calculate it. But, I'll really be surprised if it's not being calculated somewhere already. Jon _______________________________________________ Flightgear-devel mailing list [email protected] http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
