> Hi, > > I'm sorry but its sounding a little anomalous to me. > > >From the kinematic relationships; > > p = phidot - psidot sin(theta) > > q = thetadot cos(phi) + psidot cos(theta) sin(phi) > > r = psidot cos(theta) cos(phi) - thetadot sin(phi) > > now for a steady turn, theta can be approximated close to zero and for > the thetadot is also close to zero and negligible. So we are left > with roughly; > > p = phidot > > q = psidot sin(phi) > > r = psidot cos(phi) > > If we p q and r were to be measured in the body axis, I guess they > would be zero. But in the inertial frame; > > p = phidot = 0 since its in a level turn the bank angle would > be constant > > q = psidot sin(phi) = non zero since phi has a value and in the > inertial frame the heading is changing > > r = psidot cos(phi) = non zero again > > Therefore q and r should have values and so should psidot, but > thetadot and phidot should be zero or close to zero. > > Am I missing something? Please do let me know.
Sorry. I confused myself. I may have been thinking of body accelerations, not rates. Or something. Your equations look good. I ran a test script with the JSBSim c172. In a constant turn I saw this at steady state: P = ~0 Q = ~3.5 deg/sec R = ~6 deg/sec Pdot = ~0 Qdot = ~0 Rdot = ~0 phi = ~30 deg theta = ~4 deg psi = from 200 deg to 20 deg phidot = ~0.0 thetadot = ~0.0 psidot = ~6 deg/sec I think this works out about right. So, at least JSBSim is working correctly. Jon ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
