On Wed, 3 Nov 2004 14:05:59 -0500 David Megginson <[EMAIL PROTECTED]> wrote:
I've thought of a simpler way to approach this problem. Let's say that I have a plane and the three Euler angles of rotation, phi, theta, and psi (roll, pitch, and yaw). Given those three angles, I'd like to determine which direction around the z axis is most directly uphill and how steep the hill is.
For JSBSim, the order of rotation is z, y, x (heading, pitch, roll). Given that, note that pitch and roll don't affect heading. I assume you are talking about the aircraft z axis in your last sentence. Also, I assume that you mean, which angle about the z axis is most vertical with respect to the local horizontal? I _think_ this answer might have something to do with constructing an omega rotation vector using the Euler angles, transforming it to the local frame, and taking a dot product, but I'd have to think about this one for a little bit. This is kind of a cool problem. Probably someone else will have figured this out by the time I post this email ... :-)
Jon
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