LM and CM - Pitch, Roll, and Yaw
Hi Dave, When I read your most recent, it suddenly occurred to me that you might be confusing the systems of LM and CSM axes. In fact, when the LM landed, plus-X was up, plus-Y was out the righthand (LMP) side, and plus-Z was out the forward hatch. No question about that. Plenty of references in the transcripts and in my discussion with you and the others. I've uploaded three pertinent diagrams http://home.exetel.com.au/honais/LM-Axes.jpg http://home.exetel.com.au/honais/CSM-Axes.jpg http:/home.exetel.com.au/honais/VirtualCM.jpg For both spacecraft, plus-X is in the thrust direction and, for the LM, that is up through the docking hatch. For the CSM, it's out the CM nose. For the LM, plus-Z is out the forward hatch and plus-Y is out the righthand (LMP) side. It's a righthanded set of axes. (Put your right hand with the thumb sticking out toward plus-Z. The fingers show the direction of rotation to move plus-X toward plus-Y. Similarly - with cyclical interchange of the letters - thumb=X shows Y rotates to Z, and thumb = Y shows Z rotates to X) For the CSM, plus-Z is down toward the crew's feet (minus-Z is up thru the hatch), plus-Y out the righthand side from the perspective of the crew lying on the couches. It's also a right handed set of axes. Now for the direction of positive pitch, etc Referring to the CM diagrams from Virtual Apollo ( http:/home.exetel.com.au/honais/VirtualCM.jpg ), especially the labeling and placement of the thrusters: For the CM, positive pitch is right-hand-rule rotation of the spacecraft nose around the Y-axis toward minus-Z (which is righthand rule), positive yaw is right-hand-rule rotation of the spacecraft nose around the Z-axis toward plus-Y, and CW (positive) roll is righthand rule rotation around the X-axis (clockwise for an observer at minus-X looking toward plus-X. Referring to the LM diagram ( http://home.exetel.com.au/honais/LM-Axes.jpg ): For the LM, positive pitch is right-hand-rule rotation of the nose of the spacecraft ( the docking hardware) around the Y-axis toward minus-Z, positive roll is right-hand rule-rotation of the spacecraft nose around the Z-axis toward plus-Y, and CW (positive) yaw is right-hand rule rotation as viewed from minus-X toward plus-X. From a spacecraft perspective, the two set-ups are exactly the same with the names "roll" and "yaw" reversed. From a crew perspective, positive pitch is right-hand-rule rotation around the axis going out the spacecraft to their right (plus-Y in both spacecraft) with their heads going back; positive roll is right-hand-rule rotation around the axis coming out their belly buttons with their heads going down to their right; and positive yaw is right-hand-rule rotation around the axis going from their feet to their heads, turning left. From the crew perspective, the LM and CM set-ups are identical except that LM+Z is CM+X and LM+X is CM-Z. I agree that it's a complicated subject. Eric