scott siler asked 2 years ago
hey I was wondering if there is a way to choose a different orientation for the system? I would like to stay using a right-hand system, however, is there a way to reorient the coordinate system so that the X-axis is pointing forward out of the leading edge of the wing and the Z-axis is pointing down instead of up? i only ask because thats what i’ve always been taught is the standard coordinate orientation for a body-fixed coordinate system. thanks.
scott siler answered 2 years ago
Hey Andre,
if that is true, and Flow5 utilizes the standard orientation of a body-fixed axis system, then i am confused by the results i am getting. i modeled a basic wing with no taper, an aspect ratio of 6, and a flap on the left wing tip modeling an aileron deflection down. i get a negative roll moment (L) and a positive yaw moment (N). however, for a left aileron down, i should get a positive roll moment (L) indicating a roll to the right and a negative yaw moment (N) due to the adverse yaw. if you can tell me an email address, i can send screen shots of what i am getting.thanks for your help.
can you tell me an email 
techwinderHello, the axes and signs have been a pain since the beginning due to the need of converting quantities from body to stability axes and vice-versa. I’m reasonably confident in the absolute values, but I’ll revisit the whole thing and post back.
André
The axis system cannot be set manually. However it uses the standard stability axes with the x-axis pointing forward and the z-axis pointing downards as defined in Etkin & Reid.
A recap of the method can be found in lecture 16 of the this course https://ocw.mit.edu/courses/16-61-aerospace-dynamics-spring-2003/pages/lecture-notes/
See the figure on page 5.
André
Hey Andre,
if that is true, and Flow5 utilizes the standard orientation of a body-fixed axis system, then i am confused by the results i am getting. i modeled a basic wing with no taper, an aspect ratio of 6, and a flap on the left wing tip modeling an aileron deflection down. i get a negative roll moment (L) and a positive yaw moment (N). however, for a left aileron down, i should get a positive roll moment (L) indicating a roll to the right and a negative yaw moment (N) due to the adverse yaw. if you can tell me an email address, i can send screen shots of what i am getting.thanks for your help.
can you tell me an email