Flip the scene Horizontally

using the mouse rotation feature I can rotate the scene and I can flip the scene Vertically. Same with the arrow key, left and right rotate and up/down flip vertically.  I can't flip Horizontally so i can view my 3D model from the side.  There must be a way.   I don't seem to be able to find any documentation on the Helix Toolkit so thought I'd ask here.  I'm sure it's really simple.