"I am concerned with the strength of my homemade tailwheel bracket. That is the reason for my question about 2 on board."
Ryan, Have you already explored the FAR-23 requirements for a tailwheel landing conditions? There you will find the basic rules for loadings on main and tail wheels as a function of the wing loading. If you are interested I will send you privately a copy of the relevant pages of FAR-23. Regards, Stefan Balatchev Ottawa, ON, Canada
