How to draw a tube frame?
For my T-Bird I airframe not really. I know the hoop tube that goes over, and around you is 28" wide ID. The square tube that goes under you that it attaches to, is 2" x 2' .25 wall and I think 31" long. I can try and get some measurements. I do have the plans for another single seat plane in PDF if you e-mail me, I will send them to you. Armilite@aol.com Most of these planes use alot of the same type of parts, 1"OD tube or 1.125"OD tube. Grade 5 bolts with nylon lock nuts, tube connectors, etc.
Draw the shape in a 3D sketch and use a tube weldment to make the pipes. Watch some weldment tutorials to get the technique. You must be able to assign groups in the right order to have the pipes automatically fit properly at the joints.