After getting very frustrated while trying to weld bits and pieces of scrap, I finally started to "get the hang" of this gas welding business!
When I was finally able to weld four pieces of tubing together in the shape of a square, add a valve stem and then pressurized this assembly without any pressure loss, I proceeded to deform this assembly (while under pressure) and checked the assembly for leaks. It took some more practice but I finally achieved this "milestone".
I knew that I was still a long ways away from the aircraft welding level so I decided to assemble a miniature version of the fuselage for additional welding practice but also to practice the tube cutting and notching techniques.
I obtained some mild steel from local hardware store and started to teach myself the tricks of cutting, shaping, and welding tubing.
This is a photo of the upper and lower practice fuselage sections.
This photo shows the assembled practice fuselage section.
A different view of the practice "fuselage" section.
Here is a good view of how a joint should NOT look!!
I severely undercut (I think that is the right terminology) the angle tube and consequently needed to add a LOT of filler.
UGLY!
Here is a view of the "tail" section.
A close up view of one of the last joints I welded on this "practice" fuselage.
This one did not turn out too bad.
Here is a view of a practice cluster weld with simple 45 degree joints.