Now some words on how to run that simple numbers., based on post #53.
1. You draw your truss. Scale is irrelevant, only angles have to be right.
2. Starting from load - in this case tail (100mm - 1mm=10 kg as per example) - we draw our force triangles/squares as per Sport aviation article. They can be drawn separately or in one pile as in my this example. If all done right - latest line will be equal to our reaction force * sine of truss member.
3. We delete our load vector constraint.
4. Using
Buckling Calculator — Column Buckling and starting from your known tube length we enter critical load as a length of any element. I prefer to start from highly loaded one.
5. Now we need to check next members. From Cremona diagram we take load, from drawing - lenght. If all is ok - we go to next element. If not - we have to decrease length of element. And we have to go from our reaction point to the load.
6. If we see, that latest element is too long to hold necessary load - we have to redraw our truss and add new element or pick up next size of tube and start from first step.
7. If we have run out of space and our last element is very short - we can again take smaller size of tube or just delete/ignore it.
Repeat 5-7 till most of tubes (especially longest) are similarly stressed.
