Round or Square Tube Longerons

[bestdoorman]

I am putting together a materials lists for the tube and wanted to get your insight on the pro's or con's of the round or square tubing. The plans give you the option. Is one better over the other? If not why the option?

Thanks

[schrome]

Hi, bestdoorman. This was discussed about a month ago. Try searching.

Ed

[davewilcox]

Square tubes on top longerons may help form a better interface with the canopy. I see no advantage to using square longerons on the bottom except it is easier to scarf intersecting tubes.

[chuck59]

I believe the square tube longerons came from John's ill fated attempt at making fiberglass panels to do away with the fabric covering. The square tail feathers came at the same time..

[raceair]

Chuck....That's right....I was there and looked at that prototype. One of the reasons he scrapped the idea was weight, the other was 'oilcanning' of the fuselage sides aft of the cabin. About that time he decided to manufacture fuselages as well, and the labor saved from not fishmouthing was substantial. Most of the cuts can be done with a chop-saw.
I built my 'Zippy 2' prototype the same way....Square longerons, round cross tubes and diagonals....On the negative side.....the square tubing clusters have somewhat 'less' linear weld bead around them.....Ed

[4trade]

You need seal between canopy and frame, so there is no advantage for square tube. Sq tube is only heavy option to reduce couple of hours notching.

Notching round tube take only few hours more than cutting sq tube.