Images here

Link to sketchup rendering of design

Just began my BS in ME so forgive me if I'm not using correct terminology, trying to communicate the issue as specifically as possible. We built a peacock art car for burning man and cantilevered five metal feathers off of the back at around 120 degrees. Looking from the front, the outside feathers are angled out from the vertical at about 15 and 30 degrees. Each weighs between 15-25 lbs and is about 9 feet long. The feathers use steel square tubing for the structural support "quill," laser cut aluminum for the pretty parts.

We attempted to reduce bending by supporting the feathers from the front using dyneema rope (which is supposed to have minimal stretch) anchored to each, high on the feather. These five ropes were then tied to a single ring which was then tensioned using a single piece of dyneema through a cam cleat and tied off with a dock cleat (my dad is a sailor). We also attempted to reduce bending to the side on the outside feathers by tying them to each other (imagine the five feathers as the fingers of your hand, we tied the thumb to the pinky and separately the pointer to the ring finger).

This worked fairly well for a few years but significant bouncing (rough roads) at last years event slowly bent the steel tubing "quills" at the supports leading to catastrophic failure on the last night. All five feathers are significantly bent. We are attempting to find ways to change the design or add to what we currently have to make sure our feathers do not bend in the future. We have bent them each back to straight (though I'm worried they have lost their structural integrity in the process) and inserted solid steel into each to try to reinforce them (though I worry that the added weight cancels out the added strength).

Curious what ideas you all might have or feedback you can give.

Some ideas we have with drawbacks in parentheses:

- Horizontal support shelf underneath the feathers in the back with vertical beams going up to a high point on each feather to stop them from falling back/down (attachments will be difficult, lots of work, affects aesthetics)

- Weld second set of quills on back and sides of current quills with spacers between (unclear whether it will work, may have to redo lighting)

- Replace some portion or all of quills with next size up steel tubing and weld new sleeve supports on top of current ones with next size up tubing (lots of work)

- Support from front with steel cables with turnbuckles instead of rope, secure each cable to its own hook rather than coming to a single point (unclear whether it will be enough on its own, not all that different from what we’ve already done)

- 90 degree supports going back and up to support feather higher, similar to horizontal shelf (affects aesthetics, unclear how supports attach or how big/tall they will have to be to be useful)

- Weld thick metal tabs on back and sides of sleeves to support, moving bending moment up feather (these will likely eventually bend too)

- Change angle of feathers (lots of work, may not solve problem)