Alabama · Balsa sticks, 1/16 to 1/4 in
35.5 in gap · weights hung from the lower chord at 2 points · no mass limit
Official rules (PDF)(opens in a new tab)The rules don't mention AI tools. Check with your teacher or the organizer before you enter a design from this site.
Read it in the rulebook(opens in a new tab)Soon this page will show ready-made designs for this contest, each checked against every rule below, loaded until it breaks, and buildable with a hobby knife, with a printable build pack. For now, here are the rules in plain words.
Our summary of the official rules. If anything here disagrees with the rulebook or the organizer, they win.
Where a rule can be read two ways we use the reading the organizer most likely meant and show the other. Where ours is the looser one, ask your organizer before you rely on it.
Two equal point loads on the bottom chords at x = +-6 in; bottom-chord nodes must sit exactly there.
The other reading: Loads on a deck at the third points.
The hatched 1/2 in bands at the loading points are where the hanger passes between the trusses, so no bracing or floor beam may cross them (4 in wide, centred on each loading point).
The other reading: The bands are in the truss plane, so no web member may cross them (needs a special panel layout).
“span between the bridge supports will be 36 inches”
“at least 37 inches ... can NOT be longer than 39 inches”
“length of the supports will be less than or equal to 1/2 inches”
“between 5 inches and 7 inches wide”
“can range between 5 inches and 10 inches”
“no member ... greater than 1/4 inch by 1/4 inch, and 24 inches”
“Layering members on top of one another (laminating) is not allowed”
“Overlapping of members no greater than 1/2 inch”
“Gusset Plates with maximum dimensions of 1/2 x 1/2 x 1/16”
“Wood glue used for carpentry and residential use”
Nothing hangs below the supports in the middle third. The open space drawn above the top chord is satisfied by any bridge whose top chord is its highest part.
The other reading: A 3 in clear zone above a fixed height.
Height between 5 and 10 in, and width between 5 and 7 in, are treated as hard rules, although the score only adds 10 g per violation.
The other reading: Soft rules traded against penalty mass.