What are the dimensions of the bridge (angles and lengths) when it is completely pushed down? We would like to build a “ramp” resembling the bridge at its steepest (i.e. pushed down all the way) to test chassis prototypes?
Here are the drawings
http://www.usfirst.org/roboticsprograms/frc/2012-Official-FIRST-Field-Drawings
Please take the time to download all the files, and look over them to find the information you need. It’s all in there, but it will take some detective work on your part to figure it out. The hinge mechanism has an interesting design.
Yeah, I would recommend building the ‘inexpensive version’ of the bridge. You should be able to get everything you need for <$100 and Home Depot or Lowe’s should be willing to cut the plywood for you if you give them the measurements.
Be aware that this version requires less force to tip in either direction that the competition bridge. You can modify it with weights, springs, surgical tubing, or something like that to get it to behave correctly.
I would recommend building it like the competition one. A fixed ramp might work if it was like the 2001 bridge, which stayed in whatever position it was left in. This one levels if it gets a chance. You can always put a tote under the “up” end to lock it into a stationary state for chassis testing; testing getting it to where you need it for the chassis to be able to go up it is a bit harder. And when it comes time for driver practice, you really want to be able to experience the dynamics.
If you do the math the steepest inclination is a approximately 16 degrees relative to the ground.
theta = arcsin(12" / 44") ~= 15.8 degrees