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[DPRG] Contest Course

Subject: [DPRG] Contest Course
From: David P. Anderson dpa at io.isem.smu.edu
Date: Tue Aug 15 13:42:06 CDT 2000

Howdy,

It appears that a new DPRG contest course is still in the planning
stage, and the current course will be used for the September contest.

This seems like a good thing to do, and gives the design process some
time to cook now that folks are thinking about it.

In the meantime, perhaps we could spruce up the old contest walls a bit,
and maybe come up with an easier method of setup.  Here are some
thoughts in that direction.

For those who are not familiar with the course, it is made of 10 sections
of foam board laminate each 8' x 13" x 1/2".  These are held together
with metal clips and duct-tape.  Metal shelf angle brackets
attached to short sections of wooden 2x4 are taped to the walls at
every 48 inches to act as supports for the walls.  These are always
getting kicked by curious onlookers.  The course sets up in the shape
of a "T" 24x16 feet with an 8 foot width.

I made some paper models of the course to see if I could come up with
some method to make the walls self-supporting.  

The sections of the course that are connected at 90 degrees will support
each other, without need of additional supports, if "hinges" are used to
connect the sections, like this:


                    +----------+
                    |          |
                    |          |
                    |          |
                    |          |
         +----------+          +-----------+
         |                                 |
         |                                 |
         |                                 |
         |                                 |
         |                                 |




It is the "long wall" where three 8 foot sections are connected end-to-
end that sags and pulls out of alignment without additional supports.  


         +----------+----------+-----------+


The cardboard DPRG mini-T handles this problem with an external triangular
truss attached to the long wall at the center two hinge points, like this:



         +----------+----------+-----------+
                     \        /
                      \      /
                       \    /
                        \  /
                         \/
                         /\



This design stiffened up the flimsy paper models enough to convince
me that the 1/2 size miniT could be made from heavy cardboard.  That
turns out to work nicely.

I'm not necessarily suggesting this same truss for the full size course.
The thing that makes this work on the paper models and the 1/2 size course
is that fact that the wall sections are hinged together, not separate
pieces.  Seems like we could do the same for the full size foam board
sections, either with real hinges or with strapping tape.

I wanted the miniT course to be able to rapidly fold up for storage and
transport.  This means the hinges must allow the sections to be straight
(long wall) or 90 degrees (all other sections) and also fold back flat
against each other for storage.

Normal hinges won't do this.  For the cardboard miniT, where the cardboard
walls are about 1/4 inch think, We made hinges from strapping tape and left
about a 1/4" gap between the wall sections.   This allows the pieces to
fold flat.  Like this:


            wall sections

                |   |
                |   |
                |   |
                |   |            +---------
  strapping     +-|-+            /
  tape hinge -->  |             /+---------        _____
                +-|-+        +-/-+              +-/-+ +-\-+
                |   |        |   |              |   | |   |
                |   |        |   |              |   | |   |
                |   |        |   |              |   | |   |
                |   |        |   |              |   | |   |

   
               straight    90 degrees         flat (180 degrees)


Any ideas?

If we can come up with some similar hinge arrangement for the foam board
walls, and some kind of stiffener or support for the long wall sections,
instead of the metal angle brackets and 2x4s all the way around, the
rigidity of the course could be much improved, and the setup time greatly
reduced.


regards,
dpa



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