| MadSci Network: Engineering |
I must confess, I had never heard of this one prior to your asking. At first I had visions of a lever shaped like a boomerang that could return to you when you threw it! After visiting at least one web site, I realized the word comes from a combination of "boom" like the end of a crane that lifts heavy objects and "cantilever", which is a type of beam used in engineering to describe something that is attached to a wall and has a load applied to the end.
The rules I found are below. Your rules may be different, so check carefully. But I drew a sketch of the apparatus described by these rules to give you an idea of what it might look like.
The objective of this event is to design and build the lightest boomilever capable of supporting a given load at the end of the boomilever. It must support a loading block which will initially hold the load at least 400 mm horizontally from the vertical testing wall. Each team may enter only one boomilever that must be built prior to the competition. This is an engineering event, so failure to adhere to measurements as given in the rules will cause disqualification of the boomilever (but, disqualified boomilevers will still be tested and ranked in order of efficiency behind all boomilevers that are not disqualified). Participants will still be eligible for at least a participation point.
A TEAM OF UP TO: 2 MAXIMUM TIME. 10 MINUTES
THE COMPETITION:
1. Materials
a) The boomilever is to be constructed of wood and bonded by glue. No
other materials may be used.
b) All construction materials are to be provided by the student.
c) Particle board or commercially laminated wood may not be used except for
the attachment base(s) which attach the boomilever to the vertical testing
wall.
d) The boomilever must be constructed from wood which is 1/4" x1/4"or less
in cross-section except for the attachment bases(s). Individual wood
pieces can be of any length. Any type of bonding material (glue) may be
used.
2. Construction:
a) All construction is to be completed prior to impounding at the
tournament.
b) Sound engineering construction practices such as good truss construction
and mitered joints are encouraged.
c) Do not coat the boomilever with any material (i.e. paint, stain, or
glue). Excess glue on joints is discouraged but not cause for penalty.
d) Unlimited lamination (i.e.. bonding together layers of wood) by the
student is allowed. Commercially laminated wood is only allowed for the
attachment block(s).
The boomilever must be constructed so that the center of the holes in the
attachment bases are 20 cm apart horizontally. The boomilever must be
designed to support a loading block a minimum horizontal distance of 400 mm
from the vertical testing wall. No part of the boomilever may touch the
testing wall further than 20 cm below the 2 attachment holes. The device
must be supported entirely by the vertical testing wall.
h) The center of the 1/4" diameter attachment holes holding the boom to the
testing wall must be 1 cm from the top of the boom so that a bolt and
washer will not interfere with the construction material.
i) The event supervisor will provide 2 bolts, washers, and nuts to attach
the boomilever to the vertical testing wall through the attachment bases
and holes.
3. Testing:
a) All boomilevers are to be impounded by the event supervisor prior to the
event.
b) All boomilevers will be assessed prior to testing for construction
requirements and dimensions by the event supervisor. Boomilevers that do
not meet the construction guidelines will be disqualified and therefore
ranked below all boomilevers that were not disqualified.
c) The loading block and testing wall will be provided by the event
supervisor.
d) Students must provide and wear eye protection during practice and during
the loading and testing of the boomilevers.
e)The testing wall will be a piece of 3/4" plywood with centers of holes 20
cm apart horizontally and 1/4" in diameter.
f) The center of the loading block will be placed at least 400 mm from the
vertical testing wall.
g)The loading block will be 50 mm wide x 50 mm wide x 20 mm high.
h) The load will be applied to the loading block by an eyebolt, a chain or
rod, and will be attached to the loading bucket. The loading bucket will be
a standard 5 gallon plastic bucket (30 cm in diameter).
i) Sand will be added to the bucket by the student.
j) Maximum allowable time for set up and loading will be ten minutes.
k) The student will add sand to the bucket until failure occurs or the
maximum load (15 kilograms) is supported.
1) The maximum load (15 kilograms) incorporates the total mass of the
loading apparatus, bucket, and sand.
m) Boomilevers that experience failure before reaching a 15 kilogram load
will not be disqualified.
Scoring:
a) All boomilevers are to be impounded by the event supervisor prior to
the event.
b) All boomilevers will be assessed prior to testing for construction
requirements and dimensions by the event supervisor.
c) Boomilevers that do not meet the construction guidelines will be
disqualified and therefore ranked below all boomilevers that were not
disqualified.
d) The loading block and testing wall will be provided by the event
supervisor.
Students must provide and wear eye protection during practice and during
the loading and testing of the boomilevers.
e) The testing wall will be a piece of 3/4" plywood with centers of holes
20 cm apart and 1/4" in diameter.
f) The center of the loading block will be placed at least 400 mm from the
vertical testing wall. The loading block will be 50 mm wide x 50 mm wide
x 20 mm high.
g) The load will be applied to the loading block by an eyebolt, a chain or
rod, and will be attached to the loading bucket. The loading bucket will be
a standard 5 gallon plastic bucket (30 cm in diameter).
i) Sand will be added to the bucket by the student.
j) Maximum allowable time for set up and loading will be ten minutes.
k) The student will add sand to the bucket until failure occurs or the
maximum load (15 kilograms) is supported.
1) The maximum load (15 kilograms) incorporates the total mass of the
loading apparatus, bucket, and sand.
Boomilevers that experience failure before reaching a 15 kilogram load will
not be disqualified.
4. Scoring:
The Boomilevers structural efficiency will be determined by the equation:
Structural Efficiency = [maximum load supported (grams)/mass of boomilever
(grams)] + [maximum load supported (grams)/l0 grams].
a) The maximum load supported can not exceed 15,000 g.
b) The boomilever with the highest structural efficiency will be the
winner. In the event of a tie, the lightest boomilever with the highest
structural efficiency will be the winner.
c) Boomilevers will be maintained in the possession of the event supervisor
until they are released at the end of the event assuming there is no
pending arbitration.
d) Event supervisors may take pictures of all boomilevers that are entered
in the tournament for future assessment and instructional purposes.
e) Boomilevers that do not meet the specifications will be ranked after
those that do.
The boomilever has to be constructed using small pieces of wood glued
together. The most obvious way is to use a truss system of triangles like
I have shown in the sketch. The top part of the boomilever will be
stretched by the load (in tension) and the bottom will be pushed together
in compression. You could make one giant triangle but you will quickly
find that the bottom will tend to bow or buckle and break without being
supported along its length by other members. The key is to use the least
amount of material to accomplish the task.
I can't give you enough engineering knowledge to understand it here, but if
you go to my web site at
http://ourworld.compuserve.com/homepages/JMSALTERNATIVES/introduc.htm
you can download a booklet I wrote for a bridge building contest made out
of paper. Although the contest and materials are different, the basic
knowledge of strength of materials, tension, compression, failure, redesign
by trial, etc will be helpful for the boomilever. Bottom line is, you'll
need to build more than one before you get to the optimum.
Good luck.
location of rules that I found: http://www.nso2000.org/boomilever.htm
Try the links in the MadSci Library for more information on Engineering.