DESIGNING A STAKE-LESS BUNGEE LAUNCHER
Problem
• I recently encountered great difficulty trying to get the stakes in the
ground with my bungee launcher. The soil has dried considerably
since my last successful flight and the stakes were enormously
difficult to hammer all the way into the ground.
• More importantly, not only are they difficult to get into the ground,
they are also difficult to extract from the ground, sometimes prying
off the plastic itself.
• Stakes can only be used in dirt/soil, so for example you cannot launch
from asphalt or concrete. With this new design, you can even set up
the bungee launcher on pavement.
Solution
• My solution was to use concrete weights to keep the bungee cord in
place.
• To make the weights, I mixed up 25 pounds of concrete into 7 quart
plastic oil pans
• The weights are easily stacked
• I drilled two holes an inch apart from each other in one of the pans,
to insert two hooks for the bungee cord.
• I also made weights for the launcher itself, setting PVC fittings inside
the concrete mixture.
One 7 quart plastic oil pan
In my first attempt, I tried using the “fast-setting” mix. It
really does set fast the moment you add water. Too fast
for me to smooth everything out. So I opted to use the
normal setting mixture.
Side node: Be sure to wear gloves and a face mask as you
do not want to breathe or get any of this stuff on you.
One 25 pound weight, complete with two hooks
for the bungee cord.
75 pounds of weights
I also added weights for the launcher.
I set up the launcher with the fittings
inside the concrete mixture before
adding water to it, so that everything
would fit more closely.
The weights for the launcher.
The bungee launcher can now
be set up on pavement, if so
desired.
It works
• After setting everything up, I used a digital scale to measure how
much tension I could achieve before the weights started to move:
Bungee Cord Side
Stacked Weight (lbs)
Grass
Pavement
25
17
8
50
28
19
75
40
34
100
40+
40+
Launcher Side
Grass
Pavement
39
29