- Hypothesis
-
- We
hypothesize that since the exhaust tubes are the cool part of the engine
they are directly proportional to the power output of the engine.
If the exhaust tubes are longer, then the engine will perform better.
We also hypothesize that the size of the air space in the engine is
indirectly proportional to the power output of the engine.
Therefore if the engine size is increased beyond a certain length,
then engine performance will be lost.
-
- In order to create an engine the quest for materials came about.
The hardware store had copper pipe, the smallest diameter of which
was 1/8 if an inch or a little over three millimeters.
This was the easy part. The
boiler presented a problem. The
very first rendition was that of a coil boiler, but the pipes were too big. The second idea was to use canning jar lids that were
soldered together. The solder
did not work so epoxy was used. This
engine did work but proved impractical to experiment on since the household
strength epoxy was quite flammable! The
third design was that of a ¾” copper pipe length with the ends capped
with pipe caps. However, in
this design the boiler seemed too spacious to work very well.
The final design simply used the copper pipe clamped down at either
end with industrial strength, 315°C
heat resistant epoxy.
- Since the copper pipe used is much thicker than the store-bought
model, a simple candle flame does not give off enough heat to create the
gradient inside the engine. Several
options were tried. The
blowtorch was used to test the engine designs before finding a
self-contained heat source. Since
a fuel holder was needed to set beneath the boiler, that is where we
started. We drilled a hole into
a pipe cap and soldered it onto a flattened piece of the ¾” copper pipe.
The pipe cap was then epoxied at the base to create a watertight
seal. First we filled it with Sterno©, which did not
burn due to the holes small size. Then
mineral oil was tried with a wick out the hole, which worked, but it created
a huge amount of smoke. Upon
testing the fuel contraption with the engines, it was found to be too large
to fit under the smallest engines. So
our final attempt was to take the little candle cup that came with the
store-bought model and fill it with isopropyl alcohol, which makes a nice,
clean, and large flame.
- Our
final conquest was for the boat upon which to mount the engines.
In the beginning, one was made with some flimsy metal cut out and
epoxied into the shape of a boat. By
the time the engines were completed it was quite apparent that the boat
would be too small to hold up the weight of an engine.
Also, the necessary switching of engines would lead to a leaking
nightmare. Thus the idea of a
pontoon boat was stumbled upon. With
a pontoon boat, the deck is above water to aid in engine switching and
trimming. We built one with two water bottles as floats and duct tape
as rigging, not the finest in sailing accommodations but utilitarian.