SPACECRAFT SYSTEMS
OUTER JACKET, PLACARD, RIGGING
TBD
CAPSULE
The shell was constructed from Corning Foamular Insulpink XPS extruded styrene insulation, R-value 7.5, wall thickness 3.8 cm. This is a variant of closed-cell styrene ('Styrofoam') sheet, but with much better mechanical properties, used in building construction to insulate walls. It is also used in the modeling industry in building scale models for special-effects. The desirable properties for this design are its mechanical stability, the lack of annoying styrofoam pilling when cut, and the higher insulation value.
The Foamular sheet cut readily with a sharp box cutter or razor, allowing fine control over dimensions and fit. The sheet was cut into pieces. These pieces were trimmed to precise corners, and hot-glued into place to form a rectangular shell closed on 5 sides. The styrene is susceptible to melting when hot glue is applied unless the temperature is lowered. Specifically, the glue slowly melts into the styrene and forms craters. It is however difficult to find a low-temperature or variable-temperature glue gun: eventually a small crafting glue gun was found that did not melt the styrene.
A separate lid was also constructed, to close the 6th side. Outer dimensions were 21.6 cm x 21.6 cm x 33.0 cm with the lid in place. The edge of the 5-side box meeting the lid was lined with vinyl weatherproofing foam, so that when the lid was secured (see below), there was a fairly tight seal with minimal air-exchange.
This shell then displaced a volume of approximately 7.9 liters; assuming a weight of water of 1000 gm/liter, the shell would experience a buoyant force of 7960 gm, more than enough to keep it afloat even with the weight of the subsystems and parachute.
The Foamular sheet cut readily with a sharp box cutter or razor, allowing fine control over dimensions and fit. The sheet was cut into pieces. These pieces were trimmed to precise corners, and hot-glued into place to form a rectangular shell closed on 5 sides. The styrene is susceptible to melting when hot glue is applied unless the temperature is lowered. Specifically, the glue slowly melts into the styrene and forms craters. It is however difficult to find a low-temperature or variable-temperature glue gun: eventually a small crafting glue gun was found that did not melt the styrene.
A separate lid was also constructed, to close the 6th side. Outer dimensions were 21.6 cm x 21.6 cm x 33.0 cm with the lid in place. The edge of the 5-side box meeting the lid was lined with vinyl weatherproofing foam, so that when the lid was secured (see below), there was a fairly tight seal with minimal air-exchange.
This shell then displaced a volume of approximately 7.9 liters; assuming a weight of water of 1000 gm/liter, the shell would experience a buoyant force of 7960 gm, more than enough to keep it afloat even with the weight of the subsystems and parachute.
CAPSULE LID
The lid itself consisted of an outer sheet, and an inner square glued to under the outer square with dimensions that matched the opening of the box. This made for a snug fit of lid to box. A set of Velcro attachment straps were glued to the outer surface of the box and the upper surface of the lid, to further secure the lid to the box.
In the center of the lid was drilled a hole large enough to fit the APR radio antenna and cable-connecter (wrapped with vinyl electrical tape). The antenna was placed through this hole, and sealed in place with silicone caulk on the both sides. This formed a lid with an antenna sticking above the the lid, and a RF cable protruding below the lid into the box, which was later attached to the APRS radio within.
As a precaution, perhaps unnecessary, a thin piece of plastic that came from a package of blank CDs, was glued in place around the antenna on the outer surface of the lid. This was to provide additional mechanical support to the lid so that cracks would not form around the opening; but the styrene sheet's strength, and the additional inner lid below would have likely prevented any cracking due to stress or impacts.
In the center of the lid was drilled a hole large enough to fit the APR radio antenna and cable-connecter (wrapped with vinyl electrical tape). The antenna was placed through this hole, and sealed in place with silicone caulk on the both sides. This formed a lid with an antenna sticking above the the lid, and a RF cable protruding below the lid into the box, which was later attached to the APRS radio within.
As a precaution, perhaps unnecessary, a thin piece of plastic that came from a package of blank CDs, was glued in place around the antenna on the outer surface of the lid. This was to provide additional mechanical support to the lid so that cracks would not form around the opening; but the styrene sheet's strength, and the additional inner lid below would have likely prevented any cracking due to stress or impacts.
APRS RADIO
TBD
CELL PHONE
TBD
STROBE LIGHTS
TBD