Package Requirements

PACKAGE REQUIREMENTS

The foregoing story is fiction, of course, but it attempts to give the reader a feel for the environmental rigors which a high-altitude balloon payload should be prepared to endure.  A well-designed and built payload package will reliably protect its contents from the environment without adding excessive weight. 

If the package fails, then so will its contents in which you and your balloon group have invested so much time and money.  Mechanical package failure can leave priceless goodies strewn along the flight path, or more likely, electrical connections may be damaged during landing shock thus shutting down the tracking beacon so important to the recovery task.  Thermal failure can cause onboard electronics to malfunction from a combination of low temperatures and condensed moisture. 

Design of a strong, well-insulated package becomes non-trivial when the burden of minimized weight is tacked on.  Helium and balloon costs rise exponentially with payload weight, and once the several FAA weight limits are passed, flight clearances and logistics are complicated.

PACKAGING MATERIALS

Edge of Space Sciences (EOSS) has flown packages made from molded Styrofoam packaging material, built-up insulation-grade Styrofoam sheet, bulk closed-cell polyethylene foam and foamcore sheet. 

Although low density Styrofoam exhibits excellent thermal insulation properties, it is difficult to cut cleanly and is easily damaged by landing shock.  It’s also difficult to find molded Styrofoam packaging even close to the right size and shape to fit the intended contents. 

Bulk polyethylene foam is even rarer, being used primarily as packaging buffers for heavy, high-cost products.  Being more rigid, it can be formed somewhat more easily than Styrofoam and exhibits excellent shock resistance.  Airtight seams and fine details are impractical to form, however, and common adhesives won’t stick well to it. 

Foamcore is readily available in large sheets.  It cuts and forms easily with sheet-metal precision, bonds with practically all adhesives, is exceptionally strong in shear stress, resists puncture, is very lightweight and offers moderate thermal insulation.  Precision details, such as pc board mounting slots, are easily fabricated.  Using foamcore, one can design an near-optimal payload package for the contents rather than trying to work around other materials’ limitations.