9/18/07
I left you the last time as we were beginning to glue 2 inch foam sheets together. EPS insulation foam comes in 4’ X 8’ X 2” sheets and they are prescored at 16” intervals. Lengths of blue EPS insulation foam were cut to fit between the bulkheads. Since the fuselage is 11” wide, we did not trim the 16” dimension. 4 layers of foam were glued together with milk based carpenter glue ( Elmer’s carpenter glue). One section of the fuselage had to be 5 layers. Wing panels were easily contained within the 2” dimension of the foam sheet.
Several common types of glue were investigated. Only the milk based water soluble glues were appropriate. (They did not dissolve or melt the foam). Polyester resin based materials damaged the foam surface. We did not determine if the effect was the result of solvent action or the huge amount of heat generated by the curing process. Some of the glues were quite effective at turning the foam into jelly or a puddle.
The fuselage was composed of 5 sections. Each section had a fore and aft bulkhead section to determine its conformation. Each wing panel was composed of six sections.
A hot wire cutting tool was manufactured from poplar and single strand wire fishing leader. The wood was cut into a bow shape with and extended handle, similar to a tall hacksaw. Heating the wire caused it to expand and lose tension. To accomodate the expansion of the wire, a shaped block of wood was pinned to the handle with a short length of dowel rod which acted as an axle and allowed the combination of the grip and the block to be squeezed to tension the hot wire. Power was derived from a 15V 15amp Radio Shack power supply. This was sufficient power to effectively cut the foam mass but there was no excess power.
I left you the last time as we were beginning to glue 2 inch foam sheets together. EPS insulation foam comes in 4’ X 8’ X 2” sheets and they are prescored at 16” intervals. Lengths of blue EPS insulation foam were cut to fit between the bulkheads. Since the fuselage is 11” wide, we did not trim the 16” dimension. 4 layers of foam were glued together with milk based carpenter glue ( Elmer’s carpenter glue). One section of the fuselage had to be 5 layers. Wing panels were easily contained within the 2” dimension of the foam sheet.
Several common types of glue were investigated. Only the milk based water soluble glues were appropriate. (They did not dissolve or melt the foam). Polyester resin based materials damaged the foam surface. We did not determine if the effect was the result of solvent action or the huge amount of heat generated by the curing process. Some of the glues were quite effective at turning the foam into jelly or a puddle.
The fuselage was composed of 5 sections. Each section had a fore and aft bulkhead section to determine its conformation. Each wing panel was composed of six sections.
A hot wire cutting tool was manufactured from poplar and single strand wire fishing leader. The wood was cut into a bow shape with and extended handle, similar to a tall hacksaw. Heating the wire caused it to expand and lose tension. To accomodate the expansion of the wire, a shaped block of wood was pinned to the handle with a short length of dowel rod which acted as an axle and allowed the combination of the grip and the block to be squeezed to tension the hot wire. Power was derived from a 15V 15amp Radio Shack power supply. This was sufficient power to effectively cut the foam mass but there was no excess power.
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