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Bell 47 H-1 |
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Tail fabrication |
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A local vacuum forming specialist was required for this next stage. In this picture one of the patterns is placed in the machine on a perforated board. The board is perforated to allow an even application of suction when the vacuum pump is switched on. |
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In this picture the white plastic styrene has been locked into position above the pattern. The electric fan heaters are then moved into position and switched on to bring the styrene to operating temperature. |
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Once the styrene has been brought to the correct
temperature the fan heaters are switched off and moved back into their
original position. Two things then happen simultaneously: - First the platform with the pattern is raised up into the styrene, and |
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- Second the air below the styrene is slowly
removed. This process takes about 10 seconds for the hot plastic to faithfully cover the pattern. |
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Once the plastic has cooled the assembly can be removed from the vac forming machine; talcum power had been used as the release agent so that the pattern is easily separated from the plastic. |
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Excess plastic is then trimmed to reveal half a tail cover. Assembly is covered in a later section. |
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Webmaster: John Neasham |
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