A series of six experiments drawing tubular fibres are compared
to some recent mathematical modelling of this fabrication process. The
importance of fibre tension in determining the internal geometry of the
fibre is demonstrated, confirming a key prediction of the models. There is
evidence of self-pressurisation of the internal channel, where an additional
pressure is induced in the internal channel as the fibre is drawn, and the
dependence of the magnitude of this pressure on fibre tension is discussed.
Additionally, there is evidence that the difference between the glass and furnace
temperatures is proportional to the furnace temperature and dependent
on the preform geometry.