  This paper reports the successful fabrication of silica aerogel Cherenkov
radiators produced in the first batches from a 96-tile mass production
performed using pin-drying technique in our laboratory. The aerogels are to be
used in a ring-imaging Cherenkov detector in the spectrometer of a planned
balloon-borne cosmic-ray observation program, HELIX (High Energy Light Isotope
eXperiment). A total of 36 transparent, hydrophobic aerogel tiles with a high
refractive index of 1.16 and dimensions of 10 cm $\times $ 10 cm $\times $ 1 cm
will be chosen as the flight radiators. Thus far, 40 out of the 48 tiles
fabricated were confirmed as having no tile cracking. In the first screening, 8
out of the first 16 tiles were accepted as flight-qualified candidates, based
on basic optical measurement results. To fit the aerogel tiles into a radiator
support structure, the trimming of previously manufactured prototype tiles
using a water-jet cutting device was successful.
