A T-28 aircraft has been extensively modified and instrumented to be used as a hailstorm penetration vehicle. The structure of the aircraft was strengthened and all leading edges were armor plated to protect the aircraft from hail damage. A larger engine was installed. Meteorological data are recorded aboard the T-28 and later combined with the Pilot's recorded visual observations to gain a fuller understanding of the interior structure of hailstorms.

The aircraft is normally directed to make horizontal penetrations through the high reflectivity zones and updraft areas between 4.88 and 7.32 km MSL. The maximum intensity storm intentionally penetrated had a radar reflectivity of 55 dBZ. Aircraft icing presented the most significant problem.

Data analysis is continuing. Results to date indicate the following:

  • There are multiple areas of updrafts and hail inside the hailstorms sampled.

  • Areas of high supercooled water content have been found in conjunction with hail indicating hail growth areas.

  • The hail appears to be size sorted by the strong updrafts.

  • Data collected to date compare favorably with numerical model studies.

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