UH-1B
The HU-1B was an improved model that was equipped with the Lycoming T53-L-5 engine of 960 shp (720 kW), revised main rotor blades of 44-foot (13 m) diameter and 21-inch (530 mm) chord, 13 inch higher rotor mast and a longer cabin that could accommodate seven passengers. This version was redesignated UH-1B in 1962.
Later production UH-1Bs were equipped with Lycoming T53-L-9 and L-11 engines of 1,100 shp (820 kW). Gross weight was 8,500 lb (3,900 kg) and the standard empty weight was 4,513 lb (2,047 kg).
Army testing of the "B" model started in November 1960 with first production aircraft arriving in March 1961. A total of 1010 "Bravo" models were delivered to the US Army. First deployment was in November 1963 when eleven were sent to Vietnam to join the "Alpha" models already in use by UTTCO.
One NUH-1B was produced for test purposes.
Bell certified a civil version of the UH-1B incorporating some minor safety improvements, such as improved door locks. The aircraft was marketed as the Bell 204B.
Read more about this topic: Bell UH-1 Iroquois Variants