Sikorsky S-51 in Rescue.
The Sikorsky (military versions H-5, R-5F, HO3S-1) (civilian version S-51) was the first helicopter to be built in large numbers and represented Sikorsky's first major success as well as it's first commercial helicopter It first flew in 1946. The S-51 was used as inter city transport and commuter work. you need s51-2k2.zip for these files to work