C-47 Skytrain was the military name for the DC-3 airframe, although as Shorty points out the DC-3s originally had single entry door instead of the clam shell doors. The very earliest DC-3s had their entry door on the right hand side. These days C-47s are still called DC-3s.
I'm presuming you mean 117 Squadron RAF, in which case your grandfather operated the Dakota (!), which was the British name for the C-47 Skytrain/DC-3. 117 had Daks from 1943 to 1945. The pic above shows a US military C-47/DC-3