This pencil drawing is one that I did for my father who worked in the Air Force on these big helicopters in the 1980s.
I used to watch these fly overhead where we lived near Hurlburt Field, Florida. They were huge and they were loud and I loved watching and hearing them.
Here is some stats on this particular model: "The MH-53J Pave Low III was the largest and most technologically advanced heavy-lift helicopter in the U.S. Air Force inventory. Built for special operations, its primary mission was the undetected infiltration, exfiltration, and resupply of commandos behind enemy lines, as well as complex combat search and rescue (CSAR) missions." (Sikorsky MH-53)