The Sikorsky S-48/VS-327/R-5 model was a follow-on to the successful R-4 helicopter. It was designed to meet a 1942 U.S. Army Air Forces (USAAF) requirement for a larger more capable observation helicopter as well as a British requirement. The XR-5 helicopters featured a 48 foot 3 bladed fully articulated main rotor and a 3 bladed tail rotor powered by the reliable Pratt and Whitney 450 hp R985-AN-5 radial engine. The S-48 had a 2 place tandem cockpit with the observer in the forward position and the pilot aft. Four Experimental XR-5 helicopters were initially built with a fifth XR-5A ordered later. The first flight was on August 18, 1943. The successful testing of the five Experimental XR-5 helicopters resulted in a USAAF order for 26 YR-5A developmental helicopters for service testing in March 1944. A follow-on production contract from the USAAF for 100 R-5D rescue configured helicopters was received in 1944 but only 34 were actually built. The end of World War II resulted in the cancellation/curtailment of many contracts. In 1945, a demonstration of the capabilities of the XR-5 was done by Sikorsky test pilot Les Morris picking up 10 people weighing over 2,000 lbs into a hover with the ladies of Sikorsky cheering them on. The link below is Paramount New coverage of the event