Advanced Helicopter Flight Principles 1 1955 US Army Training Film TF46-2210; Sikorsky H-19 / S-55

more at http://quickfound.net/

Originally a public domain film from the US Army, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/Sikorsky_H-19_Chickasaw

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

The Sikorsky H-19 Chickasaw (company model number S-55) was a multi-purpose helicopter used by the United States Army and United States Air Force. It was also license-built by Westland Aircraft as the Westland Whirlwind in the United Kingdom. United States Navy and United States Coast Guard models were designated HO4S, while those of the U.S. Marine Corps were designated HRS. In 1962, the U.S. Navy, U.S. Coast Guard and U.S. Marine Corps versions were all redesignated as H-19s like their U.S. Army and U.S. Air Force counterparts...

1,281 of the helicopters were manufactured by Sikorsky in the United States. An additional 447 were manufactured by licensees of the helicopter including Westland Aircraft, the SNCASE in France and Mitsubishi in Japan...

Major innovations implemented on the H-19 were the forward placement of the engine below the crew compartment and in front of the main cabin, the use of offset flapping hinges located nine inches (229 mm) from the center of the rotor, and the use of hydraulic servos for the main rotor controls. These features yielded an aircraft that was far more capable in a transport role than previous Sikorsky designs.

The forward engine location placed the main cabin essentially in line with the main rotor's rotational axis and close to the aircraft center of gravity, making it easier to maintain proper weight and balance under differing loading conditions. The impetus for this design choice was the recent rejection of the Sikorsky XHJS by the U.S. Navy in favor of the tandem rotor Piasecki HUP Retriever; the Navy had strongly objected to the necessity to use ballast in the cabin-forward XHJS to maintain proper weight and balance, prompting Sikorsky to seek single-rotor design alternatives that did not require this.

Another benefit of this engine location was ease of maintenance, as the engine could be readily accessed at ground level through dual clamshell-style doors; the entire engine could be changed in only two hours, and the radial engine was oriented backwards relative to a typical airplane installation, allowing more convenient access to engine accessories.

The offset flapping hinges and hydraulic servos gave more positive flight control under differing loading conditions, isolated the flight controls from vibration, and lessened control forces; the H-19 could be flown with only two fingers on the cyclic control...

The H-19 left U.S. military service when the CH-19E was retired by U.S. Navy squadron HC-5 on 26 February 1969. Surplus H-19s were sold on the open market, and civil interest was sufficient that Sikorsky (and later Orlando Helicopter Airways) offered conversion kits allowing a military surplus H-19 to be commercially operated under a standard Federal Aviation Administration type certificate as an S-55B...