This film depicts the theory and operations of the Fresnel Lens Optical Landing System for use on aircraft carriers. It provides a visual guide path for pilots as they approach landing and gives the glide slope, cut and wave off information to pilots (:30). The system utilizes an array of signal lights on the port side of an angled deck (:49). It’s vertical center unit is the indicator assembly and is divided into five cells (:56). The “meatball” appears above the line when planes are too high as they approach, low when they are too low, and red when they are dangerously low (1:32). On each side of the indicator are wave off lights (1:42). The indicator can be titled from side to side as well as up, forward and back (1:55). The film will start with a look at just what the Fresnel Lens is (2:22). First depicted is a regular lens (2:30) and followed by the Fresnel which has each segment of the lens moved down (2:52). For this film's purpose only the center of the lens is utilized (3:13). Each cell on the indicator system contains these lenses and all are yellow, save for the bottom which is red (3:33). The five lens cells are coordinated so as to project a beam that is 1 1\2 degrees high and 40 degrees wide (4:32). As the indicator moves up and down, the glide slope moves the same (4:49). Pilots will adjust their flight paths so as to see the ‘roger meatball’ indicating proper path (6:05). Without a stabilizer, in rough weather, the glide slope would be all over the place (6:22). However, the ships stabilizing element will sense the ship's movement and it’s computer will compensate for it (6:41). There are two modes of standard operation, the first being the point stabilization (6:59). An example ensues of how this operation works (7:38). The center of the glide slope beam intersects at a point of 2,500 feet aft the carrier (8:54). The stable element on the ship will measure the pitch and correct each time (9:37). There may exist slight movement, in this mode as the pilot approaches (11:11). It is necessary to have a ten foot clearing distance in order to engage the arresting wire as the pilot lands (11:44). This can be a problem with larger planes as they will be too low yet still see the meatball at appropriate height (11:57). The computer fixes this problem by rotating the indicator assembly counter clockwise (12:24).The normal operating mode is the line stabilization (13:51) and this provides a wholly stabilized glide slope throughout the center beam length. The indicator assembly is stabilized about the pitch and roll axis (14:11) regardless of the motion of the ship. However, the hook to ramp value may be too low for a safe minimum distance (15:58). The LSO sensing this, would give the pilot the wave off (16:14). The film nears it’s end notifying viewers what they have been shown are the modes of operation of the Fresnel Lens Operating Landing System (17:04).
The specific system shown in the film is the Fresnel Lens Optical Landing System, Mark 6. An optical landing system (OLS) (nicknamed "meatball" or simply, "Ball") is used to give glidepath information to pilots in the terminal phase of landing on an aircraft carrier. From the beginning of aircraft landing on ships in the 1920s to the introduction of OLSs, pilots relied solely on their visual perception of the landing area and the aid of the Landing Signal Officer (LSO in the U.S. Navy, or "batsman" in the Commonwealth navies). LSOs used colored flags, cloth paddles and lighted wands. The OLS was developed after World War II and was deployed on U.S. Navy carriers from 1955. The Mk 6 Mod 3 FLOLS was tested in 1970 and had not changed much, except for when ship’s heave was taken into account with an Inertial Stabilization system. These systems are still in wide use on runways at US Naval Air Stations.
This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD and 4k.. For more information visit http://www.PeriscopeFilm.com