Tandem Deployment SystemA parachute landing system is provided for GT-3 for final descent of the spacecraft to the Earth's surface. Deployment of the parachutes reduces the reentry module trim angle and decelerates the reentry module to a rate well within acceptable limits for water impact.
The parachute landing system includes a high altitude drogue parachute, cable guillotines, a pilot parachute, a main parachute, a bridle assembly, attachment and disconnect assemblies, mortar assemblies, reefing cutters, displays and controls.
Landing system operation begins at approximately 50,000 feet, with the astronaut deployment of the high altitude drogue parachute. It is deployed by firing mortar cartridges which eject the drogue parachute from its container.
When the spacecraft reaches approximately 10,600 feet the pilot parachute is deployed by the flight crew. Approximately 2 1/2 seconds later the rendezvous and recovery section automatically separates from the reentry module by action of a mild detonating fuse. The pilot parachute then pulls the R&R section free of the reentry module, and as it is pulled free, it draws the main parachute out of its container. The main parachute deploys in a reefed condition.
After landing, the parachute is jettisoned by the astronauts. Transfer from the single point suspension to a two-point suspension is effected by the astronaut depressing the landing attitude switch.
HIGH ALTITUDE DROGUE PARACHUTE
The high altitude drogue parachute is an 8.3-foot diameter conical ribbon chute of nylon material. It is packaged in a deployment bag stored in the drogue parachute mortar tube at the top of the R&R section. Approximately 16 seconds after the high altitude drogue parachute is deployed two redundant, lanyard-actuated reefing cutter unreef the drogue parachute. The riser from the drogue parachute is attached to the R&R section by three steel cables. The unreeled drogue parachute stabilizes the reentry module within +/- 23 degrees of the vertical axis as it descends from 50,000 feet to 10,700 feet.
Cartridge-actuated guillotines sever the high altitude drogue parachute attach cables. Actuation of these guillotines is switch controlled by the crew. With the attach cables severed, the high altitude drogue parachute pulls the pilot parachute from its mortar resulting in pilot parachute deployment.
PILOT PARACHUTE
The pilot parachute is an 18.3-foot diameter ring-sail parachute constructed of nylon material. The parachute, its reefing line, reefing cutters and risers are packaged in a deployment bag stored in the pilot parachute mortar tube in the rendezvous and recovery section. The pilot parachute is deployed in a reefed condition and within 2.5 seconds +/- 0.125 seconds after deployment, the pilot parachute draws the R&R section (released by action of a mild detonating fuse) away from the reentry module. As it does so, it deploys the main parachute in a reefed condition.
Within approximately 6 seconds after pilot parachute deployment, two redundant lanyard-actuating reefing cutters sever the pilot parachute reefing line. The unreefed pilot parachute lowers the R&R section to the sea.
An auxiliary landing sequence is available in event of malfunction of the high altitude parachute. Use of this switch controlled sequence enables the astronauts to actuate drogue parachute attachment guillotines and the apex cable guillotine, to fire the pilot parachute mortar and to initiate R&R section separation which results in main pilot parachute deployment.
MAIN PARACHUTE
The main parachute is an 84.2-foot diameter ring-sail parachute constructed of nylon material with alternating white and international orange gores. The main parachute is attached to the reentry module by a riser and a bridle arrangement. The parachute reefing lines, reefing cutters and risers are packaged in a nylon web cotton sateen bag and stored in the main parachute, a Fiberglas cylinder inside the R&R section. The main parachute is deployed in a reefed condition at approximately 9,700 feet. Within 10 seconds +/- 2.2 seconds after main parachute deployment, redundant lanyard-actuating reefing cutters sever the reefing line. Operation of any one of three reefing cutters results in the unreeling of the main parachute. The unreefed main parachute provides a rate of descent that results in allowable loads upon water impact.
Only one main parachute is provided in the Gemini landing system.
Crew escape is possible through use of the ejection system in event of spacecraft main parachute malfunction.
The spacecraft is suspended from the parachute by means of a "bridle" assembly. The bridle includes a forward and an aft leg. The forward leg is stored in a Fiberglas tray in the reentry control system section of the reentry module. It incorporates a loop at one end for connection to a disconnect assembly. The aft bridle leg is stored in a trough in the reentry module skin and incorporates a loop at one end for connection to an aft disconnect assembly. The trough, located between the hatches, is covered with a frangible insulating material which allows the aft bridle leg to tear free when two-point suspension is initiated. Following main parachute deployment, the initial mode of descent is by single-point suspension from a single riser. Transfer from the single point suspension to a two-point suspension occurs when an astronaut depresses the landing attitude switch. After landing, the parachute is jettisoned by the astronauts.
After the water landing, the astronaut depresses the parachute jettison switch which releases both the forward and aft bridle leg attachment/disconnect assemblies. This also energizes a cartridge-actuated guillotine which severs door restraints permitting a spring loaded hoist loop and attached flashing recovery light to extend. The Gemini reentry module, unlike the Mercury Spacecraft, has no attached landing bag to absorb landing shock. The Gemini Spacecraft is brought to a "pilot heads-up" position causing it to impact the water at the edge of the heat shield. Water landing forces resulting are less than the touch-down forces of Mercury, even though Mercury had a landing baa installed.
Postlanding and Survival Equipment
Postlanding and survival equipment provide recovery personnel with visual and radio reference aid in locating the reentry module after landing. It provides the crew with water, food and survival equipment and includes a mooring lanyard assembly and hoist loop for recovery of the spacecraft after sea landing.
The equipment includes a flashing recovery light, dye marker, survival equipment, UHF and HF rescue communications and beacons, splash curtains, a hoist loop, flotation material, and electrical power supplies.
The recovery light is a high intensity flasher deployed upon parachute jettisoning and located on top of the reentry module as it floats in the water. The light has a minimum flashing rate of 15 flashes per minute and is visible on a clear night at a distance of 50 nautical miles.
Fluorescent dye marker is installed in the forward end of the reentry control system section just below the flotation line. The dye is green-yellow and stored in a container having openings covered with a water soluble film for automatic deployment upon exposure to the water.
The radio recovery aids include a UHF recovery beacon, UHF voice transceiver, HF voice transceiver and the rescue beacon in the survival pack.
The mooring lanyard assembly consists of a lanyard with a fitting at one end for attachment to the "D" ring on the astronaut's parachute harness. A life raft is attached to the lanyard at a point about 8 to 12 feet from the astronaut.
During an ejection sequence the lanyard assembly extracts the life raft and a survival pack from containers in the seat as the backboard of the seat falls away from the astronaut. A cylinder charged with carbon dioxide is packed with the life raft for inflation. The life raft may be manually extracted following a normal landing in the spacecraft.
Copyright 1997-2005 by John
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