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Titan II GLV

Launch ofGemini 11 on a Titan II GLV from LC-19
Function	Human-ratedlaunch vehicle forGemini spacecraft
Manufacturer	Martin
Country of origin	United States
Size
Height	109 ft (33 m)[1]
Diameter	10 ft (3.0 m)
Mass	340,000 lb (150 t)
Stages	2
Capacity
Payload toLEO[altitude and inclination needed]
Mass	7,900 lb (3.6 t)
Associated rockets
Family	Titan
Launch history
Status	Retired
Launch sites	Cape Canaveral,LC-19
Total launches	12
Success(es)	12
First flight	April 8, 1964
Last flight	November 11, 1966
Carries passengers or cargo	Gemini
First stage
Powered by	1 ×LR87-AJ-7
Maximum thrust	1,900 kN (430,000 lbf)
Specific impulse	258 s (2.53 km/s)
Burn time	156 seconds
Propellant	Aerozine 50 /N2O4
Second stage
Powered by	1 ×LR91-AJ-7
Maximum thrust	440 kN (100,000 lbf)
Specific impulse	316 s (3.10 km/s)
Burn time	180 seconds
Propellant	Aerozine 50 /N2O4
[edit on Wikidata]

TheTitan II GLV (Gemini Launch Vehicle) orGemini-Titan II was an Americanexpendable launch system derived from theTitan II missile, which was used to launch twelveGemini missions forNASA between 1964 and 1966. Two uncrewed launches followed by ten crewed ones were conducted fromLaunch Complex 19 at theCape Canaveral Air Force Station, starting withGemini 1 on April 8, 1964.

The Titan II was a two-stageliquid-fuel rocket, using ahypergolic propellant combination ofAerozine 50 fuel andnitrogen tetroxide oxidizer. The first stage was powered by anLR87 engine (with two combustion chambers and nozzles, fed by separate sets of turbomachinery),^[2][3] and the second stage was propelled by anLR91 engine.

In addition to greater payload capability, the Titan II promised greater reliability than theAtlas LV-3B, which had been selected forProject Mercury, because Titan'shypergolic-fueled engines contained far fewer components.^{[citation needed]}

Several modifications were made to the Titan missile tohuman-rate it for Project Gemini:^[4]

• A "Gemini Malfunction Detection System" was installed to inform the crew of the rocket's status, and improve response in an emergency.
• Redundant systems were installed to reduce the chances of launch failures.
• The inertial guidance system was replaced by a lighter-weight ground-radio guidance system
• The avionics truss in the second stage was modified slightly
• To help guard against the possibility of a guidance malfunction causing the engine nozzles to gimbal hard right or left, an extra backup guidance system was added.
• The second stage propellant tanks were lengthened for longer burn time and unnecessaryvernier engines andretrorockets were removed. Because the second stage engine had had issues with combustion instability, it was equipped with baffled injectors.
• The first stage was loaded with 13,000 pounds (5.9 t) more propellant than the Titan ICBM although the storage tank size remained unchanged.
• Modifications were made to the tracking, electrical and hydraulics systems in the interest of improved reliability.
• The propellants were chilled to slightly improve vehicle performance. This allowed for more mass to be accommodated.
• First stage engine thrust was reduced slightly to cut down on vibration and G loads.
• First stage engine burn would go until propellant depletion unlike Titan ICBMs which were designed to cut off when propellant flow/pressure and engine thrust started dropping as the tanks emptied. This was to prevent the possibility of a malfunctioning pressure sensor triggering an abort condition. Also, running until depletion would slightly boost the Titan's capacity for payload.

Modifications were overseen by theAir Force Systems Command. TheAerojet company, the manufacturer of the Titan's engines, had released a revised model during mid-1963 due to deficiencies in the original design, and also to attempt to improve manufacturing procedures.^{[citation needed]}

Film footage ofGemini 10's launch revealed that the first stage oxidizer tank ruptured shortly after staging and released a cloud ofN₂O₄. As first stage telemetry had been terminated at staging, there was no data other than photographic/visual evidence to go by, however the conclusion was that either loose debris struck the oxidizer tank dome or else exhaust from the second stage engine had burned through it.^{[citation needed]}

Gemini 12's launch vehicle also experienced a tank rupture after staging and film review of Titan II ICBM launches found several occurrences of this phenomenon. Since this did not appear to pose any safety risks to the astronauts, NASA decided that it was not a concern.^{[citation needed]}

During Titan II ICBM development, it had been found that the first stage turbopump gearbox was prone to total failure caused by resonant vibration in the idler gear. This problem had not occurred on actual launches, but only static firing tests. This was considered to be a critical item to fix. Aerojet developed a totally redesigned gearbox, and all of Gemini launch vehicles except for the uncrewedGemini 1 used it.^{[citation needed]}

There was also a potentially serious problem with the turbopump bearings which led to more design changes, however the odds of failing on a Gemini launch were slim to nil since GLV boosters used specially selected and tested bearings, in addition the turbopumps would be "hot fired" as part of prelaunch checks^{[citation needed]}

Combustion instability in the second stage engine was also a concern although that too had only been witnessed in static firing runs. A new injector with improved baffling was developed for the engine and flight-tested on aTitan IIIC launch; all GLVs fromGemini 8 onwards incorporated it.^{[citation needed]}

After a Titan II propellant feed line was found to have some damage during factory inspections, NASA put out the requirement that all GLV propellant lines had to beX-rayed in order to prevent a potentially disastrous fuel leak during launch. X-ray tests later found several more damaged propellant lines, most likely due to careless handling.^{[citation needed]}

The most significant issue in man-rating the Titan II was resolving problems with resonant vibration known as "pogo" (since the action was said to resemble that of apogo stick) that could produce g-forces sufficient to incapacitate astronauts,^{[citation needed]} but the Air Force were not interested in helping NASA with a problem that did not affect the ICBM program and could potentially delay it, or require major modifications to the design. However, Martin-Marietta argued that the pogo problem could be fixed fairly easily, and also the Air Force began to develop more of an interest in man-rating the Titan II due to the proposedManned Orbiting Laboratory program. The primary changes made to resolve pogo were adding oxidizerstandpipes, increasing the pressure in the propellant tanks, and adding a mechanical accumulator to the fuel suction side.^[5]

Another nuisance problem that occurred during the Gemini program was code-named "Green Man" and involved momentary pitch oscillations of the Titan second stage following engine cutoff. This phenomenon had happened on both Gemini and uncrewed Titan II/III flights and had resulted in the failure of the ablative skirt on the second stage at least twice (those instances were dubbed "Brown Man"). Investigation following skirt failure on a Titan IIIC launch concluded that pressure buildup in the ablative skirt caused the pitch oscillations, but NASA decided that there was probably little chance of loose debris from the skirt contacting the Gemini spacecraft, so no corrective action had to be taken and in any case, the Titan IIIC incident was found to be the result of poor quality control which would not affect the more strictly supervised Gemini program.^{[citation needed]}

The assembly of these rockets was done at Martin-Marietta's plant inBaltimore, Maryland, so not to interfere with missile work at the one inDenver, Colorado, although this also saved the former plant from a planned shutdown. As with the Mercury-Atlas launch vehicles, a high degree of workmanship was stressed as well as more thorough testing of components and improved handling procedures compared with Titans designed for uncrewed flights.^[6]

The Titan II had a much higher thrust-to-weight ratio than theSaturn V. Astronauts experienced almost 6G before the second stage stopped firing at 100 miles (160 km) altitude.Richard F. Gordon Jr. compared the Titan II to "a young fighter pilot's ride. It's faster than the Saturn's old man's ride."Frank Borman said that simulations did not prepare him for the "almost deafening" noise, which he compared to a jet's afterburner or large train.Walter Schirra andGordon Cooper reported that the ride was smoother than on the Atlas, however.^[7]

Two retiredTitan II missiles are on display repainted as Gemini Launch Vehicles, along with a few replicas.

• A retired Titan II missile, repainted asGLV-3 12558 (Gemini 3), is on display atKSC Rocket Garden since 2010.^[8]
• Another retired Titan II missile, repainted asGLV-9 12564 (Gemini 9A), is on display at theStafford Air & Space Museum.^[9]
• A Gemini-Titan II full-scale replica was erected for the 1964New York World's Fair. It remains on display at theNew York Hall of Science,Corona Park, NY.^[10]
• Another full size replica is on display at theKansas Cosmosphere and Space Center.^[11]
• A third replica was displayed at theParque de las Ciencias Luis A. Ferré,Bayamon, PR.^[12]
• A mockup, created from twoTitan I first stages, was on display at KSC Rocket Garden until 2006.^[13] In 2010 this replica was shipped toJohnson Space Center in Texas.^[14]

• 
  Titan II missile, repainted as GLV-3 12558 (Gemini 3), atKSC Rocket Garden.
• 
  Titan II missile, repainted as GLV-9 12564 (Gemini 9A), atStafford Air & Space Museum.
• 
  Gemini-Titan II replica (right) at theNew York Hall of Science,
• 
  Gemini-Titan II mockup, created from two Titan I first stages, atKSC Rocket Garden.
• 
  Gemini-Titan II replica (bottom) at theKansas Cosmosphere and Space Center.

• SM-65D Atlas
• Soyuz (rocket)
• Voskhod (rocket)

• Krebs, Gunter."Titan-2-GLV". Gunter's Space Page. RetrievedApril 29, 2009.
• Wade, Mark."Titan". Encyclopedia Astronautica. Archived fromthe original on August 5, 2008. RetrievedApril 29, 2009.

Media related toTitan II Gemini at Wikimedia Commons

• Project Gemini
• Titan (rocket family)
• Rockets and missiles
• NASA space launch vehicles

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