The SM-65C Atlas,or Atlas C was a prototype of the Atlas missile. First flown on 24 December 1958,the Atlas C was the final development version of the Atlas rocket,prior to the operational Atlas D. It was originally planned to be used as the first stage of the Atlas-Able rocket,but following an explosion during a static test on 24 September 1959,this was abandoned in favor of the Atlas D. Atlas C was similar to Atlas B,but had a larger LOX tank and smaller RP-1 tank due to technical changes to the Rocketdyne engines. Improvements in materials and manufacturing processes also resulted in lighter-weight components than the Atlas A and B. Booster burn time was much longer than the A/B series,up to 151 seconds. All launches took place from LC-12 at CCAS.
The Atlas C test program began with the successful flight of 3C on December 23,1958. All systems performed well and the extended booster burn time was carried out with no ill effects. On January 27,Missile 4C experienced a complete Mod III GE guidance system failure at T+80 seconds. The propellant utilization system operated fuel rich,resulting in low sustainer thrust following BECO,and LOX depletion caused simultaneous sustainer/vernier cutoff 5 seconds earlier than the planned SECO. In addition,a malfunction of the pneumatic system caused decay of fuel tank pressure starting at T+120 seconds. Tank pressure remained high enough to maintain structural integrity through powered flight,the intermediate bulkhead possibly ruptured at T+320 seconds,at which point tank pressures had dropped below a safe limit. Because of the guidance system failure,no separation signal was received by the reentry vehicle. Impact occurred about 40 miles short of the target point in the South Atlantic.[1]
Missile 5C (February 20) performed well until BECO,at which point the fuel staging disconnect valve failed,causing a gradual fuel leak and decay in tank pressures. When propellant levels in the tank dropped low enough,the open staging disconnect valve allowed helium pressure gas to escape,causing a more rapid pressure loss. At approximately T+168 seconds,the intermediate bulkhead reversed,followed by explosion of the missile at T+172 seconds.[2]
Missile 7C (March 19) suffered a guidance system failure at T+85 seconds,followed by premature BECO at T+129 seconds. A backup command from the missile programmer jettisoned the booster section at T+151 seconds. After the premature booster cutoff,the missile became unstable because it was impossible for the autopilot to gimbal the sustainer engine with the booster section still attached. Missile stability was partially regained after booster jettison,then completely lost after SECO. No cutoff command was issued to the sustainer or verniers because of the guidance system failure,sustainer cutoff occurred at T+282 seconds,but the exact reason for it was not determined. During the vernier solo phase,the missile started tumbling. VECO took place at T+311 seconds when the vernier start tanks became depleted. Reentry vehicle separation also did not occur.[3]
The final two C-series flights (8C on July 21 and 11C on August 24) were successful. Missile 8C was the third attempt to fly an RVX-2 reentry vehicle (the second attempt on a D-series Atlas had failed three months earlier) and the first successful one. All missile systems performed well aside from high thrust section temperatures starting at T+85 seconds. Sixty-three minutes after launch,the RV was successfully recovered.[4] Missile 11C carried a movie camera in the nose cone which filmed missile separation and a large portion of the Earth's surface on a 250-mile (402km) lob,taking it to an apogee of 700 miles (1126km). Recovery of the film capsule was successful. Overall performance of 11C was quite good,the sustainer HS valve malfunctioned and resulted in reduced LOX flow to the engine,this resulted in low sustainer thrust and complete fuel depletion by SECO,and it was suspected that a leak in a LOX duct had affected the HS valve. The high thrust section temperatures on 8C also recurred,in addition tracking film showed debris falling off the missile between T+46 and 54 seconds,the debris was not identified and did not appear to have any adverse effect on vehicle performance.[5]
One of the more significant upgrades to the Atlas C was the addition of motion detectors in the gyroscope package to ensure proper operation. This was implemented after the first B-series Atlas had failed in flight due to launch crews neglecting to power on the gyroscopes and would soon become a standard part of all ballistic missile guidance systems.
Missile 9C was designated for the first Atlas-Able lunar probe launch,which was scheduled to launch on October 2,1959 from LC-12 at Cape Canaveral.
The Atlas C was still an R&D vehicle and NASA wanted instead to use the operational D-series Atlas for space launches,but there were none available and they had to instead settle for a modified C-series. Atlas 9C was assigned to the Pioneer-Able program and received several modifications for the mission,including deletion of vernier solo mode,autopilot modifications for the longer vehicle length,and the LOX boil-off valve being moved slightly to accommodate the Able adapter.
Atlas 9C was delivered to CCAS on April 5,1959 with the intention of a June 6 launch date. However,the launch was postponed due to repeated technical problems and the vehicle put in storage to free up LC-12 for Missiles 8C and 11C. The postflight findings from Atlas 5C necessitated modifications to the fuel staging disconnect valve;these were performed in late July. On August 27,Atlas 9C was erected on LC-12. The Able second stage was stacked on top with a dummy third stage.
At 10:12 AM EST on September 24,the PFRF test for 9C was initiated. Following a normal engine start,a fire erupted in the thrust section. After 2.5 seconds of engine operation,an automatic cutoff command was issued to the propulsion system. A LOX-fed fire quickly burned out of control and was too intense for pad fire extinguishing facilities to handle. About 37 seconds after the test began,the Atlas began to lean over and fall towards the umbilical tower,exploding in a gigantic fireball that completely leveled LC-12. Both umbilical towers and the service tower were knocked over,a one-ton piece of the latter being thrown 500 feet from the pad,and the concrete launch stand caved in. The pad was put out of use for the next six months.
Investigators concluded that the disaster was due to the above-mentioned configuration change on the Atlas C,in addition to several weight-saving modifications unique to Missile 9C. When the Atlas was assembled at Convair,workmen attached a helium vent line to a port near the bottom of the RP-1 tank,below the anti-slosh baffles. On the Atlas B missiles,the vernier helium tank was mounted in a higher location resulting in a different fuel tank attachment point above the baffles. Helium pressure gas from the vernier propellant tanks leaked into the sustainer RP-1 turbopump,leading to cavitation which caused propellant unloading,pump overspeed,and rupture of low pressure LOX ducting. This then caused the fire that led to vehicle destruction. The reason for the LOX ducting rupturing was not clear,but likely the sudden pressure change from the engine shutdown or the sustainer turbopump blades rubbing against the pump casing. The accident was ultimately ruled to be the result of poor engineering judgement in attaching the vernier helium vent line to the bottom of the RP-1 tank. This was not the first occurrence of the failure mode;Missile 6C had exploded on the test stand at Sycamore Canyon the previous March due to the vernier start tanks being connected incorrectly.
Examination of recovered missile parts found major damage in the sustainer hardware;the turbopump overspeed had caused the blades to rub against the pump casing,evidenced by the damaged condition of the blades and the presence of slag fragments. The sustainer gas generator had suffered a LOX-rich shutdown and had extensive heat damage;the turbine blades were melted away. The booster engine hardware had considerable fire and impact damage but these were secondary effects of the failure and telemetry data showed normal booster operation until cutoff. Some missile components such as the V1 vernier and most of the sustainer fuel start system remained missing and unaccounted for. Final explosion of the missile was believed to be loss of tank pressure resulting in collapse of the intermediate bulkhead and all of the LOX and RP-1 mixing and turning to gel,which then exploded with the force of 20,000 pounds of TNT. The missile cutoff had caused the LOX valves to snap shut,resulting in overpressurization of the LOX tank. The pneumatic system threw open the LOX boil-off valve to equalize the pressure,but eventually resulted in pressures too low to maintain structural integrity. Ground crews attempted to flip switches to raise the LOX tank pressure and lower the fuel tank pressure but nothing happened,possibly due to fire-induced damage to the control wiring. A large quantity of RP-1 spilled into the flame bucket at cutoff and started a fire.[6]
Partial failure. Guidance system failed,however the flight control system managed to keep the missile on a stable path and impact was close to the target point.
1959-02-20
05:38
5C
100 kilometres (62mi)
Failure. Valve malfunction during staging led to loss of tank pressure and reversal of the intermediate bulkhead. The missile destroyed itself at T+174 seconds.
1959-03-19
00:59
7C
200 kilometres (120mi)
Partial failure. Premature booster engine shutdown due to an electrical malfunction at T+131 seconds led to an unstable flight trajectory.
The SM-65 Atlas was the first operational intercontinental ballistic missile (ICBM) developed by the United States and the first member of the Atlas rocket family. It was built for the U.S. Air Force by the Convair Division of General Dynamics at an assembly plant located in Kearny Mesa,San Diego.
The R-7 Semyorka,officially the GRAU index 8K71,was a Soviet missile developed during the Cold War,and the world's first intercontinental ballistic missile. The R-7 made 28 launches between 1957 and 1961,but was never deployed operationally. A derivative,the R-7A,was deployed from 1959 to 1968. To the West it was unknown until its launch. In modified form,it launched Sputnik 1,the first artificial satellite,into orbit,and became the basis for the R-7 family which includes Sputnik,Luna,Molniya,Vostok,and Voskhod space launchers,as well as later Soyuz variants.
The Martin Marietta SM-68A/HGM-25A Titan I was the United States' first multistage intercontinental ballistic missile (ICBM),in use from 1959 until 1962. Though the SM-68A was operational for only three years,it spawned numerous follow-on models that were a part of the U.S. arsenal and space launch capability. The Titan I was unique among the Titan models in that it used liquid oxygen and RP-1 as propellants;all subsequent versions used storable propellants instead.
The PGM-17A Thor was the first operative ballistic missile of the United States Air Force (USAF). It was named after the Norse god of thunder. It was deployed in the United Kingdom between 1959 and September 1963 as an intermediate-range ballistic missile (IRBM) with thermonuclear warheads. Thor was 65 feet (20 m) in height and 8 feet (2.4 m) in diameter.
The J-2,commonly known as Rocketdyne J-2,was a liquid-fuel cryogenic rocket engine used on NASA's Saturn IB and Saturn V launch vehicles. Built in the United States by Rocketdyne,the J-2 burned cryogenic liquid hydrogen (LH2) and liquid oxygen (LOX) propellants,with each engine producing 1,033.1 kN (232,250 lbf) of thrust in vacuum. The engine's preliminary design dates back to recommendations of the 1959 Silverstein Committee. Rocketdyne won approval to develop the J-2 in June 1960 and the first flight,AS-201,occurred on 26 February 1966. The J-2 underwent several minor upgrades over its operational history to improve the engine's performance,with two major upgrade programs,the de Laval nozzle-type J-2S and aerospike-type J-2T,which were cancelled after the conclusion of the Apollo program.
Big Joe 1 (Atlas-10D) launched an uncrewed boilerplate Mercury capsule from Cape Canaveral,Florida on 9 September 1959. The purposes of the Big Joe 1 were to test the Mercury spacecraft ablative heat shield,afterbody heating,reentry dynamics attitude control and recovery capability. It was also the first launch of a spacecraft in Project Mercury.
Mercury-Atlas 1 (MA-1) was the first attempt to launch a Mercury capsule and occurred on July 29,1960 at Cape Canaveral,Florida. The spacecraft was unmanned and carried no launch escape system. The Atlas rocket suffered a structural failure 58 seconds after launch at an altitude of approximately 30,000 feet (9.1 km) and 11,000 feet (3.4 km) down range. All telemetry signals suddenly ceased as the vehicle was passing through Max Q. Because the day was rainy and overcast,the booster was out of sight from 26 seconds after launch,and it was impossible to see what happened.
The highest specific impulse chemical rockets use liquid propellants. They can consist of a single chemical or a mix of two chemicals,called bipropellants. Bipropellants can further be divided into two categories;hypergolic propellants,which ignite when the fuel and oxidizer make contact,and non-hypergolic propellants which require an ignition source.
The Atlas-Centaur was a United States expendable launch vehicle derived from the SM-65 Atlas D missile. The vehicle featured a Centaur upper stage,the first such stage to use high-performance liquid hydrogen as fuel. Launches were conducted from Launch Complex 36 at the Cape Canaveral Air Force Station (CCAFS) in Florida. After a strenuous flight test program,Atlas-Centaur went on to launch several crucial spaceflight missions for the United States,including Surveyor 1,Mariner 4,and Pioneer 10/11. The vehicle would be continuously developed and improved into the 1990s,with the last direct descendant being the highly successful Atlas II.
A vernier thruster is a rocket engine used on a spacecraft for fine adjustments to the attitude or velocity of a spacecraft. Depending on the design of a craft's maneuvering and stability systems,it may simply be a smaller thruster complementing the main propulsion system,or it may complement larger attitude control thrusters,or may be a part of the reaction control system. The name is derived from vernier calipers which have a primary scale for gross measurements,and a secondary scale for fine measurements.
The Missile Defense Alarm System,or MIDAS,was a United States Air Force Air Defense Command system of 12 early-warning satellites that provided limited notice of Soviet intercontinental ballistic missile launches between 1960 and 1966. Originally intended to serve as a complete early-warning system working in conjunction with the Ballistic Missile Early Warning System,cost and reliability concerns limited the project to a research and development role. Three of the system's 12 launches ended in failure,and the remaining nine satellites provided crude infrared early-warning coverage of the Soviet Union until the project was replaced by the Defense Support Program. MiDAS represented one element of the United States's first generation of reconnaissance satellites that also included the Corona and SAMOS series. Though MIDAS failed in its primary role as a system of infrared early-warning satellites,it pioneered the technologies needed in successor systems.
The Convair SM-65A Atlas,or Atlas A was the first full-scale prototype of the Atlas missile,which first flew on 11 June 1957. Unlike later versions of the Atlas missile,the Atlas A did not feature the stage and a half design. Instead,the booster engines were fixed in place,and the sustainer engine was omitted. The propulsion system used on the initial Atlas As was an early version of the Rocketdyne MA-1 engines with conical thrust chambers that produced a mere 135,000 pounds of thrust,compared with the 360,000 pounds of the fully operational Atlas D. Several pieces of hardware found on the operational Atlas were either missing on the A-series or only partially implemented. Powered flight on the A-series would last about two minutes and compared to later Atlases,long pad hold-down times,with up to 11 seconds between engine start and launcher release.
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The SM-65D Atlas,or Atlas D,was the first operational version of the U.S. Atlas missile. Atlas D was first used as an intercontinental ballistic missile (ICBM) to deliver a nuclear weapon payload on a suborbital trajectory. It was later developed as a launch vehicle to carry a payload to low Earth orbit on its own,and later to geosynchronous orbit,to the Moon,Venus,or Mars with the Agena or Centaur upper stage.
The SM-65E Atlas,or Atlas-E,was an operational variant of the Atlas missile. It first flew on October 11,1960,and was deployed as an operational ICBM from September 1961 until April 1966. Following retirement as an ICBM,the Atlas-E,along with the Atlas-F,was refurbished for orbital launches as the Atlas E/F. The last Atlas E/F launch was conducted on March 24,1995,using a rocket which had originally been built as an Atlas E.
The SM-65F Atlas,or Atlas-F,was the final operational variant of the Atlas missile,only differing from the Atlas E in the launch facility and guidance package used. It first flew on 8 August 1961,and was deployed as an operational ICBM between 1961 and 1966. Following retirement as an ICBM,the Atlas-F,along with the Atlas-E,was refurbished for orbital launches as the Atlas E/F.
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The Atlas LV-3B,Atlas D Mercury Launch Vehicle or Mercury-Atlas Launch Vehicle,was a human-rated expendable launch system used as part of the United States Project Mercury to send astronauts into low Earth orbit. Manufactured by Convair,it was derived from the SM-65D Atlas missile,and was a member of the Atlas family of rockets. With the Atlas having been originally designed as a weapon system,testing and design changes were made to the missile to make it a safe and reliable launch vehicle. After the changes were made and approved,the US launched the LV-3B nine times,four of which had crewed Mercury spacecraft.
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References
↑"Flight Test Evaluation Report,Missile 4C February 15,1959"
↑"Flight Test Evaluation Report,Missile 5C March 6,1959"
↑"Flight Test Evaluation Report,Missile 7C April 3,1959"
↑"Flight Test Evaluation Report,Missile 8C August 3,1959"
↑"Flight Test Evaluation Report,Missile 11C September 5,1959"
↑"Missile 9C Accident Investigation Report" Convair October 20,1959
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