Tag Archives: Rocketdyne LR79-7

17 August 1958

Thor-Able 1 Pioneer launch, 17 August 1958. NASA)
Thor-Able 1 Pioneer launch, 17 August 1958. NASA)

17 August 1958: In what was the first attempt to launch a spacecraft beyond Earth orbit, Thor-Able 1 was to place a small instrumented satellite in orbit around the Moon. Called Pioneer, the satellite carried a television camera, a micrometeorite detector and a magnetometer.

The Thor-Able was launched from the Cape Canaveral Air Force Station, Florida, at 12:28:00 UTC, 4 minutes behind schedule.

73.6 seconds into the flight, at an altitude of 9.9 miles (16 kilometers), the first stage of the rocket exploded. Telemetry from the upper stages continued and that was tracked until impact in the Atlantic Ocean. An investigation found the cause to be a turbopump failure.

The Thor Able was a two-stage orbital launch vehicle which was developed from the Douglas Aircraft Company’s SM-75 Thor intermediate-range ballistic missile.

Designated Thor DM-19, the first stage was 60.43 feet (18.42 meters) long and 8 feet (2.44 meters) in diameter. Fully fueled, the first stage had a gross weight of 108,770 pounds (49,337 kilograms). It was powered by a Rocketdyne LR-79-7 engine which burned liquid oxygen and RP-1 (a highly-refined kerosene rocket fuel) and produced 170,565 pounds of thrust (758.711 kilonewtons). This stage had a burn time of 2 minutes, 45 seconds.

The second stage was an Aerojet General Corporation-built Able, a second stage for the U.S. Navy’s Vanguard rocket. It was 21 feet,6.6 inches (6.57 meters) long with a maximum diameter of 2 feet, 9 inches (0.84 meters). The second stage had a gross weight of 5,000 pounds (2,268 kilograms). It used an Aerojet AJ10-101 rocket engine which burned a hypergolic  mixture of nitric acid and UDMH. The second stage produced 7,711 pounds of thrust (34.300 kilonewtons) and burned for 1 minutes, 55 seconds.

© 2017, Bryan R. Swopes

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10 July 1962

Telstar 1 launches aboard a Thor Delta rocket at Launch Complex 17B, 0835 GMT, 10 July 1962. (NASA)
Telstar 1 launches aboard a Delta rocket at Launch Complex 17B, 0835 GMT, 10 July 1962. (NASA)

10 July 1962: At 0835 GMT (4:35 a.m., EDT) the first communications relay satellite, Telstar 1, was launched into orbit from Launch Complex 17B, Cape Canaveral Air Force Station, Florida. The launch vehicle was a three-stage, liquid-fueled, Delta rocket.

This was the first commercial space flight, sponsored by a consortium of communications companies and government organizations, including AT&T, Bell Labs, the BBC, NASA, and British and French postal services. The satellite was used to relay live television broadcasts across the Atlantic Ocean. This had never previously been possible.

Telstar weighed 171 pounds (77.5 kilograms). Its weight and size were restricted by the availability of launch vehicles. It was placed in an elliptical orbit, varying from 591 miles (952 kilometers) to 3,686 miles (5,933 kilometers), and inclined at about a 45° angle to Earth’s Equator. The orbital period was 2 hours, 37 minutes. The properties of Telstar’s orbit restricted its use to about 20 minutes during each pass.

In addition to its primary role as a communications relay satellite, Telstar also performed scientific experiments to study the Van Allen Belt.

The Delta was a three-stage expendable launch vehicle which was developed from the Douglas Aircraft Company’s SM-75 Thor intermediate-range ballistic missile.

Designated Thor DM-19, the first stage was 60.43 feet (18.42 meters) long and 8 feet (2.44 meters) in diameter. Fully fueled, the first stage had a gross weight of 108,770 pounds (49,337 kilograms). It was powered by a Rocketdyne LR-79-7 engine which burned liquid oxygen and RP-1 (a highly-refined kerosene rocket fuel) and produced 170,565 pounds of thrust (758.711 kilonewtons). This stage had a burn time of 2 minutes, 45 seconds.

The second stage was an Aerojet General Corporation-built Delta 104. It was 19 feet, 3 inches (5.88 meters) long with a maximum diameter of 4 feet, 6 inches (1.40 meters). The second stage had a gross weight of 9,859 pounds (4,472 kilograms). It used an Aerojet AJ10-104 rocket engine which burned a hypergolic  mixture of nitric acid and UDMH. The second stage produced 7,890 pounds of thrust (35.096 kilonewtons) and burned for 4 minutes, 38 seconds.

The third stage was an Allegany Ballistics Laboratory Altair 1. It was 6 feet long, 1 foot, 6 inches in diameter and had a gross weight of 524 pounds (238 kilograms). This stage used a solid-fuel Thiokol X-248 rocket engine, producing 2,799 pounds of thrust (12.451 kilonewtons). Its burn time was 4 minutes, 16 seconds.

The three stages of the Delta rocket accelerated the Telstar satellite to 14,688 miles per hour for orbital insertion.

The day prior to launch, the United States detonated a 1.45 megaton thermonuclear warhead at an altitude of 248 miles (400 kilometers), near Johnston Island in the Pacific Ocean. (Operation Dominic-Fishbowl Starfish Prime). Radiation from this test, combined with residual radiation from the Soviet Union’s  57 megaton detonation over Novaya Zemlya Archipelago (RDS-220, known as “Big Ivan,” or “Tsar Bomba”) on 21 October 1961, damaged the satellite’s circuitry and it went out of service in December 1962.

Engineers were able to work around the damage and restore service by January 1963, but Telstar 1 failed permanently 21 February 1963.

Telstar is still in Earth orbit.

Telstar 1 communications relay satellite. (Bell Laboratories)

© 2016, Bryan R. Swopes

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1 April 1960, 11:40:09 UTC, T minus Zero

TIROS-1/Thor-Able 148 launches from Launch Complex 17A at Cape Canaveral, Florida, 11:40:09 UTC, 1 April 1960. (NASA)

1 April 1960: TIROS-1, the first successful Earth-orbiting weather satellite, was launched at 6:40:09 a.m. (11:40:09 UTC), from Launch Complex 17A at the Cape Canaveral Air Force Station, Cape Canaveral, Florida, aboard a Thor-Able II liquid-fueled rocket. The satellite’s name is an acronym for Television Infra Red Observation Satellite.

The satellite was placed into a nearly-circular low Earth orbit with an apogee of 417.8 miles (672.4 kilometers) and perigee of 396.2 miles (637.6 kilometers). It is still in orbit and circles the Earth once every 1 hour, 37 minutes, 42 seconds. TIROS-1 remained operational for 78 days. It is still in orbit.

“TIROS undergoes vibration testing at the Astro-Electronic Products Division of RCA in Princeton, New Jersey.” (NASA)

TIROS-1 was built of aluminum and stainless steel. It had a diameter of 3 feet, 6 inches (1.067 meters) and height of 1 foot, 7 inches (0.483 meters.) The satellite weighed 270 pounds (122.47 kilograms). Two television cameras were installed on the satellite. They received electrical power from storage batteries charged by 9,200 solar cells. Images were stored on magnetic tape, then transmitted when in range of a ground receiving station. The first image, which showed large-scale cloud formations, was transmitted the day of the launch.

Technicians mount the TIROS-1 weather satellite to the Thor-Able upper stage carrier. (NASA)

The launch vehicle, Thor 148, consisted of a liquid-fueled Douglas Aircraft Company Thor DM-18A first stage (based on the SM-75 intermediate range ballistic missile) and an Aerojet Able-II second stage, which was developed from the Vanguard rocket series. The Thor-Able was 91 feet (27.8 meters) tall and 8 feet (2.44 meters) in diameter. It weighed 113,780 pounds (51,608 kilograms). The first stage was powered by a Rocketdyne LR79-7 rocket engine which burned RP-1 and liquid oxygen. The engine produced 170,560 pounds of thrust (758.689 kilonewtons) and burned for 165 seconds.

The Able-II second stage was powered by an Aerojet AJ-10 engine which produced 7,800 pounds of thrust (34.696 kilonewtons). The propellant was a hypergolic combination of nitric acid and UDMH (hydrazine). It burned for 115 seconds.

There were sixteen Thor-Able two-stage rockets launched. TIROS-1 was placed in orbit by the last of that series.

The first television image of Earth, transmitted by TIROS-1, 1 April 1960. (NASA)
The first television image of Earth, transmitted by TIROS-1, 1 April 1960. The image shows Maine, Nova Scotia, the Gulf of St. Lawrence and the Atlantic Ocean. (NASA)

© 2018, Bryan R. Swopes

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