Viking (rocket engine) | Wikipedia audio article
Channel: wikipedia tts
Date: 17/05/2019

This is an audio version of the Wikipedia Article:
https://en.wikipedia.org/wiki/Viking_(rocket_engine)


00:02:42 1 Technical Data
00:02:51 2 See also



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SUMMARY
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The Viking rocket engines were members of a series of bipropellant engines for the first and second stages of the Ariane 1 through Ariane 4 commercial launch vehicles, using storable, hypergolic propellants, N2O4/UH 25 (mixture 75% UDMH and 25% Hydrazine.)
The earliest versions, developed in 1965, had a sea-level thrust of about 190 kN. By 1971, the thrust has improved to 540 kN, with resulting engine named Viking 1 and adopted for the Ariane program. The engine first flown on Ariane 1 rocket in 1979 was Viking 2, with the further improved thrust reaching 611 kN.
The version used on the Ariane 4 first stage, which clustered four together, had 667 kN thrust each. The second stage of Ariane used a single Viking.
Over 1000 were built, and achieved a high level of reliability from early in the program.
The 144 Ariane 1 to 4 used a total of 958 Viking engines. Only 2 engines have led to a failure. The first failure (on second Ariane 1 flight 23 May 1980) was due to a chamber combustion instability. The vehicle has lost an attitude control and broke up. Several injector changes were implemented in the aftermath of the failure, and fuel swapped from the UDMH to the UH 25.
The second failure is of human origin: a rag had been left in a water coolant pipe during installation, resulting in a loss of thrust and vehicle breakup due off-center thrust during launch 22 February 1990.Initially, all the engines were tested before being integrated on a launcher. Beginning in 1998, engineers, confident of the reliability of the engine, authorized the use of untested engines on launchers. One engine per year, randomly taken in the workshops of assembly, was tested. This confidence is very rare in the world of space engines.
The unusual feature of the Viking engines is their water tank and water pump, used to cool the exhaust gasses of the gas generator. The hot exhaust of the gas generator is cooled by water injection to 620C before been used to drive the three coaxial turbopumps (for water, fuel and oxidizer) and to pressurize the fuel tanks. The water was also used as a hydraulic fluid to actuate the valves.