This page no longer updated from 31 October 2001. Latest version can be found at UR-500MK

Family: UR. Country: Russia. Status: Design 1975.

In response to the Ministry of Defence's guidelines for third generation launch vehicles, the Ministry of General Machine Building issued on 29 April 1975 instructions for Chelomei to study boosters meeting the military's requirements. These included Lox/Kerosene propellants in place of the toxic N2O4/UDMH favoured previously. Chelomei's competitor in the design, Glushko, was then head of NPO Energia which included Glushko's former OKB-456 engine design bureau. Therefore Chelomei was forced to propose using Kuznetsov Lox/Kerosene engines from the cancelled N1 moon program.

The UR-500MK was proposed in two configurations, the 11K98 and 11K99. In keeping with the mandated modular approach, the UR-500MK consisted of a core stage with a single modified NK-43 engine with a vacuum thrust of 190 tonnes. This was boosted by three (11K98) or six (11K99) lateral stages, each with a single modified NK-33 engine of 150 tonnes thrust. All engines ignited at lift-off, throttled to over 100% of their rated thrust. The core engine was apparently fed from the lateral stages or throttled back early in the ascent to conserve propellant for the second stage burn. The use of existing Proton tankage tooling for the stages and the Kuznetsov engines would allow a high-performance vehicle to be developed at minimum cost. However Chelomei was out of favour, Kuznetsov was discredited after the N1 fiasco, and Glushko was ascendant. The proposal stood no chance. Glushko's Zenit launch vehicle became the accepted solution.

The two variants had the following characteristics:


LEO Payload: 30,000 kg. to: 200 km Orbit. at: 51.6 degrees. Payload: 3,500 kg. to a: geosynchronous orbit trajectory. Liftoff Thrust: 1,150,000 kgf. Total Mass: 1,000,000 kg. Core Diameter: 4.2 m. Total Length: 62.5 m.

UR-500MK Chronology

1975 Apr 29 -


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