Evolution of the NK-33 and NK-43 reusable LOX/kerosene engines

Abstract

The NK-33 and NK-43 rocket engines, developed for the first and second stages of the Russian N-l Lunar Vehicle, are built upon the design heritage of their predecessors, the NK-15 and NK-15B. A series of modifications were made during NK-33 and NK-43 development to increase reliability through the addition of a restart system to support engine verification testing as well as well as improve durability by modifying the engine to operate at 114%. Aerojet of Sacramento, CA began working with the NK-33 in 1991 and performed a series of five tests to demonstrate Evolved Atlas operation. Aerojet is currently modifying the NK-33 and NK-43 to meet Kistler Aerospace's design requirements. There is sufficient data indicating that Kistler's engine life requirement of 20 firings with one overhaul can be met with periodic scheduled maintenance. Engine HistoryThe Nikolai Kuznetsov Design Bureau, predecessor of NK Engines, was founded in 1946 and for 51 years has been designing and developing aircraft gas turbine engines and liquid propellant rocket engines for the aerospace and industrial gas turbine industries where the enterprise is well known for its high efficiency, reliable, lightweight aircraft engines.NK Engines' first turbine engine, the NK-12 turboprop, went into production in 1953. The first rocket engine, the 40-ton thrust NK-9, began production in 1959.In 1964, Sergei Korolev, head of Russia's manned spaceflight program, selected NK Engines to develop the engines for the N-l Lunar Launch Vehicle, Russia's greatest space endeavor at the time. This vehicle would be larger than the U.S. Saturn 5 and would require 43 engines for its four stages to send the Russian L-3 Lunar Complex to the Moon.The experience gained from the LOX/Kerosene NK-9 engine and its upper stage version (NK-9B) would be used to develop the N-l propulsion. The NK-9B would be used for the N-l third and fourth stages, and new 154-ton and 175-ton thrust engines designated NK-15 and NK-15B, would be designed for the first and second stages. As engine development progressed, the engine designations changed, as shown in Table 1.The test program for these engines was one of the most rigorous ever seen for a space launch vehicle. The NK-15 engine, the direct predecessor of the NK-33, accumulated more than 100,000 sec of test operating time before it was first flown on N-l in February 1969. After the second N-l flight later that year, the NK-33/43 design and development program for a multi-start version of the single start NK-15/15B engine was initiated.