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To: [email protected], @nyrath Dear Mr. Chung, I have been a user of your website for quite a while. However, I’ve stumbled onto a virtually unknown piece of Red Atomic Rockets history that I’d like to share with you. I’ll stick mostly to direct translation of sources to avoid putting my spin onto it. So, there I was trawling through the full list of Energomash rocket engines at http://www.npoenergomash.ru/dejatelnost/engines/, trying to make sense of their classification scheme. I knew RD-1xx were kerolox, RD-2xx were hypergolic, RD-3xx involved fluorine and had to be given a wide berth, RD-4xx were early, solid-core NTRs, RD-5xx used peroxide, and RD-7xx switched from kerolox to hydrolox on the fly to maximize total Δv. I was trying to find out what the heck an RD-6xx was, thinking it may have been the bimodal NTR branch. There was only the RD-600. What has a vacuum thrust of 600 tonne-forces, an Isp of 2000 sec and chamber pressure of 500 kg/cm2? I was hooked already, and the Russian Wikipedia, messy as it is, answered me with an article about the solid-core twisted-ribbon RD-0140 (https://ru.wikipedia.org/wiki/%D0%A0%D0%94-0410) that contained a timeline apparently copied from https://mipt.ru/education/chairs/physmech/science/research/nuclear_reactor.php, which is a webpage of the Department of physical mechanics of the Moscow physico-technical university. Translation follows: PURPOSE OF RESEARCH AND DEVELOPMENT To produce a gas-core nuclear rocket motor with high specific impulse (>3000 sec) for missions to planets of the Solar system. HISTORY 1957 – Initiation of research as suggested by V.M. Ievlev and approved by I.V. Kurchatov, M.V.Keldysh and S.P. Korolev (by then known as the Three Ks as a result of their ICBM work – ed.) Image caption: Keldysh, Treskin, Ievlev, Kurchatov, Aleksandrov 1953 – Government decree on research into “cruise missiles propelled by ramjets exploiting nuclear energy” 1955 – formation of research group at Air Industry Ministry NII-1 (currently Keldysh Research Centre – ed.). Led by V.M.Ievlev (K.I.Artomonoc, A.S.Koroteev et al). Objective: development of NTRs “type A” (Isp=850-900 sec) and “type V” (up to 2000 sec). 1956 – Government decree on “creation of a long-range ballistic missile with an atomic engine”. Chief designers: overall – S.P.Korolev, engine – V.P.Glushko, reactor – A.I.Leypunskyi; personnel recruitment and training at the Moscow Aviation Institute – N.N.Ponomarev-Stepnoi. 1958 – Government decree on initiating NTR research; overall command relegated to M.V.Keldysh, I.V.Kurchatov and S.P.Korolev 1958 – construction of reactor test stand and “hot lab” commences at Ministry of Defence Proving Grounds №2 (Semipalatinsk nuclear testing site) 1964 – combined Central Committee of the Communist Party of the Soviet Union and Government of USSR decree on initiating construction of the Baikal firing complex at the Semipalatinsk NTR test site. 1966 – creation of 11B91, an A-type NTR (non-GRAU designation RD-0140 – ed.). Scientific supervision – Keldysh Centre (V.M.Ievlev), manufacturing – Chemical Automatics Design Bureau (A.B.Konopatov), fuel elements – Perm research and technological institute (I.I.Fedik) 1968 – development of RD-600 GCNR; scientific supervision by the Keldysh Centre, lead design by NPO Energomash under V.P.Glushkon; thrust 6 MN, Isp 2000 sec 1968 – Government decree on development of RD-600 GCNR and construction of the Baikal-2 test stand 1970 – NPO Energomash and the Keldysh Centre complete a draft proposal for a 3.3 GWt gas-core powerplant, EU-610 1972 – criticality of an IVG high-temperature research reactor at Baikal (N.N.Ponomarev-Stepnoy) 1978 – criticality of the first 11B91 NTR Image caption: high-temperature GCNR variant (“Type V”) GCNR DEVELOPMENT IN THE US 1955 – commencement of work on a Type A NTR (SCNR) at Los-Alamos under the Rover program 1960 – conceptual development of a Type V NTR (GCNR) by Weinstein, Kerrebrock (MIT) and Los-Alamos; Isp=(600-2000) sec 1963 – development of Nuclear Engine for Rocket Vehicle Applications (NERVA) by Westinghouse and Los-Alamos 1962-1968 – experiments in hydrodynamics, plasma stability, heat physics and radiation of uranium plasma, optical qualities of hydrogen, neutron calculations of reactor criticality 1973 – cessation of TR research (US-USSR AGREEMENT) A NEW STAGE FOR NTRS 1985 – Los-Alamos and NASA conduct systemic analysis of Lunar missions, concluding that resumption of research on Type V systems is crucial (twofold cost and flight duration reduction). Equipment and systems are preserved in Los-Alamos and Nevada (Keldysh Centre and Semplatinsk). 1989 – President Bush announces the Space Exploration Initiative – a manned mission to Mars by 2018 (see Russian space program). NTRs assumed as baseline by NASA and Los-Alamos. DOE/NASA task force on NTRs formed. 1991 – GCNR conference in Los-Alamos 1992 – research into stability, neutrons, displacement, quantitative modelling, MHD (presumably, magnetohydrodynamic generators or magnetohydrodynamics in general – ed.) 2005 – China and Kazakhstan declare research into spaceborne nuclear power a priority The GCNR program in the US has been unsuccessful due to “lack of experimental data on thermophysical qualities of substances and the calculating power for modelling high-temperature hydrodynamics and turbulence (from MIT report by R.Patrick & Kerrebrock). The USSR has resolved these issues with participation of the Department of physical mechanics Both the US and USSR would relegate large rocket projects to a triad of R&D Centre-University-Test Ground, e.g. Los-Alamos-MIT-Nevada and Keldysh Centre-Moscow Institute of Physics and Technology-Semipalatinsk Key development aspects: • Handling and operation of a gaseous fuel element • Thermophysics of nuclear fuel and reaction mass • Vortex and magnetic hydrodynamics • Radiative and convective heat and mass exchange • Thermal protection of reaction chamber walls and the egress canal • Achieving GCNR criticality • Achieving stable GCNR operation despite high mobility of fission fuel GCNR parameters: • Pressure – 1000 atm • Temperature: fuel 40-60 thousand K, reaction mass 8-10 thousand K • Molten uranium at 1500-2300 K • High-pressure hydrogen at up to 2800 K • Chemically aggressive environment due to alkali metals at up to 2800 K Sources A.S.Koroteev, E.E.Son Development Nuclear Gas Core Reactor in Russia: AIAA-2007-0035, 45th AIAA Aerospace Sciences Meeting and Exhibit, 2007, Reno, Nevada. Here’s that actual paper: (paywall warning!) http://arc.aiaa.org/doi/pdf/10.2514/6.2007-35 By then I was thoroughly intrigued and began to go up and down Yandex search results while trying to filter out the mentions of the RD-600 turboshaft engine. I’ve stumbled upon the questionably legal (as is most of Russia’s internet) online version of a collection of Glushko’s works, published by Energomash in 2008 with a total run of 250 books, that contains a few interesting official documents of his own authorship. http://epizodsspace.airbase.ru/bibl/glushko/izbran-rab-glushko/1/04.html August 18 1963 OUTLINE OF REPORT to the research and development council of the USSR State commission on defence technology on prospective R&D at OKB-456 The research and development conducted at OKB-456 have led to the following conclusions: 1. Further development of oxygen and RFNA engines at OKB-456 is inexpedient, as most of the expected pathways of rocket development are better served by other engine types. This does not mean that oxygen and RFNA motors are undeserving of further development, as occasionally they are highly fit for purpose. For example, when performance takes a back seat to propellant liquidity range, RFNA engines are quite applicable. Liquid oxygen, non-toxic and cheap, is also quite successful, despite difficulties associated with its low boiling temperature… (sections 2, 5, 10, 11, 15 missing – ed.) 3. At the present stage the development of high-powered liquid propellant rocket motors for surface-to-surface missiles and space boosters at OKB-456 relies entirely on UDMH and N2O4. The use of storeable, hypergolic fuel components already mastered by the chemical industry has ensured the development of highly effective motors for R-36, 67S4, R-56 and the first stage of UR-500 (a.k.a. original variant of Proton – ed.) in accordance with the Decrees of CC of CPSU and Government of USSR. These engines range, in thrust from 12 (vacuum) to 600 (sea level) tf, and in specific impulse at sea level from 272 to 300 sec, in vacuum up to 325 sec. 4. OKB-456’s current plan outlines the development of a gas-core nuclear motor with liquid hydrogen as reaction mass, with thrust of 200-600 tf (RD-600) and specific impulse of 2000 seconds. The creation of such an engine would be a true revolution in rocket science due to the dramatic leap in specific impulse. Further development of this engine class can allow, with time, specific impulses in the 2500 sec range, allowing creation of booster rockets with an order of magnitude greater payload than regular chemical-powered ones. 6. For boosters intended for first or second space velocities (orbital and planetary escape trajectories respectively – ed.) the optimal design is as follows: the chemical motors on the first stage loft the second stage carrying the GCNR to the minimum safe altitude dictated by the contamination of the exhaust by fission products… 7. The low-altitude loft stage in the abovementioned GCNR-based system should rely on the use of chemical rockets using high-density storeable propellants (UDMH and N2O4), as under such conditions the fuel is more energetically efficient than kerolox and, due to its chemical stability and hypergolicity, more convenient. An UDMH-N2O4 first stage can achieve Isp of 300-320 sec and a mass ratio of 1.18 (e.g. 8D420 engines). 8. Use of a GCNR makes the development of an entirely reusable booster more realistic by allowing the use of an airbreathing first stage… 9. In case of two-way missions to the planets and their moons using a GCNR the payload mass can be further increased by using a third stage with refireable electric rockets with Isp in the 10000-20000 sec range. (here and henceforth bold added as emphasis – ed.) 12. (sales pitch for high-energy, storeable lander propellants, including UDMH-N2O4, late RD-5xx series motors burning H2O2 and pentaborane, and the RD-550 using H2O2 and beryllium hydride (!); sly suggestion to cease development of all cryogenic chemical rockets – ed.) 13. The preceding deliberations on GCNR application can only be realized once there is confidence of the possibility of creation of said motor, backed by experimental research, including stand tests of a single fuel element motor with a gas core reactor, in a state approaching operational (plasma temperatures up to 30000 K, pressure up to 500 atm)… 14. The prospective development plan of OKB-456 has been developing for the last few years along the lines laid out in sections 1-13 and currently ranges out to 1970. In accordance with it: d) Key developments are I) High-powered UDMH-N2O4 motors: for first stages of R-36 and 67S4 (8D723, 8D724), for first stages of UR-500 and R-56 (PD43), for second and third stages of R-56 (11D44, 8D724) and a high-performance motor with ASL thrust of 600 tf and specific impulse of 300 sec ASL and 323 sec in vacuum for the first stage of heavy boosters (8D420); II) Upper stage motors of 10-12 tf using: UDMH-N2O4 (8D725, Isp=325 sec), H2O2-pentaborane (11D11, Isp=375 sec), H2O2-beryllium hydride (RD-550, Isp=400-460 sec, under investigation); III) Gas-core nuclear rocket with liquid hydrogen reaction mass with thrust 200-600 tf (RD-600, Isp=2000 sec) as second-stage engine… 16. (section on weaker chamber pressure in US chemical rockets leading to poorer performance at comparable mass – ed.) OKK-456 chief designer, academician GLUSHKO Archive № 1727 (123-130) Backtracking a bit, I’ve found an earlier memo containing some of the points missing from the above report http://epizodsspace.airbase.ru/bibl/glushko/izbran-rab-glushko/1/03.html May 6 1963 TO THE CHAIRMAN OF THE COMISSION OF THE SUPREME COUNCIL ON PEOPLE’S ECONOMY OF THE USSR on MILITARY-INDUSTRIAL MATTERS comrade SMIRNOV L.V. CHAIRMAN OF THE USSR STATE COMMITTEE on DEFENSE TECHNOLOGY comrade ZVEREV S.A. PRESIDENT OF THE USSR ACADEMY OF SCIENCES academician KELDYSH M.V. … 9. The above deliberations on expedient applications of liquid-fuel rocketry using storeable and cryogenic propellants, solid-core and gas-core NTRs and electric rockets can only be realized once the creation of GCNR is proven feasible in the coming years, backed by experimental research, including stand tests of a single fuel element motor with a gas core reactor, in a state approaching operational (plasma temperatures up to 30000 K, pressure up to 500 atm). Creation of the testbed facility and an experimental single fuel element motor is planned for late 1965, with tests commencing in 1966. First experimental results are likely to be produced by 1967. Should development outcomes prove favourable, a flight-ready GCNR (RD-600) can be deployed by 1970. … OKK-456 chief designer, academician GLUSHKO Archive № 1727 (66-71) Here’s the economic aspect: April 29 1969 TO HEAD OF 2nd MAIN DIRECTORATE OF THE MINISTRY OF GENERAL MACHINEBUILDING comrade ABRAMOV I.I. Re: development of Type V NTR In accordance with the Decree of CC of CPSU and Government of USSR №524-215 of June 19 1964 the Ministry has initiated the program “Development of RD-600 nuclear rocket motor” at an estimated cost of 20 million roubles. Over 1960-1968 Energomash and related organizations have conducted a range of design, theoretical, production and experimental studies the results of which are found in the following reports: 1. Draft project of RD-600 GNCR (original sent to MGM on September 30 1964) 2. Report on preliminary project of a testbed loop-type motor with a single gas-core fuel element (original sent to MGM on April 9 1965) 3. Report on progress on RD-600 NTR for 1966 (original sent to MGM on December 31 1966) 4. Report on progress on RD-600 NTR for 1967 (original sent to MGM on January 4 1968) 5. RD-600 nuclear rocket motor. Abbreviated results of theoretical and research studies (original sent to MGM on December 18 1968); said report is equivalent in content to a complete pre-draft project; it has been approved in that capacity by Central Research Institute of Machine Building in correspondence of April 15 1969. Over the process of developing the RD-600 a phased approach to development of Type V nuclear rocket motors has been determined to be expedient, including the initial development of a testbed motor with a single gas-core fuel element, alongside the requisite testing facilities. The above-mentioned phased approach is approved by the Decree of CC of CPSU and Government of USSR №388-146 of May 24 1968. In particular, the decree outlines the development of a high-performance on-board powerplant based around the single gas-core fuel element design. The technical objective set by the Central construction bureau of experimental machinebuilding (currently RKK Energiya, earlier KB-1, the late Sergei Korolev’s outfit – ed.) calls for a powerplant developing 3 mln kWt (sic), which is achievable by using a reactor of a Type V NTR with a thrust of approximately 50 tf. Due to the above I request your permission to close the program titled Development of RD-600 nuclear rocket motor”, to disburse the actual expenses of 9325 thousand roubles, and to commence a program titled “Development of an experimental testbed reactor with a single gas-core fuel element and a draft project of a high-performance powerplant” in accordance with the draft project file attached to my letter of April 1 1969, with an estimated cost of 2416 million (sic) roubles. Chief designer GLUSHKO Archive № 82/125 (36-37) One of the last documents in the collection is an overview of Glushko’s entire NTR business at the height of its glory. Believe me, most of the more informative materials on Soviet rocketry, such as Gubanov’s memoirs about Energiya-Buran, are this dry and technical. http://epizodsspace.no-ip.org/bibl/glushko/izbran-rab-glushko/1/05.html July 26 1973 Outline of development of nuclear rocket motors at KB Energomash Increase of the specific impulse, being one of the cardinal directions of rocket motor design, has driven the effort to exploit the energy of nuclear fission in this rapidly developing field of technologies. The successes of national rocket design in 1950-1955 have allowed the Physico-energetic institute of the Ministry of medium machinebuilding (cover name for Soviet nuclear armament and energy agency; similar to the Ministry of general machinebuilding seen earlier – ed.) to put forward the concept of integrating a solid-core nuclear reactor into a rocket engine. Based on PEI’s proposal, relying on a uranium-graphite reactor heating up hydrogen, KB Energomash began ongoing research work on solid-core nuclear rockets (Type A) in 1956. Research in cooperation with PEI over 1956-1958 revolved around neutron flux and thermal calculations and covered a variety of thrust levels (tens to hundreds of tf), reaction masses and reactor types (by moderator material, fuel distribution, et cetera). In 1958 Energomash formed a permanent design taskforce focused on nuclear motors, evolving in 1961 into a full-fledged NTR design section. From the start the unit was led by R.S.Glinik; some of the first members ncluded E.M.Matveev, G.L.Lioznov, V.Ya.Sirotkin, K.K.Nekrasov and V.N.Petrov. Based on research by PEI and Energomash along with parallel investigation of rocket propulsion through fission energy by the Keldysh Centre, in 1958 the CC CPSU and Government of the USSR issued a joint decree that, among others, outlined he development of a draft design of a high-thrust Type A NTR using ammonia as reaction mass. The draft design was completed in 1959 with assistance from PEI (neutron flux) and the Keldysh Centre (thermal physics, fuel rod design, engine dynamics research), yielding two variants, RD-401 with a water moderator and RD-402 with a beryllium moderator. RD-402 produced superior performance, at 168 tonne-force vacuum thrust, 428 sec Isp, weight to power ratio 22 kg/tf of thrust (note that the original refers to it as specific power – ed.) and a length of 6760 mm. The draft proposal presented the following innovations: proof of applicability of heterogenous multi-fuel rod reactors for thrust up to 500 tf; application of a solid beryllium moderator; fuel rod design providing high reaction mass temperature (up to 3000 K) with minimal fluctuations along the cross-section of the fuel element; homogenized reactor control system using absorber gas in isolated canals; closed-cycle turbopump feed, with the working fluid heated by dedicated fuel rods; steering via gimballing the engine; multi-nozzle design dramatically shrinking the length of the motor; mounting of the booster pump in the outboard section of the rocket’s tankage; proof of the necessity of cooling most of the components due to atomic radiation. Although overall the energetics of the RD-402 were relatively unimpressive, the design and development allowed many of the complex issues in construction of Type A NTRs to be exposed and solved. By 1960 positive outcomes of use of liquid hydrogen in rocket design and the availability of requisite tankage technology have allowed to push forward with the draft design of a Type A NTR using hydrogen reaction mass; the CC CPSU and Government of the USSR authorized it in 1960. As a result by 1962 Energomash in cooperation with a range of other units, under general leadership of the Keldysh Centre and with reactor design input by PEI, developed the draft design of the RD-404. RD-404 was rated for 200 tf vacuum thrust, 950 sec specific impulse and weight-to-power ratio of 45 kg/tf of thrust including radiation shielding for the tankage, and was 7770 mm long. RD-404’s design included a number of design solutions developed specifically for Type A NTRs. After researching a range of moderator options, the final design used an optimized arrangement of beryllium into autonomous cells mated with the fuel rods. A modified sectioned design of the fuel rod was substantiated and implemented, with the initial graphite-coated zone and a post-heat section coated in a metal-carbide composite leading to average hydrogen temperatures in the 3000 K range. A liquid control “rod” system using mercury was conceived and researched. An engine control system relying on specialized pyroautomatics was also developed. A complex study was conducted in order to optimize weight-to-power ratio while also developing rocket-engine system design. Research into start cycle and throttling was performed, along with the terminal stage and shutdown cycle using the remnant heat of a subcritical reactor; reverse systems were developed to minimize post-shutdown thrust. Engine subsystem design, tankage protection and engine-to-rocket coupling were investigated with regards to reactor radiation effects. A steering system using vanes on nozzle edges was also tested and implemented. Initiation calculations very verified by a set of experiments on fuel rod material resistivity, component durability, physical assembly tests, gas-dynamic tests of the multi-nozzle design, tests of the mercury control system, et cetera. A considerable contribution to Type A NTR design was on part of a Keldysh Centre taskforce led by V.M.Ievlev and including K.I.Artamonov, R.B.Akopov, V.N.Bogin, A.I.Gori, V.A.Zaitsev, G.V.Konyukhov, E.P.Terekhov. The development of RD-401, -402 and -404 essentially led to establishing the key principles of Type A NTR and subsystem design, along with many aspects of manufacturing, testing and operation. Over the course of these projects the organizations involved brought up new creative collectives while laying the groundwork for extensive industrial cooperation. (standard canned Communist phrases, if you can’t tell. – ed.) The resultant draft projects of RD-401, -402 and -404 were investigated by a number of highly competent expert panels and technical councils, and were rated highly by them. Based on existing experience, in 1962-1963 a draft design was carried out for a mid-range NTR referred to as RD-405, with 30-40 tf thrust, liquid hydrogen reaction mass, specific impulse of 900-950 sec, weight-to-power ratio 55 kg/tonne-force of thrust including tankage shielding. The reactor used a zirconium hydride moderator, beryllium reflectors and fuel rods similar to those of RD-404. In actual operation requiring multiple firings the average specific impulse of a SCNR will be degraded by several tens of seconds due to lengthy reheating from standby state. Limited possibility of any further increase of specific impulse in Type A NTRs has been the key reason for cessation of research at Energomash in 1963 and relegation of this development topic to a different OKB (see: RD-0140 – ed.) It was decided that Energomash would instead focus itself on the much more promising gas-core NTR (Type V), which could lead to a revolutionary leap in aerospace design. The research at the Keldysh Centre in 1958-1963 under the overall supervision of V.M.Ievlev, covering principal schemes of gas-core reactors, gas-core fuel elements and Type V NTRs overall, had substantiated the plausibility of a highly energetic engine design, which justified initiating of design development at the construction bureau. A significantly greater specific impulse of Type V designs compared to Type A, making possible the design of spacecraft with qualitatively new capabilities, along with a number of operational advantages (absence of fissionables in the engine during manufacture, possibility of fissionable removal after tests, thus making in-situ servicing and refueling more plausible) make Type V systems exceptionally promising, despite the obvious challenges and the considerable development costs. From the very beginning of work on Type V NTR at Energomash in accordance with the Decree of CC CPSU and the Government of the USSR under general scientific supervision of the Keldysh Centre had two key directions: development of an actual high-thrust rocket motor, and the development of a testbed motor used to test off the key functioning principles of the full-scale engine, with a range of theoretical and practical problems being combated along the way and a dedicated test facility being constructed. It should be noted that the development of Type V engines benefitted immensely from the expertise accumulated when developing Type A NTRs. The RD-600 was designed in 1964-1968, rated for 600 tf of thrust at 2000 sec specific impulse, with weight-to-power ratio of ~100 kg/tonne of thrust including shielding, and a total length of 14000 mm. The reaction mass is liquid hydrogen doped by lithium. The engine includes a multi fuel element gas-core reactor with a solid moderator and reflector (beryllium, beryllium oxide, graphite), gaseous fuel elements with a central moving stream of fission fuel, and a closed circuit for nuclear fuel, complete with a condenser, separators, pump and fission products removal system. Stabilization of flow in gaseous fuel elements is performed by magnetic solenoids powered by a unipolar electric generator. Research conducted by the Keldysh Centre, PEI and a number of other institutes covered a wide array of topics around designing the principle layout of the motor and optimization of key aggregates and systems in an effort to maximize the specific impulse. Research included neutron flux measurements on physical assemblies, modelling of parallel flows, studying the effects of longitudinal magnetic fields on flow of conductive media, investigating radiative heat transfer and thermal protection of the structure from high-intensity heat, studying resilience of various construction materials when immersed in liquid uranium, seeking production and testing methods of temperature-resistant porous materials, et cetera. The executed research proved the principal possibility of producing an NTR with uniquid qualities through use of a gas core reactor, while revealing the extraordinary challenges of organizing the operation, requiring new and specialized materials and manufacturing technologies, associated with such an engine. It was proved that a range of experiments simulating the key operational processes would be crucial for the development of a GCNR, but would require specialized testbeds and a reactor stand facility. Creation of such a facility and a testbed motor was outlined by a Decree of CC CPSU and the Government of the USSR of 1968, and had taken centre stage in the work of Energomash and its associates since 1964; it is even more important now, as the theoretical solutions in gas-core reactor design take a backseat to the need for practical testing. In accordance with the aforementioned decree in 1970 another design study was completed, this time of a spaceborne electric powerplant dubbed EU-610, with an electric output of circa 3.3x106 kWt, specific power 0.7x105 kWt/kg/sec (sic), relative mass 18.7 g/kWt, length 10000 mm. The powerplant is based around Keldysh Centre’s proposed improvements to the gaseous stream fuel element design. A significant increase in magnetic field intensity coupled with special endcaps have enabled the creation of a “dead space” for fuel cooldown, allowing he creation of a reactor with a single fuel element, with an order of magnitude less power than the RD-600, and without a circulation contour for fission fuel. Further draft proposals outlined the use of this reactor core as a standardized design, producing an NTR with a thrust of 50-60 tf. High parameters of hydrogen plasma heated up by a GCNR make it especially appealing for powerplants that use high-efficiency heat-to-electricity conversion using magnetohydrodynamic generators. A draft proposal for such a system was drawn up by Energomash, the Keldysh Centre, PEI and IPPE. Over the development of the draft a significant volume of testing of key processes on model systems and of neutron flux profiles on physical assemblies were performed. A major role in theoretical and calculative work in designing the Type V system and buttressing the experimental developments was played by I.M.Ievlev and the laboratory under his leadership, namely K.I.Artamonov, N.N.Borisov, A.Ya.Goldyn, A.I.Gorin, M.M.Gurfink, A.M.Kostylev, V.N.Krylov, H.H.Kuznetsov, V.M.Matyshin, A.V.Moskolyov, O.I.Novoznov, A.B.Prishleptsov, A.A.Pavelyev, S.S.Preobrazhensky, E.P.Terekhov, R.A.Fedotov, A.A.Shirokov. The development of the EU-610 powerplant will unlock considerable capabilities in achieving astronautic and general fusion power objectives. Nuclear rocket motors and nuclear powerplants of Type V, possessing quantitatively and qualitatively greater capabilities compared to chemical and Type A nuclear rockets, are intended to ensure further progress in rocket and aerospace technology development. Glushko V.P., Glinik R.A. Archive № 82/179 (72-80) And finally, here’s an essay from a defunct… site, credited to an Aleksandr Valeryevich Khoroshikh at [email protected]); it has images, citations, technical details, and it offers a saddening finale to the whole story. http://imperus.clan.su/publ/2-1-0-8 Gas-core nuclear rockets The idea of using a nuclear motor in a rocket dates back to the dawn of that field [1]. An ammonia NTR produced a specific impulse comparable or superior to hydrogen-oxygen chemical motor [2], without requiring sophisticated cryogenics and bloated tankage to contain the low-density hydrogen. In particular, there was a program to develop an R-7-style missile, with an NTR sustainer stage surrounded by six kerolox strap-ons [2]. [see http://astronautix.com/y/yakhr-2.html – ed.] At the time it was assumed that a nuclear motor would become the core of a successful intercontinental ballistic missiles, ensuring considerable funding of that sphere. However, once chemical motors (especially ones using heptyl-amyl (official codenames for UDMH-N2O4 – ed.)) achieved performance that satisfied the military, the concept of an NTR-based ICBM was abandoned. However (sic), the USSR initiated a space program that included a manned Lunar, and later a Martian mission. One should not forget Nikita Khrushchev’s announcement of the Soviet moonshot. This reinvigorated NTR development. An ICBM could only utilize a solid-core NTR, with all other options (liquid or gaseous fuel in a hollow reaction chamber) inevitably leading to some of the fuel escaping and contaminating the environment [4] Furthermore, as mentioned above, reaching America turned out to be within the capabilities of chemical rockets. This relegated NTRs to the single role of a high-efficiency motor for upper stages of boosters and for interplanetary craft. Interplanetary missions are especially dependent on engine specific impulse, as the requisite Δv approaches tens of kilometers per second. In this aspect, gas-core NTRs are particularly outstanding, capable of exhaust velocities comparable to electric rockets [5] while also developing thrust comparable to chemical motors. Unlike electric rockets, they can achieve the requisite speed in comparatively short order, rather than months. This in turn allows rapid transit through the Earth’s radiation belts, subjecting the crew to much less radiation. Also, quite notably, not only the minimum energy Hohmann transfers, but “fast-track” trajectories, like parabolic orbits, become possible. “The decision to develop NTRs and spaceborne nuclear electric powerplants based on gas-core nuclear reactors was formulated by Energomash chief academician V.P.Glushko in 1963 and was later approved by a Decree of CC CPSU and the Government of the USSR. By then the scientific corps at Energomash had six years of experience in designing and developing SCNRs. Theoretical research into GCNRs had been conducted since 1957 under the leadership of a USSR Academy of sciences corresponding member V.M.Ievlev at the Scientific institutes of heat processes (later the Keldysh Centre). Only two countries, USSR and USA, have attempted to tackle this technology, comparable in complexity to controlled thermonuclear fusion and requiring colossal financial expenditures,” as [6] describes the beginning of GCNR research. Energomash’s lead unit on gas-core reactors and derived NTRs was a section led by R.A.Glinik. Solving the problem involved in design required cooperation with numerous institutes (primarily from the aerospace and nuclear industries) and the country’s leading universities under the overall scientific leadership of the Keldysh Centre. Considerable support was lent from the country’s leading scientists, such as academicians M.D.Millionschikov, A.A.Bochvar, Ye.P.Velikhov [6]. One of the key participants was B.I.Katorgin, who was also involved in development of RD-560 (H2O2 and beryllium hydride) and RD-600 (GCNR) engines. In addition to developing the particular systems, this development provided fundamental information on flow dynamics of pseudo-liquefied powdered fuels and combustion products within the chambers, on feeding said fuels into the combustion chamber and igniting them with decomposition products (in RD-560), along with gaseous flow dynamics (in RD-600). This work formed the basis of the candidate thesis Katorgin defended at the Bauman Moscow State Technical University in 1967 [7]. The designers encountered a range of principle difficulties. Here is a lis of some of them: [6] 1. Operation of a gaseous fuel element 2. Achieving criticality in a gas-core reactor 3. Achieving stable functioning of the gas-core reactor 4. Maintaining functionality of components and subsystems at extreme temperatures 5. Ensuring resistance of construction materials to corrosion 6. Thermal protection of the nozzle and MHD generator 7. Separation of fission products in closed-cycle GCNRs In 1963-1973 the GCNR and gas-core reactor unit of Energomash included approximately 90 people. That period saw intense experimental and production work on preparing reactor testing that was due to launch in 1975. However, in 1974 Energomash began developing the RD-170/171 – a high-performance kerolox rocket engine for the Energiya-Buran system (along with the Zenit booster, and later for ULA Atlas V in the form of RD-180, for Antares and Angara in the form of RD-190 and for Soyuz-2.1v in the form of RD-193. So much for abandoning cryogenic fuels! – ed.), which caused GCNR research to be halted and the relevant section reduced to 30 people. Over eight years the funding was only sufficient for on-paper studies, resulting in a considerable loss of technological, industrial and experimental groundwork. [5,6] Starting in 1982 full-scale development was resumed, and the restored design and development unit spent two years recovering the technological and experimental base. However, in late 1989 funding was cut almost entirely. Neither did any of the programs in the United States reach even the small-scale demonstration experiment stage. It was expected that the GCNR would consist of one or several reaction chambers surrounded by a neutron moderator-reflector. The nuclear fuel inside the chambers would be suspended in a plasma state, without contacting the chamber walls, in a quantity sufficient for a self-sustained chain reaction. The reaction mass would flow through the gap between the fissioning plasma and the chamber walls. Reaction mass heating is through radiative energy transfer, with average temperature at chamber egress reaching 104 K. Absorption of radiated heat also provides thermal protection for the chamber walls. The key problem in developing the gas-core reactor was minimizing the loss of fission fuel, which had to be kept within tens of percent of reaction mass flow. Acceptable loss level was to be ensured by laminarization of the inbound reaction mass flow, profiling the field of its initial velocities, an external magnetic field, appropriate choice of working materials, and chamber geometry. Loss of fission fuel was to be compensated by its further input in either liquid form (at 1500 K) or as a paste-like powder mix with a NaK eutectic. Spaceborne powerplants were designed along both open-cycle and closed-cycle lines. If the working fluid is ejected through a rocket nozzle, then the system is an open-cycle rocket motor. The working fluid if hydrogen that, for the purposes of increased radiative absorption and electric conductivity is doped by NaK and Li vapours along with tungsten powder; this also helps achieve acceptable reactor wall temperature. An NTR of such a design would possess extremely high specific characteristics (Isp on the order of 2000-3000 sec). If the system is designed to eject the hydrogen through a high-efficiency MHD generator, then it is an open-cycle powerplant. A closed-cycle powerplant still uses the MHD as a power converter, but all working elements are cycled through isolated loop. In this case we gain a nuclear electric powerplant of impressive efficiency (30-40%) and of low specific mass and working medium expenditure. The additives to the working mass are, among other aspects, intended to improve interaction with the MHD generator. In addition to the reactor and MHD generator, the design inevitable has to include refrigeration, separation and pumping system. The working medium is a mixture of NaK steam and helium. The excess heat is dumped into space via radiators. The power produced can be utilized for a variety of purposes, not the least to power an electric rocket. And advantage of gas-core systems over solid-fuel rods in closed-loop powerplants is the ability to considerably extend uninterrupted operation via continuous input of fresh fission fuel to replace the extracted reaction products. The conceptual design of a nuclear engine-powerplant system for a manned Mars expedition is the latest-dated, and encompasses all past experience. The design is based around a combined single cavity solid-and-gas-core transforming reactor massing 57.5 t. Gross heat output 2.14 GWt. Solid fuel assemblies, arranged in a ring around the reactor vessel and mounted on an input-extraction system, provide the necessary level of neutron flux for criticality at start-up, before the fuel is introduced to the gaseous fuel element cavity. As the fission fuel is introduced and accumulated in the central cavity, i.e. as a plasma zone appears and the gaseous fuel element is formed, the solid fuel rods are retracted from the active zone, and the reactor becomes a pure gas-core system. Thanks to the transforming design the system has two modes of operation: •thrust (gas-core) mode developing 17 tf (according to other sources, 600 tf [8]) with an Isp of 2000 sec – for boost and deceleration stages of the trajectory; •energetic (solid-core) mode developing 200 kWt of electric power for supplying the needs of a spacecraft with no loss of working medium – for coast stage of the trajectory. This mode involved the operation a closed-cycle gas turbine circuit with a He-Xe mixture as working medium, thermal energy conversion at 20% and radiative cooling via the Brayton cycle. In thrust mode, electric energy is generated by a 25 MWt MHD generator integrated into the nozzle, with electrodes and excitement busses oriented down the nozzle’s throat. [6,9] RD-600 SCHEMATIC [10] (Figure 1) Power block layout: 1 – drive electromotors; 2 – feed-screw; 3 – retractable solid fuel rods; 4 – radiation shield; 5 – coaxial coils; 6 – reaction zone; 7 – reactor structure; 8 – solenoid; 9 – carbon fiber reinforcement coiling; 10 – solenoid heatshield; 11 – lateral moderator-reflector; 12 – high-temperature molybdenum bulkhead; 13 – integrated MHD generator; 14 – supersonic expander nozzle; 15 – front endcap; 16 – fuel rods (graphite with dispersed uranium carbide); 17 – rear endcap; 18 – channels filled with 3He (!? – ed.) (reactor control system actuators); 19 0 electrodes for the multipolar Faraday MHD generator A layout of a Mars Expeditionary Complex using a block of two above-described gas-core nuclear systems is depicted in Figure 2. At assumed payload of 150 tons for this mission type, approximate mass of the complex in Earth orbit would be 520-540 t depending on launch date. For comparison, an SCNR results in 730-800 t and chemical rockets in 1700-2500 t. MEC LAYOUT (Figure 2) (the awful quality is inherited from the original; curiously, it’s annotated in both English and Russian. The scale at the bottom-right is 10 m. Going left-to-right/aft-to-bow, the spacecraft consists of a pair of engines, a V-shaped radiator array around a load-bearing truss that also contains the lithium tanks. Everything between that and the truss section further to the right are hydrogen tanks (jettisonable? There are three distinct sets); the foremost section costs of an orbital habitat with an Earth Return Vehicle stuck to one side and a very vaguely-depicted Mars Landing Vehicle on the other. – ed.) Gas-core reactor and derived GCNR development strategy was based around three incremental phases. The initial stage involved the still-operational unique testing facility based around an Impulse Graphite Reactor (IGR) at the Semipalatinsk nuclear range, Kazakhstan. It involved brief (up to 5 sec) operational tests of reduced-scale modes of gaseous fuel elements, up to 100 mm in diameter and 250 mm in length. The second phase would involve constructing a new IGR-type reactor called Nephrite, capable of testing samples thrice the size and for an order of magnitude greater durations. The final stage would involve a full-scale prototype testbed gas-core or, more precisely, combined solid-and-gas-core reactor dubbed Lampa (before you ask, no other mention of lightbulbs or quartz in anything I’ve found – ed.), with an active zone capable of housing a “dead zone” type, self-contained gas-core fuel element. The last two stages would take place at the Baikal-2 stand complex, also at Semipalatinsk. Baikal-2 has had significant research invested into it, with considerable attention paid to safety concerns, primarily radiological and nuclear; in particular, the system was built entirely for closed cycle. The preparation for first stage of practical testing of a scale model of a gaseous fuel element in the IGR reactor took the most time and resources. The experimental ampula, containing a model of a fuel elements and all the requisite systems, was to be located into the vertical canal at the centre of the reactor. Over the course of the experiment a displacement-type system was to introduce the fission fuel into the working chamber, located in the middle of IGR’s own active zone. The furl could be a paste composed of small particulate powder of uranium and alkaline metals, or liquid uranium heated before introduction into the chamber. The fuel introduction tract had highly effective and compact neutron shielding in order to prevent overheating of fuel and the surrounding container. Primary dimensions of the interior of the working chamber: diameter 80 mm, length 240 mm. The uranium-containing stream, once injected into the chamber, would be hit by the intense neutron stream, heat up, vaporize and ionize. Radiation from the plasma heated up the working medium. The conical inner wall of the entry section of the working chamber was composed of a high-melting-point alloy. The wall was made permeable to allow injection of hydrogen and helium alongside the fuel. This prevented the formation of a recircularization zone in the fuel vaporization are, and inflow turbulence. The incoming hydrogen, on the other hand, provided a coaxial boundary layer that isolated the chamber walls from the primary uranium plasma stream. The cylindrical section of the working chamber had an ablative coating along its interior, providing reliable protection to the outer structure, including in cases of metallic uranium condensing on the ablative material (by the ablation forcing uranium back into the primary stream). Upon exiting the chamber the high-temperature stream of reaction mass was to enter the condenser. The walls of the condenser had rows of slots used to inject gaseous hydrogen for the purpose of dilution. Furthermore, the interior of the condenser also had the anti-uranium coating. To reduce heat flow from uranium while passing through the condenser, the exterior of the condenser was also equipped with neutron shielding. The resultant gas mixture containing fission products would then be forced through a transonic nozzle towards the filtration system located near the bottom neutron shield of the reactor. Large particles would be intercepted by the inertial traps, while smaller ones would be caught in metal-ceramic filter cartridges. The use of a transonic nizzle would stabilize the pressure in the working chamber should hydraulic resistance of filtering cartridges change over the course of the experience. Gaseous products would then be routed to the test stand exhaust containment system. To limit head generation and filter heat-up it was also equipped by stationary lateral and bottom neutron shielding. Once the fission fuel was exhausted and the test was completed, the shutdown was performed by cooling the heat-producing fuel residue in the ampule filter with a stream of gas. The experimental ampule (Figure 3), produced at a pilot plant, had a diameter of 185 mm and a length of 6500 mm, and included the following components: fission fuel feed system, working chamber, condenser, and filter. This, along with communication systems, measurement sensors and overall assembly elements, was packaged into the airtight shell. It was assumed that the requisite supply of the fission fuel would be loaded into the ingress tract of the ampule immediately before commencing the operation. After the test, all solid and liquid products are retained within the filter. Therefore, radiation safety across all stages of operation is ensured through localization and containment of the fission fuel and the bulk of the fission products within the ampule’s interior. Leakage of radioactive substances into the environment was completely excluded. The central canal of the IGR impulse reactor, which would hold the experiment ampule, had a water-cooled airtight shell separating it from the uranium-graphite cladding of the active zone. The upper part of the ampule mounted the connections to the test stand’s communications. Considerable attention was paid to safety measures preventing damage of IGR reactor core and radioactive contamination of testing facilities in case of possible failure modes of functional subsystems within the experimental ampule. Two complete test packages with miniaturized fuel elements were completed and ready for delivery to the test facility (Figure 5) (missing here, see same at http://engine.aviaport.ru/issues/06/page12.html – ed.). Specialized test stand equipment kits and expended experimental radioactive material handling and transport equipment were already dispatched there. In addition to the experimental ampule, a draft design of an advanced gas-core fuel element with a “dead space” cooling area and magnetic stabilization was also completed [6,9]. Sources: 1. Б. Е. Черток "Ракеты и люди. Книга 4 Лунная гонка" 2. http://www.lpre.de/energomash/index.htm 3. Первушин "Битва за звёзды. Космическое противостояние" 4. Л. Гильберг "Покорение неба", стр. 325-326 5. http://epizodsspace.testpilot.ru/bibl/molodtsov 6. "Двигатель", "Газофазные ядерные двигатели для космических аппаратов", №5 1999 г. 7. http://www.novosti-kosmonavtiki.ru/content/numbers/263/03.shtml 8. http://www.lpre.de/energomash/index.htm 9. "Двигатель", "Газофазные ядерные двигатели для космических аппаратов", №6 1999 г. 10. http://www.novosti-kosmonavtiki.ru/content/numbers/219/37.shtml I’ve tracked down the citations. №1 is Boris Chertok’s somewhat less technical autobiographical work covering the Soviet rocket program since he was hunting for leftover V-2s alongside Sergei Korolev; it’s available at http://militera.lib.ru/explo/chertok_be/index.html. №2 and 8 are the same master list of Energomash engines I started from. №3 and 4 are aerospace tech populariser paperbacks. №5 is a dead link to the same site I got Glushko’s correspondence from. №7 and 10 are obsolete links to a periodical that’s behind a paywall; the up-to-date links are http://novosti-kosmonavtiki.ru/mag/2001/1411/ and http://novosti-kosmonavtiki.ru/mag/2005/1043/. №6 and 9 are from a journal with the telling name Engines, a two-part article about GCNRs by Grigory Lioznov, an Energomash engineer whom we’ve heard about earlier; they’re available online at http://engine.aviaport.ru/issues/05/page41.html and http://engine.aviaport.ru/issues/06/page12.html. Aside from several more images, I’ve gleaned two very interesting sections not covered above: Miniaturization and reduction in mass of GCNRs are facilitated by: •Use of uranium-233 fission fuel •Maximization of use of metallic beryllium, including large-crystal beryllium, in the moderator-reflector assembly, with the rest composed of graphite •Maximization of use of metals with improved isotope composition and high melting temperatures in the design of reaction chamber interior, and of high-durability titanium alloys and reinforcing carbon composites in the reactor frame. •Use of hyperconductive aluminium (0.9999 purity) in high-current magnetic stabilization, MHD excitation and turbopump power feed systems due to its ability to conduct up to 50-100 A/mm2 when cooled by liquid hydrogen, while developing less than a tenth of resistivity of copper. It is obvious that the temperature extremes in operation of many GCNR components and the highly chemically aggressive environment (molten uranium, high-pressure hydrogen, alkali metals) required significant materials science investigations. As a result, high melting point alloys based on tantalum-tungsten-hafnium as well as niobium were developed for the fission fuel feed system. Certain areas of the reactor vessel have necessitated the development of heat-resistant porous materials based on tungsten and molybdenum, for the high-temperature fuel filters – on nickel and nichrome. Estimated parameters of a gas-core fuel element Pressure in reaction chamber, kgf/cm2 200 Uranium expenditure, g/sec 200 Hydrogen expenditure in the reaction chamber, g/sec 10 Velocity of fuel when entering the reaction chamber, m/s 1.7 Power, kWt 1000 Share of vaporized uranium in the egress flow, % 80 Temperature of uranium plasma, K 8-10x103 (unclear – ed.) Thermal neutron flow, neutrons/cm2/sec 1015 (unclear – ed.) Final reflections? Just… holy hell. You never know if that old Soviet closet has a skeleton or a suit of Mobile Infantry powered armour in it. Yours sincerely, Denis Danilov

Last Thursday Putin made his last state of the nation address this term. The unexpected second half of the address can be summed up as the following: Among a menagerie of superweapons presented was the RS-28 Sarmat heavy ICBM with Yu-71 Avangard maneuvering reentry vehicles (surprising no-one) and a nuclear turbojet-propelled cruise missile (which, as far as past actions go, surprised everyone). These do present a tangible boon to Venus exploration, as I’ll detail towards the end. First, some ground rules: We’re talking about the missile and not about Putin; the thread slipping into political flaming will send us all off to the Gulag, so don’t do it We, however, charitably assume that the retired KGB lieutenant-colonel isn’t lying While the information on the turbojet is extremely sketchy, the past lack of evidence or international furore suggests it’s not a fallout-spewing death machine. One would expect broad-spectrum nuclear contamination above Scandinavia, both from a running Project Pluto jet and from crashed “hot” reactors. Instead, what we get is a burst of ruthenium in the Urals, and a minor, elisive spike of iodine-131 that USAF promptly threw its best CBRN recon platform at. Similar to the Moon landing, you wouldn’t expect the other side to keep quiet. This is consistent with past Soviet developments, though. One is the reactor ejection and recovery system envisioned for the ASW variant of An-12, and the other was previously considered for the atomic Tu-95 - a closed-cycle jet with no exposure of the core to outside air. Lack of air inside the core makes operating the reactor immensely easier - NERVA designers got a lot of grey hair trying to factor in the neutron moderation properties of the propellant flow. This also means the nuclear turbojet can safely operate with media other than Earth air. We know full well that turbojets can’t operate on Venus - chemical turbojets. Many KSPers have toiled with electric propellers on Eve, and some did resort to Project Pluto. Separately, Russia’s Venera-D probe is progressing at a snail’s pace, with the primary aim of building a lander that will last 24 hours. That... isn’t terribly ambitious. What if we injected some old-school Apollo coсk-jousting and armed Venera-D with a cruise missile? Currently, studies of Venus atmospheric missions are dominated by advanced derivatives of VeGa baloon probes. These can last for a while depending on the power source, but they are at the mercy of the wind and the initial deployment location. A high subsonic cruise missile-derived drone would cover infinitely more ground throughout a lifetime comparable to most competing aerobots, with a reliable energy budget from its propulsion system. The requisite core capabilities are implicit in the weapons systems being presented. Aside from the nuclear powerplant, the intercontinental cruise missile/loitering munition would have to be capable of advanced autonomouc operations and even threat charecterization, which is crucial because it would only get brief comm windows with Earth. Meanwhile, the Avangard MARV by necessity provides experience with aerodynamic deceleration in aggressive reentry modes, and with precise autonomous navigation and maneuvering in said reentry modes - a Venus aerobot won’t be able to rely on GLONASS. So, does this cloud of fallout has a silver lining?

They label themselves a hard sci-fi, non-open-world starfighter sim a la Star Citizen. Their dev team profiles have notable names on them. They namedrop big things. But am I the only one who fails to see a connection between rather ordinary starfighter sim gameplay that goes on on the screen, and the hard sci-fi fluff they push on the side? Visible lasers, extremely close-range dogfighting, some of the ships noticeably lack radiators, one of the ships has pronounced atmospheric features... hell, it seems there aren’t any SC-style gimballed weapon moints!