Donald W. Culver

Low Thrust, Deep Throttling, US/CIS Integrated NTRE

In 1993 our international team performed a follow‐on “Nuclear Thermal Rocket Engine (NTRE) Extended Life Feasibility Assessment” study for the Nuclear Propulsion Office (NPO) at NASAs Lewis Research Center. The main purpose of this study was to complete the 1992 study matrix to assess NTRE designs at thrust levels of 22.5, 11.3, and 6.8 tonnes, using Commonwealth of Independent States (CIS) reactor technology. An additional Aerojet goal was to continue improving the NTRE concept we had generated. Deep throttling, mission performance optimized engine design parametrics, and reliability/cost enhancing engine system simplifications were studied, because they seem to be the last three basic design improvements sorely needed by post‐NERVA NTRE. Deep throttling improves engine life by eliminating damaging thermal and mechanical shocks caused by after‐cooling with pulsed coolant flow. Alternately, it improves mission performance with steady flow after‐cooling by minimizing reactor over‐cooling. Deep throttling a...

Human Exploration and Settlement of the Moon Using LUNOX-Augmented NTR Propulsion

An innovative trimodal nuclear thermal rocket (NTR) concept is described which combines conventional liquid hydrogen (LH2)‐cooled NTR, Brayton cycle power generation and supersonic combustion ramjet (scramjet) technologies. Known as the liquid oxygen (LOS)‐augmented NTR (LANTR), this concept utilizes the large divergent section of the NTR nozzle as an ‘‘afterburner’’ into which LOX is injected and supersonically combusted with nuclear preheated hydrogen emerging from the LANTR’s choked sonic throat—‘‘scramjet propulsion in reverse.’’ By varying the oxygen‐to‐hydrogen mixture ratio (MR), the LANTR can operate over a wide range of thrust and specific impulse (Isp) values while the reactor core power level remains relatively constant. As the MR varies from zero to seven, the thrust‐to‐weight ratio for a 15 thousand pound force (klbf) NTR increases by ∼440%—from 3 to 13—while the Isp decreases by only ∼45%—from 940 to 515 seconds. This thrust augmentation feature of the LANTR means that ‘‘big engine’’ perform...

A unique nuclear thermal rocket engine using a particle bed reactor

Aerojet Propulsion Division (APD) studied 75‐klb thrust Nuclear Thermal Rocket Engines (NTRE) with particle bed reactors (PBR) for application to NASA’s manned Mars mission and prepared a conceptual design description of a unique engine that best satisfied mission‐defined propulsion requirements and customer criteria. This paper describes the selection of a sprint‐type Mars transfer mission and its impact on propulsion system design and operation. It shows how our NTRE concept was developed from this information. The resulting, unusual engine design is short, lightweight, and capable of high specific impulse operation, all factors that decrease Earth to orbit launch costs. Many unusual features of the NTRE are discussed, including nozzle area ratio variation and nozzle closure for closed loop after cooling. Mission performance calculations reveal that other well known engine options do not support this mission.

Multimodal space nuclear thermal propulsion and power system for space industrialization

American industry will capitalize on available aerospace and nuclear technologies to continue space industrialization if shown a highly profitable approach. One is suggested that depends upon a sequence of co‐enabling mission architecture, propulsion, and payload improvements, which are based on concepts developed recently by our aerospace, nuclear, and chemical propulsion communities. Sequential development of specific cislunar and lunar industries are suggested to minimize early investments. Lunar and subsequent inner solar system industrial growth becomes feasible with lunar oxygen use in the recommended, multimodal, space nuclear propulsion and power system that provides the high specific impulse, system flexibility, life, and reliability needed to propel and power early spacecraft and outposts as well as future vehicles in more demanding mission architectures.

US/CIS integrated NTRE

The paper describes the Nuclear Thermal Energy (NTRE) engine, developed by taking advantage of mature fuel technology developed in the former Soviet Union, thus shortening the development schedule of this engine for moon and Mars explorations. The near-term NTRE engine has a number of features that provide safety, mission performance, cost, and risk benefits. These include: (1) high-temperature long-life CIS fuel, (2) high-pressure recuperated expander cycle, (3) assured restart, (4) long-life cooled nozzle with thin inner wall, (5) long-life turbopumps, (6) heat radiation and electrical power generation, and (7) component integration synergy. Diagrams of the reactor core, the recuperated bottoming cycle flow schematic, and the recuperated bottoming cycle engine schematic are presented.

US/CIS integrated NTRE concept

The team of Aerojet, Energopool and Babcock & Wilcox has prepared a near‐term Nuclear Thermal Rocket Engine (NTRE) concept that takes advantage of mature fuel technology developed in the former Soviet Union. This proven, advanced fuel appreciably shortens the development schedule of this engine for Moon and Mars exploration. Our near term engine has a number of features that provide safety, mission performance, cost and risk benefits, including: (1) High temperature, long life CIS fuel, (2) high pressure, recuperated topping cycle, (3) assured restart, (4) long life, cooled nozzle with thin inner wall, (5) long life turbopumps, (6) heat radiation and electrical power generation, and (7) component integration energy.