Nuclear Thermal Rocket

Nuclear thermal turbo rocket (NTTR)

The NTTR utilizes a nuclear fission reactor to thermally heat hydrogen propellant into a rocket plenum.

NTTR schematic

The rocket nozzles are located at the tips of a variable pitch thrust fan connected to the plenum by passages in the fan blades, and each nozzle is a linear aerospike on the trailing edge of the blade. The thrust fan is located in a duct such that the heated hydrogen propellant is combusted with ambient sourced oxygen to augment the rocket thrust. The fan is of variable pitch to provide maximum thrust for varying inlet velocity. The duct has a variable geometry inlet, able to provide appropriate mass flow and compression to the combustor throughout the trajectory, and a variable geometry outlet to provide appropriate nozzle area for maximum thrust. The rocket nozzles act as propellant injectors during the airbreathing portion and pure rockets during low atmospheric density portions, with the NTTR utilizing a single gas path from launch to orbital velocity. The propulsion concept is of high performance and is able to transport more than 50% mass fraction in a Single Stage to Orbit (SSTO) via an air-breathing rocket trajectory with intended complete reusability. Payload fractions of up to 19% are predicted (inert mass includes reactor radiation shielding) due to a mission average Specific Impulse (Isp) of 1,662 seconds.