Overview

The Titan engine series (Titan & Titan II) is Rice Eclipse’s program to develop a flight-optimized hybrid rocket engine. Titan and Titan II use an HTPB mixture as solid fuel and liquid nitrous oxide as oxidizer. The original Titan was the team’s first flight-scale hybrid rocket engine, used a test-bed and prototype for a future flight-optimized engine. Titan II is the team’s first flight-optimized, 1200 lbf engine, to be used as the propulsion system for the team’s 2024 Spaceport America Cup 30,000 ft SRAD Rocket, “Archimedes.”

Titan II

Titan II is Rice Eclipse's student-designed, flight-optimized hybrid rocket engine. The HTPB / nitrous oxide engine was used to propel the Archimedes launch vehicle to 26,000 ft at the 2024 Spaceport America Cup, winning Rice Eclipse the 30k SRAD Hybrid division

Titan II is an overhaul of our design for the original Titan hybrid engine. Compared to its predecessor, it has a greater total impulse, smaller diameter, and is 40 lbs lighter. These significant changes ensured that the engine can realistically propel a rocket to the 30,000 ft target altitude. Titan II is designed to produce 1200 lbf of average thrust over an 7.67 second burn, producing a total impulse of 9,200 lbf·sec. The oxidizer feed system is pressure-fed, using the high vapor pressure of nitrous oxide as a self-pressurization system.

The Titan II engine is currently being tested and improved by Rice Eclipse. Three revisions of the engine’s design were completed and reviewed between Fall 2019 and Fall 2020. The engine, along with its retrofitted mobile test stand, was fabricated and assembled in Spring 2021. The engine completed two inert dress rehearsals in the Fall 2021 semester, in which the team rehearsed hot fire procedures and pressurized the oxidizer tank with nitrogen. Titan II was successfully hotfired for the first time in Spring 2023, and two further successful hotfires were performed in Spring 2024 in preparation for the 2024 Spaceport America Cup.

This year, we will be continuing to iterate and improve Titan II's performance, by varying fuel grain geometry, optimizing our injector design and decreasing engine mass. These advancements will allow Titan II to achieve even greater heights in future flights, reaching our target apogee of 30,000 ft thanks to a fully student-designed engine!

The full engine documentation can be viewed through the button below.

The team performed the first hotfire of Titan II on January 14th, 2023–– it was a huge success!

Titan

Titan, Eclipse’s first large scale hybrid engine, was the natural evolution of the Mark I hybrid rocket engine. Titan served as a ground prototype engine and test bed for Titan II. Fundamentally, the engine is designed to produce 800 lbs of thrust over the course of 10 seconds for a total impulse of 8000 lb-s. The engine weighs 154 lbs, with a maximum outer diameter of 8 in.

The Test Stand

To properly test Titan, Eclipse built a portable, vertical structure that could measure the upward thrust of the engine. Below the exit of the nozzle is a steel flame diverter, to prevent the structure itself from melting in the exhaust. The structure is split into three components; a base, an outer tower, and an inner tower. The base is bolted to the ground using anchors drilled into the cement below. The inner tower contains the entirety of the engine with each component bolted in place. To measure an accurate force reading, the inner tower is suspended in the outer tower through the load cell at the top, and held from shaking by lightly tightened bolts on the sides. The entire structure can be assembled in a few hours, and raised by hand if needed.

Testing

The team conducted two cold-flow wet dress rehearsal tests in the Spring of 2017 to assure the avionics, structure, and propulsion components worked in conjunction with each other. The first live test of the engine was in April 2017. The test fire was a fantastic learning experience for the team, despite a testing anomaly. The engine ignited and the structure held together, however, the nozzle and combustion chamber disconnected from the engine. The nozzle became lodged in the flame diverter and suffered considerable damage. The root cause was discovered in the nozzle casing’s test stand interface, and a second-iteration casing was designed to prepare for the engine’s next hot fire.

Eclipse’s first successful hot fire of the Titan engine was in Spring 2019. This test was also Eclipse’s first hot fire performed on the mobile test stand. These achievements demonstrated the team’s ability to test a flight-scale engine, setting us up for the future testing campaign of Titan II.